Medical Physiology PDF Lecture Notes

Medical Physiology Lecture notes For Nursing Institute By Dr. Asmaa Abdelmageed Mohammed Lecturer of Medical Physiology, Faculty of Medicine, Aswan University  Introduction...

Medical Physiology Lecture notes For Nursing Institute By Dr. Asmaa Abdelmageed Mohammed Lecturer of Medical Physiology, Faculty of Medicine, Aswan University  Introduction Physiology is the study of the function of living organisms. There are many types of physiology, including: bacterial physiology, viral physiology, plant physiology, human physiology and many more subdivisions. Human physiology is concerned with the way the human body works. It is the study of the functions of organs and systems and the way these functions are integrated. The human body is made up of 75- 100 trillion cells, which are arranged in a variety of combinations and form various degrees of organized structures. Collection of cells with similar properties will form tissues (e.g. muscular tissue, epithelial tissue). Different tissues combine to form organs (e.g. heart, brain, liver). Organs of complementary functions constitute the different systems (e.g. cardiovascular system, nervous system). 1  Cardiovascular system The cardiovascular system is composed of a central pump; the heart, that pumps blood and a chain of tubes; blood vessels through which blood is pumped. Function of the Cardiovascular system (CVS):  The heart pumps blood through blood vessels to supply cells with their requirements as nutrients, oxygen, minerals, and other substances and carry away cellular waste products as carbon dioxide, urea, and creatinine to eliminate them outside the body through the kidney, lungs, and skin. Functional anatomy of the heart: The heart is formed of four chambers; two atria and two ventricles. Atria and ventricles are separated by valves that allow blood to pass in one side from the atria to the ventricles and prevent blood from coming back. 2 Cardiac muscle as functional syncytium: Cardiac muscle fibers are arranged in a latticework with the fibers dividing, recombining and then spreading again. They are connected to each other with gap junctions that allow rapid spread of action potential. The heart is composed of two syncytiums; the atrial syncytium that is formed of the walls of the two atria, and the ventricular syncytium that is formed of the walls of the two ventricles. The atria are separated from the ventricles by a fibrous ring, so the potential is transmitted from the atria to the ventricles through the A-V bundle only. Interconnected nature of cardiac muscle fibers 3 Properties of cardiac muscle: 1- Excitability. 2- Automaticity and rhythmicity. 3- Contractility. 4- Conductivity. 1- Excitability: It is the ability of cardiac muscle to respond to an adequate stimulus by generating action potential which leads to mechanical activity. 2- Automaticity and rhythmicity: Automaticity is the ability of the heart to start its own contraction spontaneously independent of external stimuli. Rhythmicity is the ability of the heart to beat regularly. 3- Contractility: It is the ability of cardiac muscle to contract and relax pumping the blood. 4- Conductivity: It is the ability of cardiac muscle to transmit excitation wave. Impulses start from the pacemaker of the heart; the S-A node; a node in the wall of the right atrium, passing to atrial muscles then to the ventricles through the A-V node. 4 Heart rate: Normal heart rate ranges from 60 to 100 beats/min. with average 70 beats/min in average adult male. Tachycardia: heart rate faster than 100 beats/min. Bradycardia: heart rate slower than 60 beats/min. Physiological factors affecting heart rate: 1- Age: Heart rate in newly born infants is about 120 beats/min. that decrease with age until reaching the normal adult level at 20 years. 2- Sex: heart rate is faster in females. 3- Physical training: Athletes have slower heart rate than non-trained person. Arterial pulse wave: At each ventricular contraction (cardiac systole) blood is pimped in the aorta that sets up a pressure wave that travels along the arteries, this pressure wave expands the arterial wave giving the sensation of the pulse. Pulse is mainly detected from the radial artery; it corresponds to the heart rate. 5 Arterial blood pressure: It is the force exerted by blood stream on the lateral walls of the arteries leading to their distension. It includes: Systolic arterial blood pressure: Corresponds to cardiac systole and ranges normally between 100 - 145 mmHg with an average 120 mmHg. Diastolic arterial blood pressure: Corresponds to cardiac diastole and ranges normally between 60 – 90 mmHg with an average 80 mmHg. 6  The blood The blood is the fluid that circulates in the cardiovascular system. Functions of blood: 1- Transport function: Blood acts as a carrier of many substances as oxygen, carbon dioxide, nutrients as glucose and fatty acids, end products of metabolism as urea, and hormones. 2- Defensive function: Blood contain white blood cells which defense against invading microorganisms and tumors. 3- Hemostatic function: Blood contains substances that can stop bleeding when a blood vessel is injured. 4- Homeostatic function: By the continuous exchange of substances between blood and interstitial fluids and between blood and the external environment through the renal, respiratory, and gastrointestinal systems, blood can share in keeping the internal environment of the body constant. Blood is formed of two main parts: 1- Plasma: It is the fluid part of the blood which forms 55% of total blood volume. 2- Cells: Forms 45% of total blood volume and include red blood cells (RBCs), white blood cells (WBCs), and platelets (thrombocytes). 7  Plasma Plasma is the fluid part of the blood. Plasma clots on standing separating the serum. Composition of the plasma: 1- Water: It forms 90 % of plasma volume. 2- Inorganic substances: they form 0.9% of plasma volume.  The main inorganic cation of plasma is sodium (142 mEq/L)  The main inorganic anions are chloride (104 mEq/L) and bicarbonate (27 mEq/L).  Other anions as phosphates and sulphates are present in small amounts. 3- Organic substances: They forms 9.1% of plasma volume.  Plasma proteins.  Plasma lipids: Main plasma lipids are cholesterol, triglycerides, fatty acids, and phospholipids. They are carried in the blood in combination with plasma proteins forming lipoproteins that could be high-density lipoproteins (HDL), low density lipoproteins (LDL), and very low density lipoproteins (VLDL).  Other organic substances as glucose, amino acids, vitamins, enzymes and waste products as uric acid and urea. 4- Gases: Plasma contains soluble oxygen and carbon dioxide. Plasma proteins: Plasma proteins consist of albumin, globulin, fibrinogen, and prothrombin. Globulin is subdivided into α1, α2, β1, β2, and γ globulins. Plasma proteins concentration is 7.2 – 7.4 gm/dl. 8  Sites of formation of plasma proteins:  The liver is the main site of synthesize of plasma proteins. Albumin, fibrinogen, and 50 % of globulin are formed in the liver.  γ globulins, are antibodies and are formed from plasma cells in the lymphoid tissues. Functions of plasma proteins: 1- Osmotic function:  Plasma proteins mainly albumin are important for determining the colloid osmotic pressure of blood and thus regulating exchange of fluid between blood and interstitial fluid. 2- Defensive function:  Gamma globulins are responsible for defending against microorganisms and toxins. 3- Blood clotting:  Fibrinogen and prothrombin are essential for blood clotting. 4- Blood viscosity:  Fibrinogen contributes more than other plasma proteins in determining blood viscosity due to its elongated shape. 5- Buffer function:  Plasma proteins are responsible for 15% of the buffering power of the blood. 6- Capillary function:  Plasma proteins are essential for maintenance of capillary permeability, by closing the pores in the capillary wall controlling exchange of substances. 7- Transport and conservation of important substances:  Plasma proteins as albumin, α and β globulin act as carriers for important substances in the blood as steroid and thyroid hormones, vitamins, lipids, iron, and calcium. 9  Carrying of these substances on plasma proteins prevents their loss in urine and provides a reservoir to be used when needed. 8- As a source of amino acids for tissues: Plasma proteins can be used as a source of amino acids for tissues in cases of tissue protein depletion. Red blood cells (Erythrocytes) Concentration of RBCs: The average number of RBCs in the blood is 5.2 million/mm3 in healthy men and about 4.7 million/mm3 in women. Shape and size of RBCS: Normal RBCs are biconcave discs with a diameter of about 7.8 micrometers and thickness of 2.5 micrometers at the thickest point and 1 micrometer or less in the center. RBCs shape can change remarkably as they are squeezed when passing through capillaries. RBCs contain hemoglobin. Hemoglobin content: It is about 15 gm/dl in men, and about 14 gm/dl in women. Shape of RBCs 10 Functions of RBCs: 1- RBCs contain hemoglobin, functions of Hemoglobin: a- Transport of O2 from the lungs to the tissues. b- Transport of CO2 from the tissues to the lung. c- Acid-base buffer: the buffering power of hemoglobin is six times more than the buffering power of the plasma proteins. 2- Function of RBCs membrane: RBCs membrane keeps hemoglobin inside the RBCs and prevents its leakage to the circulation, when hemoglobin is free in the plasma, the following risks would occur: a- Hemoglobin filters in the renal glomeruli, thus blocking renal tubules. b- Hemoglobin increases blood viscosity adding more load on the heart. c- Free hemoglobin would increase plasma colloid osmotic pressure from 25 mmHg to about 70 mmHg, increasing load on the heart. White blood cells (WBCs) White blood cells, also called leukocytes, are the mobile units of the body's protective system. They are formed partly in the bone marrow and partly in the lymph tissues. WBCs are divided into: 1- Granulocytes (polymorphonuclear leukocytes): They have a nucleus that is often divided into several lobes, their cytoplasm is characterized by the presence of granules, according to the staining properties of the granules, granulocytes can be divided into three types: a) Neutrophils: Their granules stain with both the basic and acidic dyes. b) Eosinophils: Their granules stain with acidic dyes. c) Basophils: Their granules stain with basic dyes. 2- Non-granulocytes: 11  They include: a) Lymphocytes. b) Monocytes. Normal count of WBCs: The adult human has approximately 4000 – 11000 / mm3 blood. Average concentrations of different types of WBCS in the blood are as follow: Functions of leukocytes: 1- Neutrophils: They form the first defensive line against microorganisms and they act by phagocytosis in acute inflammation. 12  2- Eosinophils:  They kill parasites by releasing certain substances.  They collect in tissues in which allergic conditions occur, they detoxify inflammation inducing substances released by the mast cells and basophils.  They phagocytize and destroy allergen-antibody complexes, thus preventing excess spread of local inflammatory state. 3- Basophils:  They are similar to mast cells; they secrete heparin which can prevent blood coagulation.  Basophils and mast cells release histamine and small quantities of bradykinin and serotonin. 4- Monocytes:  They are the precursors of tissue macrophages.  They pass into inflammation areas soon after neutrophils.  They phagocytose and digest bacteria, dead neutrophils, and remnants of tissue destruction. 5- Lymphocytes:  They are formed in the bone marrow, lymph nodes, thymus, and spleen.  They play an important role in defending the body through specific immune system.  They are divided into: a) B-lymphocytes:  They are a major defense against bacterial infections. b) T-lymphocytes:  They are a major defense against infections by viruses, fungi, and few bacteria as TB. 13  Platelets and Hemostasis Platelets are small, granulated, non-nucleated round or oval bodies of about 2-4 micron in diameter. They are formed from the bone marrow. Their normal blood concentration is between 150,000 – 300,000 /mm3. Hemostasis: Hemostasis means prevention of blood loss after injury. Whenever a blood vessel is cut or ruptured, a series of changes occur to stop bleeding which are: 1- Constriction of the blood vessel. 2- Formation of a platelet plug. 3- Conversion of the platelet plug into definitive blood clot as a result of blood coagulation. 14  Blood groups At least 30 antigens have been found on the surface of RBCs, of which two antigens are much more likely than the others to determine blood groups. They are the ABO system of antigens and the Rh antigens. 1- ABO system: Two antigens (agglutinogens) are present type A and type B antigens on the surfaces of the RBCs in a large population of human beings. People may have both types of antigens on their RBCs surface, only one type of antigen, or may have neither of them on their cells. According to types of antigens on the RBCs surface blood groups are determined. When neither A or B agglutinogen is present, the blood is type O. When only type A agglutinogen is present, the blood is type A. When only type B is present, blood is type B. When both A and B are present, blood is type AB. When type A agglutinogen is not present in a person's RBCs, antibodies known as anti-A agglutinins develop in the plasma. Also, when type B antigens is not present in a person's RBCs, antibodies known as anti-B agglutinins develop in the plasma. Type O blood, contains no agglutinogens on RBCs surface and contain both type of agglutinins in the plasma. Type A blood contain type A agglutinogen on RBCs surface and anti-B agglutinin in the plasma. Type B blood contains type B agglutinogein on the RBCs surface and anti-A agglutinin in the plasma. Type AB blood contains both types of agglutinogens on the RBCs surface and contains neither of the agglutinins in the plasma. 15  2- Rh blood types: A person who has a D antigen on RBCs surface is said to be Rh positive, whereas a person who doesn't have D antigen is said to be Rh negative. About 85% of the population are Rh positive and 15% are Rh negative. Rh antibodies are formed in the plasma of a Rh negative person if he transfused with Rh positive blood and the person in this case is sensitized to Rh factor. So if the person receives Rh positive blood again, agglutination and hemolysis of RBCs will occur. Importance of Rh factor:  Erythroblastosis fetalis (hemolytic disease of the new born): - It is a disease of the fetus characterized by agglutination of his RBCs. It occurs when the mother has a Rh negative blood and the father has a Rh positive blood, the fetus could by Rh positive. - During delivery, large number of Rh positive fetal RBCs enter the mother's circulation, forming anti-D antibodies, making the mother sensitized. 16  - The first baby usually escapes the damage, but when the mother is pregnant again with a Rh positive baby, anti-D antibodies will pass from the mother to the baby destroying his RBCs. - The affected baby could be severely anemic and jaundiced due to excessive bilirubin formation. Because of the immature blood brain barrier, bilirubin can reach the brain causing brain damage (kernicterus). In most sever conditions the baby is born dead. - For prevention: Rh negative mother should never receive Rh positive blood. When Rh negative female delivers a Rh positive baby, anti-D antibodies are given to her immediately after delivery to neutralize the D antigen of the Rh positive fetal RBCs that entered the blood, preventing sensitization of the mother.  Repeated blood transfusion: - If a Rh negative person is transfused with Rh positive blood, he will produce agglutinins against Rh factor. If after some time, this person is transfused again with Rh positive blood, agglutination occurs. Blood transfusion It is important to determine blood groups of the donor and the recipient before blood transfusion. Normally donor's RBCs agglutinate with the recipient antibodies. The reverse rarely occurs due to dilution of the donor's antibodies in the large volume of the recipient blood. It is important to do cross matching test by adding the blood of the donor to the serum of the recipient before blood transfusion. O type blood group is considered universal donor while AB is universal recipient. Indications of blood transfusion: 1- To restore whole blood as in cases of hemorrhage. 17  2- To restore one deficient element as RBCs, platelets, WBCs, plasma proteins, or coagulation factors. Precautions before blood transfusion: 1- Cross matching test should be made to insure blood compatible groups. 2- Rh negative person should receive only Rh negative blood. 3- The blood must be free from diseases or contamination. Effects of incompatible blood transfusion: Incompatible blood transfusion causes a transfusion reaction in which the RBCs of the donor blood is agglutinated which leads to: 1- Jaundice: caused bb RBCs hemolysis and phagocytosis releasing bilirubin, however, if liver function is normal, bile pigments will be excreted by the way of the bile into the intestine and jaundice usually will not appear. In adult person for jaundice to appear, more than 400 milliliters of blood must be hemolyzed in less than a day. 2- One of the most lethal effects of blood transfusion is kidney failure which caused by:  Toxic substances released from the antigen-antibody reaction of the transfused blood cause powerful renal vasoconstriction.  Circulatory shock because of the toxic substances release and the immune reactions, decreasing the arterial blood pressure, renal blood flow and urine output greatly.  Filtration of the hemoglobin released from the RBCs through the renal glomeruli and its precipitation in renal tubules blocking renal tubules. 18  Respiratory system Functional anatomy of the respiratory tract Respiratory passages are divided into: 1- Upper respiratory passages: Including the nose, the pharynx, and the larynx. 2- Lower respiratory passages: that is divided into: a) Conducting zone: Including trachea, bronchi, bronchioles, and terminal bronchioles. They transport air from upper respiratory passages to the respiratory zone. b) Respiratory zone: Including respiratory bronchioles, alveolar ducts, and alveolar sacs. They are responsible for gas exchange between air and blood. 19  Lower respiratory passages zones Functions of the respiratory system 1- Transport of air to the alveoli. 2- Humidification and warming of inspired air. A rich network of capillaries release moisture and heat to warm and humidify air before reaching the alveoli. 3- Filtration of air from dust and bacteria. 4- Exchange of gases between air and blood. 5- Olfaction: as olfactory receptors are present in the mucous membrane lining the upper nostrils. 6- Vocalization: through the larynx as it contains the vocal cords. 7- Regulation of acid-base balance. 20 Pulmonary ventilation It means inflow and outflow of air between the atmosphere and the lungs. It is formed of inspiration and expiration. 1- Inspiration: It means air inflow from the external atmosphere into the lungs. It is an active process that requires contraction of inspiratory muscles (the diaphragm and the external intercostal muscles). 2- Expiration: It means air outflow from the lungs to the external environment. It is a passive process during quiet breathing that does not require muscle contraction but caused by the relaxation of the inspiratory muscles. 21 Digestive System 22  Functions of the digestive system Continual body supply of water, electrolytes, and nutrients for that digestive system requires: 1- Secretion of digestive juices. 2- Digestion of food. 3- Absorption of digestive products, water, and electrolytes. 4- Movement of food through alimentary tract. 5- Secretion of hormones to control food digestion. Functions of several parts of the digestive system  The stomach Functional anatomy of the stomach Functionally the stomach is divided into: 1- Proximal motor unit (fundus and body) responsible for storage of food. 2- Distal motor unit (antrum and pylorus) mixing of food, partial food digestion, and emptying of partially digested food into the duodenum. Function of the stomach Stomach secretes about 2.5 liters/day of acidic juice that is composed of: 1- HCl, Na+, and K+. 2- Pepsin for protein digestion. 3- Mucous to protect stomach mucosa from digestion. 4- Intrinsic factor for vit. B 12 absorption. 5- Water. 23  Functions of HCL: 1- Killing bacteria. 2- Dissolve food particles. 3- Activate pepsinogen into pepsin. 4- Provide optimum pH for the action of pepsin. 5- Helps iron and calcium absorption.  Pancreas Functional anatomy of the pancreas: The pancreas contains two portions; one is an exocrine part that secretes pancreatic juice through a duct into the duodenum, and a second endocrine part that secretes insulin directly into blood. Functions of the exocrine pancreas: Secretion of pancreatic juice with is composed of: 1- Enzymes for digestion of proteins, carbohydrates, and lipids. 2- Bicarbonate ions.  Liver Functions of the liver: 1- Blood storage (reservoir): The liver can store 200 - 400 ml of blood in liver sinusoids (useful in case of hemorrhage) 2- Filtration of blood: hepatic Kupffer cells (highly phagocytic) can remove 90% of bacteria in the portal venous blood. 3- Glucostat function maintaining constant circulating glucose levels 24  through: - Formation and storage of glycogen (glycogenesis). - Breakdown of glycogen into glucose (glycogenolysis). 4- Oxidation of fatty acids and formation of lipoproteins. 5- Deamination of proteins and formation of urea. 6- Storage of vitamins as vit. A, D, and B12. 7- Storage of iron. 8- Detoxification and excretion of drugs and some hormones as thyroxine. 9- Formation of bile.  Small intestine Functions of the small intestine: 1- Secretion of mucus. 2- Secretion of enzymes for final digestion of food particles. 3- Absorption of small food particles into the blood.  Large intestine Functions of the large intestine: 1- Absorption of water, sodium, and other minerals. 2- Secretion of mucus. 3- Excretion of undigested food. 25  Urinary system Functions of the urinary system: 1- Excretion of metabolic waste products as urea, uric acid, creatinine, and various hormones. 2- Excretion of foreign chemicals as drugs, food additives, and pesticides. 3- Regulation of water and electrolyte balance. 4- Regulation of arterial blood pressure through regulating amounts of water and sodium excreted and regulating renin secretion. 5- Regulation of acid-base balance. 6- Endocrine function as secretion of erythropoietin, active vitamin D, and renin. 7- Gluconeogenesis. 26 Formation of urine: The nephron is the functional unit of the kidney, about 1.3 million nephrons are present in each kidney. Nephrons are capable of forming urine by three processes: 1- Glomerular filtration: Through fluid filtration from blood into Bowman's capsule, a fluid that is nearly free from proteins is filtered. 2- Tubular reabsorption: It is the transfer of water and solutes from the filtrate back into the blood. 3- Tubular secretion: It is the transfer of solutes from the blood into the tubular fluid. Urine excretion (what finally comes out in urine) = Filtration rate – reabsorption rate + secretion rate 27 28  Endocrine system Endocrine system is formed of many endocrine glands that secrete hormones directly in the blood to affect their target tissues and organs all over the body.  The pituitary gland: It is the master endocrine gland  Three glands are under the control of the pituitary gland: thyroid gland, suprarenal cortex, and gonads (testis and ovaries).  Three glands are not under the control of the pituitary gland: parathyroid, suprarenal, and pancreas. 29  Pituitary gland Functions of the pituitary gland: Pituitary gland is divided into two lobes; anterior lobe and posterior lobe. Anterior lobe secretes six hormones: 1- Growth hormone (GH). 2- Adrenocorticotrophic hormone (ACTH). 3- Thyroid-stimulating hormone (TSH). 4- Prolactin. 5- Follicle stimulating hormone (FSH). 6- Luteinizing hormone (LH). Posterior pituitary lobe secretes two hormones: 1- Antidiuretic hormone (vasopressin) ADH. 2- Oxytocin. 30 Functions of growth hormone: 1- Metabolic function: - Effect on protein metabolism: It is an anabolic hormone that increases protein synthesis all over the body. - Effect on carbohydrate metabolism: It is a hyperglycemic diabetogenic hormone that decreases glucose uptake and utilization by the cells and increases blood glucose level. - Effect on fat metabolism: It is a lipolytic ketogenic hormone that enhances fat utilization for energy production. 2- Growth function: - Growth hormone enhances growth of soft tissues, bone, and cartilage. - Before adolescence (before epiphyseal closure) long bones increase in length, after epiphyseal closure no further lengthening of long bones occur instead thickness of bones increase especially the membranous bones. Disturbances of growth hormone function: 1- GH hypofunction: pituitary dwarfism. 2- GH hyperfunction: - Before adolescence: gigantism. - After adolescence: Acromegaly. Functions of ADH: 1- Reabsorption of water from renal tubules. 2- Vasodilatation of renal blood vessels. 3- Vasoconstriction of extra-renal blood vessels. 31  4- Secreted in stress along with cortisol. Functions of oxytocin: 1- Uterine contraction during labor. 2- Contraction of myoepithelial cells surrounding breast alveoli to squeeze milk into the ducts.  Thyroid gland Thyroid gland secretes: 1- Thyroid hormones; thyroxin (T4) and tri-iodothyronine (T3) from thyroid follicles. 2- Thyrocalcitonin: from parafollicular cells. Functions of thyroid hormone: 1- Metabolic function: - It is a calorigenic hormone increasing oxygen consumption. - Effect on protein metabolism: It is an anabolic hormone. - Effect on carbohydrate metabolism: 32  It is a hypoglycemic hormone that stimulates glucose absorption, uptake By cells and oxidation. - Effect on fat metabolism: It is a lipolytic hormone that increases fatty acids oxidation. 2- Growth function: - Thyroid hormones are required for normal mental, physical, and sexual development in young and normal mental, physical, and sexual functions in adults. Functions of thyrocalcitonin: - It stimulates both calcium and phosphate excretion from the kidney.  Parathyroid glands Four parathyroid glands are embedded in the four poles of the thyroid gland; they secrete parathyroid hormone (parathormone) 33  Functions of Parathormone: 1- It is a hypercalcemic hormone that increases blood calcium levels through: - Mobilization of calcium from bones. - Increasing calcium reabsorption from renal tubules. - Increasing calcium reabsorption from the intestine. 2- It is a hypophosphatemic hormone that stimulates renal phosphate excretion and decreases blood phosphate levels.  Adrenal (suprarenal) glands Adrenal glands are essential for life; complete damage to adrenal cortex causes death. Each adrenal gland is formed from two parts: 1- The adrenal cortex: which is divided into three zones and secretes: - Mineralocorticoids mainly aldosterone. - Glucocorticoids mainly Cortisol. - Adrenal androgens and small amount of estrogen. 2- The adrenal medulla: which secretes catecholamines (epinephrine, 34 norepinephrine, and dopamine). They are secreted in cases of emergency as a part of the sympathetic stimulation. Functions of aldosterone: - Maintaining extracellular fluid through increasing sodium reabsorption from urine, sweat, saliva, gastric juice, and colon that is followed by water reabsorption. - Secretion of K+ and H+ from renal tubules. Functions of cortisol: 1- Physiological functions: due to the effects of the normally present hormone levels in the plasma. - Effect on protein metabolism: It is a catabolic hormone that decreases protein synthesis and increases protein catabolism. - Effect on carbohydrate metabolism: It is a hyperglycemic, diabetogenic hormone that decreases glucose utilization by muscle and adipose tissue and increases blood glucose level. - Effect on fat metabolism: It is a lipolytic, ketogenic hormone that stimulates fat oxidation in cells. - Effect on C.V.S: essential for the maintenance of normal blood pressure - Anti-stress action 2- Pharmacological functions: due to the effect of high doses given during treatment of certain diseases of in cases of hypersecretion by the adrenal cortex. 35  - Increasing rate of bone resorption causing osteoporosis. - Anti-inflammatory function. - Anti-allergic effect. - Immuno-suppressive effect.  Pancreas Endocrine part of the pancreas (Islets of Langerhans) secrete several hormones mainly insulin and glucagon. Functions of insulin: 1- Metabolic functions: - Effect on protein metabolism: It is an anabolic hormone. - Effect on carbohydrate metabolism: It is a hypoglycemic hormone that stimulates uptake and use of glucose by muscles, adipose tissue, and liver. - Effect on fat metabolism: It is a fat sparer, lipogenic hormone that decreases fat utilization by tissues. 2- Growth function: - Insulin hormone stimulates growth of cartilage, bone, and muscle. Functions of glucagon: - It is a hyperglycemic, lipolytic hormone. Diabetes mellitus It is a syndrome characterized by hyperglycemia, glucosuria, polyuria, polydipsia, and polyphagia. It is due to insulin deficiency.  The testis It is the primary male sex organ and it has two main functions: 1- Formation and release of male gametes the "spermatozoa". 2- Production of the male sex hormone; testosterone. 36 Function of testosterone: 1- During fetal life: - Sex differentiation; secretion of testosterone at 7th week of the intrauterine life causes the male sex organs to develop from the Wolffian duct. - Development of male genitalia. - Descent of the testis. 2- At puberty: - Testosterone is essential for sperm formation (spermatogenesis). - It is essential for the development of secondary sex organs. - For the development of secondary sex characters as:  Increase muscle mass.  Growth of bones, broadening of the shoulder, narrowing of the pelvis, and early fusion of epiphyses.  Increase skin thichness and increase secretion of sebaceous glands.  Increase hair growth on face, chest, and other parts as the back.  Hair growth over the pubis and decrease hair growth in head.  Thickening of the vocal cords changing voice into deeper adult male voice.  Increase in BMR.  Increase number of RBCs.  It is an anabolic hormone. 37  The ovaries The ovaries are the female gonads and they have two main functions: 1- Formation and release of the female gametes (the ova). 2- Secretion of the female sex hormones; estrogen and progesterone Functions of estrogen: 1- In the embryonic life: - Minute amount of estrogen is secreted which are essential for the development of the uterus and vagina during intrauterine life. 2- At puberty: - Estrogen is essential for ovulation (release of ova). - It is essential for the growth, development, and maintenance of the secondary sex organs (uterus, cervix, vagina, fallopian tubes, and mammary glands). - Responsible for the secondary sex characters as:  Female body configuration with narrow shoulders, broad pelvis, and characteristic fat distribution in breast, buttocks, and thighs.  Estrogen does not stimulate the growth of vocal cords; the female keeps the high-pitched voice of children.  Less body hair and more scalp hair.  Smooth soft skin.  It is an anabolic hormone. 38  Nervous System The nervous system, along with the endocrine system provide most of the control functions of the body. 39  Anatomical classifications of the nervous system: The nervous system consists of the central nervous System (CNS) and the Peripheral Nervous System (PNS). CNS is composed of the brain (located in the cranial cavity) and the spinal cord (located in the vertebral cavity), which serve as the main control centers for all body activities. PNS is composed of nerves derived from the brain and spinal cord (12 pairs of cranial nerves and 31 pairs of spinal nerves) which serve as linkage between the CNS and the body.  The central nervous system Central nervous system is formed of the brain and the spinal cord. 1- The Brain: It is formed of the cerebrum, cerebellum, and brain stem. 40 Functions of the cerebrum: 1- Control of voluntary movements. 2- Perception of sensory stimuli as pain, touch, temperature, hearing, taste, and smell. 3- Control of intelligence, speech, memory, and learning. Functions of the cerebellum: 1- Maintenance of posture and equilibrium. 2- Maintenance of muscle tone. 3- Planning and programming of movements. 4- Coordination of complex movements. 5- Timing of movements. Functions of the brain stem: 1- Control the flow of messages between the brain and the body. 2- Control involuntary eye movements and reflexes. 3- Contain regulating centers for breathing, heart rate, digestion, and sleep. 4- Initiating reflexes like vomiting, swallowing, and sneezing. 2- The spinal cord: Spinal cord transmits signals between the body and the brain and is responsible for spinal reflexes. 41  Peripheral nervous system It is formed of nerves that arise from the brain (cranial nerves) and nerves arising from the spinal cord (spinal nerves). Peripheral nerves are functionally divided into: 1- Sensory (afferent) division: - That carry sensation from the body into the central nervous system. 2- Motor (efferent) division: - That carry motor impulses from central nervous system to the body; they are further divided into:  Somatic nervous system: that carry motor impulses to voluntary skeletal muscles.  Autonomic nervous system: that carry involuntary orders into cardiac muscle, smooth muscle, and glands. 42  Autonomic Nervous System Types of the autonomic nervous system Autonomic nervous system can be divided into sympathetic and parasympathetic branches. 1) The sympathetic nervous system It is activated in emergencies, flight– or– fight reaction, in the sense that the body can quickly either flee or "take a stand". It is catabolic. Sympathetic fibers originate from the thoraco-lumbar region of the spinal cord (T1 – L2). 2) The parasympathetic nervous system It acts during rest and digestion (anabolic). Fibers originate from Cranial nerves (III, VII, IX, and X) and middle 3 sacral segments (S2 –S4). 43 44  The effect of sympathetic & parasympathetic on various tissues 1) Functions of the sympathetic nervous system: (1) To the eye:  Dilatation of the pupil (mydriasis) → by contraction of meridional fibers of the iris that dilates the pupil.  Slight relaxation of the ciliary muscle → decreases power of lens → Far vision. (2) To the glands:  Nasal, lacrimal, salivary, and many gastrointestinal glands: Slight concentrated secretion, rich in enzymes and mucous, and vasoconstriction of glands blood vessels.  Sweat glands: Copious sweating (cholinergic).  Apocrine glands: Thick odoriferous secretion (adrenergic). (3) To the blood vessels:  Vasoconstriction to all blood vessels except coronary and blood vessels of skeletal muscles. (4) To the heart:  Increases the overall activity of the heart. Increasing the rate and the force of cardiac contraction.  Dilatation of the coronaries. (5) To the lungs:  Dilatation of the bronchi.  Mild constriction to blood vessels. (6) To the gut:  Decreases motility.  Increases tone of the sphincters. 45  Stimulates formation of concentrated secretion that contains high percentage of enzymes and mucus, but it constricts glands blood supply thus reduces their overall secretion.  Retention of feces by inhibition to plain muscles of the large intestine, but excitatory to the internal anal sphincter. (7) To the liver:  Increases glycogenolysis, increases blood glucose.  Relaxes the gall bladder wall. (8) To the urinary system:  Relaxation of detrusor muscle and contraction of the internal urethral sphincter (retention of urine). (9) To male and female genital organs:  Contraction of muscles of epididymis, vas deference, seminal vesicles, and ejaculatory ducts (ejaculation of semen) in male.  Uterine antiperistalsis in female. (10) To fat cells:  Increases lipolysis thus increasing blood fatty acids. (11) To skeletal muscles:  Increases glycogenolysis.  Increases muscle strength and delays fatigue.  Vasodilatation to skeletal blood vessels. (12) Increases BMR up to 100% and causes mild vasoconstriction to cerebral blood vessels increasing mental activity. 46  2) Functions of the parasympathetic nervous system: (1) To the eye:  Constriction of the pupil (miosis) → by contraction of the circular fibers of the iris that constricts the pupil.  contraction of the ciliary muscle → increases power of lens → near vision. (2) To the glands:  Nasal, lacrimal, salivary, and many gastrointestinal glands: Copious quantities of watery secretion.  Sweat glands: sweating on palms of hands.  Apocrine glands: no effect. (3) To the blood vessels:  Has almost no effect on most blood vessels. (4) To the heart:  Decreases heart rate and force of cardiac contraction. (5) To the lungs:  Constriction of the bronchi.  Increases bronchial secretion. (6) To the gut (Secreto-motor):  increases motility.  Relaxation of the sphincters.  Stimulates formation of large amount of watery secretion, However, the glands of small and large intestine are controlled principally by local factors and by the enteric nervous system.  Defecation by contraction of the wall of the rectum, and inhibition of the internal anal sphincter. 47  (7) To the liver:  Slight glycogen synthesis.  Contraction of the gall bladder wall. (8) To the urinary system:  contraction of detrusor muscle and relaxation of the internal urethral sphincter (urination). (9) To male and female genital organs:  Dilatation of the blood vessels of the penis (erection) in male.  Erection of the clitoris in female. (10) To fat cells:  No effect. (11) To skeletal muscles:  No effect. Parasympathetic effects are transmitted through cranial nerves (III, VII, IX, X) and middle three sacral nerves (S2,3,4): - Oculomotor nerve (CN III):  To the eye. - Facial nerve (CN VII):  To the lacrimal, nasal, sublingual and submandibular glands and anterior 2/3 of the tongue. - Glosso-pharyngeal nerve (CN IX):  To parotid gland and posterior 1/3 of the tongue. - Vagus nerve (CN X) 75% of the parasympathetic system.: 48  To thoracic and abdominal viscera.  To the alimentary tract from the esophagus to the proximal part of the large intestine. - Pelvic nerve:  Originates from S2,3,4 segments.  Supplies distal of the large intestine.  Male and female genitalia. 49 References Barrett, K. E., Boitano, S., Barman, S. M., & Brooks, H. L. (2012). Ganong’s review of medical physiology twenty-fourth edition. Hall, J. E., & Hall, M. E. (2011). Guyton and Hall textbook of medical physiology e-Book. Elsevier Health Sciences, twelfth edition. Titus, A. M., Revest, P., & Shortland, P. (2010). The Nervous System, Basic Science and Clinical Conditions. Philadelphia: Churchill Living-stone, al, second edition. 50