Class 11th

Discovering Tut: the Saga Continues Summary In English

It was 6 p.m. on January 5, 2005 when the mummy of Tutankhamun moved smoothly and quietly into CT scanner which had been carried to Tut’s resting place. The aim was to probe the persisting medical mysteries of this young ruler who died more than 3,300 years ago. His dead body was embalmed and buried in a royal grave in the Valley of the Kings.

Howard Carter, a British archaeologist discovered Tut’s tomb in 1922 after years of futile search. Its contents remain the richest royal collection ever found. They include extremely attractive artifacts in gold as well as everyday things like board games, a bronze razor, linen undergarments, cases of food and wine.

Carter first recorded the Pharaoh’s funeral treasures. Then he began investigating his three nested coffins. The first one had a shroud covered with garlands of willow and olive trees, wild celery, lotus petals and cornflowers. These proved that he was buried in March or April. Carter ran into trouble when he reached the mummy. The ritual resins had hardened. These had cemented Tut to the bottom of his solid gold coffin. The solidified material was removed with the help of chisels. Then the mummy was cut free. Carter’s men removed the mummy’s head and severed nearly every major joint. Once they had finished, they reassembled the remains on a layer of sand in a wooden box with padding that concealed the damage. The team of scientists found it resting there. Zahi Hawass, Secretary General of Egypt’s Supreme Council of Antiquities observed that the mummy was in very bad condition because of what Carter had done in the 1920s.

Archaeology has changed a lot during the last few decades. Now it pays less attention to treasure and more to the fascinating details of life and puzzling mysteries of death. It uses more sophisticated tools including medical technology. In 1968 an Anatomy Professor X-rayed the mummy. He revealed a startling fact. The breast-bone and front ribs are missing. Now CT scanning was employed to answer two questions: (i) how did he die? and (ii) how old was he at the time of his death?

On the night of the scan, workmen carried Tut from the tomb in his box. They climbed a ramp and a flight of stairs into the swirling sand outside. Then they rose on a hydraulic lift into a trailer. This trailer held the scanner. Initially, there was some problem because of sand in a cooler fan. Then the technicians scanned the mummy head to toe. 1700 digital X-ray images in cross section were created. Tut’s head was scanned in 0.62 millimetre slices to register its complicated structures. Tut’s entire body was sirnilarly recorded. Then a team of specialists in radiology, forensics and anatomy began to probe the secrets.

A technician displayed astonishing images of Tut on a computer screen. A gray head took shape from a scattering of pixels. The technician spanned and tilted it in every direction, Neck vertebrae appeared quite clearly. Other images revealed a hand, several views of the ribcage, and a narrow cross section of the skull. Zahi Hawass smiled. He felt relieved to see that nothing had gone seriously wrong.

Discovering Tut: the Saga Continues Summary In Hindi

5 जनवरी 2005 को सन्ध्या के 6 बजे थे जब तूतनखामून की ममी CT scanner में खिसकती हुई गई। इस CT scanner को उसके विश्राम स्थल पर लाया गया था। उद्देश्य था कि इस युवा शासक के विषय में सारी चिकित्सा रहस्यों को ढूंढना। जो 3300 वर्ष पहले मरा था। उसके शव पर औषधियों का लेप करके उसे राजाओं की घाटी नामक राजसी कब्रिस्तान में दफनाया गया था।

हावर्ड कार्टर नामक एक ब्रिटिश पुरातत्ववेत्ता ने कई वर्षों की निष्फल तलाश के उपरान्त 1922 में तूत की कब्र खोज ली। इसमें संग्रहित सामग्री सर्वाधिक समृद्ध राजसी भण्डार है जो अब तक पाया गया। इनमें स्वर्ण की अत्यधिक आकर्षक मानव निर्मित वस्तुएँ तथा दैनिक प्रयोग की वस्तुएँ जैसे खेलने का बोर्ड, काँसे का उस्तरा, अन्दर के वस्त्र, भोजन एवं मद्य (शराब) की पेटियाँ हैं।

कार्टर ने पहले तो मिस्र के राजा के शव के साथ के खजाने की सूची बनाई। फिर उसने तीन शव-पेटियों का निरीक्षण करना आरम्भ किया। पहली वाली में एक मोटा वस्त्र था जो सरपत तथा जैतून के पत्तों, जंगली सेलेरी, कमल की पंखड़ियों तथा अन्न के साथ उगने वाले पौधों से बनी मालाओं से ढ़का हुआ था। इनसे सिद्ध होता था उसको मार्च या अप्रैल में दफनाया गया था। कार्टर तब कष्ट में फँसा जब वह मृत शरीर की ममी पर पहुँचा। अनुष्ठान में प्रयुक्त गोंद कठोर हो गया था। इसने तूत को ठोस सोने की शव पेटी के पेंदे में पक्का चिपका दिया था। छेनियों की सहायता से इसे ठोस बने हुए पदार्थ को हटाया गया। फिर ममी को इस से काट कर मुक्त किया गया। कार्टर के व्यक्तियों ने ममी का सिर काटा तथा लगभग प्रत्येक बड़े जोड़ को पृथक किया। जब उनका काम पूरा हो गया तो उन्होंने इन अवशेषों को नर्म पदार्थ लगे हुए एक लकड़ी के सन्दूक में रेत के ऊपर रख दिया जिनसे क्षति ढक गई। वैज्ञानिकों के दल ने इसे वहाँ लेटे पाया। जाही हवास जों मिस्र की पुरातत्व की सर्वोच्च सभा के महासचिव थे, ने कहा कि 1920 के दशक में कार्टर ने जो किया उसके कारण ममी बहुत खराब दशा में थी।

पिछले कुछ दशकों में पुरातत्व शास्त्र में काफी परिवर्तन आए हैं। अब यह धन को कम तथा जीवन की आकर्षक बातों तथा मृत्यु के पेचीदा रहस्यों पर अधिक ध्यान देता है। यह चिकित्सा तकनीक सहित अधिक परिष्कृत औज़ार प्रयोग करता है। 1968 ई में शरीर रचना के एक प्रोफेसर ने ममी का एक्स-रे चित्र लिया। उसने एक चौंकाने वाला तथ्य उजागर किया। छाती की हड्डी तथा सामने की पसलियाँ गायब है। अब दो प्रश्नों का उत्तर पाने के लिए कम्प्यूटर तकनीक द्वारा जांच के लिए चित्र निकाले गये : (i) वह कैसे मरा? तथा (ii) अपनी मृत्यु के समय वह कितने वर्ष का था।

जाँच की रात, श्रमिक तूत को उसकी कब्र से सन्दूक में ले गए। वह एक ढलान तथा सीढ़ियों तथा बाहर लहरदार रेत पर चढ़े। फिर वे पानी द्वारा चलने वाली लिफ्ट पर चढ़कर एक गाड़ी में पहुँचे। इस गाड़ी में जाँच की मशीन थी। आरम्भ में कूलर के पंखे में रेत आने के कारण कुछ समस्या हुई। फिर कुशल कर्मचारियों ने ममी के सिर से अँगूठे तक तीन आयामों के चित्र लिये। 1700 digital प्रणाली की X-ray छवियाँ लम्बे बल समकोण के कटाव में ली गई। तूत के सिर की जाँच 0.62 मिलीमीटर के टुकड़ों में की गई ताकि इसके पेचीदा बनावट का विवरण सही दर्ज किया जा सके। इसी प्रकार तूत के पूरे शरीर का विवरण लिखा गया। फिर विकिरण विशेषज्ञ, अपराध शास्त्र के वैज्ञानिक तथा शरीर रचना विशेषज्ञ गुप्त रहस्यों को ढूंढने लगे।

एक कुशल तकनीकी कारीगर ने कम्प्यूटर के पर्दे पर तूते की आश्चर्यजनक छवियों को दर्शाया (दिखाया) । बिखरे हुए चमकदार बिन्दुओं को एकत्र करने से भूरे बालों वाले एक सिर का आकार बनता गया। तकनीकी कारीगर ने इसे प्रत्येक दिशा में घुमाया तथा टेढ़ा किया। गर्दन रीढ़ की हड्डी के टुकड़े बिल्कुल स्पष्ट उभरे। अन्य आकृतियों में एक हाथ, पसलियों के कई कोणों से दृश्य तथा खोपड़ी की तंग लम्बाकार छवि थी। ज़ाही हवास मुस्कराया। उसने यह देख कर चैन की सांस ली कि कुछ भी गम्भीर रूप से नहीं बिगड़ा था।

We’re Not Afraid to Die… if We Can All Be Together Summary In English

In July 1976, the narrator, a 37 year-old businessman, his wife Mary, six year old son, Jonathan and seven year old daughter, Suzanne set sail from Plymouth, England. They wished to go round the world on a long sea journey as Captain James Cook had done 200 years earlier. They started in 23 metre, 30 ton wooden-hulled boat named Wavewalker.

The first part of their planned three-year, 105,000 kilometre journey passed pleasantly. They sailed down the west coast of Africa to Cape Town. They took on two crewmen-Larry Vigil, an American and Herb Seigler, a Swiss to help them cross the rough southern Indian Ocean.

On their second day out of Cape Town, they faced extremely strong winds, which blew continuously for next few weeks. Waves rose up to 15 metres. On December 25, they were 3500 kilometres east of Cape Town. Though the weather was very bad, they enjoyed Christmas and New Year’s Day.

The weather changed for the worse. On January 2, there were mighty waves. They were sailing at eight knots. They slowed down the boat by dropping the small sail and fastened mooring rope in a loop across the hind part of the boat. Then they attached lifelines, put on water proof clothes and life jackets and waited for the storm. The first sign of the imminent disaster came as portentous silence. The wind dropped and the sky immediately grew dark. Then came a growing roar and a very huge wave. A tremendous explosion shook the deck. The narrator’s head struck on the wheel and he flew over the side of the boat into water. He was sinking below the waves. He accepted his coming death.

Suddenly his head appeared out of water. A few metres away Wavewalker was about to turn over in water. Then a wave threw her upright. Succeeding waves threw the narrator around the deck like a rag doll. His left ribs cracked. His mouth was filled with blood and broken teeth. He, somehow, found the wheel and lined up the stern for the next wave. There was water .everywhere on the ship, but he could not leave his place in order to investigate the situation. Suddenly his wife, Mary, opened the door in the deck and shouted that they were sinking as the decks were broken.

The narrator asked her to take the wheel. Then he moved quickly to the door. Larry and Herb were pumping water out of the ship. The wooden beams had broken. The whole starboard side had bulged inwards. Clothes, crockery, charts, tins and toys moved around noisily in water. He crawled into the children’s cabin. Sue had got a big bump on her head. He had no time to attend to her.

He found a hammer, screws and canvas and started repair work. He managed to stretch canvas and secure water proof hatch covers across the gaping holes. Most of the water was now being deflected over the side. Then the hand pumps started to block up with debris. The electric pump had a short circuit. Water level rose up dangerously. He found that their two spare hand pumps had been pulled away by currents along with the forestay sail, the jib, the dinghies and the main anchor. He searched another electric pump, connected it to an outpipe and water was pumped out throughout night. They got no replies from their Mayday calls. Sue’s head had swollen alarmingly. She had two enormous black eyes and a deep cut on her arm.

On the morning of January 3, the pumps had reduced the amount of water on board. Each of them took rest for two hours turn by turn. They had survived for 15 hours since the wave hit the Wavewalker, but she was not strong enough to take them to Australia. He checked the charts. He calculated that there were two small islands a few hundred kilometres to the east. He hoped to reach Le Amsterdam, a French scientific base. On January 4, after 36 hours of continuous pumping, they reached the last few centimetres of water. Now they had to keep pace with the water still coming in. Mary found some corned beef and cracker biscuits.

They ate their first meal in almost two days. Their relief was short lived. At 4 pm black clouds began building up. Within an hour, the wind was back to 40 knots. The seas were getting higher. Throughout the night, the weather became worse. By dawn on January 5, their situation was extremely dangerous. The narrator went in to comfort the children. Jon asked if they were going to die. The narrator tried to assure him that they could make it. Then Jon said. “We aren’t afraid of dying if we can all be together.” The narrator could find no words to respond. He determined to fight the sea. To protect the weak starboards side, he decided to stop the ship with the undamaged port-hull facing the on coming waves. He used an improvised sea anchor of heavy nylon rope and two 22 litre plastic barrels of paraffin. More water rushed in through the broken planks in the evening.

On the morning of January 6, the wind became less severe. The narrator got a reading on the sextant. He made quick calculations. She came in and gave him a card she had made. She had drawn caricatures of Mary and the narrator. It also had a message expressing love and thanks. At 2 p.m., after checking calculations, the narrator asked Larry to steer a course of 185 degrees. He could then expect to see an island at about 5 p.m. Then he went below, climbed on his bunk and dozed off. He woke up at 6 p.m. Jon entered and asked if he could embrace his Daddy. She was right behind him. They called him the best daddy in the whole world and the best captain. They informed him that they had found the island.

The narrator rushed on deck. He saw the outline of the island of Ile Amsterdam. That night they anchored offshore. The next morning all 28 inhabitants of the island cheered them and helped them ashore. After reaching the land, the narrator thought of Larry and Herbie. They had been cheerful under direst stress, Mary had stayed at the wheel for those crucial hours. Then he thought of his seven year old girl, who did not want them to worry about her head injury and of the six-year old boy who was not afraid to die..

We’re Not Afraid to Die… if We Can All Be Together Summary In Hindi

जुलाई 1976 में 37 वर्षीय व्यापारी, वर्णनकर्ता, उसकी पत्नी मेरी, 6 वर्षीय पुत्र जोनाथन तथा 7 वर्षीया पुत्री सुजैन नाव में इंग्लैंड की प्लाई माउथ, बन्दरगाह से रवाना हुए। संसार के चारों ओर एक लम्बी समुद्री यात्रा के लिये जाना चाहते थे जैसे कि 200 वर्ष पहले जेम्स कुक ने की थी। उन्होंने 23 मीटर लम्बी, 30 टन भारी लकड़ी पेंदे वाली नौका ‘वेववाकर’ में यात्रा आरम्भ की।

उनकी 3 वर्ष की, 105,000 किलोमीटर की नियोजित यात्रा का प्रथम चरण सुहावने ढंग से गुजरा। वे अफ्रीका के पश्चिमी तट में केपटाइन तक नौका में चले गये। वहाँ उन्होंने दो कर्मचारी लिए, अमरीकी लैरी विजिल तथा स्विट्जरलैंड निवासी हर्ब सीगलर-जो कि खराब मौसम वाले दक्षिणी भारतीय समुद्र को पार करने में उनकी सहायता कर सकें।

केप टाउन से निकलने के दूसरे ही दिन उन्हें अत्यधिक तेज पवन का सामना करना पड़ा जो अगले कई सप्ताहों तक लगातार (उसी वेग) से चलती रही। लहरें 15 मीटर ऊपर तक उठ जाती थी। 25 दिसम्बर को वे केपटाउन से 3500 किलोमीटर पूर्व में थे। यद्यपि मौसम बहुत खराब था, फिर भी उन्होंने क्रिसमस तथा नववर्ष के पहले दिन का आनन्द लिया।

मौसम और भी खराब हो गया। 2 जनवरी को अत्यन्त शक्तिशाली लहरें उठीं। वे आठ नॉट की गति से नौका चला रहे थे। उन्होंने छोटी पाल गिराकर तथा निर्धारित स्थान में पोत को रखने के लिए बांधने वाली रस्सियों के छल्ले पीछे के भाग में बांध कर गति धीमी की। फिर उन्होंने जल-रोधी वस्त्र तथा जीवन रक्षक जैकेट पहने तथा तूफान की प्रतीक्षा करने लगे। भावी अमंगलमय विपत्ति के प्रथम चिन्ह अपशकुन भरी चुप्पी से आये। वायु (पवन) थम गई तथा तत्काल अन्धेरा हो गया। फिर एक बढ़ती हुई दहाड़ की आवाज के साथ विशाल लहर आई। एक बहुत बड़े विस्फोट ने डेक को हिला दिया। वर्णनकर्ता का सिर चालन-पहिये से टकराया तथा वह नौका के पहलू से उड़ता हुआ पानी में जा गिरा। वह लहरों के नीचे डूब रहा था। उसने अपनी आगामी मृत्यु को स्वीकार कर लिया।

अचानक उसका सिर पानी से बाहर निकला। कुछ मीटर दूर ‘वेववाकर पानी में उलटने वाली थी। फिर एक लहर ने उसे सीधा कर दिया। आगामी लहरों ने वर्णनकर्ता को चिथड़ों की गुड़िया की भाँति डेक पर फेंक दिया। उसकी बाईं पसलियाँ टूट गईं। उसका मुँह रक्त तथा टूटे हुए दाँतों से भर गया। उसने किसी प्रकार चालक पहिए को पा लिया तथा नौको के पिछले भाग को अगली लहर के लिए सीधा किया। जहाज पर प्रत्येक स्थान पर जल था, किन्तु वह स्थिति की जाँच करने के लिये अपने स्थान को नहीं छोड़ सकता था। अचानक उसकी पत्नी, मेरी, ने डेक का द्वार खोला तथा चिल्लाई कि वे डूब रहे हैं क्योंकि डेक टूट गया था।

वर्णनकर्ता ने उसे पहिया संभालने को कहा। फिर वह शीघ्रता से द्वार की ओर गया। लैरी तथा हर्ब जहाज में से पम्पों द्वारा पानी निकाल रहे थे। लकड़ी के शहतीर टूट गये थे। दाहिनी ओर का पूरा पक्ष भीतर की ओर धंस गया था। वस्त्र, चीनी मिट्टी के बर्तन, चार्ट, टिन तथा खिलौने शोर करते हुए पानी में चारों ओर घूम रहे थे। वह रेंगता हुआ बच्चों के कक्ष में गया। स्यू के सिर पर एक बड़ा सा उभार निकल आया था। उसका उपचार करने का उसके पास समय नहीं था।

उसने एक हथौड़ा, पेंच तथा कन्वास ढूँढा तथा मरम्मत का काम आरम्भ कर दिया। वह किसी तरह छेदों को बंद करने में सफल हो सका। अब अधिकतर पानी पहलू से दिशा बदल कर जा रहा था। फिर कूड़े-कर्कट के कारण हाथ से चलाने वाले पम्पों ने काम करना बन्द कर दिया। बिजली वाले पम्प की तारों में खराबी आ गई। जल-स्तर बड़े खतरनाक ढंग से ऊपर उठने लगा। उसने पाया कि उनके दोनों अतिरिक्त हाथ से चलाने वाले पम्प, आगे लगने वाली पाल, तिकोनी पाल, छोटी नौकाओं तथा मुख्य लंगर के साथ ही लहरों द्वारा बहाई ले जाई गई थी। उसने एक अन्य बिजली वाला पम्प ढूँढा, इसे बाहरी पाइप से जोड़ा और सारी रात पानी बाहर निकाला गया। स्यू का सिर भयानक ढंग से सूज गया था। उसकी आँखें सूज गई थीं तथा उसके बाजू पर गहरा घाव था।

3 जनवरी को प्रातः तक पम्पों ने जहाज के ऊपर जल राशि को कम कर दिया था। उनमें से प्रत्येक ने बारी-बारी दो-दो घण्टे तक विश्राम किया। जब से लहरें ‘वेववाकर’ से टकराई थी, वे 15 घण्टे से जीवित बचे थे, किन्तु वह इतनी सुदृढ़ नहीं थी कि उन्हें आस्ट्रेलिया ले जा सके। उसने चार्टी की जांच की। उसने गणना की कि पूर्व की ओर कुछ सौ किलोमीटर पर दो द्वीप थे। वह ‘इले एमस्टरडम’ नामक फ्रांसीसी वैज्ञानिक आधार पर पहुँचना चाहता था। 35 घण्टे तक लगातार पम्पों से पानी बाहर निकालने के पश्चात् वे 4 जनवरी को अन्तिम कुछ सेंटीमीटर जलराशि तक पहुँचे। अब उन्हें केवल उस पानी के साथ गति बनाये रखनी थी जो अब भी पोत में आ रहा था। मेरी ने नमक लगाकर सुरक्षित रखा हुआ कुछ गौ मांस तथा पतले नमकीन बिस्कुट तलाश किए। लगभग दो दिन में उन्होंने पहली बार भोजन किया। उनका यह सुख कुछ समय तक ही सीमित रहा। साँय 4 बजे काले बादल छाने लगे। एक घंटे के भीतर, पवन ने फिर से 40 नॉट की गति पकड़ ली। समुद्र का जल ऊँचा होने लगा। पूरी रात मौसम और अधिक खराब होता रहा। 5 जनवरी को भोर तक, उनकी स्थिति अत्यधिक खतरनाक हो गई थी। वर्णनकर्ता बच्चों को आराम देने भीतर गया। जॉन ने पूछा कि क्या वे मरने वाले थे। वर्णनकर्ता ने उसे विश्वास दिलाया कि वे बच निकलेंगे। फिर जान ने कहा, “हमें मरने से भय नहीं है यदि हम सब इकट्ठे हों।” उसे उत्तर देने के लिये वर्णनकर्ता को कोई शब्द नहीं मिल सके। उसने समुद्र से लड़ने का निश्चय किया। कमजोर दाहिनी पृष्ट की रक्षा करने के लिये उसने जहाज को रोकने का निर्णय किया ताकि क्षतिरहित पतन की ओर वाली पेंदी आनेवाली लहरों की ओर रहें। उसने भारी नाइलॉन की रस्सी तथा 22 लीटर वाले मिट्टी के तेल के दो प्लास्टिक के ड्रम से कामचलाऊ लंगर बनाया। शाम को टूटे हुए तख्तों में से अधिक पानी भीतर घुस गया।

6 जनवरी को सवेरे, पवन कुछ कम कठोर हुआ। वर्णनकर्ता ने कोण तथा दूरी मापने वाले यन्त्र पर सूचना देखी। उसने शीघ्र गणना की। स्यू भीतर आई तथा उसे एक कार्ड दिया जो उसने बनाया था। उसने मेरी तथा वर्णनकर्ता के हास्य जनक रेखाचित्र बनाए थे। इसमें प्रेम तथा धन्यवाद व्यक्त करता हुआ एक संदेश भी था। 2 बजे अपराह्न में, गणना की जाँच करने के उपरान्त, वर्णनकर्ता ने लैरी को 185 अंश के मार्ग पर चलने को कहा। तब वह 5 बजे अपराह्न तक एक द्वीप देखने की आशा कर सकता था। फिर वह नीचे गया, अपनी शयन पटरी पर चढ़ा तथा लेटते ही ऊँघने लगा। वह 6 बजे शाम को जागा। जान भीतर आया तथा कहने लगा कि क्या वह अपने पिता का आलिंगन कर सकता था। स्यू उसके बिल्कुल पीछे थी। उन्होंने उसे पूरे संसार में सबसे अच्छा पिता तथा कैप्टन कहा। उन्होंने उसे सूचना दी कि उन्होंने द्वीप पा लिया है।

वर्णनकर्ता तेजी से दौड़कर डेक पर आया। उसने इले एम्सटर्डम द्वीप की बाहरी फैलाव की आकृति देखी। उस रात उन्होने तट के पास ही लंगर डाला। अगले प्रातः द्वीप के सभी 28 निवासियों ने प्रसन्नता से उनका जोश बढ़ाया तथा तट पर जाने में सहायता की। भूमि पर पहुँचने के पश्चात् लेखक लैरी तथा हर्बी के विषय में सोचता रहा। वे तनाव के भयंकर समय में भी प्रसन्नचित्त रहे थे। मैरी उन महत्त्वपूर्ण क्षणों में संचालन के पहिये पर डटी रही थी। फिर उसने अपनी 7 वर्ष की बेटी के विषय में सोचा जो नहीं चाहती थी कि वे उसकी सिर की चोट के विषय में चिन्ता करें तथा अपने 6 वर्षीय पुत्र के बारे में सोचा जिसे मरने का भय नहीं था।

The Portrait of a Lady Summary In English

In ‘The Portrait of a Lady’, Khushwant Singh has given an account of his grandmother. He draws a life-like portrait. She was very old. Her face was wrinkled. Her hair was white. It was hard to believe that once she had been young and pretty. His grandfather’s picture hung above the mantelpiece in the drawing room. He wore a big turban. His clothes were loose. He looked at least a hundred years old. It was hard to believe that he had once a wife or children.

Khushwant Singh’s grandmother was a short lady. She was fat and slightly bent. She couldn’t walk straight. She hobbled about the house. She had to keep one hand on her waist. It was to balance her stoop. In the other she held a rosary. She was always telling the beads. Her lips constantly moved in prayer. She put on white clothes. Her silver locks scattered over her pale face. She looked like snowy mountains in winter. She was a picture of peace and contentment. She was very old. Perhaps she could not have looked older. She looked the same for the last twenty years.

Khushwant Singh and his grandmother were good friends. His parents went to city. They left him with her in the village. She took good care of him. She used to wake him up in the morning. She got him ready for the school. She said her morning prayer in sing-song manner. She hoped that he would learn it by heart. He liked her voice but never bothered to learn it. Then she would fetch his wooden slate. She had already washed it and plastered it with yellow chalk. She would take an earthen inkpot and a reed-pen. She would tie them in a bundle and hand it to him. She would given him a thick stale chapatti with little butter and sugar spread on it. It was his breakfast. She carried several stale chapattis with her for the village dogs.

His grandmother always went to school with him. The school was attached to the temple. The priest taught children the alphabet and the morning prayer. The children sat in two rows in the verandah. They would sing the alphabet or the prayer in a chorus. The grandmother sat inside the temple. She would read holy books. Then they would walk home together. The village dogs would gather at the temple door. They threw chapattis to them. The dogs would growl and fight with each other.

The narrator’s parents sent for them in the city. It was a turning-point in their friendship. They shared the same room. But grandmother no longer went to school with him. The narrator used to go to an English school in a motor bus. There were no dogs in the streets. So grandmother took to feeding the sparrows.

Years rolled by. They saw less of each other. Sometimes she would ask him what the teacher had taught him. She did not believe in the things they taught at the English school. She was unhappy. She did not like English or Science. She felt sad that there was no teaching about God and the scriptures at school. The narrator one day told her that they were being given music lessons. She was disturbed. She thought music quite indecent. For her it was good only for prostitutes and beggars. It was not meant for gentle folk.

The narrator went to university. He was given a room of his own. The common link of friendship was broken. The grandmother accepted her loneliness quietly. She was always busy with her spinning wheel and reciting prayers. She rarely talked to anyone. In the afternoon, she relaxed for a while. Then she would feed the sparrows. She sat in the verandah. She broke the bread into little bits. Then she would throw them to sparrows. Hundreds of sparrows came there. They created a hell of noise. Some came and sat on her legs. Others would sit on her shoulders. Some would sit even on her head. She smiled but never frightened them away. Feeding the sparrows was the happiest half-hour of the day for her.

The narrator decided to go abroad for higher studies. He was to remain away for five years. The grandmother was very old. She could die any moment. The narrator was worried. But the grandmother was not upset. She showed no emotion. She came to the railway station to see him off. Her lips moved in prayer. Her mind was lost in prayer. Her fingers were busy telling the beads of her rosary. She kissed his forehead silently. The narrator thought that it was the last sign of physical contact between them.

The narrator returned home after five years. His grandmother met him at the station. She did not look a day older. She did not speak anything. She held him in her arms. She went on reciting her prayers. In the afternoon she fed the sparrows as usual. In the evening a change came over her. She didn’t pray. She collected the women of the neighbourhood. She got an old drum. She continued thumping the old drum for several hours. She started singing. She sang of the home-coming of warriors. They had to persuade her to stop. She might overstrain herself. It was for the first time that she had forgotten to pray.

The next morning she fell ill. She had a mild fever. She told them that her end was near. She realised that she had forgotten to pray. She didn’t want to talk. It would be waste of time. She ignored their requests. She lay peacefully in bed. She was praying and telling beads. Then her lips stopped moving. The rosary fell down from her lifeless fingers. Her face looked pale but peaceful. She was dead. She was laid on the ground. She was covered with a red shawl. Arrangements for her funeral were being made.

It was evening. The sun was setting. They brought a wooden stretcher. They stopped half-way in the courtyard. Thousands of sparrows sat near her dead body. They did not chirrup. Everyone felt sorry for the birds. The narrator’s mother brought some bread. She broke it into little crumbs. She threw these crumbs to the sparrows. The birds took no notice of them. Then they carried her dead body outside. The sparrows flew away quietly. The crumbs of bread still remained lying there in the courtyard. Evidently, the sparrows had come to mourn the death of the grandmother.

The Portrait of a Lady Summary In Hindi

‘एक महिला का चित्र’ में खुशवन्त सिंह ने अपनी दादी का वर्णन किया है। वह उसका सजीव चित्र प्रस्तुत करता है। वह अत्यन्त वृद्धा थी। उसके चेहरे पर झुर्रियाँ थीं। उसके बाल श्वेत थे। यह विश्वास करना काफी कठिन था कि कभी वह युवा एवं आकर्षक थीं। उसके दादा का चित्र बैठक में चिमनी की कोर्निस के ऊपर टंगा हुआ था। उसने एक बड़ी पगड़ी पहनी हुई थी। उसके वस्त्र ढीले थे। वह कम से कम एक सौ वर्ष का लगता था। यह विश्वास करना कठिन था कि कभी उसकी एक पत्नी अथवा बच्चे भी थे।

खुशवन्त सिंह की दादी छोटे कद की महिला थी। वह मोटी तथा थोड़ी सी झुकी हुई थी। वह सीधी नहीं चल सकती थी। वह घर में इधर-उधर लंगड़ाती सी घूमती-फिरती थी। उसे अपना एक हाथ कमर पर रखना पड़ता था। वह उसे अपने झुके हुए शरीर को सन्तलित करने के लिए था। दसरे (हाथ) में वह एक माला पकडे रहती थी। वह सदा माला के मनके फेरती रहती थी। उसके होंठ लगातार प्रार्थना में हिलते रहते थे। वह सफेद वस्त्र पहनती थी। उसके चांदी जैसे बाल उसके चेरहे पर बिखरे पड़े रहते थे। वह सर्दी के (सफेद) पर्वतों जैसी लगती थी। वह शान्ति एवं संतुष्टि का चित्र प्रतीत होती थी। वह अत्यन्त वृद्धा थी। शायद वह इससे अधिक वृद्धा नहीं दिखाई पड़ सकती थी। पिछले बीस वर्षों से वह वैसी ही दिखाई देती थी।

खुशवन्त सिंह तथा उसकी दादी अच्छे मित्र थे। उसके माता-पिता नगर में चले गये थे। वे उसे गाँव में दादी के पास छोड़ गये। वह उसकी अच्छी देखभाल करती थी। वह उसे सवेरे जगाया करती थी। वह उसे स्कूल के लिए तैयार करती थी। वह अपनी प्रार्थना एक रटे-रटाये गाने के रूप में करती थी। वह आशा करती थी कि वह उसे मौखिक रूप से याद कर लेगा। वह दादी की आवाज पसंद करता था किंतु उसने इसे सीखने की कभी भी परवाह नही की। फिर वह उसकी लकड़ी की तख्ती लाती। इसे उसने पहले ही धोकर पीली चाक-मिट्टी से पोता हुआ था। वह एक मिट्टी की दवात तथा सरकंडे का कलम लेती। वह उन्हें एक बंडल में बांध ती तथा उसे दे देती। वह उसे एक मोटी बासी रोटी के ऊपर थोड़ा-सा मक्खन तथा चीनी बिखेरकर देती। यह उसका नाश्ता था। वह गाँव के कुत्तों के लिए काफी बासी चपातियाँ अपने साथ ले जाती थी। उसकी दादी सदा उसके साथ पाठशाला भी जाती थी। पाठशाला मंदिर से जुड़ी हुई थी। पुजारी बच्चों को वर्णमाला तथा प्रात:कालीन प्रार्थना सिखाता था। बच्चे बरामदे में दो कतारों में बैठते थे। वे एक सामूहिक गान के रूप में ही वर्णमाला अथवा प्रार्थना गाते थे। दादी मंदिर में भीतर बैठती थी। वह धार्मिक पुस्तकें पढ़ा करती थी। फिर वे दोनों एक साथ घर आते थे। गाँव के कुत्ते मंदिर के द्वार पर एकत्रित हो जाते। वे उनको चपातियाँ फेंकते। कुत्ते एक दूसरे पर गुर्राते तथा झगड़ते थे।

वर्णनकर्ता के पिता ने उन्हें नगर में बुला लिया। वह उनकी मित्रता में मोड़ (घुमाव) का एक बिंदु था। वे एक ही कमरे में रहते थे। किंतु दादी अब उसके साथ विद्यालय नहीं जाती थी। वर्णनकर्ता एक मोटर बस में सवार होकर एक अंग्रेजी विद्यालय में पढ़ने जाया करता था। वहाँ (नगर में) गलियों में कुत्ते नहीं थे। अत: दादी ने चिड़ियों को भोजन खिलाना आरंभ कर दिया।

वर्ष बीतते गये। वे एक दूसरे से कम मिलते थे। कभी-कभी वह उससे पूछ लेती थी कि उसके अध्यापक ने उसे क्या पढ़ाया है। वह उन चीजों में विश्वास नहीं करती थी जो वे अंग्रेजी विद्यालय में पढ़ाते थे। वह दु:खी थी। वह अंग्रेजी अथवा विज्ञान को पसंद नहीं करती थी। वह यह सोचकर उदास हो जाती थी कि विद्यालय में ईश्वर तथा धार्मिक ग्रन्थों के विषय में शिक्षा नहीं दी जाती थी। वर्णनकर्ता ने एक दिन उसे बताया था कि संगीत में पाठ दिए जा रहे हैं। वह परेशान हो गयी। वह संगीत को अशोभनीय समझती थी। उसके अनुसार यह केवल वेश्याओं तथा भिखारियों के लिए ही था। वह भद्र पुरुषों के उपयुक्त नहीं था।

वर्णनकर्ता विश्वविद्यालय में गया। उसे अपना निजी कमरा दिया गया। मित्रता का आपसी संबंध टूट गया। दादी ने अपने एकाकीपन को चुपचाप स्वीकार कर लिया। वह सदा चरखा चलाने तथा प्रार्थना गाने में व्यस्त रहती। वह बहुत कम बातें करती थीं। अपराह्न (दोपहर-बाद) में वह थोड़ा सा सुस्ताती थी। तब वह चिड़ियों को भोजन कराती थी। वह बरामदे में बैठती थी। एक रोटी के छोटे-छोटे टुकड़े तोड़ती। फिर वह इन्हें चिड़ियों को फेंक देती। सैंकड़ों चिड़ियाँ वहाँ आ जाती थीं। वे बहुत सा शोर करती थी। कुछ आजी तथा उसकी टांगों पर बैठ जाती। अन्य उसके कन्धों पर बैठ जाती। कुछ तो उसके सिर पर भी बैठ जाती। वह मुस्कुराती किंतु कभी भी उन्हें डराकर नहीं भगाती थी। चिड़ियों को भोजन खिलाना उसके लिए दिन का सबसे प्रसन्नता भरा आधा घण्टा था।

वर्णनकर्ता ने उच्चतर शिक्षा के लिए विदेश जाने का निर्णय किया। उसे पाँच वर्ष तक बाहर रहना था। दादी अत्यन्त वृद्धा थी। वह किसी भी क्षण मर सकती थी। वर्णनकर्ता चितिंत था। किंतु दादी विचलित नहीं हुई। उसने कोई भावुकता नहीं दिखायी। उसे विदा करने वह रेलवे स्टेशन आई। उसके होंठ प्रार्थना में हिलते थे। उनका मन प्रार्थना में लगा हुआ था। उसकी उंगलियाँ माला के मनके फेरने में व्यस्त थी। उसने चुपके से उसके माथे को चूमा। वर्णनकर्ता ने सोचा कि उन दोनों के बीच शारीरिक संबंध के रूप में यह अंतिम चिन्ह था।

वर्णनकर्ता पाँच वर्ष के उपरांत घर लौट आया। उसकी दादी स्टेशन पर उससे मिली। वह एक दिन भी अधिक बूढ़ी नहीं दिखाई देती थी। वह कुछ नहीं बोली। उसने उसे बाहों में भर लिया। वह अपनी प्रार्थनाएँ गाती रही। दोपहर बाद सदा की तरह उसने चिड़ियों को भोजन खिलाया। संध्या समय उसमें एक परिवर्तन आ गया। उसने प्रार्थना नहीं की। उसने पड़ोस की सारी स्त्रियों को एकत्रित किया। वह एक पुराना ढोल ले आई। वह कई घंटों तक इस पुराने ढोल को पीटती रही। उसने गाना आरंभ किया। वह योद्धाओं की वापसी के गीत गाती रही। उन्हें उसे रोकने के लिए मनाना पड़ा। हो सकता है कि वह स्वयं पर अधिक तनाव डाल ले। यह पहला समय था जब वह प्रार्थना करना भूल गयी थी।

अगली प्रात: वह बीमार पड़ गयी। उसे हल्का सा ज्वर आ गया। उसने उन्हें बताया कि उसका अन्त समीप है। उसने अनुभव किया कि वह प्रार्थना करना भूल गयी थी। वह बातें नहीं करना चाहती थी। यह तो समय को व्यर्थ करना होगा। उसने उनकी प्रार्थना अनसुनी कर दी। वह चुपचाप बिस्तर में लेटी रहीं। वह प्रार्थना करती रही तथा मनके फेरती रही। फिर उसके होंठ हिलने बन्द हो गये उसकी निर्जीव उंगलियों से माला गिर गयी थी। उसका चेहरा पीला किन्तु शान्त दिखाई पड़ा। वह मर गयी थी। उसे भूमि पर लिटा दिया गया। उसे लाले कफ़न से ढक दिया गया। उसके दाह संस्कार के प्रबंध किये जाने लगे।

संध्या का समय था। सूर्य अस्त हो रहा था। वे एक लकड़ी की अर्थी ले आये। वे आँगन के बीच में रुक गये। हजारों चिड़ियाँ उसके मृत शरीर के समीप बैठी थीं। उन्होंने चहचहाहट नहीं की। प्रत्येक को चिड़ियों के लिए खेद था। वर्णनकर्ता की माँ कुछ रोटी ले आई। उसने इसे छोटे-छोटे टुकड़ों में तोड़ा। उसने ये टुकड़े चिड़ियों को फेंके। पक्षियों ने इनकी ओर कोई ध्यान नहीं दिया। फिर वे उसके शव को बाहर ले गये। चिड़ियाँ चुपचाप उड़ गईं। रोटी के टुकड़े अब भी आँगन में वहीं पड़े रहे। स्पष्टतया चिड़ियाँ दादी की मृत्यु पर शोक मनाने आई थीं।

Class 11 Biology Revision Notes for Chemical Coordination and integration of Chapter 22

In animals, control and coordination is performed by neural system and endocrine system jointly. As the nerve fibres do not innervate all cells of the body, the endocrine system is required to coordinate the functions.
Endocrine Glands

• Endocrine glands are ductless glands. They release their secretion directly into blood which is then transported to specific target organs to initiate a particular metabolic change.
• The endocrine glands secrete chemicals called hormones.
• Hormones are non-nutrient chemicals which act as intercellular messengers and are produced in trace amount.

Human Endocrine System
The endocrine glands and hormone producing tissues/cells are located in different parts of the body. Gastrointestinal tract, kidney, liver and heart also produce small quantity of hormones to control and coordinate the function of respective organs.

Hypothalamus contains several groups of neurosecretory cells called nuclei which produce hormones. Hormones released by Hypothalamus regulate the synthesis and secretion of pituitary hormones.
Hypothalamus produces two types of Hormones:

• The hormones released from hypothalamus reaches the anterior pituitary through portal circulatory system and regulate its function.
• The posterior pituitary is under direct control of hypothalamus.

Pituitary Gland is located in sella tursica, a bony cavity. It is attached to the hypothalamus by a stalk.

• Excess secretion of Growth Hormone causes over growth of the body leading to gigantism and low secretion causes stunted growth called dwarfism.
• Prolactin stimulates growth of mammary gland and production of milk.
• TSH stimulates production and release of thyroid hormone.
• LH and FSH stimulate activity of the gonads. In male, LH stimulates synthesis and secretion of androgen hormone from testis. In female, LH induces ovulation of fully mature ovum from ovary.
• Oxytocin helps in contraction of uterus during child birth and milk ejection from mammary glands.
• Vasopressin stimulates absorption of water and electrolyte in kidney.
• MSH acts on the melanocytes and regulates skin pigmentation.

The pineal Gland- located on dorsal side of forebrain and release melatonin hormone that helps to regulate diurnal rhythm of body like sleeps wake cycle and body temperature.
Thyroid Gland- composed of two lobes on either side of trachea connected by isthmus.
Thyroid gland is made of follicles and stromal tissues:

• Iodine is essential for synthesis of thyroid hormones. Deficiency of iodine leads to hypothyroidism (Goitre). During pregnancy, hypothyroidism may cause stunted growth of baby and mental retardation.
• Thyroid hormones regulate the basal metabolic rate. They support the process of red blood cell formation. They control the metabolism of carbohydrates, proteins and fats. Thyrocalcitonin hormone regulates blood calcium levels.

Parathyroid Gland– located on the back side of thyroid gland, secretes peptide hormone called parathyroid hormone (PTH). PTH regulates the calcium ion concentration in the blood. It also helps in reabsorption of calcium from renal tubules and digestive tracts.
Thymus– located on the dorsal side of heart and the aorta. This gland releases peptide hormone thymosins that help in differentiation of T-Lymphocytes for cell-mediated immunity. It also promotes production of antibodies to provide humeral immunity.
Adrenal Gland – located on anterior part of each kidney, composed of two types of tissues central adrenal medulla and outside adrenal cortex. Adrenal medulla secretes adrenaline and noradrenaline hormone commonly called as catecholamines. These hormones are also called as emergency hormone. These hormones increase alertness, pupilary dilation, sweating, heart beat, rate of respiration, glycogenolysis.
The adrenal cortex secretes glucocorticoids and mineralocorticoids. Glucocorticoids stimulate gluconeogenesis. Mineralocorticoids regulate water and electrolyte contents of the body.
Pancreas – acts as both endocrine and exocrine gland. Endocrine pancreas consists of “Islets of Langerhans” which contain α-cells and β-cells. The α-cells secrete hormone glucagon and β-cells secrete insulin. Both hormones are involved in maintenance of blood sugar levels.

• Glucagon is a peptide hormone that stimulates glycogenolysis resulting in increased blood sugar (hyperglycemia).
• Insulin is a peptide hormone that play major role in regulation of glucose homeostasis. It triggers rapid movement of glucose from blood to hepatocytes and adipocytes resulting in decreased blood glucose levels (hypoglycemia).

Testis – perform dual functions as a primary sex organ as well as endocrine glands. Leydig cells or interstitial cells produce androgen mainly testosterone which regulate maturation of primary sex organs and spermatogenesis.
Ovary – produce two groups of steroid hormones called estrogen and progesterone. Estrogen is synthesized and secreted by growing ovarian follicles. After ovulation, ruptured ovum called corpus luteum, secretes progesterone. Estrogen produces wide range actions like growth of female secondary sex organs, development of growing ovarian follicles, and regulation of female sexual behaviour.
Progesterone regulates pregnancy.
Hormones of Heart, Kidney and Gastrointestinal Tract

• Atrial wall of heart secretes peptide hormone called atrial natriuretic factor (ANF) which decreases blood pressure.
• The juxtaglomerular cells of kidney produce erythropoietin hormone which stimulate erythropoiesis.
• Gastro-intestinal tract secrete four major peptide hormones:
  1. Gastrin stimulates the secretion of hydrochloric acid and pepsinogen.
  2. Secretin acts on the exocrine pancreas and stimulates secretion of water and bicarbonate ions.
  3. Cholecystokinin (CCK) stimulates the secretion of pancreatic enzymes and bile juice
  4.Gastric inhibitory peptide (GIP) inhibits gastric secretion and motility.

Mechanism of Hormone Action

• Hormone produce their effects on target tissues by binding to specific protein called hormone receptors located in the target tissue.
• Binding of hormones to receptor leads to the formation of hormone receptor complex. This binding leads to change in target tissue.

On the basis of chemical nature, hormones are grouped as-

1. Peptide, polypeptide and protein hormones- insulin, glucagon, pituitary hormone, hypothalamic hormones.
2. Steroids- cortisol, testosterone, progesterone.
3. Idothyronines- thyroid hormones.
4. Amino acid derivatives- epinephrine.

The hormones that bind with membrane bound receptors normally do not enter the target cells but generate second messenger which in turn regulate cellular metabolism.
The hormones (steroid hormones) which interact with intracellular receptors mostly regulate gene expression or chromosome function by interaction with hormone-receptor complex with the genome. These biochemical actions results in physiological and developmental effects.

Class 11 Biology Revision Notes for Neural Control and Coordination of Chapter 21

• Coordination is the process through which two or more organs interact and complement the function of each other.
• Neural system provides an organized network of point to point connection for quick coordination. The endocrine system provides chemical integration through hormones.
• Neural system of animals is composed of specialized cells called neuron, which can detect, receive and transmit different kinds of stimuli. In hydra neural system is composed of network of neuron. In insects it consists of brain and a number of ganglia. Vertebrates have highly developed neural system.
• Central nervous system (CNS) includes brain and spinal cord. It is the site for information processing and control.

• Peripheral nervous system includes all nerves associated with CNS. There are two types of nerve fibres-

• Afferent fibres- transmit impulses from tissue/organ to CNS.
• Efferent fibres- transmit regulatory impulses from CNS to concerned peripheral organs.
  Somatic neural systems relay impulses from CNS to skeletal muscles. Autonomic neural system transmits impulses from CNS to involuntary system and smooth muscles.

Neuron as Structural and Functional Unit of Neural System
Neuron is made up of three major parts- cell body, dendrite and axon.

• Cell body contains cytoplasm, cell organelles and Nissl’s granules. Short fibres projecting out from cell body is called dendrites. The axon is long fibre having branched structure at the end that terminates into knob like structure called synaptic knob.
• Based on number of axon and dendrites neuron are of three types-
  1. Multipolar– one axon and two or more dendrite found in cerebral cortex.
  2. Bipolar– one axon and one dendrite found in retina of eyes.
  3. Unipolar– cell body with only one axon found in embryonic stage.

• There are two types of axon-
  • Myelinated– fibres are enveloped with Schwann cells to form myelin sheath around the axon. The gap between two myelin sheaths is called nodes of Ranvier. Found in spinal and cranial nerves.
  • Unmyelinated- fibre is enclosed by Schwann cells that do not form myelin sheath around the axon. Found in autonomous and somatic neural system.

Generation and Conduction of Nerve Impulse

• Ion channels are present in neural membrane which is selectively permeable to different ions. When neuron is not conducting impulse (resting), axonal membrane is more permeable to K+ ions and impermeable to Na+ ions.
• Ionic gradient across the resting membrane is maintained by active transport of ions by sodium-potassium pump. This will develop positive charge outside the axonal membrane and negative charge on inner side.

• The electrical potential difference across the resting membrane is called resting potential.
• When stimulus is applied at site A, the membrane becomes permeable to Na+ ions to make rapid influx of Na+ ions to create outer surface negatively charged and inner membrane positively charged that create Action Potential or nerve impulse.
• The nerve impulse from A moves to B in inner surface and B to A on outer surface. This process is repeated several times to transmit the impulse.
• Nerve impulse is transmitted from one neuron to another neuron through synapse.
• There are two types of synapse-

1. Electrical synapse- the membrane of pre and post synaptic neuron is very close to each other and current flow directly from one neuron to another.
2. Chemical synapse- pre and post synaptic neuron is separated by fluid filled space called synaptic cleft. Neurotransmitters are involved in transmission of impulses.

Central Neural System –Brain is the central information processing organ of our body and act as command and control centre. Human brain is protected by skull (cranium) and three layers of cranial meninges- outer dura mater, middle arachnoid and inner pia mater.

Brain can be divided 3 parts- forebrain, midbrain and hindbrain.
Forebrain– consists of cerebrum, thalamus and hypothalamus. Cerebrum is divided into left and right cerebral hemispheres which are covered by cerebral cortex (grey matter). Cerebral cortex contains sensory neuron, motor neuron and association area. Association area controls complex functions like intersensory associations, memory and
communication.
Thalamus– cerebrum wraps around a structure called thalamus. It is a major
coordinating centre for sensory and motor signaling.
Hypothalamus controls the urge for eating, drinking and body temperature. They also release hypothalamic hormones. Limbic system is involved in controlling sexual behavior and expression of emotional reactions.
Midbrain is located between hypothalamus and pons of hindbrain. Dorsal portion consists of four round lobes called corpora quadrigemina. They are involved in relay of impulses back and forth between cerebrum, cerebellum, pons and medulla.
Hind brain consists of pons, medulla oblongata and cerebellum.
Pons consists of fibre tracts that interconnect different regions of the brain.
The medulla contains centres which control respiration, cardiovascular reflexes and gastric secretions.
Cerebellum controls balance and posture.
Reflex action is a spontaneous autonomic mechanical response to a stimulus without the will of the organism. It is controlled by spinal cord. The afferent neuron receives the signal from sensory organs and transmits the impulse to CNS. The efferent neuron carries the impulse from CNS to effector. Ex- knee-jerk reflex. The path followed by reflex action is called reflex arc.

Human Eye – spherical structure consists of three layers, external layer is sclera whose anterior part is called cornea, middle layer choroid and innermost layer is called retina.
Retina contains three layers of cells – inner ganglion cells, middle bipolar cells and outer photoreceptor cells.
There are two types of photoreceptor cells called rods and cones. The daylight (photopic) vision and colour vision are functions of cones. The twilight (scotopic) vision is the function of the rods.
Mechanism of Vision
The light rays of visible wavelength fall on retina through cornea and lens to generate impulses in rods and cones. Photosensitive pigments opsin and retinal get dissociated due to light to change its shape. Change in shape of opsin cause change of permeability to generate action potential that is transmitted to brain via optic nerve.
Human Ears

Divided into three regions: outer ear, middle ear and inner ear.
The middle ear contains three ossicles called malleus, incus and stapes. The fluid
filled inner ear is called the labyrinth, and the coiled portion of the labyrinth is called cochlea.
The organ of corti contains hair cells that act as auditory receptors and is located on the basilar membrane.
Mechanism of Hearing
External ear receives the sound wave and directs them to ear drum. Vibration of ear drum leads to vibration of ear ossicles. The vibration reaches cochlea that generate wave in lymph. The waves generate ripples in basilar membrane and hair cells in them. As a result, nerve impulses are generated in afferent neuron that passes to brain via auditory nerves.

Class 11 Biology Revision Notes for Locomotion and Movement of Chapter 20

Locomotion is the voluntary movement of an individual from one place to another. Walking, running, climbing, swimming are the examples of locomotion. All locomotion are movement but all movements are not locomotion.
Types of Movement
Cells of the human body show three main types of movements:

• Macrophages and leucocytes in blood exhibit amoeboid movements. Coordinated movement of cilia in trachea to remove dusts particles and passage of ova through fallopian tube is example of Ciliary movements.
• Movement of limbs, jaw, tongue, etc. need muscular movement. Contractile property of muscles is used in movement in higher organism including human beings.

Muscles are specialized tissues of mesodermal origin. They have property like excitability, contractility, extensibility and elasticity.
Based on their location, three types of muscles are identified

• Skeletal Muscle is made up of muscles bundles (fascicles), held together by collagenous connective tissue called fascia.

• Each muscle bundle contains a number of muscle fibres. Each muscle fibre is lined by plasma membrane called sarcolemma enclosing sarcoplasm. Partially arranged myofibrils are present in muscle bundle having alternate light and dark bands due to presence of protein- actin and myosin
• Light bands contain actin and is called I-band (isotropic band) and dark band contains myosin, called A-band (anisotropic band). Both bands are present parallel to each other in longitudinal fashion.
• In centre of each I-band is elastic fibre called ‘Z’ line. In the middle of A-band is thin fibrous ‘M’ line. The portion of myofibrils between two successive ‘Z’ lines is the functional unit of contraction called a sarcomere.
• At resting stage thin filament overlaps the thick filament. The part of thick filament not overlapped is called ‘H’ zone.

Structure of contractile Protein
Each thin filament (actin) is made of two ‘F’ actins helically wounded to each other. Two filaments of another protein, tropomyosin runs close to it. A complex protein
Troponin is distributed at regular intervals on the tropomyosin.

Each myosin filament is made of many monomeric proteins called Meromyosins. Each meromyosin has globular head with short arm and tails. Globular head has ATP binding sites.
Mechanism of muscle contraction

• The mechanism of muscle contraction is explained by sliding mechanism theory in which thin filament slide over thick filament.
• Muscle contraction start with signal sent by CNS via motor neuron. Neural signal release neurotransmitter ( Acetyl choline) to generate action potential in the sarcolemma.
• This causes the release of Ca ++ from sarcoplasmic reticulum.
• Ca ++ activates actin which binds to the myosin head to form a cross bridge.
• These cross bridges pull the actin filaments causing them to slide over the myosin filaments and thereby causing contraction.
• Ca ++ are then returned to sarcoplasmic reticulum which inactivate the actin. Cross bridges are broken and the muscles relax.

Muscles are classified as:
Red fibres (aerobic muscles-) contain myoglobin that has plenty of mitochondria to use large amount of oxygen stored in them.
White fibres-the muscle fibres containing less number of myoglobin are called white fibres.
Skeletal System
Framework of bones and cartilage forms the skeletal system. In human beings, it consists of 206 bones and some cartilages. The two principle division of skeletal system are:

1. Axial Skeleton (80 bones)- includes skull, vertebral column, sternum and ribs constitute axial system.

• The skull (22 bones) is composed of cranial and facial bones. Cranial (8 bones) forms protective covering for brain (cranium). The facial region consists of 14 skeletal systems that form front part of skull. Hyoid bone (U-shaped) forms the base of buccal cavity.
• The middle ear bone (Malleus, Incus and Stapes) collectively called Ear Ossicles. Skull joins with vertebral column with two occipital condyle.
• Vertebral column consists of 26 serially arranged vertebrae. First vertebra is atlas that combines with occipital condyle. Other includes Cervical-7, thoracic -12, lumbar -5, sacral – 1 coccoygeal -1.
• 12 pairs of ribs connected dorsally to vertebral column and ventrally to sternum. 11th and 12th rib bones are not connected with sternum and are called floating ribs.

Appendicular Skeleton- includes bones of limbs and girdles. Each limb contains 30 bones.
 

Pectoral and Pelvic girdle bones help in the articulation of the upper and the lower limbs
respectively with the axial skeleton.
Pectoral girdle consists of a clavicle and a scapula.
Pelvic girdle consists of two coxal bones. Each coxal bone is formed by the fusion of three bones – ilium, ischium and pubis.

1. Fibrous joints– do not allow any movements. Present in flat skull bones to form cranium.
2. Cartilaginous joints– bones are held together with the help of cartilage present in vertebrae. Permits limited movements.
3. Synovial joints– fluid filled synovial cavity, provide considerable movements. Ball and socket joint, hinge joints, pivot joints, gliding joints etc.

Disorders of Muscular and Skeletal System

• Myasthenia gravis- auto immune disorder affecting neuromuscular junction causing fatigue, weakening and paralysis of skeletal system.
• Muscular Dystrophy- degeneration of skeletal muscles due to genetic disorder.
• Osteoporosis – decreased bone mass in old age leading to chance of fracture due to decreased estrogen.
• Arthritis- inflammation of joints.
• Gout- inflammation of joints due to accumulation of uric acid crystals.
• Tetany- Rapid spasms in muscle due to low Ca ++ in body fluid

Class 11 Biology Revision Notes for Excretory Products and their Elimination of Chapter 19

• Elimination of metabolic waste products from the animal body to regulate the composition of body fluids and tissues is called excretion. These waste products include ammonia, uric acid, urea, carbon dioxide and ions like Na+Na+, K+K+, Cl^– and phosphates and sulphate.
• Ammonia is the most toxic and uric acid is the least toxic. The process of removing ammonia is called ammonotelism and organisms that excrete ammonia are called ammonotelic (bony fishes, aquatic amphibians and insects).
• The organism that release urea as nitrogenous wastes are called ureotelic (mammals, terrestrial amphibians). The organism that excretes uric acids is called uricotelic (reptiles, birds and land snails).

Human Excretory System
Human excretory system consists of:

1. A pair of kidneys
2. A pair of ureters
3. A urinary bladder
4. A urethra

• Kidneys are reddish brown bean shaped structure situated between last thoracic and lumber vertebra. Each kidney has a notch on its inner side called hilum through which ureter, blood vessels and nerves enter.

• Inside the hilum has broad funnel shaped space called renal pelvis with projection called calyces.

• Inside the kidney are two zone- outer cortex and inner medulla. Medulla is divided into medullary pyramids projecting into calyx.
• Cortex extends between medullary pyramids as renal column called Columns of Bertini.

• The functional unit of kidney is nephron. Each kidney contains about one million nephrons.
• Each nephron has two parts- the glomerulus and renal tubules. Glomerulus is the tuft of capillaries formed by afferent arteriole. Blood from glomerulus is carried away by efferent arteriole.
• Renal tubules starts with Bowman’s capsule continue with tubular parts divided into Proximal Convoluted tubules, Henle’s loop and Distal Convoluted tubule.

• The malpighian tubules, PCT and DCT of nephron are situated in cortical region where as loops of Henle’s into medulla.

Urine formation

• Glomerular capillaries blood pressure cause filtration of blood through 3 layers (endothelium of glomerular blood vessels, epithelium of Bowman’s capsule and basement layer between two membranes as ultra-filtration.
• The amount of filtrate formed by kidneys per minute is called glomerular filtration rate (GFR) which is 125 ml/minute.
• Glomerular Filtration rate is controlled by Juxta glomerular apparatus (JGA).
• 99% of filtrate has to be reabsorbed by renal tubules called reabsorption.

Function of Tubules

1. Proximal Convoluted Tubules (PCT) – all the important nutrients, 70-80% electrolytes and water are reabsorbed.
2. Henle’s Loop– maintains high osmolarity of medullary interstitial fluid.
3. Distal Convoluted Tubules (DCT) – conditional reabsorption of Na+ and water. Maintains pH and sodium- potassium balance.
4. Collecting Duct– large amount of water is reabsorbed to produce concentrated urine.

Mechanism of concentration of urine– The flow of filtrate in two limbs of Henle’s loop is in opposite direction to form counter current. The flow of blood in two limbs of vasa recta increase the osmolarity towards the inner medullary interstitium in the inner medulla.

• The transport of substance facilitated by special arrangement of Henle’s loop and vasa recta is called counter current mechanism.

Regulation of kidney function–

• Functioning of kidney is monitored by hormonal feedback mechanism of hypothalamus and JGA. Change in blood volume, body fluid and ion concentration activates the osmoreceptors in the body that stimulate the hypothalamus to release ADH or vasopressin hormones. The ADH facilitates water absorption in tubules.
• Decrease in glomerular blood pressure activate JG cells to release renin which converts angiotensinogen to angiotensin I and II that increase the glomerular blood pressure and release of aldosterone that increase absorption of Na+ ions and water.

Micturition – The process of expulsion of urine from the urinary bladder is called micturition. The neural mechanism that causes it is called micturition reflex. Urine formed in nephron is stored in urinary bladder till a voluntary signal is given by CNS. This initiates the contraction of smooth muscles of the bladder and simultaneous relaxation of the urethral sphincter causing the release of urine.

• Lungs, liver and skin also play important role in process of excretion. Lungs remove CO2CO2 and water, liver eliminates bile containing substances like bilirubin, biliverdin. Sweat glands remove NaCl, small amount of urea and lactic acid. Sebaceous glands excrete sterol, hydrocarbons and waxes.

Disorders of Excretory System

• Uremia– there is high concentration of non-protein nitrogen (urea, uric acid, creatinine). Urea can be removed by hemodialysis.
• Renal failure– also known as kidney failure where glomerular filtration is ceased and both kidney stops working. Kidney transplant is the ultimate method in correction of acute kidney failure.
• Renal Calculi– formation of stone or insoluble mass of crystallized salts formed within the kidney.
• Glomerulonephritis (Bright’s Disease)-inflammation of glomeruli of kidney due to entry of protein or red blood corpuscles in to filtrate due to injury.

Class 11 Biology Revision Notes for Body Fluids and Circulation of Chapter 18

Body fluids are the medium of transport of nutrients, oxygen and other important substances in the body.

Blood is the most commonly used body fluid in most of the higher organisms. Lymph also transports certain substances like protein and fats.
Blood
Blood is a fluid connective tissue composed of a fluid matrix, plasma and the blood corpuscles. It forms about 30-35% of the extracellular fluid. It is slightly alkaline fluid having pH7.4.

• Plasma is straw coloured viscous fluid that constitutes 55% of blood volume. It consists of 90-92% water, 6-8% protein (fibrinogens, albumins and globulins), glucose, amino acids and small amount of minerals like Na+, Ca++, Cl^– etc.
• Erythrocytes, leucocytes and platelets are collectively called formed elements.
• Erythrocytes are most abundant cells in human body. Total blood count of RBCs is 5-5.5 million, which is slightly less in females due to menstruation. It is formed in bone marrow. Nucleus is absent in mammalian RBCs having biconcave shape.
• Every 100 ml of blood contain 12-16 gm. of haemoglobin. They have life span of 120 days. They are destroyed in spleen( graveyard of RBCs)
• Leucocytes or WBCs are colourless due to absence of haemoglobin. 6000-8000 of WBCs are present in each ml. of blood.

• Neutrophils are most abundant and basophils are least abundant WBCs. Monocytes and neutrophils are phagocytic cells which destroy foreign organisms.

• Basophils secrete histamine, serotonin and heparin that are involved in inflammatory reactions.
• Eosinophils resist infection and allergic reactions. B and T lymphocytes are responsible for immune response of the body.

Thrombocytes or platelets are cell fragments produced from megakaryocytes in bone marrow. 150000-350000 platelets are present in each ml of blood. Platelets are involved in clotting or coagulation of blood in case of injuries.
Blood Groups – blood of human beings differ in certain aspects although it appear same in all individuals. Two main types of grouping are ABO and Rh.
ABO grouping is based on presence or absence of two surface antigens RBC, antigen A and antigen B. The plasma of an individual also contains two antibodies produced in response of antigens.

• During blood transfusion, blood of donor has to be matched with blood of recipients to avoid clumping of RBCs.
• Group ‘O’ blood can be donated to any individual with any blood group, so it is called universal donor.
• Person with ‘AB’ blood group can receive blood from any person of any group, so it is called universal recipient.

Rh grouping – Rh antigen (similar to Rhesus monkey) are observed on surface of RBCs of majority of individuals (about 80%). Such people are called Rh positive (Rh+Rh+) and those in whom this antigen is absent are called Rh negative (Rh−Rh−).

• Erythroblastosis foetalis– if father blood is Rh+ and mother blood is Rh−Rh−, the foetus blood is Rh+. During the delivery of first child there is a possibility of exposure of mother blood with foetus blood to develop antibodies in mother blood. In subsequent pregnancy the mother’s blood can leak into foetus blood and destroy the foetus RBC. This case is called erythroblastosis foetalis.

Coagulation of blood (Blood Clotting)
When an injury is caused to a blood vessel bleeding starts which is stopped by a process called blood clotting. An injury or trauma stimulates the platelets in the blood to release certain factors that activate the mechanism of coagulation. Calcium play important role in blood clotting.
Lymph
During flow of blood through capillaries, some water soluble substances move out in the space between cells of tissues. This fluid released out is called interstitial fluid or tissue fluid. It is similar to the blood but has fewer blood proteins, less calcium and phosphorus and high glucose concentration.

• It is a colourless fluid containing specialized lymphocytes that provide immune response to body.
• Main function of lymph is to provide immunity, carry proteins and fats molecules and transport oxygen, food materials, hormones etc.

Circulatory Pathways

• All vertebrates have a muscular chambered heart.

Fish – 2 chambered heart
Amphibian and Reptiles (except crocodile) – 3 chambered heart.
Crocodile, Birds and Mammals – 4 chambered heart.
Human Circulatory System – consists of 4 chambered muscular heart, closed branching blood vessels and circulatory fluid blood.
Heart is the mesodermally derived muscular organ, present in thoracic cavity between the two lungs protected by double membrane of pericardium.

• The upper two chamber is called atria and lower two chambers are called ventricles. Interatrial septum separate the right and left atrium and thick walled inter ventricle septum separate the ventricles.
• The opening between right atrium and right ventricle is guarded by a three muscular flaps called tricuspid valve. Bicuspid or mitral valve guards the left atrium and ventricle.
• The opening of right and left ventricle to pulmonary artery and aorta respectively is controlled by semilunar valve.
• The nodal tissue present on upper right corner of right atrium is called SAN (sino-atrial node) and those on lower left corner of right atrium is called AVN ( atrio-ventricular node).
• The purkinje fibres along with right and left bundles form the bundle of HIS. The nodal musculature has ability to generate action potential.
• SAN generate maximum number of action potential and is responsible for rhythmic contraction of heart. Therefore it is called pace maker.

Cardiac Cycle

• To begin with, all four chambers are in relaxed state called joint diastole. As the bicuspid and tricuspid valves are open, blood from pulmonary vein and vena cava flows to left and right ventricle respectively. Semilunar valves are closed at this stage.
• SA node generates action potential that contracts both atria (atrial systole). The action potential passes to AV node and bundle of HIS transmit it to ventricular musculature to cause ventricular systole. At the same time atria undergoes relaxation diastole to close the bicuspid and tricuspid valve.
• Semilunar valves open into circulatory system that relax the ventricle and close the valves to prevent back flow of blood.
• As the pressure inside ventricle decreases the bicuspid and tricuspid valve open to repeat the process or cardiac cycle.
• During each cardiac cycle two sounds are produced. The first sound (lub) is due to closure of bicuspid and tricuspid valve and 2nd heart sound (dub) is due to closure of semilunar valve.

ECG (Electrocardiograph) is a graphical representation of electrical activity of heart during cardiac cycle. The electrocardiograph machine is used to obtain electrocardiogram. The patient is connected to three electrical leads to wrists and left ankle.

• The P-wave represents the electrical excitation of atria (depolarisation) which leads to contraction of atria.
• The QRS-wave represents the depolarisation of ventricles, which initiates the ventricular contraction.
• The T-wave represents the return of ventricle from exited to normal state (repolarization). The end of T-wave marks the end of systole. Counting the number of QRS complex in given period of time determine the heartbeat rate.

Double Circulation
Flow of same blood twice through the heart once in oxygenated form and other in deoxygenated form is called double circulation. It includes systematic and pulmonary circulation.
Systematic circulation includes flow of oxygenated blood from the left ventricle to all parts of body and deoxygenated blood from various body parts to the right atrium. All systematic circulation starts form aorta and ends at superior vena cava, inferior vena cava or coronary sinus to right atrium.
The systematic circulation provides oxygen, nutrients and other substances to the tissues and take CO2 and other harmful substances away for removal.

Pulmonary Circulation
The flow of deoxygenated blood from the right ventricle to the lungs and the return of oxygenated blood from the lung to the left atrium is called pulmonary circulation.
Two pulmonary veins from each lung transport the oxygenated blood to the left atrium.
Double circulation prevents the mixing of oxygenated and deoxygenated blood.
Regulation of Cardiac Activity

• Normal activities of heart are regulated by nodal tissue (SA and AV node), so the heart is myogenic.
• A special neural centre in medulla oblongata moderates the cardiac function by ANS. Sympathetic nerve can increase the rate of heart beat and parasympathetic nerve of ANS decrease the rate of heart beat.
• Adrenal medullary hormone also increases the cardiac output.

Disorder of Circulatory System

1. Hypertension (high blood pressure) – Blood pressure higher than (120/80) . 120 mm Hg is the systolic that is pumping pressure and 80 mm Hg is the diastole, resting pressure. It leads to heart disease and affect vital organs like brain and kidney.
2. Coronary Artery Disease (CAD)- commonly called atherosclerosis that affects the blood vessels that supply blood to heart muscles due to deposition of fat, calcium, cholesterol that makes the arteries lumen narrower.
3. Angina- also called angina pectoris, acute chest pain due to less supply of oxygen to heart muscles. It may occur in elderly male and female. It occurs due to restricted blood flow.
4. Heart failure– heart does not pump enough blood to meet the requirement of body. It is also known as congestive heart failure because congestion of lung is one of its causes. Heart failure is different from heart attack ( heart muscle is damaged by inadequate blood supply) and cardiac arrest ( when heart stops beating).
5. Coronary Thrombosis- formation of clot in the coronary artery is coronary thrombosis. It occurs most frequently in the left anterior descending coronary artery.

Class 11 Biology Revision Notes for Breathing and Exchange of Gases of Chapter 17

The process of exchange of O₂ from the atmosphere with CO₂ produced by the cell is called breathing. It occurs in two stages of inspiration and expiration. During inspiration air enters the lungs from atmosphere and during expiration air leaves the lungs.

Respiratory Organs – Mechanism of breathing varies in different organism according to their body structure and habitat.

Human Respiratory System

• Human respiratory system consists of a pair of nostrils, pharynx, larynx, bronchi and bronchioles that finally terminates into alveoli.
• Nasal chamber open into pharynx that leads to larynx. Larynx contains voice box (sound box) that help in sound production.
• The trachea, primary, secondary and tertiary bronchi and initial bronchioles are supported by incomplete cartilaginous rings to prevent collapsing in absence of air.
• Each bronchiole terminates into an irregular walled, vascularized bag like structure called alveoli.

• The branching network of bronchi, bronchioles and alveoli collectively form the lungs.
• Two lungs are covered with double layered pleura having pleural fluid between them to reduce the friction on lung surface.

• Conducting parts include nostrils, pharynx, larynx and trachea. Main functions include-

1. Transport of atmospheric air to alveoli.
2. Removing foreign particles from air, humidifying it and bringing it to body temperature.

• The exchange parts are alveoli. It is the site of actual diffusion of O2O2 and CO2O2 between blood and atmospheric air.

Steps of Respiration

1. Breathing in which Oxygen rich atmospheric air is diffused in and CO2O2 rich alveolar air is diffused out.
2. Diffusion of gases across alveolar membrane.
3. Transport of gases by blood.
4. Diffusion of O2O2 and CO2O2 between blood and tissues.
5. Utilization of O2O2 by cells to obtain energy and release of CO2O2 (cellular respiration).

Mechanism of Breathing

• Breathing involves inspiration and expiration. During inspiration atmospheric air is drawn in and during expiration, alveolar air is released out.
• Movement of air in and out takes place due to difference in pressure gradient.
• Inspiration occurs when pressure inside the lung is less and expiration occurs when pressure is more in lungs than outside.
• The diaphragm and external and internal intercostal muscles between the ribs help in developing pressure gradient due to change in volume.

• The contraction of intercostal muscles lifts the ribs and sternum causing an increase in volume of thoracic cavity that results in decrease in pressure than the atmospheric pressure. This causes inspiration.
• Relaxation of the diaphragm and intercostal muscles reduce the thoracic volume and increase the pressure causing expiration.
• The volume of air involved in breathing movements is estimated by using spirometer for clinical assessment of pulmonary functions.

Respiratory Volume and Capacities
Tidal volume (TV) – volume of air inspired or expired during a normal respiration. It is about 500mL in healthy man.
Inspiratory Reserve Volume (IRV) – additional volume of air a person can inspire by forceful inspiration. It is about 2500 mL to 3000mL.
Expiatory Reserve Volume (ERV) – additional volume of air a person can expire by forceful expiration. It is about 1000 mL to 1100mL.
Residual Volume (RV) – volume of air remaining in lungs even after a forcible expiration. It is about 1100mL to 1200mL.
Inspiratory Capacity (IC) – TV + IRV
Expiratory Capacity (EC) – TV + ERV
Functional Residual Capacity (FRC) – ERV + RV
Vital Capacity (VC) – maximum volume of air a person can breathe in after a forceful expiration. ERV+ TV+ IRV
Total Lung Capacity (TLC) – total volume of air accommodated in lung at the end of forced inspiration. RV+ ERV+ TV+ IRV or Vital capacity + Residual Volume.

Exchange of Gases

• Exchange of gases takes place at two sites

1. Alveoli to blood
2. Between blood and tissues.

• Exchanges of gases occur by simple diffusion due to pressure/ concentration gradient, solubility of the gases and thickness of membrane.
• Pressure contributed by individual gas in a mixture of gas is called partial pressure represented by pCO2O2 and pO2O2 .
• Partial pressure of Oxygen and carbon dioxide at different part involved in diffusion varies from one part to another and moves from higher partial pressure to lower partial pressure.
• Solubility of CO2O2 is 20-25 times more than solubility of O2O2 , so CO2O2 diffuse much faster through membrane.
• Diffusion membrane is three layered thick, that is alveolar squamous epithelium, endothelium of alveolar capillaries and basement substance between them.

Transport of Gases

• Blood is the medium of transport for CO2O2 and O2O2 . Most of oxygen (97%) is transported through RBC and remaining 3% by blood plasma.
• 20-25% of CO2O2 is transported by RBC, 70% as bicarbonate and rest 7% in dissolved state by blood plasma.

Transport of Oxygen

• Haemoglobin in RBC combines with O2O2 to form Oxyhaemoglobin. Each haemoglobin combine with four oxygen molecules.
• Binding of O2O2 is related with partial pressure of O2O2 and CO2CO2, hydrogen ion concentration and temperature.
• Percentage saturation of haemoglobin and partial pressure of oxygen forms sigmoid curve (oxygen dissociation curve).
• In the alveoli, pO2O2 is more and pCO2O2 is less, less H+ ions concentration and lower temperature favour the binding of O2O2 with hemoglobin. Where opposite condition in tissues favour the dissociation of Oxyhaemoglobin.

Transport of Carbon dioxide

• Carbon dioxide is transported by haemoglobin as carbamino-haemoglobin. In tissues pCO2O2 is high and pO2O2 is less that favour the binding of carbon dioxide with haemoglobin. Opposite condition help in dissociation of carbamino- haemoglobin in alveoli.
• Enzyme carbonic anhydrase help in formation of carbonate ions to transport carbon dioxide.

Regulation of Respiration

• Human beings have ability to maintain and moderate the rate of respiration to fulfill the demand of body tissues by neural system.
• Respiratory rhythm centre is located in medulla region of hind brain. Pneumotaxic centre in pons moderate the function of respiratory rhythm centre.
• Chemo-sensitive area near rhythm centre is highly sensitive to CO2O2 and H+ ions that ultimately control the respiratory rate. Oxygen do not play major role in controlling rate of respiration.

Functions of Respiration–

1. Energy production
2. Maintenance of acid-base balance.
3. Maintenance of temperature
4. Return of blood and lymph.

Mountain Sickness is the condition characterised by the ill effect of hypoxia (shortage of oxygen) in the tissues at high altitude commonly to person going to high altitude for the first time.
Symptoms-

• Loss of appetite, nausea, and vomiting occurs due to expansion of gases in digestive system.
• Breathlessness occurs because of pulmonary oedema.
• Headache, depression, disorientation, lack of sleep, weakness and fatigue.

Disorder of Respiratory System

1. Asthma– it is due to allergic reaction to foreign particles that affect the respiratory tract. The symptoms include coughing, wheezing and difficulty in breathing. This is due to excess of mucus in wall of respiratory tract.
2. Emphysema– is the inflation or abnormal distension of the bronchioles or alveolar sacs of lungs. This occurs due to destroying of septa between alveoli because of smoking and inhalation of other smokes. The exhalation becomes difficult and lung remains inflated.
3. Occupational Respiratory Disorders– occurs due to occupation of individual. This is caused by inhalation of gas, fumes or dust present in surrounding of work place. This includes Silicosis, Asbestoses due to exposer of silica and asbestos. The symptom includes proliferation of fibrous connective tissue of upper part of lung causing inflammation.
4. Pneumonia– it is acute infection or inflammation of the alveoli of the lungs due to bacterium streptococcus pneumoniae. Alveoli become acutely inflamed and most of air space of the alveoli is filled with fluid and dead white blood corpuscles limiting gaseous exchange.

Class 11 Biology Revision Notes for DIGESTION AND ABSORPTION of Chapter 16

The process of conversion of complex food into simpler absorbable form is called digestion and is carried out by digestive system by mechanical and biochemical methods.
Digestive System- Human digestive system consists of alimentary canal and associated glands.

• Alimentary canal begin with anterior opening mouth and opens out posteriorly through anus. It comprises of following parts:-

1. Mouth- leads to oral cavity or buccal cavity which contains teeth and tongue.
   Upper surface of tongue has small projections called papillae, some of which contain taste buds.
   Each teeth is embedded in socket of jaw bone (thecodont). Milk teeth is replaced by permanent or adult teeth, this type of dentition is called diphyodont. Four different types of teeth (Heterodont) are incisors (I), canine (C), premolar (PM) and molar (M).Dental formula: Each half of the upper and lower jaw has following number of teeth- 2123212321232123
2. Pharynx – oral cavity opens into pharynx which acts as common passage for food and air. Cartilaginous flap called epiglottis prevents the entry of food into wind pipe (glottis) during swallowing.
3. Stomach- Oesophagus leads to stomach. The opening of stomach is guarded by a sphincter (gastro-oesophageal). Stomach is divided into three parts- cardiac, fundic and pyloric.
4. Small intestine- is the longest part of alimentary canal divided into duodenum, jejunum and ileum. Pyloric sphincter is present between stomach and duodenum.
5. Large intestine- ileum opens into large intestine, which is divided into caecum, colon and rectum. Caecum is a blind sac which host microbes. Vermiform appendix arises from caecum. Rectum opens through anus.

Histology of Alimentary canal-
The wall of alimentary canal from Oesophagus to rectum consists of four layers.

1. Serosa– it is the outermost layer made up of squamous epithelium and areolar connective tissue.
2. Muscularis– it is composed of outer longitudinal and inner circular muscle fibres. Muscles fibres are smooth and have network of nerve cells.
3. Submucosa– it consists of loose connective tissue richly supplied with blood and lymphatic vessels. Meissner’s plexus is present between the muscular coat and mucosa that controls the secretion of intestinal juice.
4. Mucosa– is innermost layer lining the lumen of the alimentary canal. It has irregular folding in stomach called rugae and villi in small intestine. Mucosa forms glands in the stomach (gastric glands) and crypts in between the bases of villi in the intestine (crypts of Lieberkuhn).
   

Salivary Glands- secrete saliva in oral cavity. In human beings salivary glands are three pairs- parotid, sublingual, and submandibular.
Liver- it is the largest gland in human body lies in upper right side of the abdominal cavity just below the diaphragm. Hepatic lobules, covered by Glisson’s capsule, are structural and functional unit of liver made up of hepatic cells. The secretion is stored and concentrated in gall bladder. Bile duct and pancreatic duct open together in duodenum by common duct guarded by sphincter of Oddi.

Pancreas- It is soft lobulated greyish pink gland which weighs about 60 gm., consists of exocrine and endocrine portion. The exocrine portion secretes alkaline pancreatic juice and endocrine secretes hormones insulin and glucagon.
Digestion of food
Carbohydrates, fats, proteins and nucleic acids occur in food in the form of large and complex insoluble macromolecules (polymers). These macromolecules are converted into small monomers by the action of enzyme.

• In buccal cavity, teeth and tongue help in mastication and mixing of food. Mucus in saliva mix with masticated food to form bolus.
• Bolus is passed to pharynx and Oesophagus by swallowing or deglutition.
• Chemical digestion of food starts in oral cavity by the action of enzyme salivary amylase and lysozyme.
  Lysozyme acts as antibacterial agent in mouth to prevent infection.
  Salivary amylase breaksdown starch into maltose
• Mucosa of stomach have gastric glands having three types of cells- mucus neck cells that secrete mucus, peptic or chief cells that secretes proenzyme pepsinogen and pariental or oxyntic cells that secretes HCl.
• Food mixes with gastric juice due to churning action of muscular wall to form chyme. HCl activates the pepsinogen to pepsin to digest protein into peptones  and proteoses
• Mucus and bicarbonates present in gastric juice play important role in lubrication and protecting inner wall of stomach from the action of HCl. Renin is a proteolytic enzyme found in gastric juice of infants to digest milk protein.
• The Bile, pancreatic juice and intestinal juice are released in small intestine. Pancreatic juice contain inactive trypsinogen, chymotrypsinogen, procarboxypeptidases, amylases, lipases and nucleases.
• Trypsinogen is activated by enzyme enterokinase in to trypsin, which further activates the other enzyme of intestinal juice.
• Bile contains bile pigments (bilirubin and bil-verdin), bile salts, cholesterol and phospholipids which help in emulsification of fats.
• Secretion of brush border cells of mucosa and goblet cells contain enzyme succus entericus, containing variety of enzymes to complete the process of digestion.

Function of large intestine

1. Absorption of water, minerals and certain drugs.
2. Secretion of mucus for adhering of the undigested food and lubricating it for easy passage.

Absorption of Digested Food
Absorption is the process by which nutrients pass from the alimentary canal into the blood and lymph through its mucous membrane.

• Amino acids, monosaccharide, fatty acids, glycerol, salts, vitamins and water are to be absorbed. About 90% of absorption occurs in small intestine and rest 10% in stomach, mouth and large intestine.
• The passage of different absorbent depends upon concentration gradient for some substances like glucose and amino acids and electrolytes.

Absorption in different part of alimentary canal-

Disorder of Digestive System
The inflammation of intestinal tract due to bacterial infection, fungal infection and parasitic infection caused by tapeworm, round worm, threadworm and pin worms.

1. Jaundice– it is a disease of liver. In jaundice the skin and the eyes turn yellow due to large quantities of bilirubin pigments in the extra cellular fluid.
2. Vomiting – it is the ejection of stomach content through the mouth. This reflex action is controlled by the vomit Centre in the medulla.
3. Diarrhoea- frequent defection of liquid faeces is known as Diarrhoea. It reduces the absorption of food.
4. Constipation– in constipation the faeces are retained within the rectum as the bowel movements occur irregularly.
5. Indigestion– incomplete digestion usually accompanied by one or more of the following symptoms- pain, nausea, vomiting, heartburn, acid regurgitation, accumulation of gas and escape of gas from the stomach.