Human Physiology PDF - NSEJS Batch 2024

1 HUMAN PHYSIOLOGY For NSEJS BATCH 2024 NUTRITION IN ANIMALS Animals are heterotrophic in nature. They are directly or indirectly dependent on plants to obtain their food Th...

1 HUMAN PHYSIOLOGY For NSEJS BATCH 2024 NUTRITION IN ANIMALS Animals are heterotrophic in nature. They are directly or indirectly dependent on plants to obtain their food The mode of nutrition may be parasitic or saprotrophic but usually animals are holozoic. All the basic steps of holozoic nutrition are same in unicellular to multicellular organism. Holozoic nutrition in animals consists of following 5-steps Ingestion: The process of intake of food. Digestion: It is the breakdown of large and complex molecules into simpler, smaller and soluble forms. Absorption: Taking up of the digested food through intestinal wall to blood or body fluid. Assimilation: In this process absorbed food is taken by body cells. Egestion: The process by which undigested matter is expelled out. (i) Nutrition in Amoeba: It is a unicellular organism living in water. Mode of nutrition is holozoic. The process of obtaining food is by phagocytosis (cell eating) Steps involved in nutrition in amoeba are: I. Ingestion: Since it is unicellular so a single cell is responsible for carrying out all the vital activities. Food is ingested with the help of pseudopodia. Animal engulfs the food particle lying near it by forming pseudopodia around it and forming a food vacuole which is considered as its temporary stomach. II. Digestion: The enzymes from surrounding cytoplasm enter the food vacuole and break down the food into smaller & soluble forms. It is intracellular in Amoeba. III. Absorption: The digested food is now absorbed by cytoplasm by simple diffusion. IV. Assimilation: The food absorbed in amoeba is used to obtain energy from respiration, for its growth and reproduction. PW OLYMPIAD WALLAH 1  NSEJS BATCH 2024 V. Egestion: Undigested food is thrown out of the cell. (ii) Nutrition in Human Beings: Humans are holozoic and follow same 5- steps of nutrition. Humans have highly evolved and complicated digestive system consisting of an alimentary canal and different types of digestive glands. Concept Boosters:  Jaws present in buccal cavity of humans are provided with four different types of teeth this is called Heterodont.  Thecodont means “Socket tooth”, means that thecodont teeth are set in sockets of jaw bones.  Dental plaque is a biofilm or mass of bacteria that grows on surfaces within the mouth.  Diastema: It is a space or gap between two teeth.  Enamel: It is the hardest substance of human body. It covers the crown portion of the tooth.  Dentine: It is the hard dense bony tissue forming bulk of teeth & it is second hardest tissue in body after enamel.  Periodontium: It refers to the specialized tissues that surround & support the teeth, maintaining them in their respective bones.  Reverse peristalsis or retro peristalsis is the reverse of peristalsis, usually occurs before vomiting.  The duodenum part of small intestine receives secretions from Liver and Pancreas through a common duct called the “Hepato-Pancreatic Duct”.  Liver secretes “Bile” which provides alkaline medium and emulsifies the fat molecules.  Duodenal wall secretes enterokinase which activates the trypsin Trypsinogen ⎯Enterokina ⎯⎯⎯ ⎯→ Trypsin se Chymotrypsinogen ⎯Tryp ⎯⎯ ⎯→ Chymotrypsin sin Polypeptides ⎯Chymotryp ⎯ ⎯ ⎯⎯→ Peptide fragments sin  Dysphagia: Difficulty or discomfort in swallowing.  Coprophagy: It is the consumption of own faecal matter. It has been observed in rabbits. I. Alimentary canal: Long, hollow, tubular structure consisting of various organs for digestion. Alimentary canal consists of following organs: 1. Mouth: It is a small slit through which food is ingested. 2. Buccal cavity: Mouth opens into a chamber called as buccal cavity. It has following components: Soft palate: Posterior muscular extension of hard palate is called soft palate. Tongue: At the floor of this cavity thick muscular structure is present called tongue. It helps in chewing, swallowing, tasting and speaking. Tongue has various types of taste papilla. Teeth: Jaws present in buccal cavity are provided with four different types of teeth (Heterodont): Incisors : For cutting Canines : For tearing Premolars : For grinding Molars : For grinding Dental formula of humans: In human beings two set of teeth appear during their life time (Diphyodont) – Milk teeth: These are temporary, arise at 6 – 11 month age, 20 in number PW OLYMPIAD WALLAH 2  NSEJS BATCH 2024 Permanent teeth: In adults 3. Oesophagus: Also called as food pipe. It leads the food from mouth to stomach. Oesophagus has highly muscular walls, no digestion occurs here. 4. Stomach: It is a ‘J’ shaped bag present on left side of abdomen. It contains several branched and tubular glands present on the inner surface of its wall, which secrete gastric juice. 5. Small Intestine: It is a coiled and narrow tube having 3 regions: duodenum, jejunum, and ileum. On the inner wall of small intestine numerous finger like projections are found which are called as villi, they increase the surface area of absorption. Duodenum is proximal part of small intestine, receives secretion from liver and pancreas. 6. Large intestine: Small intestine opens into large intestine from where the undigested food material is passed to anus through rectum. It is divided into three parts: Caecum, Colon and Rectum. Fig.: Digestive System of Human II. Histology of alimentary canal Fig.: T.S. of Alimentary Canal PW OLYMPIAD WALLAH 3  NSEJS BATCH 2024 The wall of alimentary canal from oesophagus to rectum possesses four layers namely serosa, muscularis, sub-mucosa and mucosa. Serosa is the outermost layer and is made up of a thin mesothelium (epithelium of visceral organs) with some connective tissues. Muscularis is formed by smooth muscles usually arranged into an inner circular and an outer longitudinal layer. An oblique muscle layer may be present in some regions. The sub-mucosal layer is formed of loose connective tissues containing nerves, blood and lymph vessels. In duodenum, glands are also present in sub-mucosa. The innermost layer lining the lumen of the alimentary canal is the mucosa. This layer forms irregular folds (rugae) in the stomach and small finger-like folding called villi in the small intestine. The cells lining the villi produce numerous microscopic projections called microvilli giving a brush border appearance. These modifications increase the surface area enormously. Villi are supplied with a network of capillaries and a large lymph vessel called the lacteal. Mucosal epithelium has goblet cells which secrete mucus that help in lubrication. Mucosa also forms glands in the stomach (gastric glands) and crypts in between the bases of villi in the intestine (crypts of Lieberkuhn). All the four layers show modifications in different parts of the alimentary canal. III. Digestive glands: They secrete enzymes / hormones which help in digestion. The digestive glands include: 1. Salivary glands: It produces saliva. They help in chemical digestion. They secrete an enzyme called salivary amylase or ptyalin. It helps in digestion of starch. Parotid glands: largest glands present just below the external ear. In this glands, virus causes mumps disease. (Parotid duct/Stenson’s duct) Submaxillary glands / Submandibular glands: These lie beneath the jaw-angles. (Wharton’s duct) Sublingual glands: Smallest glands which lie beneath the tongue and open at the floor of buccal cavity.(Duct of Rivinus) 2. Gastric glands: Present in stomach. They secrete hydrochloric acid, protein digesting enzymes and mucus. Present in the mucosa of the stomach. ❖ These are of 3 types: Cardiac glands: secrete an alkaline mucus. Pyloric glands: secrete an alkaline mucus. Fundic glands: each gland has 5 types of cells. Peptic/Zymogen cells - secrete pepsinogen, prorennin Oxyntic cells - secrete HCI Goblet cells - secrete mucus Argentaffin cells - produces serotonin somatostatin and histamine G-cells - secrete and store the hormone gastrin. PW OLYMPIAD WALLAH 4  NSEJS BATCH 2024 3. Liver: It consists of a large right lobe, a small left lobe and two small lobes called quadrate lobe and caudate lobe behind the main lobes. On the right lobe lies gall bladder, which, temporarily stores bile juice, secreted by the liver. It is the largest gland, secretes bile into the small intestine. Bile juice contains no enzyme but possesses bile salts and bile pigments (bilirubin-yellow and biliverdin-green). Bile is alkaline in nature and helps in digestion of fats, it also helps in absorption of fats. Functions of liver: Formation of glucose from excess organic acids. Storage of vitamins: A, D, E, B. Synthesis of vitamin A from carotene. Secretions of blood anticoagulant named heparin. Synthesis of blood or plasma proteins, fibrinogen and prothrombin Secretion of bile, detoxification of harmful chemicals. Elimination of pathogens and foreign particles through phagocytic cells called Kupffer’s cells. 4. Pancreas: It lies parallel and below the stomach. It secretes pancreatic juice into small intestine. Pancreatic juice contains trypsin and pancreatic amylase. Besides these two enzymes pancreas secretes two hormones also i.e. insulin and glucagon, so it has both exocrine as well as endocrine functions. Both bile and pancreatic juice are released into the duodenum by a common duct. 5. Intestinal glands: They secrete intestinal juice and mucus. IV. Process of Nutrition: This system involves following process: 1. Ingestion: Intake of food is done through mouth, food is then chewed and masticated and sent to oesophagus through pharynx by swallowing. 2. Digestion: Saliva secreted in buccal cavity starts digestion of starch into maltose. This partially digested food is then passed to stomach by oesophagus through peristaltic movements. Food is churned in stomach for about three hours and broken down into smaller pieces. Due to presence of hydrochloric acid, medium of stomach becomes acidic. In acidic medium protein digestive enzyme pepsin breaks down proteins into peptones. Gastric lipase is also secreted here which partially break down lipids. Secretion of gastric juice is stimulated by the sight, smell or thought of food. Now the partially digested food moves to small intestine i.e. in the duodenum. Duodenum receives the secretion from liver and pancreas through a common duct which contains bile and pancreatic juice, and alkaline in nature. So the digestion and emulsification of fats occurs at this place. Here in the duodenum fats are emulsified by bile, remaining proteins are digested by trypsin and starch by pancreatic amylase. Mind it: Duodenal wall secretes bicarbonate ions which make the medium alkaline. This partially digested food now enters into the ileum where intestinal juice i.e. “Succus entericus” is secreted. At this place digestion is completed. Carbohydrates ⎯⎯⎯⎯→ Glucose Proteins ⎯⎯⎯⎯→ Amino acids Fats ⎯⎯⎯⎯→ Fatty acids and glycerol PW OLYMPIAD WALLAH 5  NSEJS BATCH 2024 3. Absorption: Almost no absorption takes place in mouth and oesophagus. Water, alcohol, simple salts, and glucose are absorbed in the stomach. ln the small intestine, absorption of all digested materials takes place by active, passive, and facilitated transport. Glucose, sodium, and amino acids are absorbed actively. The absorption of glucose or amino acids involves carrier mediated transport which binds glucose/amino acid at one site and Na + at other site. Therefore, the movement of glucose/amino acid is coupled to the concentration gradient of Na+. Na moves along concentration gradient while glucose/amino acids are moving against concentration gradient. The rate of absorption of galactose is highest. Fructose is absorbed by facilitated diffusion. The products of fat digestion, monoglycerides, fatty acids, and glycerol are first incorporated into water- soluble droplets called micelles (a combination of fatty acids, monoacylglycerols, and bile salts); reconstructed to triglycerides in the absorptive cells and released into lymph in the form of protein-coated water-soluble fat droplets called chylomicrons. In the large intestine, only water is absorbed. Absorption of vitamin B12 (cobalamine) in man requires a glycoprotein, called intrinsic factor (IF) secreted by the parietal cells of the stomach. Failure to absorb cobalamine causes pernicious anaemia associated with a failure of RBC maturation and neurological abnormalities. Mind it: Walls of small intestine have tiny finger like projections called villi, they increase the surface area for absorption. Fig.: A Section of small intestine showing mucosa showing crypts of leiberkuhn PW OLYMPIAD WALLAH 6  NSEJS BATCH 2024 4. Assimilation: The absorbed food materials are transported by blood and lymph. Lymph is finally transferred to the blood circulation. The blood transports absorbed food materials to different body cells where food materials become integral component of the living protoplasm and are used for energy, growth and repair. This is called assimilation of food. Amino acids are not stored but are taken up by the cells in connection with the synthesis of proteins. Proteins are used for growth, repair, etc. Excess amino acids can be converted into glucose and then to fat and are thus stored. This is an irreversible reaction. Amino acids can also be converted to glucose and used as fuel for the cell. During their conversion to glucose, the amino acids are deaminated (removal of amino groups-NH2). The liver is the chief site for deamination, i.e., a process by which the amino group is removed from amino acids resulting in the production of ammonia. Ammonia is soon converted into urea, which is filtered from the blood in the kidney. The excess of monosaccharides (glucose, fructose, and galactose) are usually stored in the liver and muscle cells in the form of glycogen (glycogenesis). Whenever, there is a deficiency of glucose in the blood, glycogen is converted into glucose (glycogenolysis). Muscle glycogen is utilized during muscle contraction. Glucose is utilized in the production of energy for various body activities. A considerable amount of glucose is converted into fat and stored as such. The fat is stored in the fat deposits of the body, such as subcutaneous layers, mesenteries, etc. The stored fat is a readily available source of fuel for the cells. Fat has important insulating properties in connection with the conservation of heat and maintenance of body temperature. Fat also plays a protective role as filling or packing material, between and around the organs. In the liver, phospholipids are formed which are returned to the blood, to be used by all the cells. In liver cells, it is are converted into amino acids and carbohydrates. Vitamins, salts, and water are also useful for various metabolic processes. 5. Egestion: The undigested food along with water (about 75%) and excess of digestive enzymes is then collected in large intestine where water is absorbed and remaining waste is expelled out or egested through anus. Colon absorbs water and transports excess of ions as Ca +2 , Mg+2 etc. from blood to large intestine. The faeces are formed of 75% water, 25% solid matter which contains roughage 30%, fats 20%, inorganic matter 15%, proteins 2% and bacteria 3%.Brown colour of faeces is due to stercobilins. V. Disorders of digestive system The inflammation of the intestinal tract is the most common ailment due to bacterial or viral infections. The infections are also caused by the parasites of the intestine like tapeworm, roundworm threadworm, hookworm, pin worm, etc. 1. Jaundice: The liver is affected, skin and eyes turn yellow due to the deposit of bile pigments. 2. Vomiting: It is the ejection of stomach contents through the mouth. This reflex action is controlled by the vomit centre in the medulla. A feeling of nausea precedes vomiting. PW OLYMPIAD WALLAH 7  NSEJS BATCH 2024 3. Diarrhoea: The abnormal frequency of bowel movement and increased liquidity of the faecal discharge 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: In this condition, the food is not properly digested leading to a feeling of fullness. The causes of indigestion are inadequate enzyme secretion, anxiety, food poisoning, over eating, and spicy food. 6. Mumps: It is the viral infection in parotid gland. 7. Hernia: It is protrusion of the intestine into inguinal canal and may extend into scrotal sac. PW OLYMPIAD WALLAH 8  NSEJS BATCH 2024 RESPIRATION Respiration : It is a biochemical process of enzyme including oxidative breakdown of organic compounds inside living cells releasing energy in the form of ATP. Food+O2 ⎯Oxidation ⎯ ⎯⎯→ CO2+H2O + Energy (ATP) Breathing : The process by which organisms obtain oxygen from environment and release carbon dioxide produced during oxidation of food to the outer environment is called as Breathing. It is a part of respiration. (a) Difference between breathing and respiration : S. No. Breathing Cellular Respiration It is a physical phenomenon where exchange It is a biochemical process where glucose is 1. of oxygen and carbon dioxide takes place. oxidized to produce carbon dioxide and water. 2. Energy is not released. Energy is released. A series of respiratory enzymes are involved to 3. Enzymes are not involved. bring about the oxidation. 4. It is extra cellular. It is intracellular. (b) Differences between respiration and combustion: S. No. Respiration Combustion 1. It is a biochemical process. It is a chemical process. 2. It takes place at normal temperature. It takes place at high temperature. Respiration is a slow process completed in Combustion is fast process in which the energy several steps. Thus, the energy is also 3. is liberated only in one step resulting in liberated in several steps and remain stored in increase in temperature and production of fire. the form of ATP. 4. A series of respiratory enzymes are involved. No enzymes are involved. PW OLYMPIAD WALLAH 9  NSEJS BATCH 2024 (c) Types of Respiration : (i) Aerobic : When oxidation of food takes place in presence of oxygen. Food ⎯Glycolysis ⎯ ⎯⎯→ Pyruvic acid In cytoplasm ⎯⎯ ⎯ ⎯ ⎯ ⎯2⎯→ 6CO2 + 6H2O + 38 ATP In presence of O Kreb cycle in mitochondr ia It is called as Aerobic respiration. (ii) Anaerobic respiration : When oxidation of food material does not require oxygen or it occurs in absence of oxygen, it is called as Anaerobic Respiration. In yeast 2C2H5OH + 2CO2 + 2ATP Food Pyruvic (During fermentation) In muscles acid Lactic acid + 2ATP (During vigorous exercise) Difference between aerobic & anaerobic respiration : S. No. Aerobic Anaerobic It occurs in bacteria, certain fungi, germinating 1. It occurs in all living cells of higher plants. seeds, fleshy fruits and muscle cells. 2. It requires oxygen. Oxygen is not required. The end products are alcohol & CO2 or lactic 3. The end products are CO2 and H2O. acid. The oxidation of one molecules of glucose The number of ATP molecules produced is 4. produces 38 ATP molecules. only 2 ATP. All the reactions except the reactions of 5. All the reactions take place in cytoplasm. glycolysis take place inside mitochondria. Organic compounds are completely Organic compounds are incompletely oxidized 6. oxidized and high amount of energy is and very small amount of energy. released. 7. Non toxic to higher organisms. Toxic to higher organisms. (d) Step of respiration : (i) External respiration : Exchange of gases between an organism and its environment. (ii) Internal respiration : Exchange of gases between tissue cells and extracellular environment. (iii) Cellular respiration : Involves oxidation of food along with release of energy, inside cell. RESPIRATION IN ANIMALS Respiration in animals takes place as a single unit, they have different types of organs for respiration due to which mode of respiration also varies according to the organism but the basic mechanism is same. PW OLYMPIAD WALLAH 10  NSEJS BATCH 2024 − Mastery Point S. No. Animals Type of Respiration Diagram Diffusion : Exchange of gases takes 1. Amoeba (Protozoa) place through general body surface. Moist skin Cutaneous Respiration : Exchange of 2. Earthworm (Annelida) gases occur through moist skin. Gill cover Eyes Branchial Respiration : Exchange of Nostril Gill arch 3. Fish (Pisces) Mouth gases through gills. Tracheal Respiration : Exchange of 4. Grasshopper (Arthropoda) gases through spiracles. − Mastery Point  The structure and function of fish gills : PW OLYMPIAD WALLAH 11  NSEJS BATCH 2024  A fish continuously pumps water through its mouth and over gill arches, using coordinated movements of the jaws and operculum (gill cover). (A swimming fish can simply open its mouth and let water flow past its gills.) Each gill arch has two rows of gill filaments, composed of flattened plates called lamellae. Blood flowing through capillaries within the lamellae picks up O2 from the water. Notice that the countercurrent flow of water and blood maintains a partial pressure gradient that drives the net diffusion of O2 from the water into the blood over the entire length of a capillary.  A tracheal system. Some important characteristics of respiratory organs of animals are : They have large surface area to get enough oxygen. They have thin walls for easy diffusion and exchange of gases. They have rich blood supply for transport of respiratory gases. RESPIRATION IN HUMANS (i) Human respiratory tract : I. External nostrils : First part of respiratory system. It opens into nasal cavity and is meant for inhalation of air from outside. Figure : HUMAN RESPIRATORY SYSTEM PW OLYMPIAD WALLAH 12  NSEJS BATCH 2024 II. Nasal cavity : This cavity is separated from oral cavity by means of a hard and bony palate. It is lined by Pseudostratified ciliated columnar epithelial cells which are rich in mucus, it brings about warming, moistening and sterilization of air. It contains hair and mucus which entrap the dust particles. III. Internal nares : Nasal cavity opens into it and it leads to pharynx. IV. Pharynx : It is a common part between both alimentary canal and respiratory system. V. Larynx : It is an enlarged, upper part of trachea which is also called as ‘voice box’. It produces voice by passage of air between vocal cords. It contains three different types of cartilages. Among them a ‘c’ shaped thyroid cartilage protruding out in neck region is called Adam’s Apple. Can you think why ? Why C-shaped rings are present on Trachea ?  Fig. : Bronchial intercom inside lung VI. Trachea : It is also called wind pipe. It is 10-12 cm long tube. It’s walls are supported by 16 – 20 ‘c’ shaped cartilagenous rings which prevent them to collapse when air is absent in them. VII. Bronchi : Trachea is branched into two bronchi left and right each of which enters into the lungs. VIII. Lungs : The lungs occupy the greater part of the thoracic cavity. Surrounding each lung is a double-walled sac within the walls of which lies the pleural cavity. The right lung is divided into three lobes and left into two. Inside the lung, each bronchus divides into numerous bronchioles, each of which terminates into an elongated saccule, the alveolar duct, which bears on its surface air sacs or alveoli. The number of alveoli in the human lungs has been estimated to be approximately 300 million. The lungs are covered by a thin double layer of simple squamous epithelium called the pleura. The outer or parietal pleuron remains attached to the wall of thoracic cavity. The space between the two pleural membranes contains pleural fluid for reducing function and makes the movement of lung easy. Inflammation of the pleura causes a disease called pleurisy. Lungs are pink at birth, they become dark grey and mottled in adults due to deposition of carbonaceous materials. PW OLYMPIAD WALLAH 13  NSEJS BATCH 2024 Darkening increases in smokers and persons exposed to pollutants. The right lung is shorter by about 2.5 cm due to raised position of diaphragm on the right side to accommodate liver. The left lung is longer. It is, however, narrower than the right lung because it contains a cardiac notch for accommodating asymmetrically placed heart. Left lung is divisible by an oblique fissure into two lobes. Right lung has two fissures, horizontal and oblique. They divide the right lung into three lobes. IX. Diaphragm: It is a sheet of muscles that lies below the lungs and separates thoracic cavity from abdominal cavity. X. Intercostal Muscles : Intercostal muscles are several groups of muscles that run between the ribs, and are mainly involved in the mechanical aspect of breathing. These are of 2 types: 1. External Intercostal muscles - Assist in the process of inspiration. 2. Internal Intercostal muscles - These are not involved in the process of normal breathing. They help in the process of forceful breathing. XI. Thoracic Cage: Lungs are situated in the thoracic chamber which is anatomically an air tight chamber. The thoracic chamber is formed. Dorsally by vertebral column. Ventrally by sternum. Laterally by ribs. On the lower side by dome shaped diaphragm Respiratory System of man PW OLYMPIAD WALLAH 14  NSEJS BATCH 2024 − Mastery Point  Vocal cord : In larynx, 2 pairs of vocal cord is found outer pair is false vocal cord where as, inner pair is true vocal cord when air is forced through the larynx it cause vibration of true vocal cords and sound is produced.  Trachea & nasal cavity are lined by pseudo stratified ciliated columnar glandular epithelium.  Epiglottis : It prevents the entry of food into the trachea.  Left lung is smaller than right lung due to the presence of cardiac notch at left side.  Step of respiration : (A) Breathing (B) Transportation of gases (C) Cellular respiration A. Breathing : (i) Inspiration : Intercostal and Phrenic muscles of diaphragm contract to increase the volume of thoracic cavity, therefore outside air rushes inside. (ii) Expiration: Intercostal & Phrenic muscles relax. Due to decrease in volume of thoracic cavity air pressure within lungs increase, the greater pressure within lungs causes forceful expiration of air from lungs to outside of body. PW OLYMPIAD WALLAH 15  NSEJS BATCH 2024 B. Transportation of gases: Gaseous exchange occur in Alveoli following diffusion of pressure gradient that causes diffusion of O2 from high pressure in alveoli into blood & CO2 from blood into alveoli. Fig.: Transportation of gases (i) Transport of oxygen: There are two ways for oxygen transport. As much as 97 per cent of the oxygen is transported from the lungs to the tissues in combination with haemoglobin and only 3 percent is transported in dissolved condition by the plasma. 100 ml of blood can carry upto 20 ml of O2. (ii) Transport of Carbon dioxide: Carbon-dioxide is transported from the tissues to the lungs by three methods. When a respiring tissue releases carbon-dioxide, it is first diffused in the blood. From here it diffuses into the red blood cells. About 23% of carbon dioxide entering into the erythrocytes combines with the globin (protein) part of haemoglobin to form carbaminohaemoglobin, which is transported to the lungs. About 70% of carbon-dioxide is transported in the form of bicarbonates dissolved in water. Only 7% is transported in dissolved form in plasma. Fig. : Transport of Carbon dioxide & Oxygen PW OLYMPIAD WALLAH 16  NSEJS BATCH 2024 C. Cellular respiration : It refers to the oxidation of food taking place inside the cell. As this process is at cellular level so it is called cellular respiration. It takes place in three steps : (i) Glycolysis (ii) Kreb Cycle (iii) Electron Transport System Carbohydrates During digestion Glucose Glycolysis Pyruvic acid in absence of O2 in presence of O2 Anaerobic respiration Aerobic respiration C2H5OH + CO2 + 2ATP Kreb Cycle CO 2 + H 2O + 38ATP (A) Glycolysis : Glycolysis also called EMP (Embden Meyerhof Parnas) pathway : Site: Cytoplasm of cell. (i) In this cycle glucose is converted into pyruvic acid in presence of many enzymes and co-enzymes. (ii) Oxygen is not required during glycolysis. (iii) 1 molecule of glucose gives rise to 2 molecules of pyruvic acid. (iv) In this process 4 molecules of ATP are formed, among them 2 ATP molecules are utilized thus there is a net gain of 2 ATP molecules. (v) 2 NAD molecules are reduced to 2 NADH2, which later produces 6ATP molecules. (vi) Net production of ATP in glycolysis is 2ATP + 6ATP = 8 ATP. (vii) There is no production of CO2 during this process. Mind it: After glycolysis, pyruvic acid is converted into acetyl Co-A with the release of CO2 and the process is called as ‘oxidative decarboxylation’. It occurs in mitochondria of the cell. Besides this 2 NAD molecules are reduced to 2 NADH2, which later produces 6ATP molecules. (B) Kreb’s Cycle : Site : Mitochondria of cell (i) Also called aerobic oxidation. (ii) Discovered by Sir Hans Kreb. (iii) Another name TCA cycle (tricarboxylic acid cycle) or Citric acid cycle. (iv) It brings about the conversion of pyruvic acid, fatty acids, fats and amino acids into CO 2 and water by oxidation. (v) It is the common path for oxidation of carbohydrates, fats and proteins. (vi) It starts with acetyl Co-A which is then converted into several intermediate compounds with the release of ATP, hydrogen atoms (NADH2 and FADH2) and then Acetyl Co-A is regenerated back. (vii) For each glucose molecule the Krebs’s cycle occurs twice, so produces 2 ATP, 6 NADH2 and 2 FADH2. Therefore it accounts for total 24 ATP molecules. PW OLYMPIAD WALLAH 17  NSEJS BATCH 2024 (C) Electron Transport System or ETS : Site : Mitochondria of cell (i) n this hydrogen atoms produced during oxidation of various intermediates during Glycolysis, Oxidative- decarboxylation and Kreb cycle are first broken into protons and electrons. (ii) These protons and electrons after passing through a series of coenzymes and cytochromes combine with oxygen to form water molecules. (iii) During these series of events 1 NADH2 releases 3ATP molecules and 1 FADH2 gives 2 ATP molecules which were produced during Kreb cycle and glycolysis. Mind it : The net gain of ATP molecules during respiration is 38ATP molecules among them: (A) 8ATP from glycolysis (B) 6 ATP from conversion of pyruvic acid into acetyl Co-A. (C) 24 ATP from Krebs cycle Besides this CO2 and H2O are also released. CONTROL OF BREATHING IN HUMAN  The neurons mainly responsible for regulating breathing are in the medulla oblongata, near the base of the brain. Neural circuits in the medulla form a breathing control center that establishes the breathing rhythm. When you breathe deeply, a negative-feedback mechanism prevents the lungs from over expanding. During inhalation, sensors that detect stretching of the lung tissue send nerve impulses to the control circuits in the medulla, inhibiting further inhalation. In regulating breathing, the medulla uses the pH of the surrounding tissue fluid as an indicator of blood CO2 concentration. The reason pH can be used in this way is that blood CO2 is the main determinant of the pH of cerebrospinal fluid, the fluid surrounding the brain and spinal cord. PW OLYMPIAD WALLAH 18  NSEJS BATCH 2024 Carbon dioxide diffuses from the blood to the cerebrospinal fluid, where it reacts with water and forms – carbonic acid (H2CO3). The H2CO3 can then dissociate into a bicarbonate ion (HCO3 ) and a hydrogen ion (H+ ): CO2 + H2O H2CO3 HCO3– + H+ Increased metabolic activity, such as occurs during exercise, lowers pH by increasing the concentration of CO2 in the blood. Sensors in blood vessels and the medulla detect this pH change. In response, the medulla’s control circuits increase the depth and rate of breathing. Both remain high until the excess CO2 is eliminated in exhaled air and pH returns to a normal value.  Dissociation curve for haemoglobin : (b) pH and haemoglobin dissociation: Because hydrogen ions affect the shape of haemoglobin, a drop in pH shifts the O2 dissociation curve towards the right (the Bohr shift). At a given PO2, say 40 mm Hg, haemoglobin gives up more O2 at pH 7.2 than at pH 7.4, the normal pH of human blood. The pH decreases in very active tissues because the CO2 produced by cellular respiration reacts with water, forming carbonic acid. Haemoglobin then releases more O2, which supports the increased cellular respiration in the active tissues. SOME RESPIRATORY DISORDERS Emphysema It occurs due to infection, smoking etc. It occurs due to obstructions in bronchioles caused by breaking of alveolar septa. Bronchodilators and O2 therapy are used, for curing this disease. Asthma Air passages are narrowed and lead to obstruction in breathing. Pneumonia Lymph and mucus accumulate in alveoli and bronchioles. It occurs due to bacterial and viral infection. Bronchitis Swelling in living membranes of respiratory tract due to excessive smoking. Tuberculosis Bacterial infection in lungs. Pleurisy Inflammation of lung membrane called as pleurisy. PW OLYMPIAD WALLAH 19  NSEJS BATCH 2024 − Mastery Point  Forceful respiration is controlled by Pons.  The average breathing rate in an adult man at rest is about 15 to 18 times per minute.  Tidal Volume : Volume of air inspired or expired with each normal breathing.  Residual volume : It is the volume of air left in the whole respiratory tract after forceful expiration. It is 1.2 liters.  The deficiency of haemoglobin in the blood of a person reduces the oxygen carrying capacity of blood resulting in breathing problems, tiredness and lack of energy.  Carbon Monoxide effect : Carbon monoxide binds very strongly with haemoglobin in the blood and prevents it from carrying oxygen to the brain and other parts of the body. The resulting deficiency of oxygen causes headache, dizziness, nausea and even death.  Sudden contraction of diaphragm along with loud closure of glottis causes Hiccup.  Sudden and violent expulsion of air through mouth and nose is called Sneezing.  Mountain Sickness : In order to oxygenate the body effectively, breathing rate (even while at rest) has to be increase in the blood, but not to sea level concentrations. The fail in oxygenation of blood produces the symptoms of mountain sickness. These symptoms include breathlessness. Headache, dizziness, nausea, vomiting, mental fatigue and a bluish tinge on the skin, nails and lips. Can you think why ? Why is breathing rate increased during physical exercise ? − Mastery Point  Respiratory distress syndromes Experiment : Few scientists at Harvard University Medical School, wondered whether a lack of surfactant caused respiratory distress syndrome (RDS) in preterm infants. She obtained autopsy samples of lungs from infants that had died of RDS and from infants that had died of other causes. She extracted material from the samples and allowed it to form a film on a water surface. Then Dr. Avery measured the tension (in dynes per centimeter) across the surface of the water and recorded the lowest surface tension observed for each sample. Result : Conclusion: The lungs of infants with a body mass over 1,200 g (2.7 pounds) contain a substance that reduces surface tension. That substance is absent in the lungs of infants with RDS.   Breathing in birds Two cycles of inhalation and exhalation are required to pass one breath through the system: 1. First inhalation: Air fills the posterior air sacs. 2. First exhalation: Posterior air sacs contract, pushing air into lungs. 3. Second inhalation: Air passes through lungs and fills anterior air sacs. 4. Second exhalation: As anterior air sacs contract, air that entered body at first inhalation is pushed out of body. PW OLYMPIAD WALLAH 20  NSEJS BATCH 2024 TRANSPORTATION IN ANIMALS (a) Types of circulatory system: Among animals two types of circulatory systems are found: (i) Open circulatory system (ii) Closed circulatory system − Concept Boosters  In an open circulatory system, such as that of a grasshopper, hemolymph surrounding body tissues also act as the circulatory fluid.  In a closed circulatory system, such as that of a earthworm, interstitial fluid surrounding body tissues is distinct from blood acting as the circulatory fluid. PW OLYMPIAD WALLAH 21  NSEJS BATCH 2024 − Concept Boosters  Examples of circulatory schemes. (a) Single circulation: fish  Bony fishes, rays, and shark have a single circuit of blood flow and a single circulatory pump – a heart with two chambers. (b) Double circulation: amphibian PW OLYMPIAD WALLAH 22  NSEJS BATCH 2024 (c) Double circulation: reptiles (d) Double circulation: mammal and birds  Amphibians, reptiles, and mammals have two circuits of blood flow and two pumps fused into a multi- chambered heart. Note that circulatory system are depicted as if the animal is facing you. The right side of the heat is shown on the left, and vice versa.  PW OLYMPIAD WALLAH 23  NSEJS BATCH 2024 (b) Transportation in humans: In humans there is a circulatory system (Closed circulatory system) that uses blood or lymph as carriers of materials (fluid exchange medium) and the heart as the pumping organ to help in circulation. Circulatory system consists of blood vascular system (blood as carrier) and lymphatic system (lymph as carrier). (i) Blood Vascular System: The higher multicellular animals with higher metabolic rates possess a well developed blood vascular system. This system helps in the quicker supply of nutrients and oxygen to the body tissues and also in the rapid disposal of toxic waste materials and carbon dioxide. The blood acts as the circulatory fluid. Blood vascular system consists of blood, blood vessels and heart. I. Blood: The blood is a specialized kind of living connective tissue which is made to circulate, by the muscular pumping organ called as heart. In adult human beings there is 5.5 to 6 liter of blood. The blood consists of fluid part (the plasma) and blood corpuscles. The red blood corpuscles (RBCs), white blood corpuscles (WBCs) and blood platelets are present in the plasma. The formation of blood is called “Haemopoiesis”. 1. Plasma: The plasma consists of water (90% & above) inorganic and organic substances. In the plasma, RBCs, WBCs and blood platelets float. Inorganic salts (0.9%) are also present. The organic substances are glucose, amino acids, proteins, hormones, digested and waste excretory products. The blood proteins (7%) are fibrinogen, albumin, globulin and prothrombin. Mind it: Serum is plasma from which fibrinogen is removed.(Plasma–Fibrinogen = Serum.) 2. Blood Corpuscles: Red Blood Corpuscles (RBCs) or Erythrocytes: The number of RBCs is about 5.5 million per mm3 of blood. The total number of RBC is about 30 billion. Each RBC is a biconcave disc-like structure devoid of nucleus. The mammalian erythrocytes do not possess nuclei, mitochondria and endoplasmic reticulum. The erythrocytes contain haemoglobin. Haemoglobin consists of globin (protein) and Fe2+ porphyrin complex (haem). 100 ml of blood contains 15 g of haemoglobin. If the amount of haemoglobin in blood is less, the person suffers from anaemia. The haemoglobin carries oxygen to the different cells of the body and brings carbon dioxide from the cells. The life span of a RBC is 120 days. White Blood Corpuscles (WBCs) or Leucocytes: The number of leucocytes is comparatively fewer i.e. 1mm3 of blood contains 5000 – 10000 leucocytes in humans. The total number of WBCs is about 75 millions. The number of leucocytes increases in infections like pneumonia, blood cancer (Leukemia) etc. These are large in size and contain nucleus. White blood corpuscles are of two types: Granulocytes: Contains granules in the cytoplasm. They are of three types: Eosinophils, Basophils and Neutrophils. Agranulocytes: Monocytes and lymphocytes are two different types of agranulocytes. Lymphocytes secrete antibodies which destroy microbes. The monocytes are phagocytic in nature. PW OLYMPIAD WALLAH 24  NSEJS BATCH 2024 Flow Chart Fig.: Different types of Blood Corpuscles Blood platelets: These are small and without nuclei. Their number varies from 0.15 to 0.45 million per mm3 of blood. Their normal life span is one week. These help in blood clotting at the site of injury by liberating thromboplastin. 3. Functions of Blood: Blood performs the following functions: Transportation of nutrients: The digested and absorbed nutrients like glucose, amino acids, fatty acids are first transported to the liver and then to all the tissues for their storage, oxidation and synthesis of new substances. Transportation of respiratory gases: The respiratory gases (oxygen, carbon-dioxide) are transported by the blood. Oxygen is transported from the respiratory surface (lung, skin and buccal cavity) to the tissues and carbon dioxide from the tissues is taken to the respiratory organ for its removal. Transportation of excretory products: Different wastes from the different parts of the body are collected by the blood and then taken to the organs (kidneys, lungs, skin and intestine) from where they are excreted. Transportation of hormones: Hormones are produced by endocrine glands. These hormones have target organs (place to act). These are carried by the plasma of blood and bring about the coordination in the working of the body. Maintenance of pH: The plasma proteins act as buffer system and maintains required pH of the body tissues. PW OLYMPIAD WALLAH 25  NSEJS BATCH 2024 Regulation of body temperature: The blood flows in all the parts of body, so it equalizes the body temperature. It carries heat from one place to another place in the body. Transportation of metabolic intermediates: The blood carries metabolic intermediates from one tissue to another for further metabolism. In the muscle cells due to anaerobic respiration lactic acid is produced. This lactic acid is carried to the liver for further oxidation. Water balance: The blood maintains water balance to constant level by distributing it uniformly in the body. Protection from diseases: The WBCs (neutrophils and monocytes) engulf the bacteria and other disease causing organisms by phagocytosis. The B- lymphocytes produce antibodies to neutralize the action of toxins produced by pathogens. Clotting of blood: Blood forms a clot at the site of injury and thus prevents the further loss of blood. Support. Blood flows under pressure in arteries. Due to this tissue become stiff as in the case of erection of nipples, clitoris and penis. 4. Blood Clotting: At the site of injury of the blood vessels, the platelets induce blood coagulation through the release of thromboplastin (thrombokinase). Thromboplastin changes prothrombin of blood plasma into thrombin. Thrombin converts soluble protein fibrinogen to insoluble fibrin. Fibrin forms a network which entangles RBCs and blood platelets to form plug or clot over the injured area. Blood clotting is usually completed within 2-3 minutes. Injured tissue + Blood platelets ⎯⎯ → Thromboplastin released Prothrombin ⎯⎯⎯⎯⎯ Thromboplastin Ca ++ → Thrombin Fibrinogen ⎯⎯⎯⎯ → Fibrin Thrombin (Soluble) (Insoluble) Fibrin + Red blood corpuscles ⎯⎯ → Clot of blood 5. Blood Groups: Landsteiner discovered that blood of different individuals did not match each other but there were biochemical differences. He discovered Antigens A and B and blood groups (ABO systems). Antigen (agglutinogen) is a glycoprotein present on RBCs. For each antigen there is a corresponding antibody. Thus there are two antibodies (agglutinin) a and b occurring in the blood plasma. There are four types of blood groups depending on the presence or absence of these antigens. Blood is a life saving fluid. It is often needed during accident and operation. The transfusion of blood is only done when blood group is known. These groups are A, B, AB and O. Blood of O group is a universal donor i.e. it can donate blood to any group (A, AB, B and O) but it can receive blood from O blood group. AB group is a universal recipient (receiver). It can receive blood from any group (A, B, AB, and O) but it can donate to AB group only. PW OLYMPIAD WALLAH 26  NSEJS BATCH 2024 6. Blood Transfusion: The transfusion of blood from a healthy person to a patient suffering from blood loss due to injury or surgical operation is called as “blood transfusion”. For this all major hospitals have blood banks where blood is collected from voluntary and professional donors. Before preservation the blood is tested for its blood group and Rh factor. Though theoretically a patient may be able to receive blood of two or more types, it is always advisable to have the donor blood of the same group as that of the recipient. The blood of donor is always cross matched before transfusion to exclude any chance of incompatibility. When blood from a donor is added to blood of the recipient, it is necessary to avoid bringing together corresponding antigen and antibody. This causes clumping of RBCs. Thus antigen A in RBCs of group A individuals reacts with antibodies of plasma of group B individuals. This phenomenon is called “agglutination”. ✓ Compatible  Incompatible Rh factor: Rh factor is also a type of antigen found on RBCs. Rh factor (in blood) can be genetically determined. Most of the people (more than 85%) are Rh-positive (Rh+) while a few are Rh negative (Rh–). Both people lead normal life. If an Rh– woman marries with an Rh+ man then Ist pregnancy is normal but in 2nd pregnancy the mother with Rh– blood may lose the baby due to incompatibility of Rh factor. This is known as Erythroblastosis foetalis. By new techniques and procedures, now the child can be saved. II. Blood Vessels: These are hollow tubes through which the blood flows. 1. Arteries: These are thick walled and deep seated blood vessels which generally carry the oxygenated blood away from the heart to various body parts. 2. Veins: These are thin walled and superficially located blood vessels which generally carry deoxygenated blood from the body parts to heart. 3. Capillaries: These are thinnest blood vessels and connect the branches of arteries and veins which make the diffusion of various substances possible. PW OLYMPIAD WALLAH 27  NSEJS BATCH 2024 III. Heart: Heart is a hollow muscular organ that lies obliquely in the thoracic region in a cavity between the two lungs that is pericardial cavity. It is lined by 2 layers outer and inner pericardial membranes. These are filled with a fluid called “pericardial fluid”. It protects the heart from shock and injury. Note: Heart is 2 chambered in fishes (Venous heart), 3 chambered in amphibians, incompletely 4 chambered in reptiles and 4 chambered in birds and mammals. Heart is made up of 4 chambers: upper 2 chambers are auricles/atrium and the lower 2 chambers are ventricles. Auricles are the receiving chambers and ventricles are the pumping chambers. Walls of ventricles are thicker as they have to pump the blood. Partition between right and left auricle is called “interauricular septum” and between right and left ventricles is “inter ventricular septum”. Fig.: Structure of Heart Four pulmonary veins enter into left auricle, two from each lung bring oxygenated blood. There is one auriculoventricular aperture with a bicuspid or mitral valve in left auricles which opens into left ventricle. Left ventricle has aortic valve having 3 semilunar cusps for large artery i.e. dorsal aorta which takes the oxygenated blood to all body parts. Right auricle has openings for superior venacava that brings deoxygenated blood from head, neck and upper limbs, inferior venacava receives deoxygenated blood from rest of the body and lower limbs. A coronary sinus that drains venous blood from heart muscles into right auricle. Blood enters in to right ventricle through tricuspid valve. Right ventricle has pulmonary valve having 3 semilunar cusps for pulmonary artery carrying deoxygenated blood to lungs. Note: During foetal condition a flap valve called “foramen o vale” is present at interauricular septum after birth this foramen closes remain as a depression called as fossa ovalis. If it remains after birth it results “a hole in the heart”. IV. Types of circulation: 1. Single circulation: In this, blood passes once through the heart to supply once to the body. It is found in fishes which have two chambered (one auricle and one ventricle). 2. Double circulation: In double circulation, the blood passes twice through the heart to supply once to the body. Double circulation involves two circulations: PW OLYMPIAD WALLAH 28  NSEJS BATCH 2024 Systemic circulation: Blood completes its circulation from left ventricle to right auricle through the body organs. Pulmonary circulation: Blood completes its circulation from right ventricle to left auricle through the lungs. Fig.: Double blood circulation V. Cardiac Cycle: The serial wise or sequential changes which take place in the heart are called cardiac-cycle. The contraction of the auricles is termed as auricular systole or atrial-systole, and their relaxation is called atrial-diastole. Same way the contraction and relaxation of ventricles is termed as ventricular systole and ventricular diastole. The time of cardiac-cycle is the reverse ratio of heart beat per minute. If heart beat per minute is 72, then the time of cardiac-cycle is 60/72 = 0.8 seconds. Cardiac Events: Following events are related to the Cardiac-cycle- Outer circle → Auricles – Systole Inner circle → Ventricles – Diastole Fig.: Common diagram showing events of both auricles & Ventricles In a single cardiac cycle of man - 1. Auricular systole = 0.1 sec 2. Auricular diastole = 0.7 sec 3. Ventricular systole = 0.3 sec 4. Ventricular diastole = 0.5 sec PW OLYMPIAD WALLAH 29  NSEJS BATCH 2024 1. “Ventricular-systole”- It is an important process because during it the blood is pumped out of the heart into the arteries. Walls of the ventricles start contracting, due to which pressure is more in the ventricles. Due to the increase of this pressure the “Cuspid valves” close producing “LUBB” sound. During ventricular systole, the auricles receive blood from the veins. 2. “Ventricular Diastole”- Ventricles start relaxing now due to which pressure inside them falls further. As a result of this, closure of semilunar valves occurs due to which ‘DUP’ sound is heard at the onset of ventricular diastole. 3. “Auricle-Systole” – Due to contraction in the auricles the remaining blood comes into the ventricles so the atrial pressure now becomes zero. 4. “Auricle-Diastole” – Auricle start relaxing now. Due to the presence of almost zero pressure in the auricles, during diastole the auricles start receiving further blood from the veins. Joint Diastole 0.8 – 0.4 = 0.4 sec. (Period during which entire heart is in Diastole) Cardiac output it is the amount of blood pumped by the each ventricle per minute. Its value in a normal adult is about 5 liter/minute. Cardiac output = stroke volume x heart rate. Heart Sounds: The first sound “LUBB” is produced when the atrio-ventricular valves get closed sharply at the start of ventricular systole. The second sound “DUPP” is produced when at the beginning of ventricular diastole, the semilunar valves at the roots of aorta and pulmonary artery get closed. VI. Blood Pressure: It is the pressure of the flow of blood in the aorta and its main arteries. The blood pressure varies according to the contraction and relaxation of the heart. In the condition of contraction or systolic phase (Lubb sound) it is about 120 mm of Hg. This is called “systolic pressure”. In the relaxation or diastolic phase (Dupp sound) it is about 80 mm of Hg and is called “diastolic pressure”. The normal blood pressure of man (20 years) is 120/80. Fats and anxiety increases the blood pressure. The maximum normal blood pressure (systolic) should not exceed 150 in males and 140 in females. The blood pressure is measured by “Sphygmomanometer”. PW OLYMPIAD WALLAH 30  NSEJS BATCH 2024 Detection of Normal functioning of Heart: The muscle fibres of heart are specialized at certain parts called sinoatrial node (SA node or pacemaker) that generate tiny electrical currents which cause the normal heart beats. The “electrocardiograph” (E.C.G.) is the device to record these electrical changes. Electrocardiogram is a record of electrical behaviour of heart and remains constant in a normal man. Doctors use the E.C.G. for detection of various heart diseases. Sometimes the sinoatrial node (SA node or pacemaker) gets damaged and fails to generate cardiac impulses at normal rate. It becomes abnormally slow and irregular and ventricles fail to pump the required amount of blood. It can be corrected by the surgical grafting of an artificial pacemaker instrument in the chest of the patient. This instrument stimulates the heart electrically at regular intervals to maintain the beats. VII. Electrocardiogram (ECG) It is a graphical representation of the electrical activity of the heart during a single cardiac cycle. The electrocardiogram is obtained by a machine known as electrocardiograph. The study or the process of recording of electrocardiogram is called electrocardiography. The impulse generated by the SA node causes contraction and relaxation of heart chambers. To obtain an ECG, a patient is connected to the machine with three electrical leads (i. e., one to each wrist and one to the left ankle), monitoring the activity of heart continuously and heart’s functioning is evaluated by attaching multiple leads to the chest region. Reading an ECG An ECG consists of five peak, identified with the letter P to T that corresponds to a specific electrical conductivity of the heart. These corresponds to a specific electrical activity of the heart as follows: Fig.: Diagrammatic representation of a standard ECG P-Wave: It is the first and the foremost wave of low amplitude. It represents the electrical excitation or depolarisation of the atria which leads to contraction of both the atria. QRS-Wave or Complex: The Q, R and S wave together forms the QRS complex. This represents the depolarisation of the ventricles, which initiates the ventricular contraction. It marks the spread of impulse from AV node to ventricles, through bundle of His and Purkinje fibres. The contraction starts shortly after Q and marks the beginning of the systole. T-Wave: It is a broad and smoothly rounded deflection, which represents the return of the ventricles from excited to normal state (repolarisation). The end of T-wave marks the end of systole. It has been observed that, by counting the number of QRS complexes, that occur in a given time period, one can easily determine the rate of heartbeat of an individual. However, the deviation in the ECG of any person from the normal shape ECG, indicates a possible abnormality or a disease. PW OLYMPIAD WALLAH 31  NSEJS BATCH 2024 Significance of ECG It gives accurate information about the normal functioning of atria and ventricles. Indicates the functioning of valves. Also helps in indicating any damage to local tissues of the heart in detection of overgrowth of cardiac/heart chambers. VIII. Regulation of Cardiac Activity: The normal activities of the heart are intrinsically regulated, i. e., autoregulated by the specialized muscles, (nodal tissue). Thus, the heart is known as myogenic heart. The neurogenic heartbeat is initiated by a nerve impulse, e. g., annelids and most arthropods. The rate of its formation and conduction is regulated by the following 1. Neural Regulation: In medulla oblongata, a special neural centre is present, which can moderate, the cardiac function through the Autonomic Nervous System (ANS). The neural signals through the sympathetic nerves (part of ANS) increase the rate of heartbeat by stimulating SA node, it also increases the strength of ventricular contraction and Hereby, the cardiac output. Whereas, the neural signal through parasympathetic nerves (another component of ANS) can decrease the rate of heartbeat by inhibiting the SA node, speed of conduction of action potential, thereby decreasing the cardiac output. 2. Hormonal Regulation: Adrenaline and noradrenaline hormones secreted by the medulla of adrenal gland has significant role in regulating heartbeat and thus increasing the cardiac output. The nor-adrenaline accelerates the heartbeat, while adrenaline does this function at the time of emergency. IX. Disorders of circulatory system: Many diseases may affect the blood vessels and the normal functioning of the heart. Some of the common disorders are as follows 1. High Blood Pressure (Hypertension): The pressure exerted by the flow of Blood on the elastic walls of the arteries is known as blood pressure. Hypertension is the term used for blood pressure higher than the normal. The normal blood pressure in humans is measured as 120/80 mm Hg (millimeters of mercury pressure), Persistent increase in Blood pressure above 140 mmHg (systolic) and 90 mmHg (diastolic) is termed as hypertension. Condition of Hypertension may lead to many heart diseases and also affects vital organs of the body, like the brain and kidney. 2. Coronary Artery Disease (CAD): It is the hardening of arteries and arterioles due to the thickening of the fibres tissue and the consequent loss of elasticity. It is often referred to as atherosclerosis. This mainly affects the vessels, which are mainly responsible for supplying blood to the heart muscle. It seems to occur due to deposition of calcium, far cholesterol and fibrous tissues, making the lumen of arteries narrower. 3. Angina (Angina Pectoris): This tends to occur when enough oxygen does not reach the heart muscles. It occurs both in men and women of any age but seems to be more common among the middle-aged and elderly individual. A symptom of acute chest pain occurs in individual suffering from angina, which mainly occurs due to the conditions that affect the blood flow. PW OLYMPIAD WALLAH 32  NSEJS BATCH 2024 4. Heart Failure: It is the condition of the heart when it fails to pump blood effectively to meet the needs of the body. The heart failure is sometimes called the congestive heart failure, as its main symptom is congestion of lungs. 5. Bradycardia and Tachycardia: Tachycardia is a term applied to a rapid heart or pulse rate (over l00/ mins) Bradycardia is the term indicating a slow heart or pulse rate (under 50/min). Mastery Point:  Portal System When the vein of any organ of the body does not open in the caval vein or heart but it divides into capillaries in any other organ and its blood is transported by vein of that other organs to the heart, then this type of system is termed as portal system. It is of following types:- (i) Renal portal system (ii) Hepatic portal system (iii) Hypophysial portal system In mammals, renal portal system is absent. In Frog both the portal systems; renal portal system and hepatic portal system are present. (ii) Lymphatic System: The lymphatic system comprises the lymph, lymphatic capillaries (simply lymphatics), lymphatic vessels and nodes. Lymph serves as the middle man between the blood and organ for exchange of any material. The lymph is the tissue fluid present in the intercellular spaces in the tissues. So it is also called as “extracellular fluid”. The lymph resembles the blood except that the lymph is devoid of R.B.Cs, blood platelets and some plasma proteins. Lymphatic system runs parallel to the veins. The lymphatic capillaries are present in the form of network under epithelial surface.The ends of lymphatic capillaries are blind. The lymphatic capillaries unite to form lymphatic vessels and these vessels resemble with the veins. The lymphatic vessels possess the valves which prevent back flow of lymph. Neighboring body muscles help in the flow of lymph. The small lymphatic vessels unite to form large vessels. Larger lymphatic vessels unite to form large ducts i.e. right lymphatic duct and thoracic duct. Right lymphatic duct opens into right subclavian vein and left thoracic duct opens in to left subclavian vein. Before the lymph reaches the blood, it always passes through the lymph nodes. The lymph nodes are enlargements of the lymphatic vessels. Lymphocytes and other plasma cells are present in the lymph nodes. The lymph is cleaned or filtered by lymph nodes. These cells also kill the germs and produce antibodies. PW OLYMPIAD WALLAH 33  NSEJS BATCH 2024 Fig.: Diagram of Human lymphatic system Functions of Lymph: (i) It provides immunity through lymphocytes. (ii) Fats are absorbed through lymph vessels in the intestine. (iii) It supplies digested food and oxygen to various parts of the body. (iv) It helps in removal of waste products like parts of dead cells. (v) It returns proteins and excess tissue fluid to the blood from the tissue spaces. Mastery Point:  Spleen Spleen is known to be the largest lymph node of body. It is the blood bank of the body. Spleen is also called " Graveyard of RBC". Spleen originates from embryonal mesoderm. Spleen is red- coloured lymph node, it is found attached by mesentery to the lateral side of stomach. It is the largest solid mass of reticule endothelial tissue in the body. It is covered by a capsule formed of elastic fibrous connective tissue and smooth muscles. It is called splenic capsule.  Functions of spleen:- 1. Its macrophages engulf or phagocytize and destroy worn-out blood cells, live or dead pathogens, cell debris etc. 2. In the embryonal stage it produces RBCs. 3. Some antibodies are synthesised here. 4. In adult stage spleen works as blood bank. Its sinuses serve as reservoirs of blood when required their blood is squeezed into circulation. 5. Spleen stores iron. 6. The size of spleen increases at the time of malaria because lymphocytes & dead RBC number is increased in it at that time (splenomegaly). PW OLYMPIAD WALLAH 34  NSEJS BATCH 2024 EXCRETION IN ANIMALS There are various metabolic activities which take place inside the living organisms. All these activities are chemical reactions. As a result in animal body several end products are formed which are of no use to the cells. These are called as metabolic wastes. These must be removed from the body for proper functioning of the body. The elimination of these metabolic waste products from the body is called as excretion. Waste materials are ammonia, urea, uric acid, carbon dioxide, pigments, salts, digestive wastes, excess of water etc. Ammonia, urea, uric acid are waste nitrogenous products. The excretory products are both volatile & nonvolatile. These are removed from the body by different methods. Excretory Organs and Main Nitrogenous Wastes of Different Animal Groups − Concept Boosters  (A) Osmoregulation in fish: (i) Osmoregulation in marine fish (ii) Osmoregulation in fresh water fish PW OLYMPIAD WALLAH 35  NSEJS BATCH 2024  (B) Osmoregulation in marine birds: Salt is transported from the blood into secretory tubules, which drain into central ducts leading to the nostrils. PW OLYMPIAD WALLAH 36  NSEJS BATCH 2024 Table: Excretory Organs of Different Animal Groups S. Animal Groups Excretory Organs No. 1. Protozoans (e.g. Amoeba, Paramecium) Plasma membrane 2. Sponges (e.g. Sycon) Plasma membrane of each cell. 3. Cnidaria (e.g. Hydra) Plasma membrane of each cell. 4. Platyhelminthes (e.g. Planaria) Flame cell (Solenocytes). 5. Nemathelminthes (e.g. Ascaris) H-shaped excretory system of canals and renette cells. 6. Annelids (e.g. Neries, Earthworm) Nephridia; chloragogen cells (yellow cells) in earthworm. 7. Arthropods (a) Prawn (b) Most insects (c) Antennary/Green glands Malpighian tubules, Coxal Scorpion and spiders glands, hepatopancreas and nephrocytes. 8. Mollusca (e.g. Unio, Pila) Kidney, In Unio kidneys are called organs of Bojanus. 9. Echinoderms (e.g., Starfish) Dermal branchiae and tube feet. 10. Hemichordates (e.g. Balanoglossus) Glomerulus. Evolutionary variations in excretory system: (i) Protonephridia: The excretory system of flatworms (phylum Platyhelminthes) consists of units called Protonephridia which form a network of dead-end tubules. PW OLYMPIAD WALLAH 37  NSEJS BATCH 2024 (ii) Metanephridia: Most annelids, such as earthworms, have metanephridia (singular, metanephridium), excretory organs that collect fluid directly from the coelom. Each segment of a worm has a pair of metanephridia, which are immersed in coelomic fluid and enveloped by a capillary network. A ciliated funnel surrounds the internal opening. As the cilia beat, fluid is drawn into a collecting tubule, which includes a storage bladder that opens to the outside. (iii) Malpighian tubules: Insects and other terrestrial arthropods have organs called Malpighian tubules that remove nitrogenous wastes and that also function in osmoregulation. The Malpighian tubules extend from dead-end tips immersed in hemolymph (circulatory fluid) to openings into the digestive tract. (iv) Kidney: In vertebrates and some other chordates, a specialized organ called the kidney functions in both osmoregulation and excretion. Like the excretory organs of most animal phyla, kidneys consist of tubules. The numerous tubules of these compact organs are arranged in a highly organized manner and are closely associated with a network of capillaries. The vertebrate excretory system also includes ducts and other structures that carry urine from the tubules out of the kidney and, eventually, the body. HUMAN EXCRETORY SYSTEM As a result of various metabolic processes going on in our body a number of waste products are formed. These have to be eliminated as they are toxic to the body. (a) Human Excretory Products: (i) Carbon dioxide which is liberated during respiration; and is eliminated by the lungs. (ii) Nitrogenous metabolic wastes, such as urea and uric acid produced in the liver from excessive proteins. (iii) Bile pigments: Bile pigments (e.g., bilirubin) derived by the breaking down of haemoglobin of the erythrocytes, in liver. (iv) Excess salts, water and vitamins: Concentration of these substances above the required level, is harmful to the body. PW OLYMPIAD WALLAH 38  NSEJS BATCH 2024 (b) Human excretory System: The excretory system of man consists of two kidneys, two ureters, urinary bladder and urethra. (i) Kidney: The kidneys are reddish-brown bean shaped structures present in the upper part of the abdominal cavity, on either side of the vertebral column. Each kidney is made up of large number of coiled tubes called nephrons (uriniferous or renal tubules). These filter the nitrogenous waste materials and excess of water and salts from the blood and form the urine. (ii) Ureters: These are a pair of long, narrow, thin walled and tubular structure which starts from the kidney, run downward and open in urinary bladder. (iii) Urinary bladder: It is a thin walled, elastic, pear-shaped and distensible (able to swell) sac present in lower part of abdomen. The urinary bladder stores the urine. When the muscles around the urinary bladder contract, the urine is excreted out through a small opening called the urethra. (iv) Urethra: It is muscular and tubular structure which extends from the urinary bladder to the outside. It carries the urine to the outside. Fig.: Excretory System of Human, L.S. of Kidney (v) Nephrons: Structural and functional units of kidneys. Each kidney is made up of a millions of nephrons. Structurally a nephron has following 5 parts: Fig.: Structure of Nephron PW OLYMPIAD WALLAH 39  NSEJS BATCH 2024 1. Bowman’s capsule: It is a single-cell thick, double walled cup-shaped structure present in the cortex region of the kidney. The cup-shaped capsule contains a network of capillaries called Glomerulus. Glomerulus and Bowman’s capsule are together called as Renal corpuscle/ Malphigian body. 2. Proximal convoluted tubule (PCT): It starts after the Bowman’s capsule and is greatly twisted. The whole PCT lies in the cortex region. 3. Henle’s loop: Henle’s loop is a U-shaped tubule located in the medulla region. It consists of - A thin-walled descending limb in the medulla A thick-walled ascending limb in the medulla. Henle’s loop is long in those animals which pass hypertonic urine. 4. Distal convoluted tubule: The ascending limb continues into the distal convoluted tubule which forms several coils in the cortex. 5. Collecting duct: Collecting tubule receives distal tubules of several uriniferous tubules. Several such tubules unite to form a large collecting duct. The collecting ducts are held together and converge to form a pyramid. The pyramid opens into the pelvis which leads into the ureter. (c) Mechanism of Urine formation: Main function of nephron is to form urine. There are three main processes involved in the urine formation: (i) Glomerular ultrafiltration: The blood flows through the glomerulus under great pressure which is much greater than in the capillaries elsewhere. The reason for this greater pressure is that the efferent (outgoing) arteriole is narrower than the afferent (incoming) arteriole. This high pressure (hydrostatic pressure) causes the liquid part of the blood to filter out from the glomerulus into the renal tubule. This filtration under extraordinary force is called ultrafiltration. During ultrafiltration almost all the liquid part of the blood (plasma along with most of its organic and inorganic substances including urea, glucose, amino acids, etc.) comes out of the glomerulus and passes into the funnel shaped cavity of the Bowman's capsule. The fluid entering the renal tubule is called the glomerular filtrate. The glomerular filtrate consists of water, urea, salts, glucose and other plasma solutes. The thicker part of the blood left behind in the glomerulus after ultrafiltration, namely, the two kinds of corpuscles, proteins, and other large molecules are carried forward through the efferent arteriole. Thus, the blood proceeding away from the glomerulus is relatively thick. Effective Filteration Pressure (EFP) It is the net filteration pressure responsible for ultrafiltration. EFP = GHP – [BCOP + CHP] = 75 – [30+20] = 25mmHg = 10-25 mmHg PW OLYMPIAD WALLAH 40  NSEJS BATCH 2024 Glomerular Hydrostatic Pressure (GHP) - It develops due to difference in diameter of afferent and efferent arterioles. It favors ultrafiltration. Diameter of afferent arteriole is more than that of efferent arteriole. Blood Colloidal Osmotic Pressure (BCOP) - It is the osmotic pressure of blood which develops due to presence of plasma proteins. It resists ultrafilteration. Capsular Hydrostatic Pressure (CHP) - It develops due to the glomerular filterate present in Bowman’s Capsule. It resists ultrafilteration. Glomerular Filteration Rate (GFR) - It is the amount of filterate entering the Bowman’s capsule per unit time. GFR = 125 ml./min. or 180 liters/day. (ii) Tubular reabsorption: Glomerular filtrate contains a lot of useful materials like glucose, salts such as that of sodium and water. These substances are reabsorbed from the renal tubule at various levels and in varied proportions. But their reabsorption is only to the extent that the normal concentration of the blood is not disturbed. This is called selective reabsorption. (iii) Tubular secretion: During this process substances like creatinine, potassium (K+), hydrogen (H+), NH4+, urea, foreign substance (pigments, drugs like penicillin) etc. are actively secreted into different parts of nephron (PCT, Henle’s loop and DCT). This passage involves the activity of the cells of the tubular wall, and hence it is called tubular secretion. All these processes involved in urine formation require energy, hence the oxygen demand of the kidneys is 6 to 7 times higher than what is required by muscles. (d) Urine excretion - Final urine passes into collecting ducts to the pelvis and through the ureter into the urinary bladder by ureteral peristalsis (waves of constriction in the ureters) and due to gravity. Urine is expelled from the urinary bladder through the urethra (in the penis in males, and directly in females) by relaxation of the urinary bladder into sphincter muscles located at the opening of the urinary bladder into the urethra under impulse from the nervous system. Such a process is called micturition. (e) Chemical Composition of Urine: Normal human urine consists of about 95% water and 5% of solid wastes. Besides the normal constituents, certain hormones and medicines like the antibiotics and excess vitamins are passed out with urine. Organic compounds (gm/l): Urea – 2.3; Creatinine – 1.5; Uric acid – 0.7. Inorganic Compounds are Ammonia – 0.6, NaCl, KCl. Normally a man excretes 1000-1750 ml of urine daily, depending upon the water intake, diet, climate, mental state and physiological condition. Tea, coffee, alcohol and other beverages increase the formation of urine. PW OLYMPIAD WALLAH 41  NSEJS BATCH 2024 HOMEOSTATIC REGULATION OF THE KIDNEY (A) Regulation by antidiuretic hormone: Osmoreceptors in the hypothalamus monitor blood osmolarity via its effect on the net diffusion of water into or out of the receptor cells. When blood osmolarity increases, signals from the osmoreceptors trigger a release of ADH from the posterior pituitary, as well as thirst. Drinking water reduces blood osmolarity, inhibiting further ADH secretion and thereby completing the feedback circuit. (B) Regulation by RAAS (Renin-Angiotensin-Aldosterone System): A second regulatory mechanism that helps maintain homeostasis by acting on the kidney is the renin- angiotensin aldosterone system (RAAS). The RAAS involves the juxtaglomerular apparatus (JGA), a specialized tissue consisting of cells of and around the afferent arteriole that supplies blood to the glomerulus. When blood pressure or blood volume in the afferent arteriole drops (for instance, as a result of dehydration), the JGA releases the enzyme renin. Renin initiates a sequence of chemical reactions that cleave a plasma protein called angiotensinogen, ultimately yielding a peptide called angiotensin II. PW OLYMPIAD WALLAH 42  NSEJS BATCH 2024 DIALYSIS In case of loss or damage of one kidney, the other kidney performs the function of both the kidneys and the person can lead to a normal life. But the failure of both the kidneys leads to death. Artificial kidney is a dialysis machine which cleans blood of waste products, thus acting like a kidney. The dialyser of a dialysis machine made of long tubes of selectively permeable membrane (like cellulose) which are coiled in tank containing dialyzing solution. The dialysis solution contains water, glucose and salts in similar concentration to those in normal blood. As the patient’s blood passes through the dialyzing solution, most of the wastes like urea present in its pass through the selectively permeable cellulose tubes into the dialyzing solution. From artery to pump Tube system made of a selectively permeable membrane Dialysing From apparatus solution to vein Fresh dialyzing Used dialyzing solution solution (with urea excess salts) PW OLYMPIAD WALLAH 43  NSEJS BATCH 2024 − Mastery Point  Kidney transplant: The best long term solution for kidney failure is the kidney transplant. The damaged kidney is removed and a matching kidney donated by a healthy person is transplanted in its place by a surgical operation. (f) Role of other organs in excretion: (i) Lungs: Carbon dioxide produced by the oxidation of glucose or other food substances in the tissues is removed by the blood. This carbon dioxide is carried to the lungs through the blood vessels (veins) where it diffuses into the alveoli and out through the respiratory tract. Water vapour in small amount is also exhaled during expiration from the lungs. (ii) Skin: Substances like soluble food matter, oxygen, water, dissolved mineral salts, traces of urea and uric acid diffuse from the thin walls of capillaries into the walls of the sweat glands. Oxygen and food substances are used for metabolic activities of the cells of sweat glands but the remaining metabolic wastes are excreted out of the gland through the sweat duct which opens on the surface of the skin through sweat pore. Sweat contains 99% water, traces of salts, urea and uric acid However, after heavy exercise, lactic acid forms a major constituent of sweat. Profuse sweating may lead to sodium deficiency, leading to muscle cramps. An adaptation of prevention of water loss is the impermeability of our skin to water. However, in aquatic animals, skin is the major excretory organ. They excrete ammonia through their skin by diffusion as ammonia is highly soluble in water. (g) Disorders of the excretory system: Malfunctioning of kidneys can lead to several disorders of the excretory system. Some of these are as follows (i) Uremia: It is the presence of an excessive amount of urea in the blood. Urea is highly harmful as it poisons the cells at high concentration and may lead to kidney failure. (ii) Kidney Failure (renal failure): Partial or total inability of kidneys to carry on excretory and salt- water regulatory functions is called renal or kidney failure. (iii) Renal Calculi: It is the formation of stone or insoluble mass of crystallised salts (calcium, magnesium, phosphates and oxalates, etc.), formed within the kidney. (iv) Glomerulonephritis: It is the inflammation of glomeruli of kidney. Polyurea – More urine passes out. Uremia – Urea concentration in blood increases. Alkaptonuria – Homogentisic acid passes with urine. Glycosuria – Glucose in urine. Anuria – Failure of kidney to form urine. Hematuria – Blood in urine. Albuminuria – Albumen in urine. Ketosis – Ketone bodies (Acetoacetic acid, b-Hydroxybutyric acid & Acetone) in urine. Dysuria – Painful urination. Diuresis – Increased volume of urine is excreted. CONTROL AND COORDINATION IN ANIMALS Animals receive external information through specialized structure called sense organs (receptors). These are photoreceptors for light, phonoreceptors for sound and olfactoreceptors for smell. Control and coordination is achiev