KINS 1132 Systems Physiology II PDF

KINS 1132: Systems Physiology II Cardiovascular System: Blood, Vessel Anatomy, Capillary Exchange Lecture Outline o Blood o Blood Vessels o Function and Properties o Plasma o Formed Elements o Red Blood Cells o White Blood Cells o Platelets o Blood Disorders o Structure and Function o Arteries...

KINS 1132: Systems Physiology II Cardiovascular System: Blood, Vessel Anatomy, Capillary Exchange Lecture Outline o Blood o Blood Vessels o Function and Properties o Plasma o Formed Elements o Red Blood Cells o White Blood Cells o Platelets o Blood Disorders o Structure and Function o Arteries & Arterioles o Capillaries o Venules & Veins o Capillary Exchange Blood: Functions & Properties o Transportation o o o o Oxygen and carbon dioxide Nutrients Hormones Waste products o Regulation o Homeostasis o Regulation of pH o Regulation of body temperature o Cell water content o Protection o Clotting o Disease Blood: Functions & Properties o General characteristics o o o o o Males 5 – 6 liters, Females 4 – 5 liters Slightly alkaline pH from 7.35 – 7.45 Roughly 38 °C Colour depends on oxygen content Important regulatory hormones regulating volume: o Aldosterone o Antidiuretic hormone o Atrial natriuretic peptide o Two main portions o Plasma o Formed elements Blood: Functions & Properties o Whole Blood o 55% plasma o 45% formed elements o > 99% RBCs o < 1% Buffy Coat o WBCs and platelets Blood: Plasma o Plasma (55%) o 91.5% Water o Absorbs, transports and releases heat Blood: Plasma o Plasma (55%) o 7% Proteins o Mostly produced by the liver o Responsible for colloid osmotic pressure and viscosity o Transport some hormones, fatty acids, minerals (iron and calcium) and fat-soluble vitamins (A, D, E and K) o Help regulate blood pH o 1.5% Other Solutes o Electrolytes (e.g., Na+, K+, Ca++, Cl-, HCO3-) o Regulatory role in cell function o Nutrients (e.g., amino acids, glucose, fatty acids, vitamins and minerals) o Gases (e.g., O2 and CO2) o Regulatory substances (e.g., enzymes, hormones) o Waste Products (e.g., urea, uric acid, creatine) o Most breakdown products of protein metabolism Blood: Formed Elements o Formed Elements (45%) o Red blood cells (99%) o Buffy coat (<1%) o White blood cells o Platelets Blood: Formed Elements o Red blood cells (erythrocytes) o Transport oxygen and carbondioxide o White blood cells (leukocytes) o Immune and inflammatory response o Platelets (thrombocytes) o Release chemicals for blood clotting Blood: Formed Elements o Negative feedback regulates total number of RBCs and platelets o Percent RBCs contribute to total blood volume called hematocrit o Males = ave 47%, Females = ave 42% o Total number of WBCs varies in response to pathogens and foreign antigens o Formation of cells: Hemopoiesis o Takes place in red bone marrow o Highly vascularized connective tissue between trabeculae Lecture Outline o Blood o Blood Vessels o Function and Properties o Plasma o Formed Elements o Red Blood Cells o White Blood Cells o Platelets o Blood Disorders o Structure and Function o Arteries & Arterioles o Capillaries o Venules & Veins o Capillary Exchange Blood: Red Blood Cells aka Erythrocytes o Lack ER, golgi bodies, mitochondria and nuclei o More space for oxygen! o No mitochondria so produce ATP anaerobically. Therefore, all oxygen carried is delivered o But, little capacity to regenerate. Live for 120 days then must be reproduced (erythropoiesis) o Biconcave disc allows greatest surface area for volume → larger area for diffusion of gas o Thinness and flexible cell membrane allows for movement through narrow capillaries Blood: Red Blood Cells aka Erythrocytes o Each RBC contains 280 million hemoglobin molecules o Hemoglobin structure: o 4 globin proteins o 4 nonprotein pigments called hemes Blood: Red Blood Cells aka Erythrocytes o Hemoglobin function: o Transports oxygen o O2 binds to iron ion (Fe2+) in the heme part of hemoglobin (becoming oxyhemoglobin) and release oxygen at the tissues (becoming deoxyhemoglobin) o Transports carbon dioxide o CO2 binds to globin part of hemoglobin o Alters blood pressure o Binds to nitric oxide (NO) produced by endothelial cells of blood vessels o NO released from hemoglobin → vasodilation o Assists in buffering o Contain enzyme carbonic anhydrase which catalyzes chemical reaction between CO2 and water to transport CO2 as carbonic acid (H2CO3), and yield bicarbonate ions (HCO3-) Blood: Red Blood Cells aka Erythrocytes o Production of RBC: Erythropoiesis o Direct stimulus for RBC production is kidney cell hypoxia → synthesis of hormone erythropoietin (EPO) by kidneys → production of RBCs Lecture Outline o Blood o Blood Vessels o Function and Properties o Plasma o Formed Elements o Red Blood Cells o White Blood Cells o Platelets o Blood Disorders o Structure and Function o Arteries & Arterioles o Capillaries o Venules & Veins o Capillary Exchange Blood: White Blood Cells aka Leukocytes o WBCs contain a nucleus and organelles but lack hemoglobin Blood: White Blood Cells aka Leukocytes o Lymphocytes: o Major combatant in immune responses o Increased number of lymphocytes can be an indication of a viral infection and immunodeficiency diseases o Eosinophils o Monocytes: o Enter tissue fluid and release enzymes to combat effects of histamine (histamines trigger inflammatory responses of allergic reactions) o Basophils o Intensify inflammatory response o Travel through blood to tissues → macrophages o Fixed macrophages and wandering macrophages which gather at sites of infection or inflammation o Neurotrophils and macrophages o Release histamine → inflammation o Release serotonin → vasoconstriction o Active in phagocytosis ingesting bacteria and dead matter Blood: Platelets aka Thrombocytes o Platelets are fragments of precursor cells o Vesicles but no nucleus o Chemicals within vesicles promote blood clotting o Initiates chemical reactions → formation of protein threads called fibrin o Promotes vascular spasm o Contraction of artery or arteriole wall in response to damage o Blood clot: o Gel-like mass composed of fibrin threads, platelets and trapped blood cells o Acts as a plug to prevent blood loss o Pulls edges of damaged vessel together Lecture Outline o Blood o Blood Vessels o Function and Properties o Plasma o Formed Elements o Red Blood Cells o White Blood Cells o Platelets o Blood Disorders o Structure and Function o Arteries & Arterioles o Capillaries o Venules & Veins o Capillary Exchange Blood Disorders o Anemia o Abnormally low hematocrit o Symptoms? o Causes: o Iron-deficiency anemia o Most common, most common in women o Hemorrhagic anemia o Most common due to heavy menstruation but also via large wounds, stomach ulcers o Megaloblastic and pernicious anemia o Megaloblastic caused by inadequate intake of vit B12 or folic acid → large abnormal RBCs o Pernicious anemia caused by insufficient hemopoiesis due to decreased intrinsic factor (produced by stomach) needed to absorb vit B12 Blood Disorders o Polycythemia o Abnormally high hematocrit (>65%) o Symptoms? o Causes: o o o o Dehydration Blood doping Erythropoietin (EPO) injection Tissue hypoxia Lecture Outline o Blood o Blood Vessels o Function and Properties o Plasma o Formed Elements o Red Blood Cells o White Blood Cells o Platelets o Blood Disorders o Structure and Function o Arteries & Arterioles o Capillaries o Venules & Veins o Capillary Exchange Blood Vessels o Anatomy of blood vessel walls o Arteries o Tunica interna o Endothelium o Basement membrane o Internal elastic lamina o Tunica media o Smooth muscle o External elastic lamina o Tunica externa Blood Vessels o Anatomy of blood vessel walls o Veins o Tunica interna o Endothelium o Basement membrane o Internal elastic lamina o Tunica media o Smooth muscle o External elastic lamina o Tunica externa Blood Vessels o Anatomy of blood vessel walls o Capillaries o Endothelium o Basement membrane Blood Vessels: Arteries o Blood vessels: Arteries o Primary efferent blood transport system o Elastic and muscular arteries Blood Vessels: Arteries o Elastic Arteries o Largest in body, wall diameter thin compared to lumen size o Thick tunica media with many elastic fibres (elastic lamellae) o Serve as pressure reservoir Berne and Levy, Principles of Physiology, 2000. Blood Vessels: Arteries o Muscular Arteries o o o o Smaller arteries in the body, thicker walls Tunica media has more smooth muscle (less elastic fibres) Muscular tunica media maintains vascular tone Regulate blood flow through vasodilatation & vasoconstriction constricted flow flow dilated Blood Vessels: Arteries o Arterioles and Metarterioles o Thin, with sympathetic nerves in tunica externa o Regulate blood flow from arteries into capillaries o Vasoconstriction (smooth muscles in vessel walls) o Pre-capillary sphincters Blood Vessels: Capillaries o Exchange vessels o Transfer of gases, nutrients, wastes between blood and tissues o Very thin-walled to allow rapid diffusion o Usually arranged in capillary beds of o 10 -100 capillaries o Increases area over which diffusion can occur Blood Vessels: Capillaries o Continuous capillaries o Most common o Gaps between neighbouring endothelial cells but otherwise continuous cells o Located in CNS, lungs, muscle, skin o Fenestrated capillary o Plasma membrane of endothelial cells have many fenestrations o Located in kidneys, villi of small intestine, choroid plexus, endocrine glands o Sinusoid o Wider with unusually large fenestrations in endothelium, incomplete or no basement membrane, large gaps between cells o Located in liver, spleen anterior pituitary, parathyroid, adrenal glands Blood Vessels: Capillaries o Blood → tissue transfer occurs by: 1. Diffusion (primary method) o Fat soluble through cell membrane o Fat insoluble through pores in membrane 2. Filtration o e.g. pressure forces H2O across membrane 3. Transcytosis o Transfer of large fat-insoluble molecules in “vesicles” Blood Vessels: Veins o Venules o Immediately after capillary bed o Merge into veins o Postcapillary venules o Smallest, weakest endothelium and porous o Site of nutrient exchange and white blood cell emegration (process of WBC leaving blood stream) o Muscular venules o Thicker walls (i.e., no exchange) o Very distensible walls, blood volume reservoir Blood Vessels: Veins o Primary afferent blood transport system (organs to heart) o Much less muscular than arteries (withstand less pressure) o Contain valves (to assist with returning blood against gravity) o More numerous than arteries o Paired to accompany medium to small muscular arteries o Blood volume reservoir (contains about 3 liters; ~64% of total blood vol.) o Superficial veins o Deep to the skin, not accompanied by arteries o Larger in upper limbs o Deep veins o Between skeletal muscles o Larger in lower limbs Lecture Outline o Blood o Blood Vessels o Function and Properties o Plasma o Formed Elements o Red Blood Cells o White Blood Cells o Platelets o Blood Disorders o Structure and Function o Arteries & Arterioles o Capillaries o Venules & Veins o Capillary Exchange Capillary Exchange o Blood → tissue transfer occurs by: o Diffusion (primary method) o Passive movement from high to low pressure o Movement of solutes o Bulk flow (filtration and reabsorption) o Passive movement from high to low pressure o Net filtration pressure determines the direction of flow (into or out of the capillary) o Net filtration pressure = pressures that promote filtration – pressures that promote reabsorption o Important for regulation of relative volumes of blood and interstitial fluid (not just movement of solutes) o Large numbers (more than diffusion alone) of ions, molecules or particles move together o Transcytosis o Large fat-insoluble molecules cross within vesicles via endocytosis and exocytosis Capillary Exchange o Diffusion: passive movement down a concentration gradient o Most common form of transfer across capillaries o Solutes move from high concentration to low concentration solutes: substances dissolved in a solvent (solutes + solvent = solution) The Vessels: Capillaries o Fick’s law of diffusion J = -DA c x J = diffusion rate -D = diffusion coefficient A = area c = concentration x = distance traveled Adolph Eugen Fick 1829 -1901 40 The Vessels: Capillaries o Fick’s Law of Diffusion – in words! ..not math ;) o Diffusion is affected by 5 factors: 1. 2. 3. 4. 5. Diffusion rate Diffusion coefficient Area Concentration Distance traveled The Vessels: Capillaries 1. Diffusion rate (e.g. molecules/sec) o o Rate at which solute will be transported across membrane Increase diffusion rate → increase the rate of transport across membrane o Affected by Transit Time o Transit time through capillaries is very short, therefore transport across membrane must be rapid The Vessels: Capillaries 2. Diffusion coefficient o Characteristic of solute molecule in a specific environment o Increase diffusion coefficient → increase rate of transport across membrane o e.g. the diffusion coefficient in water for CO2 is 32 times that of O2 therefore CO2 diffuses 32 times faster than O2 The Vessels: Capillaries 3. Area o Increase area → increase rate of transport across membrane o Capillary beds increase area over which diffusion can occur, therefore capillary beds increase diffusion rate The Vessels: Capillaries 4. Difference in concentration o The greater the concentration difference the faster the diffusion o e.g. Increase O2 concentration in blood (increased ventilation) and decrease O2 concentration in tissue (increased metabolism) → faster diffusion The Vessels: Capillaries 5. Distance o Increase distance → decrease transport o Capillary walls are extremely thin e.g. pulmonary diffusion Alveolar membrane (0.2 – 0.6 microns) capillary wall (0.5 microns) diffusion air blood Lecture Outline o Blood o Blood Vessels o Function and Properties o Plasma o Formed Elements o Red Blood Cells o White Blood Cells o Platelets o Blood Disorders o Structure and Function o Arteries & Arterioles o Capillaries o Venules & Veins o Capillary Exchange