Human Digestive System PDF

9609544344 1  9609544344 Human Digestive System Complex nutrients (carbohydrates, fats and proteins) present in food are formed by adjustment of lar...

9609544344 1  9609544344 Human Digestive System Complex nutrients (carbohydrates, fats and proteins) present in food are formed by adjustment of large molecules of nutrients and the units of those nutrients are connected to each other by dehydration bonds. They react with water and break down into small units and the body converts them into usable state. This entire process is called digestion. So, the degradation of solid, complex, large insoluble food molecules into liquid, simple and small soluble molecules with the help of various enzymes and through various chemical reactions is called digestion. The system that takes part in the digestion process is called the digestive system. Human digestive system: For the convenience of study, the digestive system of humans can be divided into two parts- Alimentary canal and Associated digestive glands Alimentary canal The alimentary canal of humans or any vertebrate animal is a long, coiled tube that starts from the mouth and ends in the anus. The following are the main parts of the alimentary canal of humans- Buccal cavity Oesophagus Stomach Intestine Buccal cavity The buccal cavity is the first part of the alimentary canal. The human mouth is like a crack which opens into a cavity located between the two jaws, which is called the buccal cavity. The upper part of the mouth cavity is called the palate. The human mouth cavity is surrounded by the upper and lower jaws. There are two lips (upper and lower) to close the mouth cavity. The mouth cavity contains the tongue and teeth. 2  9609544344 The tongue is a thick and fleshy structure located on the floor of the mouth cavity. Its front end is free and the back end is attached to the floor. On the upper surface of the tongue there are many small papillae, which are called taste buds. Through these taste buds, a human being gets to know the different tastes of food such as sweet, salty, sour, bitter etc. The front part of the tongue senses the sweet taste, the back part (near the throat) senses the bitter taste and the side part senses the sour taste. The tongue helps in swallowing the food through its movement. One row of teeth is found in both the upper and lower jaws of the mouth cavity. The human being's teeth are of thecodont, diphyodont and heterodont types. The meaning of incisors is that they are embedded in the bones of the jaw, the meaning of bicuspid means that they come out twice in life. Whereas the meaning of heterodonts is that they are of more than one type. A human has 16 teeth in one jaw and a total of 32 teeth. Half the teeth of the jaw are located on the right side and half on the left side. On each side of the jaw there are two incisors, one canine, 2 premolars and 3 molars. Incisors are the foremost, flat and sharp which work to cut the food. Canines are pointed, which tear the food. Premolars and molars work to grind the food. A human's teeth come out twice. In the first infancy stage, their number is 20. The teeth of infancy are called milky teeth. The teeth that emerge in adulthood are called permanent teeth. A human tooth has three parts- Upper part- Crown Middle part- Neck and Lower part- Root. The part of the tooth which emerges above the gum is called crown or head. The part between the root and the crown is called neck. 3  9609544344 The part of the tooth which is sunk in the gum is called root. There is a cavity inside each tooth which is called pulp cavity. Above this is dentine, which forms the majority of the tooth. It is harder than bone and is yellow in colour. A shiny layer of enamel is found on the upper part or crown of the tooth which provides protection to the tooth. Enamel is the hardest part of the human body. The posterior part of the oral cavity is called the pharynx. It has two openings- (i) Gullet which opens into the next part of the food pipe i.e. the oesophagus, and (ii) Glottis which opens into the trachea. Beyond the gullet is a band-like structure which is called the epiglottis. When a person eats, this band covers the gullet due to which the food does not go into the trachea. Oesophagus The saliva-soaked food from the mouth reaches the oesophagus through the gullet. The oesophagus is a long tube which opens into the stomach. Its wall is muscular and contractible. As soon as the food reaches the oesophagus, the wall of the oesophagus starts contracting like a turban and relaxing or expanding which is called peristalsis. Due to this type of movement, the food slowly slides downwards. There is no digestive process of any kind in the oesophagus. The food reaches the stomach from the oesophagus. Stomach The stomach is located on the left side of the abdominal cavity. It is a bilobed sac like structure. Its length is approximately 30 cm. The anterior part of the stomach is called Cardiac and the posterior part is called Pyloric. The part between Cardiac and Pyloric is called Fundic. Like other parts of the alimentary canal, this layer of columnar epithelium cells is present on the inner wall of the stomach. This layer of cells is sunken inwards at places. The cells of these sunken parts form gastric glands. These glands secrete gastric juice in the stomach. There are three types of cells in gastric glands- 4  9609544344 (i) Mucous cells (ii) Parietal or oxyntic cells and (iii) Chief or Zymogen cells The combined form of the secretion of these three types of cells is called gastric juice. Gastric juice contains hydrochloric acid, mucus and inactive pepsinogen. Hydrochloric acid is secreted from oxyntic cells. Hydrochloric acid converts inactive pepsinogen into an active enzyme called pepsin. Pepsin acts on the protein of food and converts it into peptone. Hydrochloric acid also acts as a bactericide and destroys the bacteria that come with the food. Mucus is secreted from mucus cells. Mucus protects the stomach wall and gastric glands from hydrochloric acid and pepsin enzymes. Chyme reaches the small intestine through the pyloric hole of the stomach. Intestine The entire intestine of a human being is divided into two parts- Small intestine and Large intestine Small intestine Its initial part which is bent like the English letter ‘U’ is called duodenum. The length of duodenum is approximately 25 cm while the remaining 30 cm long part is called ileum. Finger like structures are found on the inner surface of the wall of ileum which are called intestinal villi. These villi increase the absorption surface of the intestinal wall. Pancreas is found between the bend of duodenum and stomach. Bile duct and pancreatic duct together form a common duct. This common duct opens into duodenum. The small intestine opens into the large intestine at the back. The small intestine helps in digestion of food and absorbs the digested food. The small intestine is the longest part of the alimentary canal. The process of digestion is completed in this part of the alimentary canal. In humans, its length is about 6 meters and width is 2.5 cm. Large intestine The front part of the small intestine alimentary canal opens into the large intestine. The large intestine is also divided into two parts. These parts are called colon and rectum. 5  9609544344 There is a small tube at the joint of small intestine and large intestine, which is called caecum. There is a finger-like structure on the top of the caecum, whose end remains closed. This structure is called appendix. Appendix has no function in the alimentary canal of humans. It is a vestigial organ. The colon is divided into three parts. These parts are- Ascending colon, Transverse colon and Descending colon. The descending colon opens into the rectum which finally opens outside the body through the anus. A valve is found at the joint of ileum and colon which is called ileocecal valve which prevents the food from going back into the small intestine. Associated digestive glands The glands associated with the alimentary canal that help in the digestion of food are called digestive glands. These are mainly of two types Internal digestive glands: The digestive glands that are present in the wall of the alimentary canal are called internal digestive glands. All mucous glands, stomach wall, gastric glands and Brunner’s glands of the intestinal wall come under this category. External digestive glands: The digestive glands found in other parts of the body other than the alimentary canal are called external digestive glands. The following three external digestive glands are found in humans- Salivary glands Three pairs of salivary glands are found in humans. The first pair of salivary glands are present on both sides of the tongue in the number of one each, which are known as sublingual glands. The second pair of salivary glands are present on both sides of the maxilla bone in the middle of the lower jaw in the number of one each, which are known as Submaxillary glands. The third pair of salivary glands are present below both ears in the number of one each, which are known as Parotid glands. Human saliva contains about 99% water and the remaining 1% is enzyme. Mainly two types of enzymes are found in saliva. These are- Ptylin and Lysozyme. 6  9609544344 Liver This is the largest gland in the human body. It weighs between 1.5 to 2.0 kg. It is located on the right side of the upper part of the abdominal cavity. It is dark grey in colour. It is divided into two parts by a deep trough. In its lower part, there is a small pear-shaped pouch which is called gall bladder. Bile secreted by the liver is stored in the gall bladder itself. This bile intensifies the action of enzymes present in the intestine. Apart from this, the liver takes an active part in the metabolism of carbohydrates, proteins and lipids and protects the body by neutralising the toxins produced in it. Functions of the Liver: The liver produces and stores glycogen under carbohydrate metabolism. When there is a lack of fat in the food, the liver converts some part of the carbohydrate into fat. The liver actively participates in protein metabolism. As a result of protein decomposition in the body parts, water, CO2 and other nitrogenous substances such as ammonia, urea, uric acid etc. are produced along with other things. Ammonia is a toxic substance which the liver converts into urea. Apart from this, the liver converts most of the protein into carbohydrates. Normally, some toxic substances are produced due to putrefaction of protein in the large intestine, which the blood brings to the liver through the peripheral vein. The liver neutralizes these toxic substances by converting them into non-toxic compounds, which get out of the body through urine. Gall bladder The gall bladder is a pear-shaped sac, which is located below the liver. The bile duct is connected to the liver. The bile produced in the liver reaches the duodenum through the bile duct. The bile falls into the duodenum by reflex action. Bile 7  9609544344 It is a yellow coloured alkaline fluid. Its pH value is 7.7. It contains 85% water, 12% bile pigments, 0.7% bile salts, 0.28% cholesterol, 0.3% medium fats and 0.15% lecithin. No enzyme is found in bile. It is alkaline in nature. It helps in mixing the fat of chyme with water to form an emulsion. About 700-1000 ml of bile is produced in a human being every day. Bile also destroys harmful bacteria that come with food. The inorganic salts present in bile make the medium of food coming from the stomach alkaline so that pancreatic juice can act. Bile increases the peristaltic movements of the intestine so that digestive juices mix well with the food. Bile performs the function of excreting many excretory and poisonous substances and metals. It also helps in the absorption of fat. It helps in the absorption of vitamin K and other vitamins in fats. If the liver cells stop taking bilirubin from the blood, then bilirubin spreads throughout the body through the blood. This is called jaundice. Pancreas This is the second largest gland in the human body. Its main characteristic is that it is both an endocrine (ductless) and an exocrine (ducted) gland. It is located in the ‘U’ shaped part of the small intestine. It is a yellow colored gland just below the stomach and surrounding the duodenum. The pancreas has many thin tubes which join together to form a large pancreatic duct. The pancreatic duct and the main bile duct join together to form a large duct, then this duct opens into the duodenum through a hole. The pancreas secretes a type of pancreatic juice which reaches the duodenum through the duct. A part of the pancreas is called Islets of Langerhans. Insulin is secreted from the β-cell of islets of Langerhans, glucagon from the α-cell and somatostatin from the γ-cell. Insulin determines the amount of sugar in the blood. Diabetes is caused by hyposecretion of insulin. Pancreatic juice It is secreted from pancreatic cells. It contains 98% water and the remaining 2% contains salts and enzymes. It is an alkaline fluid whose pH value is 7.5-8.3. 8  9609544344 Pancreatic juice contains enzymes to digest all three types of main food items. For this reason it is called complete digestive juice. It mainly contains five enzymes trypsin, amylase, carboxypeptidase, lipase and maltase. In this, maltase and amylase digest carbohydrates, trypsin digests protein and lipase digests fat. Process of digestion in human beings In humans, the digestion of food starts from the mouth itself and continues till the small intestine After ingestion of food in the mouth, it is thoroughly ground and chewed by the teeth so that it is divided into fine particles. The food ground by the teeth is thoroughly mixed with the saliva secreted by the salivary glands located in the mouth. Two enzymes ptyalin and lysozyme are found in saliva. Out of these, Tylin breaks down the starch present in the food into Maltese sugar, then an enzyme called Maltase converts Maltose sugar into Glucose. An enzyme called Lysozyme works to destroy the harmful bacteria present in the food Apart from this, the remaining substances present in the saliva work as buffers. Now this food is pushed into the oesophagus by the tongue from where it reaches the stomach. On reaching the stomach, Hydrochloric acid (HCl) combines with the food and deactivates Tylin. Along with this, it makes the food acidic. Apart from this, Hydrochloric acid also destroys the harmful bacteria present in the food. The food that reaches the stomach gets mixed with the gastric juice and gets converted into a semi- liquid pulp. Enzymes called Pepsin, Rennin and Mucin are present in the gastric juice. Pepsin converts the protein present in food first into proteose and then into peptone. Rennin converts milk into curd by converting milk soluble protein casein into calcium paracaseinate. Mucin reduces the acidic effect of gastric juice. It makes the food smooth and forms a protective cover on the mucous membrane so that the digestive enzymes do not affect the alimentary canal. After this in the stomach, the food is called chyme. Chyme from the stomach reaches the duodenum. Here it first meets bile juice secreted by the liver. No enzyme of any kind is found in bile juice. It is alkaline and also changes the nature of chyme from acidic to alkaline. It helps in making emulsion by mixing the particles of chyme with water. Here, pancreatic juice secreted from pancreas also joins the chyme. Pancreatic juice contains enzymes called Trypsin, Lipase, Amylase, Carboxypeptidase and Maltase. Trypsin converts proteins and peptones into polypeptides and amino acids. Amylase converts starch into soluble sugar. Lipase converts emulsified fats into glycerine and fatty acids. 9  9609544344 As a result of the action of these enzymes on chyme, the chyme becomes very liquid and now it reaches the ileum. Here, intestinal juice acts on the chyme. Intestinal juice is alkaline (pH-8). In a healthy human, approximately 2 liters of intestinal juice is secreted every day. The following types of enzymes are present in intestinal juice- Erepsin: It converts the remaining proteins and peptones into amino acids Maltase: It converts maltose into glucose sugar. Sucrase: It converts sucrose into glucose and fructose. Lactase: It converts lactose into glucose and galactose. Lipase: It converts emulsified fats into glycerol and fatty acids. 10  9609544344 Blood circulatory system ( मानव शरीर- रुधिर पररसंचरण तंत्र ) The circulation of pure blood through the blood circulatory system takes place from the heart to the arteries. And the circulation of impure blood takes place from the heart to the veins in the body. The blood circulatory system was discovered by William Harvey. There are two types of circulatory systems which are called open and closed circulatory systems respectively. 1.Open circulatory system The open circulatory system is of developed type in animals of Arthropoda phylum (cockroach, crab, lobster, mosquito, fly etc.) and Mollusca phylum (goiter, clam, octopus) etc. Birds and mammals have a closed circulatory system (blood flows in the vessels). 2.Closed circulatory system- This type of circulatory system is found in all developed animals like fish, frog, earthworm, ascaris and mammals (humans). Insects have an open circulatory system (blood is in direct contact with the organs). Humans have a closed, developed and double circulatory system. Human circulatory system is made up of three components. 1. Heart 2. Blood 3. Blood vessels Human Body Circulatory System Circulatory system means circulation of blood in the entire body. Blood vessels and heart mainly function in the human circulatory system. Heart is a muscular organ, which weighs about 280 grams. Heart works like a pump. Blood from the heart goes to different parts of the body through arteries and from there it returns to the heart through veins. In this way, blood continues to travel throughout the body throughout life through heart, arteries and veins. Circulation : 11  9609544344 Pure or oxygenated blood comes from the lungs to the heart. The heart, by pumping, sends this blood to the entire body through arteries. The oxygen present in the body's blood is used and impure or de-oxygenated blood comes back to the heart through veins. The heart sends this blood back to the lungs to get oxygen. Thus, this cycle continues. Capillary Network : The main artery divides into thin branches after going to different parts of the body. These branches further divide into thin branches like a net. These are called arterial capillaries. The net of arterial cells turns into venous capillaries. Venous cells join each other to form venules and venules join together to form the main vein. The circulatory system is a closed loop of veins, heart arteries, arterioles, artery cells and vein cells in which blood keeps flowing all the time. Heart The human heart is a red triangular, hollow and fleshy organ made of muscular tissues. It is surrounded by a cover called pericardium. It is filled with pericardial fluid which protects the heart from external shocks. The wall of the heart is made of three different layers- endocardium, myocardium, epicardium. The heart mainly has four chambers, which can be divided vertically into two parts. The crocodile is such a reptile in which the heart is 4 chambered. The heart is 4 chambered in the bird class and mammal class. Earthworms have 4 pairs of hearts (8 hearts). Cockroaches have 13 chambers in their heart. Weight of heart is 250 grams in females and 300 grams in males. Heart is the busiest organ of human body. The function of heart is to pump blood to different parts of the body. This function is done by rhythmic contraction and relaxation (contraction and expansion) of atrium and ventricle. When heart pumps blood in arteries, the pressure exerted on the walls of arteries is called blood pressure. 12  9609544344 The instrument used to measure blood pressure is called sphygmomanometer. Each blood particle takes about 60 seconds to complete its cycle in the body. In this process, the oxidized blood comes from the pulmonary vein to the left atrium, from there it flows into the body through the left ventricle via the aorta. The impure or unoxidized blood from the body comes to the right atrium through the great vein, and passing through the right ventricle, it goes to the lungs to be oxidized through the pulmonary artery. The same process continues. The heart of an adult beats 72 times in a minute. While that of a newborn baby beats 160 times. The heart pumps 70 ml of blood in one beat. There are valves between the atrium and the ventricle in the heart. Which prevent the blood from flowing in the opposite direction. The closing of the valves produces a lub-dub sound in the heart. The blood pressure (BP) of a normal human being is equal to 120/80 mm Hg mercury pressure. The amount of hemoglobin in human blood is 12 to 15 grams per 100 milliliters. The pacemaker controls the heartbeat. The heart is located in the right atrium and is also called the heart of the heart. The artery that supplies blood to the heart is called the “coronary artery” And when the amount of “cholesterol” increases in this artery, it causes heart attack. Heart beat being faster than normal – Tachycardia Heart beat being slower than normal – Bradycardia The study of heart is called cardiology. The first heart transplant – was done by Dr. C. Bernard (Africa) on 3 December 1967 and The first heart transplant in India was done by Dr. Venugopal in Kerala on 3 August 1994. Jarvis-7 is the first artificial heart. Made by Robert Jarvik. Artificial kidney was made by Suborai. The lowest heart beat is of Blue Whale which is 25/minute and the highest heart beat is of Shrew – 800/minute. 2. Blood Blood is a type of liquid connective tissue. 13  9609544344 Blood is formed in the red bone marrow and in the embryonic stage, blood is formed in the spleen. A normal person has about 5 to 6 liters of blood. Which is found to be seven to eight percent in percentage. Blood is formed from two components which are called blood plasma and blood corpuscles respectively. The pH value of blood is 7.4 (slightly alkaline). The liquid part of blood is called plasma. Which is 55 percent in the blood. And the remaining 45 percent is corpuscular (corpuscles). The study of blood is called hematology. The process of blood formation is called hemopoiesis. The amount of RBC increases when we go to high altitude. The main function of red blood cells is to transport oxygen. The normal blood pressure in human body (Blood Fresher) is 120/80 mm. The condition of high blood pressure is created when the heart contracts, which is called systole. And the condition of low blood pressure is created when the heart expands, which is called diastole. Plasma Plasma contains about 92% water and 8% organic and inorganic substances in dissolved form or in the form of colloids. Plasma provides immunity to the body. It distributes heat equally. It carries hormones from one place to another. Red blood cells (RBC) RBC are known as erythrocytes. They are formed from the red bone marrow. RBC are formed from the spleen and liver in the embryonic stage. RBC are oval in shape. These are 99% of the total cells. These are nucleus-less cells. Hemoglobin is found in them. Iron metal is found in the nucleus of hemoglobin. Due to which the color of blood is red. Hemoglobin transports O2 and CO2 in the body. Its deficiency causes anemia. Red blood cells are destroyed in the spleen. 14  9609544344 So the spleen is also called the graveyard of red blood cells. The number of red blood cells in an adult human is approximately 5 to 5.5 lakh/mm3 and its life span is 120 days. The main function of RBC is to transport oxygen. The nucleus is not found in the RBCs of all mammals in the world, but camel and llama are two such mammals. Whose RBCs have nucleus. Camel is one such mammal whose RBC size is the largest. The RBC size of deer is the smallest. If a person is left in space or on Mount Everest for a few days, then both the number and size of RBC will increase. White blood cells (WBC) These provide immunity. It is also called leukocyte. WBC is formed from the white bone marrow in the human body. The lifespan of WBC in human body is about 8 to 10 days The number of WBC in human body is about 5000 to 9000 per cubic millimetre. The ratio of RBC and WBC in blood is 600:1. WBC is amoeba shaped i.e. it does not have any definite shape. The main function of WBC is to protect the body from harmful bacteria. There are 5 types of white blood cells based on the shape of nucleus and granules. Uncontrolled increase of white blood cells in the blood is called leukemia. It is also called blood cancer. The largest WBC in size is monocytes. Lymphocyte type WBC is the smallest in size. Neutrophil type WBC is found in the highest number. Blood platelet Blood platelets are known as thrombocytes. Blood lamellae are formed from the red bone marrow. They are plate-shaped in structure. These are nucleus-less cells that help in blood clotting. Their life span is 5-9 days. These are found only in mammals. Blood coagulates with the help of fibrin. Its number in the human body is approximately 3 to 5 lakhs per cubic millimetre. 15  9609544344 In viral diseases like dengue, the number of platelets in the body decreases. Because the dengue virus eats up the platelets. In the “blood bank” of hospitals, blood is kept safe for 1 month at a temperature of approximately 40 degrees Fahrenheit. To prevent this blood from coagulating, sodium citrate and sodium oxalate chemicals are added. These chemicals neutralise the blood coagulating element calcium. Lymphatic system Red blood cells are absent. White blood cells are more in number and lymphocytes are the most. It is similar to blood but is a colorless fluid. Lymph corpuscles are formed by it. Lymph cells are formed from lymph nodes. Which is open at one end and closed at the other. Lymph fluid moves from different parts of the body towards the heart. It was discovered by Landsteiner. It was classified on the basis of antigen. Light yellow colored fluid in which RBC and thrombocytes are absent. Only WBC is present. Blood vessels Artery The vessels that carry pure blood from the heart to other parts of the body are called arteries. Blood flows fast and at high pressure in them. Aorta is the largest artery. But impure blood flows in the pulmonary artery. Blood flow through some important arteries Carotid artery: To the head Subclavian artery: To the arm. Pulmonary artery: To the lungs. Aorta: From the heart to the whole body. Renal artery: To the kidney. Hepatic artery: To the stomach. Gastric artery: To the stomach. Iliac artery: To the leg. Femoral artery: To the leg. 16  9609544344 Vein The vessels that bring impure blood from various parts of the body to the heart are called veins. But the pulmonary vein contains pure blood. Blood return through some important veins Jugular vein : From the head Subclavian vein : From the arm Brachial vein : From the sleeve (arm) Pulmonary vein : From the lungs Vena cava : From the body to the heart Renal vein : From the kidney Hepatic vein : From the liver Hepatic portal vein : From the intestines to the liver Iliac vein : From the leg Femoral vein : From the leg Human blood groups – Blood group Karl Landsteiner discovered in 1900 that the blood of all humans is not the same but is of different types. The reason for this difference is the presence of a special type of protein (glycoprotein) in the red blood cells of the blood, which is called antigen. There are two types of antigens Antigen A, (ii) Antigen B Based on the presence of glycoproteins in red blood cells, there are four types of blood groups in humans No antigen is found in blood group 'O', but both antibodies A and B are found, so a person with blood group O can take blood only from 'O' group and can donate to all blood groups. That is, 'AB' is universal acceptor and 'O' is universal donor. Rh Factor In 1940, Landsteiner and Wiener discovered another type of antigen in blood. They discovered this antigen on a monkey named Rhesus, so this antigen in children was named Rh-factor on the basis of the blood group of the parents. The blood of those people in whose blood this element is found is called Rh-positive (Rh+) and the blood of those in whose blood it is not found is called Rh-free (Rh-Negative, Rh–) 17  9609544344 The Rh-factor is also checked at the time of blood transfusion. Only Rh+ blood is given to Rh+. If blood of Rh+ blood group is given to a person with Rh– blood group, then there will be no effect due to less quantity for the first time, but when blood transfusion is done for the second time in the same way, the person with Rh– blood group dies due to blood synthesis. Erythroblastosis fetalis If the father's blood is Rh+ and the mother's blood is Rh–, then the first child will be normal But the child born after that dies in pregnancy before birth or immediately after birth. Note: Two colleagues of Dr. Landsteiner, Alfred von Decastello and Adriano Sterli, identified the fourth blood group, AB, in 1902. Possible blood groups in children based on the blood group of the parents blood group of Possible blood groups in Not Possible blood groups in parents children children O×O O A, B, AB O×A O, A B, AB O×B O, B A, AB A × AB A, B O, AB A×A A, O B, AB A×B A, B, O, AB कोई नहीं A × AB A, B, AB O B×B B, O A, AB B × AB A, B, AB O AB × AB A, B, AB O 18  9609544344 SKELETAL SYSTEM ▪ The skeletal system forms the framework of our body. ▪ It controls the voluntary activities of our body. ▪ The skeletal system develops from the mesoderm layer. ▪ It is made of connective tissue or skeletal tissue. ▪ Calcium and phosphorus are required for the growth and development of bones. ▪ The number of bones is 306 in a newborn, 270 in childhood and 206 in an adult. ▪ The longest bone in the body is the femur, which is found in the thigh. ▪ The stapes is the smallest bone in the body, which is found in the ear. ▪ The bone that bears the maximum weight in the body is the tibia, which is found in the legs. ▪ The strongest bone in the body is the mandible, which is found in the jaw. ▪ Femur, patella, tibia and fibula are the bones found in the legs. Humerus, radius and ulna are the bones found in the arms. ▪ Pectoral girdle is the bone found in the shoulder. ▪ While pelvic girdle is the bone found in the hips. ▪ Collar bones, which are also called Cavicle Bone or Hansuli bone or Clavicle bone. ▪ This is called Beauty Bone. ▪ The number of ribs in the body is 24. ▪ At the time of birth of a child, there are 33 bones in the spine, and later their number becomes 29. ▪ An adult has 26 bones in the spine. ▪ The place where a bone is connected to the muscles is called tendon. ▪ The place where a bone is connected to another bone is called ligaments. Vitamin D deficiency causes rickets in children and a disease called osteomalacia in adults. Both these diseases are related to bones, in which bones become weak and deformed. ▪ Increase in fluoride content in underground water causes fluorosis disease, in which bones become weak and yellow spots appear on teeth. ▪ Arthritis is a bone-related disease, in which joints become swollen and start paining, and this problem increases with age. 19  9609544344 ▪ The study of skeletal system is called Osteology. ▪ Skeleton System protects the internal organs of our body such as heart, spinal cord, liver. ▪ There are a total of 656 muscles in our body. Exo Skeleton System :- ▪ The skeleton found on the outer surface of the body is called Exo Skeleton System. Example - Upper shell of turtle, nails and hair in mammals. Endo Skeleton System: ▪ The skeleton found inside the body is called Endo Skeleto System. Example - Reptiles, sharks, mammals etc. Bone ▪ It is a type of connective tissue. ▪ It provides protection and movement to the body ▪ It works to produce RBC and WBC. ▪ Bone stores minerals inside it, which include important calcium and phosphorus. ▪ The cells present in it are called osteocytes which are also called mature bone cells. ▪ They are made from collagen protein. ▪ Calcium phosphate is found in the highest quantity in bones. ▪ It has two parts: - (I) Osteoblast - forms bone. ▪ (ii) Osteoclast - absorbs bone tissue. ▪ The empty space (cavity) found in bones is called medullary cavity. ▪ Red bone marrow and yellow bone marrow are found inside the medullary cavity. ▪ Most RBC is formed in red bone marrow. WBC is also formed. ▪ Fat in yellow bone marrow works to form fat. Cartilage ▪ This is a smooth flexible tissue or connective tissue. ▪ It makes the structure of our body organized or balanced. ▪ It is not as hard as bones, it is a little soft, it can be easily broken. ▪ It originates from Mesodermal. ▪ The living cells present in Cartilage are called Chondriocyte. ▪ It is made up of two types of fibers - Collagen Fiber and Elastin Fiber. ▪ The structure of Cartilage is in the form of matrix. There is empty space in the middle, where there is a sac-like structure, which is called lacunae. Living cells are present in these. ▪ NOTE:- The number of bones in a newborn is 300+. And the number of bones in an adult is 206. 20  9609544344 ▪ The human skeletal system is divided into two parts. (i) Axial skeleton: The number of bones in it is 80. (ii) Appendicular skeleton: It has 126 bones. Axial Skeleton:- Their distribution is as follows (a) Bones of head -29 (b) Bones of chest -25 (c) Bones of spine -26 Division of bones of head ▪ Skull (bones of skull or brain) - ▪ It has 29 bones in total. ▪ Out of these, 8 bones are Cranial bones which are called bones of skull. These protect the brain. ▪ 14 bones are Facial bones which are called bones of face. These form the face. Neck Bones ▪ This is one. Which is called Hyoid Bone. Ear Bones ▪ There are 6 of them in total. There are 3 bones in each ear. ▪ Names of ear bones - Malleus, Incus, Stapes ▪ Note: The smallest bone in the human body is "Stapes" which is found in the ear. (B) Division of the bones of the chest ▪ Ribs ▪ There are 24 bones in total and 12 pairs. ▪ It starts from the back and ends in the front. ▪ It forms a rib-cage. Joints (सधं ियााँ) There are three types of joints- In immovable joints, one bone is Fibrous Joints (Immovable Joints) connected to another bone very Immovable Joints:- strongly. This is present in the bones of the flat skull. 21  9609544344 Cartilagious Joints Incomplete together. (II) Hips (Buttocks):- Joints:- Femur (Femur) + Pelvic Girdle These move slightly. (Pelvic Girdle) join together. In this, the bones are connected by cartilage. Hinge Joints:- Example - Pubic Symphysis (Hips It moves in one direction only. Joints), Intervertebral Dise (between two vertebrae), between cartilage Its examples - (I) Knee Joint (Knee) and ribs. (II) Elbow (Elbow) (III) Fingers Synovial Joints (Complete Joints):- (Fingers) (IV) Toes (Claws) These move completely. Pivot Joints:- When a bone joins another bone, it It moves in one axis only. Examples forms a Synovial (empty space) of these - (I) Present between Atlas cavity. Which is filled with Synovial (Atlas bone) and Axis (Axis) Fluid. Gliding Joints:- Synovial Fluid maintains It is present between two plane smoothness between the bones. It bones. helps the bones to move. The joint Examples of these - (I) Carples (in that moves the most is a complete wrist) joint. Saddle Joints:- It is like the seat of a horse rider. Type Of Synovial Joints Examples of these - It is present in (Types of complete joints) - There Carpal & Metacarpal Of Thomb (in are 6 types. thumb) Ellipsoid Joints (Condyloid Joints):- Ball & Socket Joint:- It moves forward-backward and Its examples - (I) Sholder side-to-side. (Shoulder):- Humerus (Humerus) + Examples of these - (I) Metacarpals Pectoral Girdle (Part Girdle) join (II) Phalanges (Digits / Fingers).  9609544344 Human Nervous System The system of the human body which works to think, understand and remember something as well as to establish harmony and balance in the functions of various organs of the body is called the nervous system. The nervous system is made up of sensory organs, nerves, brain, spinal cord and nerve cells. The function of neural control and coordination is mainly done by the brain and spinal cord. Functions of the nervous system The nervous system operates and controls different functions of different organs. It controls all mental functions. It helps the animal to react according to the external environment. It regulates the internal environment of the body by coordinating the functions of various glands and tissues. In humans, the nervous system is divided into three parts - 1. Central nervous system, 2. Peripheral nervous system and 3. Autonomic nervous system Central Nervous System The part of the nervous system that controls the entire body and the nervous system itself is called the central nervous system. The brain and the spinal cord together form the central nervous system. The brain is an enlarged part of the spinal cord. Brain The brain is the central information and transmission organ of the human body and it acts as a command and control system. It controls voluntary movement, body balance, functions of major involuntary organs, temperature control, hunger and thirst, transportation, rhythm, actions of many endocrine glands and human behavior.  9609544344 It is also the site of seeing, hearing, speaking, memory, sharpness, emotions and thoughts. Thus, the brain is the control room of the entire body and the nervous system itself. The human brain is well protected inside the brain cell or cranium. The cranium protects the brain from external shocks. The average weight of the human brain is 1400 grams. A cover called Meninges is found around it. This cover is made up of three layers. The outermost layer of this cover is called Duramater, the middle layer is called Arachnoid and the innermost layer is called Piamater. Meninges protect the soft brain from external shocks and pressure. Cerebrospinal fluid is filled between the meninges and the brain. The cavity of the brain is also filled with this fluid. Cerebrospinal fluid helps in protecting the brain from external shocks. It keeps the brain moist. The human brain is more complex and developed than that of other vertebrates. The human brain is divided into three major parts. These are- Forebrain, Midbrain and Hindbrain Forebrain or Prosencephalon It is made up of two parts- Cerebrum It covers the top, sides and back parts of the brain. It is the largest part of the brain. It is about two-thirds of the total brain. It is divided into right and left parts by a longitudinal groove, which are called cerebral hemisphere. Both cerebral hemispheres are connected to each other by a structure called Corpus callosum made of nervous tissue. There are many irregular protruding structures in the hemisphere, which are called Gyrus.  9609544344 The depressed place between two gyrus is called sulcus. Due to this, the surface area of the cerebral cortex increases. Cortex is a thick grey cover of the cerebrum, on which there are different designated centers which efficiently control and coordinate various bodily functions This is a very important part of the brain. This is the center of intelligence and cleverness. In humans, the ability to think and understand something, memory, motivation to do something, feeling of hatred, love, fear, happiness, pain, etc. are controlled and coordinated by the cerebrum. It also controls the functions of other parts of the brain. A person whose cerebrum is smaller than average and gyrus and sulcus are less developed is a person of low intelligence. Diencephalon This is a part of the forebrain which is covered by the cerebral hemisphere. It controls the sensation of high or low temperature and functions like pain and crying. Thalamus/Conscious It is oval in shape and consists of two thick bodies. It constitutes 80% of the entire diencephalon. Its bodies act as transmission centres for carrying sensory and motor impulses to various parts of the spinal cord and brain. They transmit sensory information such as sight, taste, touch, temperature, pressure vibration, pain etc. It is capable of interpreting the sensations of touch, pressure, pain, temperature, happiness, sadness etc. Hypothalamus/Proconscious It forms the lower part of the lateral walls of the diencephalon and the floor of the third ventricle.  9609544344 It contains about a dozen large nuclei of nerve cells. It establishes a connection between the nervous system and the endocrine system. It contains higher centers of autonomic nerves, it controls body temperature and homeostasis, it secretes excitatory and inhibitory neuro hormones. 2. Midbrain or Mesencephalon This part is located in the middle of the brain. It is the upper part of the brain stem. Many nerve cells are present in many groups in it. The midbrain contains centers for controlling balance and eye muscles. The midbrain is made up of two parts. These are- corporaquadrigemin and cerebral peduncle Corporaquadigemin The upper part of the midbrain is made up of four lobe-like protrusions, which are called corporaquadigemin. These are the centers of control over vision and hearing power. Cerebral peduncle: It is a bundle of fibers that connects the cerebral cortex to other parts of the brain and the spinal cord. Hindbrain or Rhomben cephalon This is the rearmost part of the brain. It is made up of cerebellum and brain stem. Cerebellum It is also called metencephalon. It controls posture, coordination, balance, movements of voluntary muscles, etc. Its main function is to maintain the balance of the body. It controls the contraction of voluntary muscles of the body. It receives sensations from the balancing part of the inner ear. (b) Brain stem: It includes Pons varolii and Medulla oblongata. Pons varolii: Made up of nerve fibres, Pons varolii is located in the front part of the medulla. It controls respiration. Medulla oblongata This is a cylindrical structure which is found at the back in the form of spinal cord. The spinal cord starts from the back end of the brain and passes through the neural canal in the spinal bones and extends downwards till the end of the spine. The control centres of involuntary actions are located in this. The conduction of impulses through the medulla takes place between the brain and the spinal cord.  9609544344 There are many nerve centers in the medulla, which control the heart beat, blood pressure or rate of respiration. Various reflex actions like coughing, sneezing, vomiting, secretion of digestive juices etc. are controlled by this part of the brain. Spinal Cord The posterior part of the medulla oblongata forms the spinal cord. The last end of the spinal cord is in the form of a thin thread. A covering made of durometer, ochroid and pyometer is also found around the spinal cord. The spinal cord is cylindrical, hollow and flat on the dorsal and ventral planes. One groove is found on both its surfaces, which are called dorsal fissure and ventral fissure respectively. A narrow canal is found in the middle of the spinal cord which is called the central canal. The central canal is filled with cerebrospinal fluid The thick part of the spinal cord around the central canal is divided into two parts. The inner layer is called grey matter and the outer layer is called white matter. The grey matter is made up of nerve cells, their dendrons and neuroglia tendrils while the white matter is made up of medullated nerve fibres and neuroglia tendrils. Functions of the spinal cord: The spinal cord has two main functions. It controls and coordinates reflex actions. It transports stimuli coming and going from the brain. Peripheral nervous system The peripheral nervous system is made up of nerves originating from the brain and spinal cord, which are called cranial nerves and spinal nerves respectively. Humans have 12 pairs of cranial nerves and 31 pairs of spinal nerves. Autonomic or automatic nervous system The autonomic nervous system is made up of some brain and some spinal nerves. It supplies nerves to all the internal organs and blood vessels of the body. The concept of autonomic nervous system was first presented by Mr. Langley in 1921. The autonomic nervous system has two parts. 1. Sympathetic nervous system 2. Parasympathetic nervous system.  9609544344 Both the systems are not completely independent of the central and peripheral systems because they are formed by the central and peripheral nervous systems. Sympathetic nervous system It is also called thoracolumbar outflow because the preganglionic fibers join the spinal cord in the thoracic and lumbar regions. It houses a pair of ganglionic chains that lie on both sides of the spinal cord from the neck to the abdomen. The nerve fibers connect the ganglia to the visceral organs and the central nervous system. The nerve fibers that connect the ganglia to the central nervous system are called medullated nerve fibers. The preganglionic nerve fibers emerge from the spinal cord and are near the ventral roots of the spinal nerves. The nerve fibers that connect the ganglia to the organs are called non-medullated nerve fibers or post ganglionic nerve fibers. The nerve fibers that connect the ganglia to the organs are called non-medullated nerve fibers or post ganglionic nerve fibers. Pre-ganglionic fibers secrete acetylcholine and post ganglionic fibers secrete sympathine. Parasympathetic nervous system It is made up of paired ganglionic chains which start from the brain and also arise from the sacral part of the spinal cord. Parasympathetic ganglia are located in the head, neck and sacral region. It supplies nerves to all the organs which are supplied by the sympathetic system Sympathetic and parasympathetic nerves supply nerves to the same organs but their effects are opposite to each other. Reflex actions These are also called spinal reflexes. The mechanical, immediate and unintentional response to external stimuli in which the brain has no role is called reflex actions. In such actions, whatever we do is not controlled by thoughts. Knee jerk, coughing, yawning, blinking of eyelids, sneezing, shivering due to fear, mouth watering on seeing food, shivering due to cold, heart beat faster on hearing bad news etc. are all examples of reflex actions. Generally these actions are controlled by the spinal cord.  9609544344 In reflex action, stimuli or sensations are transmitted from the skin or other receptive organs to the nerve center (spinal cord) through the sensory pathway. From here, appropriate orders are issued after receiving sensations. These orders then reach the afferent organs through the motor pathway where actions are performed as per the orders of the nervous system. The entire path of impulse transmission is called reflex arc. Most of the reflexes are related to the spinal cord. Hence, they are also called spinal reflexes. Control and coordination in humans takes place through the nervous system and hormonal system. The five sense organs of our body, eyes, ears, nose, tongue and skin are called receptors. Receptors are a group of cells in the sense organ which are particularly sensitive to light, sound, smell, taste, heat, cold etc. All receptors can send messages in the form of electrical waves to the spinal cord and brain through sensory nerves. The origin of the nervous system is ectodermal. The first nerve cell was found in Coelenterata (Hydra), which was of apolar type. Cephalization occurred for the first time in Platyhelminthes. The nervous system of all animals is made up of very special types of cells, which are called neurons. It identifies and receives various stimuli and transmits them. Neural organization is very simple in lower invertebrates. For example, in hydra, it is in the form of neural network. The nervous system of insects is more organized. This brain is made up of many ganglia and neural tissues. A more developed nervous system is found in vertebrates. Neurons Neuron is the structural and functional unit of the nervous system. Neuron is also called nerve cell. Neuron is a microscopic structure Cytone/Cell Body Cytone contains cytoplasm, cell organelles and granular organelle Nissel granule.  9609544344 Dendrites The small fibers that emerge from the cyton like growths and contain Nissl granules are called dendrites They send stimuli towards the cyton. Axon A neuron has an axon. Its distal part is branched and is called the terminal axon. The axon tip contains synaptic vesicles. Neurotransmitters are found in the synaptic vesicles. Axons transmit nerve impulses away from the cyton to the synapse or neuromuscular junction The following are the types of neurons based on the number of axons and dendrites: Non-polar neuron - In this, cyton is present and axon and dendron are absent. This type of neuron is found in Hydra. Unipolar neuron - In this, both cyton and axon are present, but dendron is absent. Bipolar neuron - In this, only one dendron and one axon are found. This type of neuron is found in the nose and eyes. Multipolar neuron - This type of neurons is found in most parts of the body. Pseudo-polar neuron - It extends from the cell body. This type of neuron has an axon that divides into branches. A single process arises from the cell body and then divides into an axon and a dendrite Sensory neurons- Receive messages from receptors and send them to the central nervous system which is the spinal cord and brain. Motor neurons- The function of motor neurons is to send messages received from muscle cells to the central nervous system. Relay neurons- These work as a link between other neurons. They are present in the central nervous system. Structure of neuron Nissl granule- This is the place of protein synthesis Nissl granules are brown in colour.  9609544344 These are present in cyton and dendron and are absent in axon and axon hillock. This is a granular organelle. Axon hillock is a very sensitive part of the neuron. Neurilemma- This is the covering of the Schwann cell which is present on the Schwann cell and Ranvier's node Neurilemma is present only in the peripheral nervous system. Swann Cells- Swann cells form the myelin sheath. Swann cells are present in P.N.S. and absent in C.N.S. Nodes of Ranvier- The region between two myelin sheaths is called nodes of Ranvier. Here myelin sheaths are absent. Axolemma- The covering of axon is called axolemma. Myelin Sheath- Most of the neurons in C.N.S. are myelinated. Myelin sheath in C.N.S. is made up of oligodendrocytes. Nodes of Ranvier are very few in C.N.S. P.N.S. has both myelinated and non-myelinated myelin sheaths. SNS of P.N.S. has mostly myelinated neurons and ANS has mostly non-myelinated neurons. Myelin sheath in P.N.S. is made up of Swann’s cells. Ranvier's nodes are found in abundance in the P.N.S. Synapse The transmission of nerve impulses from one neuron to another occurs through synapses (difference between two neurons A synapse is formed by the membranes of the pre-synaptic neuron and the post-synaptic neuron, which may or may not be divided by a synaptic cleft.  9609544344 Human Excretory System The process of removing waste or toxic substances from the body cells is called excretion. The organs that participate or help in the excretion process are called excretory organs. As a result of the catabolic process, complex compounds accumulated in the body are disintegrated, as a result of which energy is released and some waste products remain. These waste substances are not only useless but also harmful or toxic, which can prove fatal for a living cell. If these substances remain in the body for a long time, it has an adverse effect on the metabolic processes and can also cause various diseases. Therefore, it is necessary to remove these waste or waste substances from the body. Excretion in human Kidney The main excretory organ in human and other mammals is a pair of kidneys which are well adapted for removing excretory substances from the blood circulation as well as for maintaining beneficial elements in the blood. The kidneys are bean shaped. One kidney is located in the abdominal cavity in the waist region towards the back, on either side of the vertebral column. A membrane called peritoneum is found around it. In an adult human, each kidney is 4 to 5 inches long, 2 inches wide and about 1.5 inches thick Itweight is about 140 grams. Its outer surface is convex and the inner surface is concave. The kidneys are covered from all sides by thick fat layers, which protect them. The inner concave surface of the kidney is called Hilum. When the kidney is cut lengthwise, it gets divided into two parts. The outer part which is relatively thin is called Cortex While the inner thick two-third part is called Medulla. The medulla is filled with cone shaped structures which are called Pyramids.  9609544344 All the pyramids are directed into a sac like cavity. This cavity is located on the inner concave surface of the kidney. This cavity is called renal pelvis. A long and narrow duct emerges from the renal pelvis which is called Ureter. The ureters on both the sides open into the urinary bladder. Each kidney has approximately 1,00,30,000 micro tubules which are called nephrons. Nephrons are the functional unit of the kidney. Nephrons are also called excretory units. These nephrons actually control the chemical composition of the blood. Structure of nephron Each nephron has a small cup-shaped structure which is called Bowman’s capsule. Bowman’s capsule is located in the cortex region. A micro coiled tube emerges from this Bowman’s capsule which becomes straight and enters the renal pelvis. After this, this tube widens and forms a loop, which is called Henle’s loop. After that this tube again goes into the cortex part of the kidney. In the cortex part, it again coils and then it opens into a large duct called collecting duct. The collecting duct is a straight tube, in which the tubes of many nephrons open. It takes the fluid to the renal pelvis. All the collecting ducts open in the renal pelvis. A duct called ureter emerges from the renal pelvis, which opens into the urinary bladder. Supply of blood in the kidneys The renal artery carries blood into the kidneys from the aorta. After entering each kidney, the renal artery divides into many thin branches which are called renal arteries. These renal arteries enter the Bowman's capsule of each nephron, which is called afferent arteriole. The afferent arteriole divides repeatedly to form a bunch of fine capillaries, which is called glomerulus. The capillaries recombine after the capillary bunch to form the efferent arteriole. The efferent arteriole leaves the Bowman's capsule and divides repeatedly to form a network of fine capillaries that covers the various reticulum parts of the nephron. The capillaries recombine to form renal venules. These renal venules ultimately open into the renal vein.  9609544344 The renal vein collects blood from the kidney and takes it back to the heart. Mechanism of working of nephron Two important functions are performed by nephrons inside the kidneys. Removal of all excretory substances from the blood and Maintaining essential nutrients in the blood. Excretory substances are removed from the blood in two stages. These are- 1. A. Filtration 2. B. Reabsorption Filtration The process of filtration takes place in the glomerulus. The glomerulus is like a sieve. Every minute about 1 liter of blood containing 5oo ml plasma flows through the glomerulus. About 10% of it is filtered. The afferent artery has a larger diameter than the efferent artery, so the blood pressure in the glomerulus increases, as a result of which the filtration process takes place at this high pressure. This process of filtration at high pressure is called ultrafiltration. By ultrafiltration, various components are filtered out from the blood plasma by the glomerulus. Water, glucose, mineral salts, etc. are filtered out from the blood plasma. Only blood cells and plasma proteins are not filtered out and remain in the blood. The filtered fluid is called filtrate. This filtrate is like blood plasma but blood cells and plasma proteins are absent in it. The filtrate collects in the cavity of Bowman's capsule from where it goes into the tube of the nephron. Due to this filtration, many beneficial components of the blood are filtered out but its diagnosis is done in the next stage. This type of selective filtration, in which some substances are filtered and some are not, is called dialysis. Each glomerulus acts as a dialysis bag.  9609544344 Reabsorption After filtering in Bowman's capsule, the blood flows through the network of capillaries present outside the nephron. While passing through various tubes of the nephron, many beneficial elements present in the filtrate are reabsorbed by the blood capillaries present around the tubes and returned to the blood circulation. This process is called reabsorption. Most of the water from the filtrate is absorbed by osmosis. Other beneficial elements that are absorbed are glucose, vitamins, hormones, mineral salts etc. Recent discoveries have shown that about 99 ml of fluid is reabsorbed from 100 ml filtrate. After reabsorption, sometimes some excretory substances are secreted from the cells of the tubule which get mixed in the filtrate. This is called tubular secretion. This filtrate is called urine. Nature and composition of urine The mixture of water filtered from the blood in the nephron or renal tubule and the remaining excretory substances is called urine. Human urine is a transparent and light yellow coloured fluid. Its yellow colour is due to a pigment called urochrome formed from the breakdown of haemoglobin The smell of urine is due to the organic matter present in it. A normal person produces about 1.5 liters of urine in 24 hours. Generally, the quantity of urine depends on the quantity of water consumed by the person, the nature of food, his physical and mental condition and the environmental temperature. Generally, fresh urine is acidic in nature. Its pH value is between 4.5 to 8.6. Its relative density is slightly higher than water.  9609544344 In the urine of a normal person, water (96%), urea (2%), protein, fat, sugar and other colloids (1.3%), uric acid (0.5%) along with very small quantity of creatinine, sodium, potassium, calcium, magnesium, chlorine, sulphate, phosphate, lead, ammonia, arsenic, iodine, nitrogen etc. are found. Diuresis The increase in the quantity of urination is called diuresis. The substances which implement it are called diuretics. Urea is a diuretic substance which affects urination a lot. Urine secretion is directly related to the quantity of urea in normal blood. Mannitol, sucrose, glucose, caffeine etc. are other diuretic substances. Function of kidneys The kidney removes various waste materials produced as a result of metabolism in mammals and other vertebrates from the body in the form of urine. It controls the hydrogen ion concentration (pH) in the blood. It controls the osmotic pressure of blood and its quantity. It maintains blood pressure by determining the quantity of water and salts in the blood and tissue fluid. By selectively excreting various substances from the blood, the kidney helps in maintaining the chemical integrity of the body. In case of lack of oxygen in the body, by secreting a special enzyme, the kidney helps in the rapid formation of red blood cells through a hormone called erythropoietin. It removes the surplus part of some nutrients like sugar, amino acids etc. It removes external substances like medicines, poisons etc. which have no use in the body. The kidney maintains a certain amount of water in the body through osmoregulation. Ammonotelic The animals which excrete nitrogenous wastes in the form of ammonia are called ammonotelic animals. Water is required in large quantities for excretion of ammonia. Therefore, only aquatic animals can do this. Like protozoa, porifera, some annelids, aquatic arthropods, mollusca, freshwater fishes etc.  9609544344 Ureotelic The animals which excrete nitrogenous wastes in the form of urea are called ureotelic animals. Most of the land animals convert ammonia (NH3) into urea. As urea is water soluble, water is required for its excretion. Like annelids, bony fish, amphibians and mammals (lion, rabbit, human) etc. Uricotelic Animals that excrete nitrogenous waste material in the form of uric acid are called uricotelic. Like insects, reptiles and mammals living in desert habitats. Water is required for excretion of uric acid because it is less toxic and insoluble in water. 1. Nephritis In this disease, there is pain in the kidney area, which seems to go downwards to the thighs. Urine comes in small amounts and repeatedly with pain, which is foul smelling. There are also blood particles in the urine. This disease is of many types. This disease is caused by bacterial infection. Secondary infections can also cause nephritis. In case of an outbreak, one should take medication from a qualified doctor. However, the use of penicillin is considered the best in this. Uremia A condition that occurs due to accumulation of waste products like urea in the body, which are normally excreted by the kidneys. The severity of this condition is estimated by measuring blood urea. The measurement of urea is easier than other nitrogen-containing toxic substances. Its treatment is completely symptomatic, which is done by a specialist. Renal Calculus or stones Crystals of mineral salts (calcium oxalate) collect in the form of a mass in the pelvis of the kidney, which causes obstruction in the urine path. When the stone comes out of the kidney and starts going into the ureter, then there is a lot of pain and suffering at that time. Calcium-rich foods are not given to such patients in their diet. This disease can be cured through surgery or shock wave lithotomy treatment.  9609544344 4. Haemodialysis Dialysis means separating large and small particles through a selectively permeable membrane Blood dialysis is required in many kidney diseases. There are two methods of this - Peritoneal dialysis and Extra-corporeal dialysis through artificial kidney. In artificial kidney dialysis method, the patient's blood is pumped through a cellophane membrane, this membrane keeps rotating in the dialysis tub; here the waste materials are removed from the blood and the pure blood is pumped into the patient's circulation. Cystitis In this disease, there is frequent urination. There is unbearable pain in the urinary bladder. Symptoms include stiffness, feeling of heaviness, cold and tremors in the limbs. It is caused by infection of B. coli bacteria. Medicines like Alcosal and Contrimoxazole are used for its treatment.  9609544344 RESPIRATORY SYSTEM Every organism needs oxygen to survive because oxygen provides energy by oxidizing or disintegrating organic food materials. This process of oxidation of food materials is called respiration. In other words, it can be said that the oxidation process that takes place in organisms in which complex food materials are gradually decomposed under the control of various enzymes at normal body temperature in the presence or absence of oxygen, as a result of which simple food material CO2 or water and CO2 is formed and energy is released, is called respiration. Humans take air inside the body through the nose or mouth. When air enters through the nose, it becomes slightly moist and warm. The nose also removes dust particles from the air. This air goes to the lungs through the windpipe. Under the process of respiration, the expansion of the chest during exhalation is the action of the muscles. This action is performed by both voluntary and involuntary muscles. In the normal process of respiration, only the intercostal muscles and the diaphragm take part. While taking a deep breath, the muscles of the shoulder, neck and abdomen also help. Lungs are very important parts of the respiratory system. They are located on both sides of the middle line of the thoracic cavity. The right lung is slightly larger than the left lung. They are spongy and each lung is protected in a bag made of a double membrane, which is called pleura. There are millions of cells in the lungs. They purify the impure blood coming from the heart with the oxygen obtained during the process of respiration and expel the carbon dioxide dissolved in the blood. After purifying the blood, it is sent back to the heart. The respiratory process is naturally controlled by the respiratory center of the brain. This center is sensitive to the carbon dioxide present in the blood. As the amount of carbon dioxide in the blood increases, this center starts sending messages to breathe more frequently and our breathing rate increases.  9609544344 Respiratory organs in humans The respiratory system includes all those organs through which air exchange takes place such as nose, pharynx, larynx, trachea, bronchi and bacterioles and lungs. Nostrils: Air (O2) enters the nostrils. There are hairs inside the nostrils, which prevent dust particles and microorganisms from entering the body. Nostrils: The cavity of the nostrils is lined with mucus membrane, which secretes mucus and makes the air moist. Pharynx: Air enters the pharynx from the nostrils. The Eustachian tube of the middle ear also opens in its lateral wall. Larynx: It is also called the voice box. Its main function is to produce sound. The upper end of the trachea is connected to the pharynx through a small hole called glottis, the glottis is closed by a valve. It is called epiglatis. It closes the glottis door and prevents the food from entering the trachea. Trachea: It is in the chest cavity. Here it divides into two branches - one of which goes to the right lung and the other to the left lung and then divides into branches. Bronchi: Trachea divides into two parts after entering the chest cavity, which are called bronchi. Lungs: It is a pair of organs in the chest cavity whose base rests on the diaphragm. Each lung contains millions of alveoli. Each lung is surrounded by a membrane called pleural membrane, which is filled with fluid that protects the lungs. Method of breathing in humans External respiration in mammals occurs in two stages- (a) Breathing (b) Exchange of gases o Breathing Mammals have a pair of flexible, spongy lungs which are safely enclosed within a pair of pleural cavities located in the thoracic cavity.  9609544344 Air is filled and expelled from the lungs at a fixed rate, which is called breathing or respiration. The process of breathing is completed in two parts. These are Inspiration When air from the atmosphere enters the respiratory organs inside the body, then that state is called expiration. In expiration, the external intercostal muscles contract, the ribs and sternum are pulled upwards and outwards, due to which the volume of the chest cavity increases. The radial muscles of the diaphragm contract, due to which the diaphragm becomes flat, due to which the volume of the chest cavity increases in the anteroposterior direction. Due to the increase in the volume of the chest cavity, the pressure decreases, the lungs expand. Expiration When after breathing, the air containing CO2 comes out of the respiratory organs into the atmosphere, then that state is called expiration. In expiration, due to the contraction of the internal intercostal muscles, the ribs come back to their place again. As a result, the volume of the pleural cavity decreases and due to pressure on the lungs, they keep contracting and the air in the lungs goes out through the same path through which it entered and goes back into the environment. The internal intercostal muscles are also called exhalation muscles. Because exhalation is done through them. Exchange of gases Exchange of gases takes place inside the lungs. As a result of exhalation, air reaches various alveoli of the lungs. A dense network of blood cells is present around the alveoli. The oxygen in the air at this time reaches the blood through the wall of fine venous capillaries. Transportation of gases The process of transport of gases i.e. oxygen and carbon dioxide from lungs to the cells of the body and their return to the lungs is called transportation of gases. Transportation of respiratory gases takes place with the help of blood circulation system.  9609544344 (a) Transportation of oxygen Transportation of oxygen takes place mainly through the red pigment haemoglobin found in the blood. Haemoglobin combines with oxygen to form a temporary compound oxyhaemoglobin which is a physical change. Hb (haemoglobin) + O2 (oxygen) → HbO2 (oxyhaemoglobin) This oxyhaemoglobin reaches various cells of the body through blood circulation. Partial pressure of oxygen in cells is low due to which oxyhaemoglobin disintegrates into oxygen and haemoglobin. In this process oxygen is released and enters the tissues. Haemoglobin is violet in colour while oxy haemoglobin is bright red in colour. The amount of oxygen that will be combined with haemoglobin depends on the partial pressure of oxygen and the pH of the blood. Haemoglobin is called respiratory pigment. It is made up of two parts. The first part is called haematin or heme. Heme is an iron porphyrin. An iron atom (Fe) is present in its nucleus. The second part of haemoglobin is called globin which is a colourless protein. It constitutes 95% of haemoglobin. (b) Transportation of carbon dioxide Only 10 to 20 per cent of carbon dioxide is transported from cells to lungs by haemoglobin. Therefore, CO2 is also transported in other ways through blood circulation, which are as follows- (i) Dissolved in plasma: Carbon dioxide dissolves in blood plasma to form carbonic acid. About 7% of CO2 is transported as carbonic acid. CO2 + H2O ⇌ H2CO3 (Carbonic acid) (ii) As bicarbonates Most of the carbon dioxide (about 70%) is transported as bicarbonates. It combines with potassium of blood and sodium of plasma to form potassium bicarbonate and sodium bicarbonate respectively.  9609544344 Formation of bicarbonate in RBC: CO2 + H2O —Carbonic anhydrase→ H2CO3 (carbonic acid) H2CO3 → H+ + HCO3– (bicarbonate) CO2 + H2O + Na2CO3 → 2NaHCO3 (sodium bicarbonate) (iii) As carbomino compounds Carbon dioxide combines with amino (-NH2) group of haemoglobin to form carboxy haemoglobin and combines with plasma protein to form carbomino-haemoglobin. Thus it transports about 23% CO2. CO2 + H2O → NHCOOH Carbomino compound HbNH2 + CO2 → Hb NHCOOH Carboxyl haemoglobin The breathing rate in humans is 12-15 times per minute. During normal respiration, approximately 1500 ml of air remains filled in the lungs at all times. This is called the functional residual capacity of the lungs. Internal respiration The gaseous exchange that takes place between blood and tissue fluid inside the body is called internal respiration. The gaseous exchange that takes place in the lungs is called external respiration. Since internal respiration takes place inside the cell, it is also called cellular respiration. The following processes are involved in internal respiration or cellular respiration. (i) Dissociation of oxyhaemoglobin: As a result of blood circulation, oxyhaemoglobin reaches the cells where the oxygen pressure is low. Hence, oxyhaemoglobin is dissociated into oxygen. In this way, approximately 25% of oxygen reaches the tissues. HbO2 (oxyhemoglobin) → Hb (hemoglobin) + O2 (oxygen) (ii) Oxidation of food stuffs In the presence of oxygen in the cytoplasm, different food stuffs are oxidized in the presence of different enzymes, resulting in the release of energy. There are two types of internal respiration- A. Anaerobic respiration B. Aerobic respiration  9609544344 Anaerobic respiration The respiration that occurs in the absence of oxygen is called anaerobic respiration. In this, glucose (cellular fuel) is partially broken down by a series of complex chemical reactions. This partial breakdown of glucose takes place in the cytoplasm with the help of 12 enzymes. The entire process that takes place under this is called glycolysis. The end product of anaerobic respiration is pyruvic acid. Aerobic Respiration This stage of cellular respiration takes place inside the cell in the mitochondria. In this stage, complete oxidation of pyruvic acid takes place with the help of a series of different chemical reactions and many enzymes and finally CO2 and water are formed as by- products and a lot of chemical energy is released which gets stored in ATP molecules. At the end of this stage, 36 ATP molecules are obtained. Thus, in complete cellular respiration, 38 ATP energy is obtained from one molecule of glucose. As a result of complete breakdown or complete oxidation of one molecule of glucose, only about 55 to 60 percent of the total energy is available to the organisms, the remaining energy is lost in the form of heat energy. ▪ C6H12O6 + 6O2 → 6CO2 + 6H2O + 2830 kJ Mechanism of respiration: The process of respiration is usually completed in two stages. These are- 1. Glycolysis and 2. Krebs cycle. Glycolysis In this process, two molecules of pyruvic acid are formed from one molecule of glucose. Oxygen is not required in this process So this process is the same in anaerobic respiration and anaerobic respiration. This entire process is completed in the cytoplasm. In the entire phase of glycolysis, 4 molecules of ATP are formed while 2 molecules of ATP are spent. Thus, in this process there is a net gain of two molecules of ATP. In this process, four atoms of hydrogen are formed which are used to convert NAD into 2NADH2. Glycolysis was discovered by three German biologists Embden-Meyerhoff and Parson, hence it is also called EMP pathway.  9609544344 Krebs cycle This process was discovered in 1937 by British scientist Hans Krebs. The entire reactions of Krebs cycle take place in mitochondria in eukaryotic organisms and on the cell membrane in prokaryotic organisms. In this, both the molecules of pyruvic acid obtained from glycolysis are completely oxidized in the presence of oxygen. The major changes taking place in this stage are as follows- Before entering the Krebs cycle, one molecule of CO2 and two hydrogen atoms are released from pyruvic acid. The remaining molecule combines with coenzyme-A to form acetal coenzyme-A. Facts related to respiration In normal conditions, the rate of respiration is 15-18 per minute. During hard work or exercise, the rate of respiration increases 20 to 25 times. About 500 ml of oxygen is released in each cycle of breathing. There is inhalation and exhalation of air. We inhale 15000 liters of air in 24 hours. During aerobic respiration, 36 to 38 ATP molecules are formed from one glucose molecule, whereas in anaerobic respiration only 2 ATP molecules are formed. Breathing capacity is reduced in smokers and people suffering from tuberculosis. On the contrary, this capacity is increased in sportspersons and singers. Epiglottis is a flap-like structure which acts as a valve. It protects the lungs while swallowing food. Epiglottis prevents the swallowed food from going into the windpipe.  9609544344 अंत: स्रावी ग्रधं ियां Endocrine Glands o In animals, control and coordination of various bodily functions is done by some specific chemical compounds in addition to the nervous system. o These chemical compounds are called hormones. o The word hormone is derived from the Greek language (Gr. Hormaein = to stimulate or excite), which means a stimulating substance o The secretion of hormones is done by some special types of glands of the body, which are called endocrine glands o Endocrine glands are also known as ductless glands because they do not have ducts for secretion o Being ductless, these glands release their secretion hormones directly into the blood circulation o They are transported throughout the body through the blood circulation system. o Types of glands: Three types of glands are found in vertebrate animals. These are- Exocrine glands o The glands of the body which have vessels or ducts to carry the secretions to various organs are called exocrine glands. o Exocrine glands are also called duct glands. o The secretion of exocrine glands is called enzyme o Sweat gland, milk gland, salivary gland, mucous gland, tear gland etc. are the main examples of exocrine glands. Endocrine Gland o Unlike exocrine glands, endocrine glands are ductless  9609544344 o Hence, they are also called ductless glands o Endocrine glands release their secretions directly into the blood circulation in the absence of a duct. o The secretions secreted by endocrine glands are called hormones. o These hormones then travel with the blood to the organs where they have an effect o Pituitary gland, thyroid gland, adrenal gland, parathyroid gland, pineal body, thymus gland, etc. are the major endocrine glands. Mixed glands o Some glands are such that they are of both types - exocrine and endocrine, they are called mixed glands. o For example - Pancreas. o Main endocrine glands of human body and functions and effects of hormones secreted by them Pituitary gland o It is present in a cavity called sellatureica in the sphenoid bone of the skull. o It is situated between the palate and the ventral surface of the brain and is connected to it by a small stalk called infundibulum o It weighs approximately 0.6 grams. It becomes a little bigger during pregnancy in women o The pituitary gland is also called the master gland, because it controls the secretion of other endocrine glands. o Along with this, it also inspires the personality, health, growth and sexual development of a person. o Hormones secreted by pituitary gland and their functions- The following hormones are secreted by pituitary gland- o Growth hormone (Growth hormone or somatotropic hormone)  9609544344 o It controls the growth of the body, especially the growth of bones. o Its excess causes gigantism or acromegaly disorder. o Due to this, the height of a person increases much more than normal and the bones become heavy and thick. o During childhood, due to less secretion of this hormone, the growth of the body stops o Due to which, a person becomes dwarf. o Thyrotropic or thyroid stimulating hormone (STH) o This hormone stimulates the functions of the thyroid gland. o It also affects the secretion of thyroxine hormone. Adrenocortico tropic hormone (ACTH) o This hormone affects the cortex of the adrenal gland and also stimulates the hormones released from it. (Gonadotropic hormone): This hormone affects the functioning of the gonads. It is of two types. Follicle stimulating hormone (FSH) o In men, this hormone stimulates spermatogenesis. o In women, this hormone induces ovulation from the ovary. o It helps in the growth of follicles in the ovary. o Lutenizing hormone (LH) o In men, this hormone affects the interstial cells and induces the male hormone testosterone, whereas in women, it induces the secretion of estrogen hormone. o Lactogenic hormone (LTH) o This is the lactogenic hormone. o The main function of this hormone is to produce milk secretion in the breasts for the baby. o Secretion of corpus luteum also starts with this hormone.  9609544344 (Melanocyte stimulating hormone) o In the following animals and birds, this hormone affects the colour of the skin by spreading the particles of melanin pigment. o As a result, the skin becomes coloured. o In humans, this hormone induces rashes and moles on the skin. Vasopressin or Antidiuretic hormone (ADH) o This hormone induces the ureters of the kidney to reabsorb water. o Apart from this, it increases blood pressure by contracting the blood vessels. o It helps in the water balance of the body. o This is why it is called antidiuretic. o Deficiency of this hormone causes a disease called diabetes insipidus. Oxytocin or Pytocin (Pitocin) o This hormone causes contraction in the unlined muscles of the uterus, which causes labour pain and helps in the birth of the child. o It also helps in the secretion of milk from the breast. Thyroid gland o In humans, this gland is a biconvex structure. o This gland is located below the larynx on both sides of the windpipe or trachea. o It is connected to a thin transverse strip of connective tissue, which is called isthmus. o It is made up of many hollow and round follicles. o Iodine-rich pink coloured colloidal substance is secreted in the cavity of these follicles, which is called thyroglobulin. o The secretion or hormone of thyroid gland is Thyroxine and Triodothyronine. o Both these hormones contain iodine in large quantity. Thyroxine o This hormone accelerates the speed of cellular respiration. o It is essential for normal growth of the body, especially for the growth of bones, hair etc. o This hormone also affects other endocrine glands. o It controls the water balance in the body by cooperating with the hormone secreted by pituitary gland.  9609544344 o Due to deficiency of thyroxine in children, a disease called Cretinism occurs. In this disease, an adult of 30 years of age appears to be a child of 4 or 5 years. o After puberty, due to the deficiency of this hormone, a disease called Myxioedema occurs in the body. o Due to the deficiency of this hormone for a long time in humans, the disease called Hypothyroidism occurs. o Due to the deficiency of iodine in food, a disease called Goitre occurs. o Due to this, the size of the thyroid gland increases a lot. o Due to the excess of thyroxine, a disease called Toxic goitre occurs. o Due to the excess of thyroxine, the eye swells and comes out of the eye socket. o This disease is called Exophthalmic goitre. o Parathyroid glands o These are lobed glands of the shape of a pea. o It is situated behind the thyroid gland and is separated from it by a capsule of connective tissue. Hormones secreted by parathyroid gland and their functions: Two hormones are secreted by this gland. Both of them control the amount of calcium and phosphorus in the blood. These hormones are- Parathyroid hormone o This hormone is released when there is a deficiency of calcium in the blood. o This hormone increases the absorption of calcium and its reabsorption in the kidney. o It releases calcium and phosphorus in the blood by melting the unnecessary part of the bones. o It controls the growth of bones and the formation of teeth.  9609544344 Calcitonin hormone o When the amount of calcium in the blood increases, then this hormone is released. o This hormone works opposite to parathyroid hormone. o It reduces bone disintegration and increases the excretion of calcium in urine. Adrenal gland o The adrenal gland is also known as the suprarenal gland. o This gland is located inside the upper end of each kidney. Actually, the adrenal gland has two parts- o Outer cortex or cortex o Inner medulla o These two parts are different from each other functionally and also in origin. o Hormones secreted by adrenal cortex and their functions: The hormones secreted by it can be classified into the following three groups- Glucocorticoids o They play an important role in food metabolism. o They control the metabolism of carbohydrates, proteins and fats. o They also help in controlling water and electrolytes in the body. o They induce gastric secretion. These hormones are anti-inflammatory, for which they control white blood cells and prevent protective reactions against irritants. o They increase the number of red blood cells in the body and control white blood cells. Mineralocorticoids o Their main function is to control the reabsorption of salt by the renal tubules and the amount of other salts in the body. o They also control the water balance in the body. Due to its effect, potassium and phosphate are excreted in large quantities through urine and sodium chloride and water are excreted in small quantities. Sex hormones o These hormones control the development of muscles and bones, external genitals, pattern of hair growth and sexual behavior. o These hormones are mainly male hormones androgens and female hormones estrogens.  9609544344 o The main male hormone is dehydroepiandrosterone. o In women, excess of this hormone causes facial hair growth. o This process is called adrenal virilism. o Hormones secreted by adrenal medulla and their functions o The following two hormones are secreted from adrenal medulla- Adrenalin o This hormone is also called adrenalin and epinephrine. o This hormone is the major part of the hormone secreted from the medulla. o This hormone starts getting secreted excessively in the state of anger, fear, mental stress and busyness, so that appropriate steps can be taken in these critical situations. o It increases the heart rate. This hormone induces goosebumps. o It dilates the pupils of the eyes. This hormone secreted by the adrenal gland is called the fight and flight hormone. Nor adrenalin or Norepinephrine o These generally increase the excitability and contractibility of the heart muscles. o As a result, blood pressure increases. o