Medical Physiology e-Book Nursing PDF (2024-2025)
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Minia University
2024
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This is a medical physiology textbook for first-year nursing students at Minia University. The book covers various key topics, including human physiology concepts, body water distribution, cell membrane functions, transport mechanisms, blood physiology, nervous system, muscle physiology, and many other body systems.
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MEDICAL PHYSIOLOGY For 1st Year Nursing Students (Credit Hours) Code: MED1202 Medical Physiology Department Faculty of Medicine Minia University (2024-2025) Index TOPIC Pag...
MEDICAL PHYSIOLOGY For 1st Year Nursing Students (Credit Hours) Code: MED1202 Medical Physiology Department Faculty of Medicine Minia University (2024-2025) Index TOPIC Page Introduction to Human Physiology 1 Body water 2 The Human Cell 4 The Cell Membrane 5 Transport Mechanisms through Cell membrane 6 Physiology of Blood; Plasma Proteins 10 Red Blood Corpuscles (RBCs) 12 Anemia 16 Polycythemia 18 Erythrocyte Sedimentation Rate (ESR) 18 Blood Groups 20 Blood Transfusion 23 White Blood Cells (WBCs) 26 Blood Platelets & Hemostasis 26 Physiology of the Nerve; The nerve Cell 27 The Nerve Impulse 29 The Resting membrane Potential (RMP) 30 Action Potential 30 Conduction of Nerve Impulse 31 Physiology of the Muscle; Types of Muscles 32 Neuromuscular Transmission (NMT) 33 Mechanism & Types of Skeletal Muscle Contractions 34 Types of Skeletal Muscle Fibers 35 Autonomic Nervous System (ANS) 35 Functions of Sympathetic Nervous System (SNS) 38 Functions of Parasympathetic Nervous System (PNS) 40 The Reflex Arc 43 Respiratory System 44 Respiratory Centers 46 Stages of Respiration 46 Assessment of Respiratory Functions 48 Dead Space (DS) 51 Disorders of Respiration 52 Endocrine System 52 Pituitary Gland 53 Thyroid Gland 57 Parathyroid Gland 59 Calcium Homeostasis 61 Adrenal Gland 62 The Pancreas 66 Circulatory system; CVS 35 Circulatory system; CVS 68 Functions of CVS 69 Physiological properties of the cardiac muscle 70 Heart Rate (HR) 73 Cardiac Output (COP) 73 Arterial blood pressure 74 Hemorrhage & Shock 75 Urinary system 77 Functions of the kidney 77 Functional anatomy of the kidney 78 Glomerular filtration 79 Transport at different tubular segments 80 Micturition 81 Renal Function Tests 82 Uremia 83 Digestive system 84 Functions of digestive system 85 Control of GIT functions 85 Gastrointestinal Secretions; Salivary Secretion 86 Gastric secretion 87 Peptic ulcer disease 87 Intestinal Secretion 88 Pancreatic Secretion 88 Bile Secretion 89 Jaundice; Definition & Types 90 GIT Motility; Mastication 91 Deglutition 91 Gastric Motility 92 Vomiting 92 Intestinal Motility 93 Defecation 93 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… HUMAN PHYSIOLOGY Definition of Human Physiology: The science which deals with the functions of the human body under different external and internal environmental conditions in order to maintain life. Organization of the Human Body: The basic living unit of the body is the cell. Cells of the same shape and function arranged side by side forming a tissue. The organ is formed of more than one tissue performing a special function; e.g. the stomach digests and the kidney excretes…etc. A system is formed of more than one organ having complementary functions. The sum of these functions will determine the role of the system in human life. The human body consists of a group of systems, each plays a specific and different role from the others, and the sum of these roles maintain human life. Examples of different systems of human body: * The endocrine system. * The digestive system. * The nervous system. * The excretory systems. * The cardiovascular system. * The reproductive system. * The respiratory system. * The musculoskeletal system. 1 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… BODY WATER The Total Body Water & its Distribution: The total body water is normally about 60% of the body weight in young adult males. Therefore, in a young adult male weighing 70 Kg, the total body water is normally about 42 liters. It is distributed as follows: (1) Intracellular fluid (ICF): This constitutes about 2/3 of the total body water i.e. about 40% of the body weight (~28 L). (2) Extracellular fluid (ECF): This constitutes about 1/3 of the total body water i.e. about 20% of the body weight (~ 14 L), and it includes the following subdivisions: (a) Intravascular fluid (i.e. plasma): This is normally about 1/4 of the ECF volume. (b) Extravascular fluid: This is normally about 3/4 of the ECF volume. It includes; Interstitial fluid: the fluid in spaces between the tissue cells Transcellular fluids: fluid present in closed spaces surrounded by epithelium as cerebrospinal fluid, intraocular fluids, and the fluids in the pleura, joints, peritoneum, etc. 2 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… Figure 1: Body fluid distribution. Functions of Body Water: 1. It is the medium for the chemical and enzymatic reactions. 2. It is the medium for the physical processes e.g. diffusion and filtration. 3. It is an ionizing medium (regulating pH and body fluid osmolarity). 4. It regulates the body temperature through heat absorption, distribution and evaporation. 5. It is a lubricant in the joints and potential spaces (e.g. the pleura). 6. It is a refractive medium in the eye. 7. The cerebrospinal fluid is a mechanical buffer that protects the brain. 8. It is the medium for exchange of O2 and CO2 in the lungs and tissues. 3 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… Normal Composition of the ECF and ICF: Table 1: Normal composition of ECF and ICF. ECF ICF Na+ (142 mEq/L) & K (4 K+ (140mEq/L) & mEq/L) Mg2+ Main cation small amounts of Ca2+ and small amounts of Na+ Mg2+ very little Ca2+ Cl- HPO4 & protein. Main anion small amounts of: HCO-3, Small amounts of Cl-, proteins, and HPO4 HCO3 and SO4 About 7 due to low pH About 7.4 HCO-3 Osmolarity The same The same THE HUMAN CELL Definition: The building (structural) unit of the human body (figure 2). Figure 2: Structure of the Human Cell. 4 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… THE CELL MEMBRANE Functions: 1. It forms the outer boundary surrounding the cell and protect it from the external environment. 2. Selective permeability; it allows certain substances to pass through and prevents others. Chemically: It is formed of phospholipids & proteins. Figure 3: Chemical structure of the cell membrane. 5 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… Transport Mechanisms through Cell Membrane I. Diffusion Definition: free movement of substance molecules through the cell membrane caused by their kinetic energy. Factors affecting the rate of diffusion: The rate of diffusion is directly proportional to: 1. Concentration difference of the substance across the cell membrane. 2. Temperature of the solution. 3. The surface area of the membrane. The rate of diffusion is inversely proportional to: 1. The thickness of the membrane (i.e. distance of diffusion). 2. The square root of M.W. of the substance. 𝐜𝐨𝐧𝐜𝐞𝐧𝐭𝐫𝐚𝐭𝐢𝐨𝐧 𝐝𝐢𝐟𝐟𝐞𝐫𝐞𝐧𝐜𝐞 𝐗 𝐒𝐮𝐫𝐟𝐚𝐜𝐞 𝐚𝐫𝐞𝐚 𝐗 𝐭𝐞𝐦𝐩𝐞𝐫𝐚𝐭𝐮𝐫𝐞 𝐓𝐡𝐞 𝐃𝐢𝐟𝐟𝐮𝐬𝐢𝐨𝐧 𝐑𝐚𝐭𝐞 ∞ 𝟐 √𝐌𝐨𝐥𝐞𝐜𝐮𝐥𝐚𝐫 𝐰𝐞𝐢𝐠𝐡𝐭 𝐗 𝐦𝐞𝐦𝐛𝐫𝐚𝐧𝐞 𝐭𝐡𝐢𝐜𝐤𝐧𝐞𝐬𝐬 Figure 4: Simple diffusion. 6 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… II.Osmosis: Definition: It's the free movement of the solvent molecules through a semipermeable membrane from the compartment of lower concentration to the compartment of higher concentration of the solution. Or it’s the diffusion of water through a semi- permeable membrane from an area of high conc. of water to an area of low conc. of water. It is a passive mechanism (i.e. NO energy needed) For ONLY solvent molecules (e.g. water) It depends on the number of particles in the solution rather than its concentration. The measuring unit of osmosis is called; Osmole = 1000 mosmole N.B. Osmole is the number of particles present in one mole of undissociated substance. Mole is the molecular weight of a substance in grams. Figure 5: Osmosis. The Osmotic Pressure: It is the pressure required to stop osmosis. The osmotic pressure is dependent on the number of particles/unit volume and not on the weight of the substance in grams. 7 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… Figure 6: Osmotic pressure. Normal plasma osmolarity = 290-300 mosmol/L. Tonicity: It is the osmolarity of the solution relative to that of plasma. Solutions compared to Plasma Osmolarity are 3 types: 1. Isotonic: Tonicity is equal to that of plasma osmolarity. They are the only solutions allowed to be given to the patient parenterally (i.v.) Ex.: Glucose 5% - NaCl 0.9% = (saline) 2. Hypotonic: Tonicity is less than that of plasma osmolarity. If given i.v. -------- it causes Shift of water into the cells ---------- leading to Cell swelling or edema ---------- cell rupture. Ex.: Water. 3. Hypertonic: Tonicity is more than that of plasma osmolarity. If given i.v. ----- it causes Shift of water out of cells ---------- leading to Cell shrinkage or crenation. Figure 7: Types of solutions relative to plasma osmolarity 8 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… III.Filtration: Definition; It means forcing a fluid to pass through a semipermeable membrane by creating a pressure difference (gradient). It is a passive mechanism (no energy needed) Importance: 1. Filtration of plasma to form tissue fluid. 2. Filtration of plasma in the kidney urine formation. IV. Active Transport:: Transport of substance against electric or concentration gradients. Requires energy from ATP. Requires a carrier protein. Requires an enzyme ATPase for hydrolysis of ATP to produce energy. Example: Sodium-Potassium pump (Na+ - K+ pump): It's present in all cell membranes. Transports 3 Na+ out and 2 K+ in. Figure 8: Na+ - K+ pump. ------------------------------------------------------------------------------------------------ 9 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… Physiology of BLOOD Blood is a fluid tissue that circulates inside blood vessels. It represents 8% of total body weight (~ 5-6 L). Functions of blood: 1. Transport function (O2, CO2, nutrients, waste products, and hormones). 2. Defensive function (WBs & antibodies). 3. Hemostasis (i.e. stoppage of bleeding). 4. Homeostasis: keeping internal environment (i.e. extracellular fluid) of the body constant for optimum function of the cell (PH, osmotic pressure, volume, gases, minerals, temperature, nutrients...). Composition of blood: Blood is formed of two main parts: blood cells & plasma: I. Blood cells: 45% of total blood volume (TBV). 1. Red blood corpuscles (RBCs): ~ 5 million /mm3. 2. White blood cells (WBCs): 4000-11000 /mm3. 3. Platelets: 250000 to 500000 / mm3. II. Plasma: 55% of TBV. Plasma is a yellow clear fluid consisting of: 1. 90 % water. 2. 10 % solids, either: a. Organic substances as; Plasma proteins = 7.1% Urea, uric acid, hormones & vitamins = 2 %. b. Inorganic substances such as; Na+, Ca++, Cl– and others = 0.9 %. 10 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… Plasma Proteins Concentration: average 7 gm/100 ml plasma (i.e. 7 gm %). Table: Types and Functions of plasma proteins: Type Concentration Function Site of formation - Osmotic pressure 4 gm/100 ml → blood volume. plasma 1.Albumin - Transport of some Liver. (Highest) substances as in conc. hormones. - Defensive function Reticuloendothelial (γ globulins) → system (RES) e.g. 2.Globulins 2.5 gm/100 ml form antibodies. liver, spleen, lymph (α, β, γ) plasma - Transport of some nodes and bone substances. marrow. 0.4 gm/100 ml plasma - Blood clotting. 3.Fibrinogen Liver. (Largest) - Blood viscosity. in size 10 mg/100 ml 4.Prothrombin - Blood clotting. Liver. plasma 11 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… The Albumin/Globulin (A/G) Ratio: This is the ratio between albumin and globulin concentration in blood. Normally, A/G ratio = (1.2 – 1.7). Significances of A/G ratio: Determination of A/G ratio helps in the diagnosis of diseases as it decreases in: 1. Liver diseases due to decreased formation of albumin. 2. Kidney diseases due to loss of albumin in urine (due to its smaller molecular size). 3. Infection and allergic diseases due to increased formation of γ globulins (i.e. antibodies). Red Blood Corpuscles (Erythrocytes) (i.e. RBCs) RBCs are non-nucleated circular biconcave discs containing the red respiratory pigment hemoglobin (Hb). Its average life span is about ~ 120 days. RBCs Count: 1. In adult males: 5.5 million/ mm3 (due to androgen hormone). 2. In adult females: 4.8 million/ mm3 (due to menstruation). 3. In newly born: 7 million/ mm3 (due to intra-uterine oxygen lack). Hematocrit value (HCT): It is the volume of packed RBCs in 100 ml blood. It is about 45% in adult male. It is lower in females (35%) Higher in newborn infants (65%) 12 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… Functions of RBCs: 1. Hemoglobin is essential to carry oxygen to and take CO2 from tissues. 2. Hemoglobin helps in the regulation of blood pH and blood viscosity which is essential for maintenance of diastolic blood pressure. 3. RBCs contain carbonic anhydrase enzyme which is important for CO2 carriage. 4. RBCs membrane keeps hemoglobin inside them and prevents its loss in urine. 5. RBCs membrane contains the specific agglutinogens that determine blood group. 6. The biconcave shape of RBCs increases the surface area and helps the exchange of gases between RBCs and tissues. 7. The plastic nature of RBCs membrane (i.e. flexibility) allows RBCs to pass through narrow capillaries easily without being ruptured. Formation of RBCs (Erythropoiesis): Sites of RBCs formation: 1. In the fetus, they are formed in liver and spleen. 2. In the last three months of fetal life and after birth, they are formed in bone marrow of all bones until adolescent. 3. By the age of 20, they are formed by the bone marrow of upper parts of humorous and femur and of membranous (flat) bones. 4. After the age of 20 years, they are formed in bone marrow of membranous bone e.g. skull, vertebra, sternum and ribs. 13 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… Factors affecting erythropoiesis: I. Oxygen supply to tissues: O2 lack (i.e. hypoxia) → releases erythropoietin hormone from the kidney mainly → stimulates bone marrow → increase production of RBCs (↑erythropoiesis). II. Dietary factors: Erythropoiesis requires: 1. Proteins: Proteins of high biological value (animal protein), containing essential amino acids are more essential for formation of globin part of Hb. 2. Minerals: mainly iron & trace elements a. Iron: - It is essential for formation of hemoglobin. - Ferrous salts are better absorbed than ferric salts. - Most of the diet iron is in ferric state which is reduced to ferrous in the stomach by HCl and vitamin C than absorbed in the upper part of small intestine (duodenum). - Ferritin is the main storage form of iron mainly in liver. Factors affecting iron absorption: 1. Gastric HCl reduces ferric to ferrous → increases its absorption. 2. Excessive oxalates, phytic acids and phosphates in diet precipitate iron and decrease its absorption. 3. Duodenal ulcers decrease iron absorption. b. Trace elements: e.g., copper and cobalt act as cofactors for hemoglobin formation. 14 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… 3. Vitamins: including; A. Vitamin B12: - It is called extrinsic factor and is important for nuclear maturation and cell division. - It unites with intrinsic factor, glycoprotein secreted by mucous membrane of the fundus of the stomach (parietal cells) forming intrinsic factor B12 complex. - Significance: Intrinsic factor protects vitamin B12 from digestion by gastric enzymes and facilitates its absorption in lower part of ileum. - Vitamin B12 is stored in large amount in liver. B. Folic acid: the same importance as vitamin B12. C. Vitamin C: It stimulates tissue growth and metabolism in general including the bone marrow. It facilitates absorption of iron from stomach. III. Hormones: either; a. Specific: e.g. Erythropoietin hormone. b. Non-specific: e.g. thyroid hormones and male sex hormones (i.e. androgen) are required for erythropoiesis. IV. Healthy organs; including: 1. Bone marrow: is essential for normal erythropoiesis. 2. Liver: liver is important for erythropoiesis as: a. It acts as a store for vitamin B12 & iron. b. Formation of globin part of hemoglobin. c. Secretes 15% of erythropoietin hormone. d. An extramedullary (outside bone marrow) site for erythropoiesis. 15 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… 3. Kidney: - It secretes 85% of erythropoietin hormone in response to hypoxia. - N.B. Patients with renal diseases or failure develop severe anemia because erythropoietin production by liver cannot compensate for the inability of the kidney to produce the hormone. 4. Stomach: - Gastric HCl is needed to convert ferric iron to ferrous. - Intrinsic factor secreted by gastric mucosa is essential for vitamin B12 absorption. 5. Small intestine: It is the site of absorption for; a. Iron (upper part). b. Vitamin B12 (lower part). Disorders of RBCs count: Anemia: It means decreased number of RBCs or their hemoglobin content or both. Normal hemoglobin (Hb) concentration: In males about 15gm/100mL blood. In females about 13.5gm/100mL blood. 16 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… Types and Causes of Anemia: I. Normochromic Normocytic Anemia: including; A. Hemolytic anemia; due to excessive hemolysis of RBCs. e.g., 1. Incompatible blood transfusion. 2. Snake venom. 3. Sensitivity to drugs. 4. Infections as some types of malaria. 5. Antibodies against red blood cells. 6. Increased fragility of RBCs as in spherocytosis, sickle cell anemia. B. Aplastic anemia; due to bone marrow depression. e.g. 1. Exposure to radiation such as X-rays. 2. Chemotherapy. 3. Drugs as antibiotics as chloramphenicol. 4. Destruction of bone marrow by malignant tumors. C. Hemorrhagic anemia; Due to acute blood loss (i.e. hemorrhage). II. Microcytic Hypochromic Anemia: A. Iron deficiency anemia, either due to: 1. Deficiency in the diet (commonest cause). 2. Failure of iron absorption due to : - Absence or removal of acid producing part of the stomach. - Excess oxalates, phytic acids and phosphates in diet. 3. Diseases of small intestine (upper part) as duodenal ulcers. 4. Liver disease (site of storage of iron) 5. Chronic blood loss, e.g., bleeding piles and menstruation in females. Treatment: Oral iron or injection (in case of gastric or small intestinal causes). 17 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… III. Macrocytic (Megaloblastic) Anemia: It occurs due to deficiency of vitamin B12 or folic acid. A. Vitamin B12 deficiency (i.e. Pernicious anemia) due to: 1. Absence of intrinsic factor from the stomach (commonest cause), 2. Malabsorption due to small intestine diseases (lower part). 3. Liver disease (site of storage). 4. Rarely due to lack of vitamin in diet. Treatment: Vitamin B12 injection for life. B. Folic acid deficiency anemia due to; Deficiency of folic acid in diet especially during pregnancy. Failure of absorption due to small intestine diseases. Polycythemia: Polycythemia means increased number of RBCs. It may reach up to 6-8 million/mm3. Erythrocyte Sedimentation Rate (ESR) It is the distance sedimented by RBCs in mm when put in a vertical stationary tube at the end of 1 and 2 hours. After the first and second hours read the levels of the sediment RBCs. 18 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… Normal values of ESR: 1. After the first hour: it is ~ 5 mm in males, and up to 10 mm in females. 2. After the second hour: it is ~ 8 mm in males, and ~ 15 mm in females. The mechanism of increased ESR: The presence of tissue damaged products or abnormal proteins accelerate clumping and sedimentation of RBCS and increase the ESR. Significance of ESR: The ESR is a nonspecific diagnostic test. It indicates the presence of tissue damage but does not indicate its cause. So, The ESR is a good prognostic test. If it decreases towards the normal level during the course of treatment it indicates that the person is recovering. ESR is increased in the following conditions: 1. Normally (Physiologically): during pregnancy and menstruation. 2. Abnormally: in all diseases accompanied with tissue damage. The ESR is increased above 100 mm in the following conditions: a.Tuberculosis (TB), b. Rheumatic activity, c. Malignancy. Figure: Erythrocyte Sedimentation Rate (ESR) 19 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… Blood Groups Blood ABO system: Human blood can be classified into four major groups A, B, AB, O. The classification is based on the antigen nature of red blood cell membrane. The membrane of RBCs contains antigens called agglutinogens. While, plasma contains specific antibodies for red cells antigens called agglutinins (α and β). As a general role, blood of any person doesn't contain an agglutinogen (e.g A) and its corresponding agglutinin (anti-A), otherwise ……. agglutination and hemolysis of RBCs will occur. Agglutination means antigen- antibody reaction. Classification of Blood Groups: 40 % 10 % 5% 45 % universal universal recipient donor 20 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… N.B. - Group A or B can accept blood from the same type or group O. - The group O is called universal donor (this is because RBCs of group O contains no agglutinogen and so no agglutination occurs when given). - Group AB is called universal recipient (no agglutinin in its plasma and so no agglutination occurs). Importance of ABO blood groups: 1. Blood transfusion: The blood group of the donor and that of the recipient should be compatible. If not → Agglutination occurs between the agglutinogens on the RBCs of the donor's blood and agglutinins of the recipient’s plasma (high concentration) → leading to destruction (hemolysis of the donor’s RBCs). The RBCs of the recipient's blood don't usually agglutinate by the antibodies of the donor's blood (low concentration) 2. The Rh blood group system: Rh factor; it is the agglutinogen which was discovered on the RBCs of Rhesus monkeys (hence the name). It is present in 85% of people (called Rh positive "Rh +ve") and is absent in 15% of people (called Rh negative "Rh -ve"). Normally, there is no anti-Rh antibody in the plasma of all parsons. However, it could be formed in the blood of both Rh +ve and Rh –ve by two methods: 1. Blood transfusion from Rh +ve person to Rh –ve person. 2. Pregnancy of Rh –ve female with an Rh +ve baby. 21 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… Figure: Rh factor Importance of Rh factor: 1. In blood transfusion; If Rh +ve blood is transfused to Rh -ve person …. Anti-Rh antibodies will develop gradually in the plasma of the Rh -ve person, but still not sufficient to reach maximum concentration to produce any harm (agglutination of the RBCs) ….. It would occur only on the second exposure to Rh +ve blood. 2. In marriage; If Rh –ve female married to Rh +ve male …. In most cases, the fetus will be Rh +ve. At time of delivery …. Some of the Rh +ve fetal RBCs containing Rh agglutinogen may reach the mother’s blood ….. The Rh –ve mother will develop anti-Rh antibodies …. But her first baby already born and NOT harmed. However, if this mother becomes pregnant again with Rh +ve fetus, the already formed antibodies from the first pregnancy will cross the placenta to her fetus and cause hemolysis of his RBCs. If hemolysis is severe, the fetus may either: - Die intrauterine. Or - Becomes severely ill & suffer from a condition called "Erythroblastosis fetalis" or hemolytic disease of the newly born. 22 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… Prevention and Treatment of Erythroblastosis Fetalis: 1. Rh –ve female should never receive Rh +ve blood (or marry Rh +ve male if possible). But if this occurs: 2. Mother must be given a single dose of Rh immune globulin (i.e. anti-D antibody) within 48 hours after delivering her first baby ….. To neutralize the antigens and prevent the formation of anti-Rh antibodies. 3. Diseased baby can be treated by ….. Repeated exchange blood transfusion with Rh –ve group O during the first weeks of life. Blood transfusion: Indications of blood transfusion: 1. Decreased blood volume as in hemorrhage of more than 20% of the blood. 2. To restore one deficient blood element as: RBCs in severe anemia when hemoglobin decreases to 40% or less. Platelets as in thrombocytopenia. WBCs as in leucopenia. Blood coagulation factors as in hemophilia. Plasma proteins as in liver & kidney diseases. 3. In erythroblastosis fetalis. 23 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… Dangers (complications) of blood transfusion: A. Donor complications: 1. Anemia with repeated transfusion. 2. Shock with large volume transfusion. B. Recipient complications: 1. Allergy (fever, itching, shivering ……etc.) from the additive substances added to the blood. 2. Transmission of diseases as malaria, syphilis, viral hepatitis and AIDS. 3. Danger of incompatibility: Agglutination of the donor's RBCs which may block blood capillaries causing severe pain and blood vessels of important organs as kidney, heart and brain. Hemolysis of the agglutinated RBCs → release of hemoglobin into blood plasma which can produce renal failure due to precipitation of hemoglobin and blocking renal tubules. Increased level of free hemoglobin coming from hemolysed RBCs → increase plasma viscosity → heart overload → heart failure. histamine release from hemolysed RBCs → vasodilatation → Hypotension & shock Hemoglobin is metabolized to yellow pigment called (bilirubin) → yellowish discoloration of skin and mucous membranes (Jaundice). 24 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… Determination of blood groups: 1. Put one drop of anti-A, one drop of anti-B and one drop of anti- D separately on a glass slide. 2. Drop of unknown blood is added to each drop, mixed well by tilting the slide. 3. Notice presence or absence of agglutination. Results: Figure: Blood Group Determination. Cross matching test: It’s done before any blood transfusion to avoid incompatibility in the subgroups. Steps: 1. A drop of donor’s RBCs is mixed with a drop of recipient’s plasma. 2. A drop of donor’s plasma is mixed with a drop of recipient’s RBCs. 3. If no agglutination occurred donor’s blood is safe for transfusion. 25 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… White Blood Cells (leucocytes) Total leucocytic count (TLC): 4000- 11000/mm3. The WBCs count in adult females is lower than adult male and show variation in the same individual from day to day and hour to hour. WBCs number increases after meal, muscular exercise & emotional stress. The main function of WBCs is defense against invading organisms. Platelets (i.e. Thrombocytes) Blood platelets are granular, non-nucleated oval bodies. Count: 250.000-500.000/mm3. Their average life span: 7-12 days. Origin: bone marrow. Old platelets are removed by reticuloendothelial cells especially (spleen). Function: Hemostasis (i.e. stoppage of bleeding) 26 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… Mechanisms (Steps) of Hemostasis: I. Vasoconstriction: 1. Immediate vasoconstriction of injured blood vessels & adjacent small arteries. 2. Vasoconstriction → causes slowing blood flow to the injured area to allow contact activation of platelets & coagulation factors. II. Platelets plug formation: It is the main function of platelets. III. Blood coagulation (formation of blood clot): By coagulation (clotting) factors (I-XIII). IV. Repair of injured blood vessel. Methods of Prevention of Blood Coagulation: a. In vitro anticoagulants; e.g. Oxalate, citrate, siliconized containers, rapid cooling or addition of heparin. b. In vivo anticoagulants; By using heparin & dicumarol (Warfarin). 27 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… Table: heparin & dicumarol. Heparin Dicumarol Origin Animal origin Plant origin Onset of Action: Rapidly (after minutes) Slowly (1-2 days) Duration Hours Days Route of administration Parenterally (s.c) Orally Use Both in vivo & in vitro ONLY in vivo Antidote to overdose Protamine sulphate 1% Vitamin K Conditions that cause bleeding tendency: 1. Vitamin K deficiency: Vitamin K deficiency can occur in newly born infants, obstructive jaundice, liver diseases & prolonged use of antibiotics. It leads to hemorrhage due to inhibition of formation of factors II, VII, IX & X in the liver e.g. as in liver diseases and obstructive jaundice, the coagulation time is prolonged due to vitamin K deficiency 2. Hemophilia: Hereditary sex-linked disease (carried by mother to her male fetus since birth) characterized by bleeding and bruises on minor trauma. Cause: due to deficiency of factors VIII or IX or XI according to type. The bleeding time is normal while coagulation time is prolonged. 28 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… 3. Thrombocytopenic purpura: Autoimmune disease affects both males and females & in young age. Symptoms: spontaneous small (petechial) hemorrhages (without trauma) in the skin & mucus membranes. Cause: decreased platelets count below 40000/mm3. Bleeding time is prolonged while coagulation time is normal. Figure: Petechial rash of thrombocytopenic purpura vs. bruises of hemophilia ------------------------------------------------------------------------------------ PHYSIOLOGY OF THE NERVE Introduction: The nervous system along with the endocrine system are the two major control systems in the body. However, the nervous system is more rapid than the endocrine system. So, it is responsible for the control of rapid body activities such as; contraction of ALL types of muscles & secretion of glands. The Nerve Cell: The nerve cell (neuron) is the structural unit of the nervous system. The human nervous system contains more than 10 billion neurons. The function of neuron is to generate nerve impulse (signal). 29 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… Each neuron is formed of 2 main parts: 1. The cell body (Soma). 2. The cell processes. 1. The cell body (Soma): It contains a large central nucleus with a well-marked nucleolus The cytoplasm contains Golgi apparatus, Endoplasmic reticulum and Mitochondria like other cells. The neuron doesn't contain a centrosome and can NEVER divide. 2. The cell processes; 2 types: A) Dendrites. B) Axon. A. Dendrites: Short processes extending out from the cell body and branch extensively. Functions of dendrites: 1. Increase the surface area of the cell body (receptive field of the neuron). 2. Conduct the nerve impulse towards the cell body. B. Axon (i.e. Nerve fiber): A single long process that originates from a thickened area of the cell body called the axon hillock. Function of the axon: 1. Conduct the nerve impulse away from the cell body and the dendritic zone. 2. Ends with terminal buttons containing the chemical transmitter. Figure: Structure of the neuron. 30 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… The Nerve Impulse It is a physicochemical disturbance produced by a stimulus of threshold intensity or more, and is propagated in the form of a wave along the nerve fiber. It is accompanied by: 1. Electric changes. 2. Excitability changes. 3. Metabolic changes. 4. Thermal changes. Excitability: It is the ability of any living tissue to respond to a stimulus. It is a property of life. The nerve is one of the most excitable tissues. A Stimulus: It is any change in the environment surrounding a living tissue that causes it to react. Types of stimuli: 1. Electrical. 2. Chemical. 3. Mechanical 4. Thermal. N.B. Threshold stimulus: it is the minimal intensity of a stimulus which can stimulate. Subthreshold stimulus: its intensity is less than the threshold and it can’t stimulate. 31 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… Resting Membrane Potential (RMP): Under normal conditions: All points on the outer surface of the nerve fiber are isopotential. All points in the inside of the nerve fiber are also isopotential. There is a potential difference between the inner and outer sides with the negativity inside (-70mV). This is called resting membrane potential (RMP). Figure: Resting membrane potential Causes of RMP: 1. Selective permeability of the membrane: The resting membrane is 50-100 times more permeable to K+ than Na+. 2. The Na+ - K+ pump: This is an active pump transmits 3 Na+ ions out for each 2 K+ ions transmitted into the inside, thus creating negativity (-) inside and positivity (+) outside the nerve membrane. Action Potential (AP): It is a series of electric changes accompanying the nerve impulse. Phases pf Action Potential: 1. Latent Period (LP). 2. Spike Potential (SP). 3. After potentials. 32 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… Figure: Phases of action potential in the nerve Conduction of nerve impulse; may be either: 1. Orthodromic conduction: - It’s the natural conduction inside the body. - Direction; is from the dendrites (receptive field) → cell body →axon → axon terminal where the transmitter is released at the synapse 2. Antidromic conduction: - It is conduction in the opposite direction of the natural conduction inside the body. - The impulse stops at the dendrite since there is NO chemical transmitter to be released. Figure: Orthodromic conduction (natural conduction inside the body) 33 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… PHYSIOLOGY OF THE MUSCLE Introduction: Muscle cells, like neurons, can be excited to produce an action potential that is transmitted along their cell membranes. The function of the muscle is contract when stimulated. Types of Muscles: 1. Skeletal (Striated) Muscles: They constitute most of the body musculature. They have well developed cross striations. They are voluntary i.e. they contract according to the well. Supplied by somatic motor nerves. (However, skeletal muscles can also contract involuntary as in reflex response). 2. Cardiac Muscle: They are present only in the heart. They have cross striations. Its involuntary muscles. Supplied by autonomic nerves. Cardiac muscle (heart). 34 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… 3. Smooth Muscles: They are present in hollow viscera and blood vessels. They have no cross striations. Involuntary muscles. Supplied by autonomic nerves Figure: Types of muscles. The Motor End Plate (MEP) Or Neuromuscular Junction (NMJ) Inside the body, the muscle is stimulated through its motor nerve. There is NO cytoplasmic continuity between the nerve and the muscle. The area of contact between the nerve fiber and the muscle fiber is called MEP or NMJ. Figure: The motor end plate (MEP). 35 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… Properties of Neuromuscular Transmission: 1. Unidirectional (from the nerve to the muscle; not in the opposite direction). 2. It has a delay of 0.5 MS. 3. Easily fatigued. 4. Blocked by curare. Mechanisms of Skeletal Muscle Contraction: Skeletal muscle can contract either: 1. By a nerve impulse reaching the muscle through its motor nerve at the MEP (natural mechanism inside the body). 2. By direct stimulation of the muscle itself (as in experimental work or during physiotherapy). Types of Skeletal Muscle Contraction: Item Isotonic contraction Isometric contraction Shortening The muscle shortens. No shortening. Tension Remains low or constant. Much increased. Work External work is done No work is done. Energy High. Very low. consumed Carrying a weight that is too heavy Example Carrying a weight against gravity. to be carried. 36 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… Types of Skeletal Muscle fibers: Item Pale fibers Red fibers Myoglobin Less myoglobin More myoglobin Blood flow less blood flow More blood flow Less mitochondria (depend more More mitochondria (depend more Mitochondria on anaerobic oxidation) on aerobic oxidation) Contraction Rapid Slow Fatigue Easily fatigued Resist fatigue Innervations Large myelinated motor nerves Small myelinated motor nerves Example Hand muscles. Muscles of the back. AUTONOMIC NERVOUS SYSTEM (ANS) Anatomically, the nervous system is divided into: 1. Central Nervous System (CNS); It is formed of the brain & spinal cord. 2. Peripheral Nervous System (PNS); Anatomically they are either; 1. Cranial nerves (12 pairs), arising from the brain. 2. Spinal nerves (31pairs), arising from the spinal cord. 37 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… Functionally, they may be: 1. Sensory: transmitting sensory impulses from periphery of body to CNS. 2. Motor: transmitting motor orders from CNS to body organs e.g. muscles, glands. 3. Mixed: contain both sensory & motor fibers. Motor functions of the body may be: A. Voluntary: controlled by the will. e.g. contraction of skeletal muscles to perform a work (controlled by somatic motor nerves). B. Involuntary: Spontaneous not controlled by the will. e.g. Contraction of smooth muscles. Contraction of cardiac muscle. Secretion of glands. N.B. The Peripheral motor nerves that control involuntary motor functions of the body are called Autonomic Nerves (i.e. ANS) 38 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… Definition of Autonomic Nervous System (ANS): It is a part of peripheral motor division of the nervous system that is concerned with the control of involuntary motor activities of the body (i.e. cardiac & smooth muscle contraction and secretion of glands). Divisions of Autonomic Nervous System (ANS): ANS is divided into: 1. Sympathetic (i.e. thoracolumbar) division. 2. Parasympathetic (i.e. craniosacral) division. N.B. Most of autonomic organs are doubly innervated (i.e. both sympathetic and parasympathetic fibers) Impulses in one type of fibers…..stimulation Impulses in the other type of fibers…..inhibition The sympathetic nervous system has a wider distribution than the parasympathetic nervous system. 39 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… Functions of Sympathetic Nervous System (SNS) (i.e. Thoracolumbar division of ANS): The SNS prepares the body for fight or flight response under stress conditions. It allows us to be excited, fight, runaway from danger and consume energy. I. Sympathetic Supply to Head & Neck: 1. Eye: a. Retraction of the upper eye lid …. To increase the visual field. b. Dilatation of the pupil ….. To increase light entering to the retina. c. In animals ….. Protrusion of the eye ball (exophthalmos). 2. Skin: a. Vasoconstriction (VC) of skin blood vessels. b. Stimulate sweat secretion in head and neck. c. Erection of hair. 3. Salivary glands: a. Stimulate myoepithelial cells in the wall of acini of salivary gland … squeezing of salivary secretion. b. Vasoconstriction of blood vessels of salivary glands. 4. Cerebral blood vessels: - Weak vasoconstriction. II. Sympathetic Supply to Thoracic Viscera: 1. On the heart: a. Increase all properties of the heart (i.e. rhythmicity, contractility, excitability and conductivity). b. Vasodilation of the coronaries. 40 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… 2. On the lungs and Bronchi: a. Brochodilatation …. To increase air entry. b. Vasoconstriction of pulmonary blood vessels. c. Decrease (inhibits) mucus secretion. III. Sympathetic Supply to Abdominal Viscera: 1. VC of abdominal blood vessels. 2. Delayed emptying of the GIT. 3. On liver, stimulate glycogenolysis → ↑ blood glucose level. 4. On suprarenal medulla, stimulate adrenaline and noradrenaline (catecholamines) secretion mainly adrenaline. 5. Squeezing of spleen to pour ~ 400 ml blood into circulation. IV. Sympathetic Supply to Pelvic Viscera: 1. VC of pelvic blood vessels & erectile tissues (penis & clitoris) → Shrinkage of these organs. 2. Retention of urine. 3. Retention of feces. 4. Ejaculation of semen. V. Sympathetic Supply to Skin & Skeletal muscles: 1. On the skin a. VC of skin blood vessels. b. Stimulate sweat secretion. c. Erection of hairs. 2. On skeletal muscles a. Vasodilatation. b. Orbelli phenomenon; including: Increased force and power of contraction. Delays the onset of fatigue & early recovery from fatigue 41 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… N.B. SNS acts as a whole to produce: 1. Increase visual field. 2. Increased pumping action of the heart to ↑ blood supply to active organs. 3. Increased oxygenation of the blood to ↑ oxygen supply to active organs. 4. Shift of blood from less active areas e.g. the splanchnic circulation and skin to areas of maximum activity e.g. skeletal muscles. 5. Increase the performance of skeletal muscles. Functions of the Parasympathetic Nervous System (PNS) i.e. Craniosacral division of ANS: The PNS allows us to relax, rest, digest, secrete, excrete and save energy. I. The parasympathetic Cranial Outflow (3, 7, 9, 10): 1. The Oculomotor nerve (3rd cranial nerve): a. Constriction of the pupil (meiosis). b. Increase lens curvature… accommodation to near vision. 42 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… 2. Facial nerve (7th cranial nerve): a. Vasodilatation of blood vessels of submandibular, sublingual salivary glands and lacrimal glands. b. Supply anterior 2/3 of the tongue. c. Stimulate salivary and lacrimal secretion (profuse and watery). 3. Glossopharyngeal nerve (9th cranial nerve): a. Vasodilatation of blood vessels of parotid salivary glands. b. Supply posterior 1/3 of the tongue. c. Stimulate parotid salivary secretion (profuse, watery). 4. Vagus nerve (10th cranial nerve): 1. On the heart: it inhibits (decreases) all cardiac properties; a. Heart rate. b. Force of contraction. c. Conduction. d. Excitability. e. Oxygen consumption due to decreased cardiac metabolism. f. VC to coronary blood vessels. 43 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… 2. On the lungs: a. Bronchoconstriction. b. Stimulates bronchial secretion. c. VD to bronchial blood vessels. 3. On the GIT: a. Accelerate emptying of the GIT. b. Increases GIT secretions. c. VD to blood vessels of GIT. d. Evacuation of the GB. II. The Parasympathetic Sacral Outflow (S 2,3,4): 1. MICTURITION. 2. DEFECATION. 3. (ERECTION). 4. Stimulates seminal & prostatic secretions. 44 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… The Reflex Arc: It is the functional unit of the nervous system. It means an involuntary response to a stimulus. Components of Reflex Arc: Receptor → afferent neuron → center → efferent neuron → effector organ. 1. Receptor: perception of stimulus. 2. Afferent neuron: conducts the impulse from the receptor to the integrating center in the CNS. 3. Center: recognizes the stimulus and sends a proper order to the peripheral tissues to counteract the environmental change and produce adjustment (homeostasis). 4. Efferent neuron: conducts the impulse (order) from the center to the effector organ. 5. Effector organ: produces the response. Figure: Components of reflex arc. ---------------------------------------------------------------------------------------------- 45 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… RESPIRATORY SYSTEM Definition of Respiration: It is the process through which the body takes O 2 from the atmosphere and gets rid of CO2 and water vapor. Other Functions of Respiration: 1. Regulation of body water balance through loss of water vapor in expired air. 2. Regulation of acid base balance through CO2 gas which can dissolve in body water and form carbonic acid (H2CO3). 3. Regulation of body temperature through loss of heat to warm cold inspired air in winter or to loss water vapor. 4. Excretion of waste products as gases e.g. alcohol, anesthetic gases. Respiratory Rate: Normally, the average respiratory rate is ~ 12-14 cycle/minute. Respiratory rate is increased in the following conditions: 1. New borne infants (~ 40 cycles/ min. 2. Physical activity (i.e. muscular exercise). 3. Emotions or stress. Each Respiratory Cycle consists of 3 phases: 1. Inspiration. 2. Expiration (longer than inspiration). 3. Expiratory pause; it disappears when respiratory rate in increased. 46 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… The Respiratory System: It consists of: 1. Bone chest wall: ribs, sternum, vertebral column. 2. Muscular chest wall: a. Muscles of inspiration: e.g. diagram, external intercostal muscles & muscles of forced inspiration; sternomastoids and scalene muscles. b. Muscles of expiration: Work only during forced expiration: e.g. Internal intercostal muscles & abdominal muscles. 3. Nerves suppling the muscles: e.g. the phrenic nerve supplies the diagram & the intercostal nerves supply the other muscles. 4. Centers of Respiration: They are present in the brain stem and control inspiration and expiration. 5. The airways including: a. Conducting airways: Nose → pharynx → larynx → trachea → bronchi → bronchioles. b. Respiratory airways: The wall is thin to allow gas exchange with blood. Terminal bronchioles → alveolar ducts → alveolar sacs → alveoli. 6. The lungs: Spongy tissue covered by very thin smooth membrane called the pleura forming a closed cavity around. The pleural cavity is formed between the visceral pleura covering the lungs and move with them and the parietal pleura lining the chest wall and moves with it. The cavity contain thin fluid for lubrication. 47 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… Respiratory Centers: These are collection of neurons present in the brain stem (i.e. pons & medulla oblongata) and they are responsible for higher control of respiration. The pace maker of respiration is the apneustic center. During Normal Breathing (i.e. Eupnea), inspiration is active (needs contraction of inspiratory muscles. While, expiration is passive (i.e. No need for Muscle Contraction). Stages of Respiration: I. Ventilation It means the inflow and outflow of air during inspiration and expiration. Factors which make ventilation easy: 1. Healthy chest wall and muscles. 2. Patent airways; The conducting airways are kept open by: a. The supporting cartilage and smooth muscles. b. Inhibitory effect of sympathetic nervous system on smooth muscles. c. Cilia, mucus lining and cough reflex expelling foreign particles. 3. The lung surfactant: Definition; It is a phospholipid material secreted by alveolar epithelial cells. Function; it lowers the surface tension of fluid lining the alveoli and makes their expansion easy. If decreased, respiration becomes difficult and causes a disease called respiratory distress syndrome) 48 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… Factors that decrease formation of lung surfactant: Premature babies. Prolonged open heart surgery. Hypothyroid children. Smokers. Cortisol deficiency. 4. Normal elasticity of the lung tissue. II. Gas Exchange: Gas exchange occurs by simple diffusion gases present in the alveoli (alveolar air) and blood gases present in pulmonary capillaries through the pulmonary membrane. The rate of diffusion is directly proportional to: 4.Concentration difference of the substance across the cell membrane. 5.Temperature of the solution. 6.The surface area of the membrane. The rate of diffusion is inversely proportional to: 1.The thickness of the membrane. 2.The square root of M.W. of the substance. Figure: Gas exchange between blood capillary & the alveoli 49 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… N.B. The diffusion of CO2 is much faster and easier than diffusion of O2. III. Blood Gas Transport: Blood gas transport occurs in 2 forms; a) Physical solution in plasma → responsible for gas tension (pressure). b) Chemical combination. Assessment of Respiratory Functions: Spirometry: It is the first lung function test done. It measures how much and how quickly you can move air out of your lungs. In this test, you breathe into a mouth piece attached to a recording device called (spirometer). Spirometry data may be helpful in the diagnosis of respiratory disease. Spirometry includes measuring of the following lung volumes and capacities: Figure: Spirometer 50 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… I. Respiratory Volumes: 1. Tidal Volume: It is the volume of air that is inspired or expired during normal breathing. It is about 500 ml. 2. Inspiratory Reserve Volume: - It is the maximum volume of air inspired by maximum deep inspiration after normal inspiration. - It is about 3000 ml. 3. Expiratory Reserve Volume: - It is the maximum volume of air expired by maximum deep expiration after normal expiration. - It is about 1000 ml. 4. Residual Volume: - It is the volume of air remaining in the lungs after maximum deep expiration. - It is about 1200 ml. N.B. Residual volume is the ONLY volume that cannot be measured by spirometer. II. Respiratory Capacities: formed of more than one lung volume 1. Inspiratory Capacity: - It means the total volume of air inspired by maximum deep inspiration. - It is the sum of Tidal volume (500 ml) + Inspiratory Reserve Volume (3000 ml) = 3500 ml 2. Expiratory Capacity: - It means the total volume of air expired by maximum deep expiration. - It is the sum of Tidal volume (500 ml) + Expiratory Reserve Volume (1000 ml) = 1500 ml 51 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… 3. Vital Capacity: - It means the total volume of air expired from the lung by deep maximum expiration after deep maximum inspiration. - It is the sum of Tidal volume (500 ml) + Inspiratory Reserve Volume (3000 ml) + Expiratory Reserve Volume (1000 ml) = 4500 ml. 4. Total Lung Capacity: - It means the total volume of air present in the lung after deep maximum inspiration. - It is the sum of Vital Capacity (4500 ml) + Residual Volume (1200 ml) = 5700 ml. N.B. The Total lung capacity is the ONLY capacity that can NOT be measured by spirometer. Figure: Chart of Spirometer. 52 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… The Dead Space (D. S.): It’s the space filled with air that allows NO gas exchange with blood. Normally = 150 ml. Types of dead space: 1. Anatomical D. S.: it’s the conducting part of air ways that have thick wall 2. Alveolar D. S.: these are alveoli with obstructed bronchi or occluded blood flow. 3. Physiological D. S.: it’s the Anatomical D. S. + Alveolar D. S. N. B.: Normally there is NO alveolar dead space so the Anatomical dead space = Physiological dead space. Importance of dead space: 1. Responsible for warming and humidifying of the inspired air, secretion of mucous, protection through ciliated epithelium and cough reflex. 2. Responsible for difference between true and minute ventilation; a) Minute ventilation = air breathed / minute = = Tidal volume X Respiratory rate = 500 X 12 = 6 liters /minute. b) True or effective ventilation = the volume of air that enters the lungs and undergoes gas exchange with blood /minute = = (Tidal volume - dead space) X Respiratory rate = (500 – 150) X 12 = 2400 ml/minute. 3. Responsible for the difference between inspired and expired air; At the end of inspiration, the dead space is filled with atmospheric air. At the end of expiration, it’s filled with alveolar air. Expired air is a mixture of alveolar and atmospheric air filling the dead. 53 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… Disorders of Respiration: 1. Hypoxia: Hypoxia means decreased O2 supply to tissues. 2. Cyanosis: It means Bluish discoloration of skin and mucous membranes due to increased concentration of reduced Hb more than 5 gm % in capillary blood (i.e. the threshold for cyanosis) ---------------------------------------------------------------------------------------------------------------- THE ENDOCRINE SYSTEM Endocrine glands: They are ductless glands secrete chemical messengers (i.e. hormones) directly into the blood stream. Exocrine glands: They secrete their secretions through a duct into the digestive tract (e.g. enzymes, bile) or through the skin surface (e.g. sweat). 54 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… Hormones: They are chemical messengers secreted by endocrine glands in very small amounts and carried by blood to their sites of actions. On target organs, hormones produce their effects by interaction with specific receptors for each hormone (either present on the cell membrane or within the target cell). Most of hormones are regulated by negative feed mechanism. THE PITUITARY GLAND It is a small gland present in a small cavity in the base of the skull. It is formed of two main lobes: Anterior lobe (i.e. Adenohypophysis). Posterior lobe (i.e. Neurohypophysis). Anterior Pituitary Hormones: 1. Growth hormone (GH): Functions: a. ↑ Growth of all tissues including bone and cartilage. b. Metabolism o Diabatogenic; hyperglycemia (i.e. ↑ blood glucose level). o ↑ Protein anabolism. o ↑ Lipolysis. c. Lactogenic effect (i.e. ↑ milk formation). 2. Prolactin: Functions: Milk synthesis (production) 55 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… 3. Thyroid stimulating hormone (TSH); Functions: Regulate the function and growth of thyroid gland. 4. Adrenocorticotropic hormone (ACTH); Functions: Regulate the function and growth of adrenal cortex. 5. Gonadotropins (GNs); Functions: Regulate the function and growth of sex gonads (i.e. ovary and testes). They include; a) Follicle stimulating hormone (FSH). b) Luteinizing hormone (LH). Disorders of Anterior Pituitary Gland: I. Hyper function of Anterior Pituitary: A. Before Puberty: Gigantism; increased bone length. B. After Puberty: Acromegaly; Increased bone thickness. Prognathism (thick protruded mandible with wide separated teeth). Kyphosis (thick enlarged vertebrae). Hand & feet; large, broad and thick. 56 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… II. Hypofunction of Anterior Pituitary: A. Decreased GH only: Dwarfism Decreased bone length 1-1.2 meter. Arrested tissue growth. Mental status is normal but emotionally unstable. B. Decreased GH & Gonadotrophic Hs (FSH & LH): Infantilism (i.e. retarded somatic growth + hypogonadism). C. Decreased all ant. Pit. H. (Panhypopituitarism): Retarded growth + hypogonadism + hypofunction of all target glands. Posterior Pituitary Hormones: 1. Antidiuretic Hormone (ADH) or Vasopressin: Formed in: in hypothalamus then stored & released from post. Pit. Stimulus of Release: a) Increased plasma osmotic pressure. b) Decreased blood volume (e.g. Hemorrhage). 57 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… Function: a) Increases water reabsorption from renal tubules so, it ↓ urine volume. b) Excess dose ---- vasoconstriction (VC) of blood vessels ….. ↑ Blood pressure. 2. Oxytocin (OT) Hormone: Formed in: hypothalamus then stored & released from post. Pit. Stimulus of Release: a) Suckling reflex. b) After delivery. Function: a) Milk ejection (i.e. let down). b) ↑ Uterine contraction …. Help in labor and involution of the uterus after labor. Disorders of Posterior Pituitary Gland: Diabetes Insipidus (DI): Cause: Decreased ADH secretion or function. Manifestations a) Polyuria (↑ urine out put up to 20 L /day). b) Fixed and low specific gravity 1002-1004. c) Polydipsia (i.e. increased water intake). d) Loss of water soluble vitamins in urine. 58 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… THE THYROID GLAND It is a small butter fly shaped gland present in the neck in front of the trachea. It is formed of two lobes connected by an isthmus. It secretes two main hormones: Thyroid hormones (i.e. T3 & T4). Calcitonin. 1. Thyroid Hormones (T3 & T4): Control of secretion: By TSH from ant. Pit. Gland. Functions: a. Increases metabolic rate and oxygen consumption by cells. b. Help mental, physical and sexual growth. 2. Calcitonin Hormone: Stimulus of Release: When plasma calcium level is increased. Functions: It decreases plasma calcium level by: ↓ Bone resorption (i.e. break down). ↑ Calcium deposition in bone. Disorders of Thyroid Gland: I. Hyperthyroidism: Cause: Adenoma in the thyroid gland. Graves’ disease (autoimmune disorder). 59 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… Manifestations of Hyperthyroidism: 1. Goiter (enlarged thyroid gland). 2. Exophthalmos. 3. Increased metabolic rate. 4. Tremors. 5. Tachycardia. 6. Dyspnea. 7. Heat intolerance. 8. Hyperphagia with loss body weight. II. Hypothyroidism: A. Before Puberty; Cretinism: Caused by: Congenital or genetic deficiency in thyroid hormones. Manifestations: 1. Dwarfism. 2. Hypogonadism. 3. Mental retardation. 4. Delayed milestones (i.e. delayed sitting, walking …..) 5. Swollen eye lids. 6. Enlarged protruded tongue. B. After Puberty; Myxedema: Manifestations: 1. Accumulation of myxematous tissue in interstitial fluid (non-pitting edema). 2. Decrease basal metabolic rate. 3. Intolerance to cold. 4. Decrease food intake. 5. Bradycardia. 6. Slow thinking. 7. Skin: pale, yellow, dry and cold. 60 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… PARATHYROID GLAND They are 4 small glands attached to the posterior surface of thyroid gland. They secret the parathyroid hormone (PTH). 1. Parathyroid Hormone (PTH): Stimulus of Release: When plasma calcium level is decreased. Functions: It increases plasma calcium level by acting on: Bone; ↑ Bone resorption and calcium pump from bone cells. Kidney; ↑ Calcium reabsorption and ↓ phosphate reabsorption. Activates vit. D3 (via activation of 1-α hydroxylase enzyme). Intestine; Increases calcium absorption (indirect effect via active vit. D 3). 61 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… Disorders of Parathyroid Gland: I. Hyperparathyroidism: Cause: Adenoma in the parathyroid gland. Manifestations: 1. Bone; weak and fragile. 2. Urinary tract stones. 3. Decreased muscle excitability (i.e. muscle weakness). 4. Constipation. II. Hypoparathyroidism: Tetany: It is a state of increased of neuromuscular excitability due to decreased ionized calcium in blood (Normal plasma calcium 9-11 mg %) Causes: 1. Hypoparathyroidism. 2. Decreased vitamin D3. 3. Alkalemia; Due to precipitation of calcium. 4. Renal failure. Types of tetany: A. Manifest tetany: Calcium level below 7 mg%. Manifestations 1. Skeletal muscles show twitches. 2. Carpopadel spasm in hands. 3. Tonic contraction of pharyngeal muscles and diaphragm. 4. Asphyxia and death may occur. 62 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… B. Latent tetany: Calcium between 7 – 9 mg %. Manifestations: In latent tetany, the manifestations are NOT apparent. It may appear if any condition tends to lower plasma calcium more. Treatment of tetany: 1. During attack; I.V. calcium gluconate very slowly. 2. In between attacks or in latent type: Oral calcium + vit. D3. Acidifying salts (to ↑ ionized calcium). CALCIUM HOMEOSTASIS Physiological Functions of Calcium: 1. Main component of bone and teeth. 2. Blood clotting. 3. Cell membrane permeability and excitability. 4. Neuromuscular transmission. 5. Release of neurotransmitters. 6. Contraction of all types of muscles. 7. Secretion of glands. Mechanism(s) of Calcium Homeostasis: Normal plasma calcium level ~ 9-11 mg%. Plasma calcium level is kept constant by the action of three hormones: 1. Parathyroid hormone (PTH); ↑ plasma calcium level when decreased (see details with PTH) 2. Calcitonin hormone; it ↓ plasma calcium level when increased. 3. Active vit. D3; it ↑intestinal absorption of calcium from GIT and ↑calcium deposition in bone. 63 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… THE ADRENAL GLAND The adrenal gland is formed of two completely separate glands: The adrenal cortex. The adrenal medulla. ADRENAL CORTEX: It is divided histologically into 3 zones: Zona glomerulosa (outer zone); concerned with secretion of mineralocorticoids (e.g. Aldosterone). Zona fasciculata (middle zone); concerned with secretion of glucocorticoids (e.g. cortisol). Zona reticularis (inner zone); concerned with secretion of sex hormones (mainly, androgens). 1. Mineralocorticoids (e.g. Aldosterone): Stimulus of Release: Renin angiotensin system (RAS). ↓ Na+ and ↑ K+ levels in plasma. 64 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… Functions: a) Keep concentration of Na+, K+, Cl- and water within normal levels in extracellular fluid. b) It acts on kidney, on ducts of sweat glands and on the intestine. c) Aldosterone causes Na+ reabsorption in exchange for K+, H+. d) Secondary water reabsorption occurs by osmosis. Disorder of mineralocorticoids Secretion: Conn’s disease (i.e. Primary Hyperaldosteronism): Cause: Adenoma of zona glomerulosa cells. Manifestations: a) Hypertension and edema (limited). b) Muscle weakness. c) Damage of kidney. d) Tetany. 2. Glucocorticoids (e.g. Cortisol): Stimulus of Release: Stress conditions (e.g. hypoglycemia, hypotension, etc.…). Functions: a) On Metabolism: - CHO → Hyperglycemia; enhance gluconeogenesis. - Fat → ↑ lipolysis. - Protein → ↓ protein synthesis and ↑ its catabolism. 65 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… b) Antinflammatory effect. c) Decreases T, B lymphocytes (i.e. Immunosuppressive effect). d) Increases RBCs and esinopenia. e) Na+ retaining effect. Disorder of Glucocorticoid Secretion: (Cushing syndrome): Causes: Adenoma of zona fasciculate cells. Manifestations: a) Deposition of fat in particular sites; - Face → moon face. - Trunk → buffalo obesity. b) Hyperglycemia. c) Hypertension. d) Hirsutism. e) Increased protein catabolism: - Skin fragile thin, - Muscle weakness, - Osteoporosis, - Delayed wound healing. f) Psychological instability. 66 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… Adrenal Insufficiency: (Addison’s disease): Cause: Atrophy of adrenal cortex → decreased mineralocorticoids and glucocorticoids secretion. Manifestations a) Hypotension. b) Muscle weakness. c) Bronze pigmentation of the skin. d) Hypoglycemia. ADRENAL MEDULLA: It secretes catecholamines (80% adrenaline and 20% noradrenaline). Theses hormones are secreted in stress conditions and produce effects similar to sympathetic nervous stimulation. 67 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… Physiological Effects of Catecholamines: as sympathetic NS 1. Increased all properties of cardiac muscle. 2. Initial apnea followed by hyperventilation (i.e. increased rate and depth of respiration). 3. Produced generalized vasoconstriction (noradrenaline). 4. Increased blood glucose level and increased metabolism (adrenaline mainly). 5. Dilation of pupil. 6. Increased cortical awareness. 7. Bronchodilation. 8. Delay empting of GIT. 9. Urine retention. Disorder of adrenal medulla (Pheochromocytoma): Cause: Secreting tumors of adrenal medulla producing excess amount of catecholamines Manifestations: 1. Paroxysmal attacks of hypertension → severe headache. 2. Hyperglycemia. 3. Tachycardia and palpitation. 4. Cold pale skin → due to VC of skin Blood vessels. 5. Excessive sweating. THE PANCREAS The pancreas is considered as a mixed gland (both exocrine and endocrine). The endocrine part of the pancreas is called islets of Langerhans. It contains three main types of cells: 1. Alpha (α) - cells, secreting glucagon hormone. 2. Beta (β) - cells, secreting insulin hormone. 3. Delta - cells, secreting somatostatin. 68 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… 1. Insulin Hormone: Stimulus of Release: Insulin is released from β-cells of islets of Langerhans in the pancreas. Its release is stimulated by increased blood glucose level. Functions of insulin: a) Decreases blood glucose level by ↑ glucose utilization by most tissues and ↑ glycogen formation (glycogenesis). b) Increases protein synthesis (i.e. anabolic effect). c) Increases triglyceride synthesis and decreases its breakdown. d) Stimulate Na+-K+ ATPase → increased extracellular Na+ and Intracellular K+ → hyperpolarization. Diabetes Mellitus (DM): Causes: 1. Absolute insulin lack: degeneration of beta cell of pancreas 2. Relative lack of insulin. 3. Insulin resistance in obesity. Manifestations: 1. Hyperglycemia, glucosuria and polyuria by osmotic diuresis. 2. Polydipsia (i.e. ↑ water intake). 3. ↑ Protein catabolism resulting in: a. Generalized muscle weakness. b. Delayed wound healing. c. In young person → growth retardation. 4. ↑ Lipolysis → Loss of weight. 5. ↑ Ketone body – acidosis → decreased synaptic transmission …. coma 6. ↑ Food intake (i.e. hyperphagia) → due to ↓ glucose utilization by feeding center. 69 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… Treatment of DM: Juvenile type (Type I) → Insulin. Old type (Type II) → Oral hypoglycemic drugs. 2. Glucagon hormone: Stimulus of Release: Glucagon is released from α-cells of islets of Langerhans in the pancreas. Its release is stimulated when blood glucose level is decreased. Functions: b) It increases blood glucose by increasing glycogen breakdown (i.e. ↑ glycogenolysis). c) ↑ Lipolysis. ---------------------------------------------------------------------------------------------------------- THE CIRCULATORY SYSTEM i.e. CARDIOVASCULAR SYSTEM (CVS) The circulatory system is a closed system of tubes (i.e. vessels) inside which blood circulates continuously by the pumping action of the heart and in one direction only by the action of valves present in the heart and veins. The circulatory system consists of the heart and blood vessels that is why it is also called the cardiovascular system (CVS). 70 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… Functions of the CVS: The CVS is a major transport system for: 1. Transporting and supplying O2 to tissues and returning CO2 back to the lungs. 2. Transporting nutrients from the intestine to the tissues. 3. Transporting wastes from the body to the excretory organs (e.g. kidneys). 4. Transporting hormones and other agents regulating body functions, from their sites of release to the sites of action. Divisions of Circulation: The circulatory system is divided into: 1. Greater or Systemic circulation; starts from the left ventricle and ends in the right atrium. 2. Lesser or Pulmonary Circulation; starts from the right ventricle and ends in the left atrium. Figure: Circulatory divisions (i.e. circuits): 71 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… Physiological Properties of the Cardiac Muscle: 1. Rhythmicity. 2. Contractility 3. Excitability. 4. Conductivity. ------------------------------------------------------------------------------------------------ 1. Rhythmicity: It means the ability of the cardiac muscle to beat (i.e. contract and relax) regularly. Rhythmicity is myogenic in nature (starts from the muscle itself independent from autonomic nerve supply that only controls its rate (either ↑ or ↓). Rhythmicity of Different parts of the Heart: 1) The sinoatrial (auricular) Node or SAN rhythm; It has the highest rhythm (120 discharge/min) so, it is called the pace maker of the heart. Pace maker means the part of the heart that the highest rhythmicity and the whole parts follow its rhythm. Its rhythm is called sinus rhythm. 2) Atrioventricular Node (AVN) rhythm; It rate is 100 discharges/min. Its rhythm is called nodal rhythm. 3) Atrioventricular Bundle (AVB rhythm; It rate is 45 discharges/min. 4) Purkinje fibers rhythm; It rate is 35 discharges/min. 5) Ventricular muscle rhythm; It rate is 25-40 discharges/min. Its rhythm is called ideoventricular rhythm. 72 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… N.B. Although the rhythmicity of the SAN is 120 /min, the resting heart rate is only 75/min, why? This is due the continuous inhibitory discharge from the vagus nerve on SAN decreasing its inherited rhythm from 120 to 75/min. This called the Vagal Tone. The vagus nerve supplies the whole cardiac muscle except the ventricles. 2. Contractility: It means the ability of the cardiac muscle to contract both isotonically and isometrically to push the blood to circulation. N.B. The cardiac muscle can NOT be tetanized: This is due to the long absolute refractory period (ARP) of the cardiac muscle that occupies the whole systole and early part of diastole. Tetanic contraction of the cardiac muscle is fatal → as it stops the pumping action of the heart → Circulatory failure → Death. 3. Excitability: It means the ability of the cardiac muscle to respond to an adequate stimulus (i.e. threshold or more) by generating an action potential followed by mechanical response. Excitability Changes during Cardiac Activity: a. Absolute Refractory Period (ARP); The excitability is completely lost (= zero). It occupies the whole systole and early part of diastole. 73 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… b. Relative Refractory Period (RRP); The excitability starts to be restored but still less than normal. It occupies the remaining part of diastole. c. Super normal Phase of Excitability: The excitability is higher than normal (i.e. can respond to subthreshold stimuli). It occupies the end of diastole. It is called the vulnerable period of the heart. 4. Conductivity: It means the ability of the cardiac muscle to transmit the excitation wave from one part of the heart to another. Velocity of conduction in Different Parts of the Heart: a. In atrial muscle → one meter / sec. b. In AVN → 0.2 meter / sec (i.e. delayed conduction). c. In AVB and Purkinje fibers → five meres / sec (i.e. rapid conduction). Factors affecting the Cardiac Muscle Properties: 1. Nervous Factors; a. Sympathetic stimulation → ↑ all properties of the cardiac muscle. b. Parasympathetic stimulation (i.e. vagus nerve) → ↓ all properties of the cardiac muscle. 2. Chemical Factors; a. Adrenaline → ↑ all properties of the cardiac muscle. b. Acetyl choline → ↓ all properties of the cardiac muscle. 74 Level 1 - Nursing (Credit Hours) Medical Physiology …………………………………………………………………………………………………………………………………………………………… 3. Physical Factors; a. Worming → ↑ all properties of the cardiac muscle. b. Cooling → ↓ all properties of the cardiac muscle. 4. Mechanical Factors;
