UnitVIICardiovascularDrugs

UnitVIICardiovascularDrugs - Unit VII: Cardiovascular Drugs...

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1 Unit VII: Cardiovascular Drugs Physiology of the Cardiovascular System Heart b Two-sided pump that circulates 5-6 liters of blood every minute b 4 chambers: 2 atria and 2 ventricles b Endocardium lines the heart chambers, myocardium is the strong muscular layer that provides pumping power, epicardium is outer, serous layer of heart b Valves function to maintain one-way flow of blood b Conduction by special cells that carry electrical impulses: SA node, AV node, bundle of HIS, right and left bundle branches and Purkinje fibers b Blood supply received from coronary arteries b Collateral circulation may provide sufficient blood supply Blood Vessels b Arteries, veins and capillaries b Intima is inner lining composed of endothelial cells next to the blood b Media in middle layer of muscle and elastic tissue b Adventitia is outer layer of connective tissue Blood b Functions to nourish and oxygenate body cells, protect the body from invading microorganisms, and initiate hemostasis when a blood vessel is injured b Made up of plasma and solid particles (cells)
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2 Regulation of Cardiac Output Determinants of cardiac output: b Average adult, 5 L/min b Cardiac output = heart rate × stroke volume b Heart rate s Controlled by the autonomic nervous system b Stroke volume s Myocardial contractility s Cardiac afterload s Cardiac preload b Preload s End-diastolic volume or end-diastolic pressure b Afterload—arterial pressure Regulation of Arterial Pressure Overview of control system: b Arterial pressure = peripheral resistance × cardiac output b Arterial pressure is regulated by s Autonomic nervous system (ANS) s Renin-angiotensin system s Kidneys Regulation of Arterial Pressure (cont’d) b Steady-state control by the ANS s Regulates AP by adjusting cardiac output (CO) and peripheral resistance b Rapid control by the ANS: the baroreceptor reflex s Constriction of nearly all arterioles s Constriction of veins s Acceleration of heart rate Regulation of Arterial Pressure (cont’d) b The renin-angiotensin-aldosterone system s Constriction of arterioles and veins (angiotensin II) s Retention of water by the kidney (aldosterone) Regulation of Arterial Pressure (cont’d) b Renal retention of water b Postural hypotension (orthostatic hypotension) b Natriuretic peptides s Protect the cardiovascular system in the event of volume overload s Three principal members b Atrial natriuretic peptide (ANP) b B- or brain natriuretic peptide (BNP) b C-natriuretic peptide (CNP) Cardiovascular Disorders b Most vascular diseases result from malfunction of endothelial cells or smooth muscle cells b Major factor in atherosclerosis, acute coronary syndromes, hypertension, and thromboembolic disorders b May involve structure or function of cardiovascular system
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3 Drug Therapy in Cardiovascular Disorders b Goal is to restore homeostasis or physiological balance between opposing factors b Drugs may be given to increase or decrease cardiac output, blood pressure, and heart rate; to alter heart
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This note was uploaded on 11/01/2010 for the course CARD 001 taught by Professor Mrkhan during the Spring '10 term at University of Malaya.

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UnitVIICardiovascularDrugs - Unit VII: Cardiovascular Drugs...

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