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Cardiovascular system Blood alkaline is composed of cellular and liquid components Blood ph. range is 7.45- 7.50 3 functions? - Distribute nutrients, o2. - Regulate fluid volume, ph and body temp - Protection from blood loss and infection Blood components 1. Erythrocytes (RBC) 44%- transport haemoglobin 2. Leukocytes (WBC) 1%- responds to foreign bodies 3. Platelets 1%- assists in blood clotting Haematocrit- percentage of erythrocytes in a blood sample Blood types Type A- Anti-body B Type B- Anti-body A Type AB- neither A or B anti-body Type 0- both A and B anti-body Heart location is in the mediastinum of the thorax 2 cardiovascular systems 1. Pulmonary circuit Right side receives deoxygenated blood and pumps to the lungs for gas exchange 2. Systemic circuit Left side of heart receives oxygenated blood pumped through body Pericardium: sac that encloses the heart 1. Fibrous pericardium: tough outer layer, protects and anchors 2. Serous pericardium: smooth, allows for gliding movement (visceral - internal surface & parietal- external heart surface). Pericardial cavity: serous fluid, no friction, movement of heart allowed. Between visceral and parietal layers. 3 layers of the heart 1. Epicardium (outer) 2. Myocardium (middle) 3. Endocardium (inner) Heart chambers Left and right atria- separated by interatrial septum Left and right Ventricles- separated by interventricular septum Fibrous skeleton: surrounds and supports valves, prevents them from stretching & basis of electrical discontinuity between ventricle and atria. Atrioventricular valves & semilunar valves direct blood in 1 way to prevent backflow. Heart conduction system 1. 2. 3. 4. 5. SA nodes fire Excitation through arterial myocardium Av nodes fire Excitation through AV bundle Purkinji fibres distribute excitation through ventricular myocardium Cardiocytes Contract in response to electrical stimulation Consist of: Mitochondria Gap junction: allow ions to spread action potentials Desmoses: functional syncytium: Mechanical junctions that prevent cardiocytes from splitting. Heart regulation Neural control – medulla centre Automatic nervous system Sympathetic system (fight or flight) Innervated by cardiac plexus Cardio stimulatory effect- increased heart rate and contraction. Parasympathetic system (rest or digest) Innervated by Vagus nerve Cardio inhibitory effect- decrease heart rate Cardiac cycle Completion of contraction and relaxation in heart chambers 75 beats/min Systole (contraction) Diastole (relaxation of ventricles) End diastolic volume (EDV): volume in ventricle at the end of diastole- 120ml. End Systolic volume (ESV): volume in atria at end of systole- 50 ml Stroke volume: volume ejected from ventricles per beat 70 ml Formula: SV= EDV-ESV Factors that affect stroke volume: Preload: cardiocytes stretch before they contract Contractility: strength achieved at muscle length Afterload: pressure needed for ventricles to eject blood Cardiac output (CO): the amount of blood pumped by ventricle per minute CO = HR (Heart rate) x SV (stroke volume). Heart sounds Lub S1: Atrioventricular valves close, systole begins (ventricle contracts and pumps blood). Dub S2: Semilunar valves close, diastole begins (relaxed, fills with blood). Arteries: Oxygenated blood carried away from the heart Veins: Deoxygenated blood towards the heart. Lower pressure then arteries. Layers of the arteries 1. Tunica Interna (inner layer): reduces friction, vessel lumen & endothelium 2. Tunica Media (middle layer): Increases vasoconstriction and decreases vasodilation 3. Tunica externa (outer layer): anchorage and protection 3 types of arteries 1. Muscular artery: blood to organs 2. Elastic artery: blood to systems 3. Arteriole: blood to tissue, arteriole diameter determines blood flow to capillaries Capillaries: blood to tissue cells - Smallest lumen to allow 1 erythrocyte through - Function: exchange O2 and Co2, nutrients and hormones between interstitial fluid 3 types of capillaries 1. Continuous: intercellular clefts (gap junctions), less permeable 2. Fenestrated: small, nutrients, hormones and filtration to pass through 3. Sinusoidal: leaky, RBCs & Molecules can pass, leaky and modified Layers of capillary wall 1. Endothelial cells: lipid soluble substances 2. Fenestrations (pores): larger soluable & water 3. Intercellular clefts: water soluable Capillary exchange: movement of fluid in – out of capillaries Semipermeable membrane- selectively allows particles to move through Microcirculation: blood flow from arteriole to venule Vascular shunt: connects the arterioles to the venules. True capillaries: site of gas exchange Bulk flow: fluid forced in and out of capillaries 1. Filtration of fluid: blood hydrostatic pressure promotes selective movement out of capillary 2. Reabsorption: Blood colloid osmotic pressure promotes interstitial fluid to move into capillaries. Filtration pressure: difference between blood hydrostatic pressure and colloid osmotic pressure If BHP STRONGER= PRESSURE OUT IF COP STRONGER= PRESSURE IN Blood hydrostatic pressure must be greater than colloid osmotic pressure in the capillary for reabsorption to occur. Veins 3 layers of veins: 1. Tunica Interna (inner): vessel lumen 2. Tunica Media (middle): innervated by sympathetic nervous system 3. Tunica Externa (outer): anchorage & protection Types of veins 1. Venule- formed when capillaries unite 2. Medium vein- formed when venules unite, large blood volume 3. Large veins- low pressure, united medium veins Pressure gradient: difference in fluid pressure Blood flow: enabled by blood pressure and peripheral resistance Sources of resistance 1. Vessel diameter- wider = lower resistance 2. Vessel length – longer = greater resistance 3. Viscosity – thickness Venous blood flow Skeletal muscle pump: muscle contraction, pressure on veins, blood to heart Respiratory pump: decreased thoracic pressure during inhalation, blood to thoracic veins and right atrium Systemic blood pressure: pressure exerted on blood vessels in systemic circulation Pressure exerted on arteries during contraction Systolic pressure: exerted pressure during ventricular contraction Diastolic pressure: lowest level of arterial pressure Pulse pressure: difference between systolic and diastolic pressure MAP (Mean arterial pressure): pressure that propels blood to tissue MAP= diastolic pressure + 1/3 pulse pressure Control of blood pressure 1. Short term neural & hormonal control: fluctuations in blood pressure by altering peripheral resistance. 2. Long term renal regulations: controls fluctuations in blood pressure by altering blood volume. Neural controls of peripheral resistance: Maintain MAP- alters blood vessel diameter Operate via reflex arcs that involve: 1. Baroreceptors (respond to changes in arterial pressure and stretch) & chemoreceptors (respond to changes in 02, CO2 and H+) 2. Vasomotor in medulla: cardio-stimulatory centre & cardio-inhibitory centre 3. Vascular smooth muscle Hormones influence BP through vasoactive effect or water regulation: Angiostenin II: vasoconstrictor, raises BP Aldersterone: Na+ and water retention by kidneys, raises BP and blood volume ANP: increase urinary na+ excretion, reduces blood volume and BP ADH: promotes water retention and raises BP. Respiratory System Functions of the respiratory system 1. 2. 3. 4. 5. Gaseous exchange Warms & filters the air Acid-base balance Phonation (voice production) Defence against pathogens Gas exchange between air and blood: lungs to tissues then back to lungs Cells in body require continuous oxygen during metabolism. Respiration process Ventilation: air in & out of lungs due to changes in pressure of the bronchial tree and alveoli. Inhalation: external intercostal pull ribs up & out, diaphragm flattens, thoracic cavity enlarges, lungs expand, intrapulmonic pressure decreases (drops below atmospheric pressure). Exhalation: respiratory muscles relax, thoracic cavity becomes smaller, intrapulmonic pressure increases, air is forced out, and atmospheric & intrapulmonic pressure becomes equal. 1. 2. 3. 4. Pulmonary process: movement of air in and out of lungs External respiration: o2 lungs to blood & co2 blood to lungs Transport of respiratory gases: o2 body tissues to cells & Co2 body tissue to blood Internal respiration: O2 blood to tissue cells & Co2 tissue cells to blood Divisions of the respiratory system 1. Upper respiratory tract: nasal cavity, paranasal sinuses, pharynx Lower respiratory tract: larynx, trachea, bronchi & lungs - External intercostal muscles pull ribs up for inhalation Internal intercostal muscles pull ribs down for exhalation Diaphragm shortens and flattens to expand thoracic cavity 2. Conducting zone: conducts gas to exchange site 3. Respiratory zone: site of gas exchange