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Unit 4B Part 1 - Structure and Function of the...

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Unformatted text preview: Structure and Function of the Cardiovascular System System Objectives Objectives Describe the functions of the normal circulatory and cardiac systems Describe pathologies that result in diseases of the veins and arteries Discuss the pathophysiologic changes present in coronary artery disease. Define left and right heart failure Differentiate between various types of shock. Circulatory System Review Circulatory Blood pumped from the heart through 2 systems: – Right heart: pumps blood through the lungs – Left heart: sends blood throughout the systemic circulation. Heart Wall Heart Pericardium – Pericardial fluid Myocardium Endocardium Structures of Heart Structures Left Atrium Right Atrium Left Ventricle Right Ventricle A­V valves – Mitrial – Tricuspid Semilunar valves – Aortic – Pulmonic Cardiac Conduction System Cardiac Electrical Impulses: Cardiac A.P. Sinoatrial node (SA): pacemaker of the heart AV node Bundle of His Bundle branches (RBB and LBB) Purkinge fibers Cardiac Action Potentials and EKG Interpretation Interpretation Cardiac Output Cardiac Quantifies cardiac performance Ejection Fraction: SV/end­diastolic volume (amount of blood ejected from the ventricle); normal 60%­70% Cardiac output determined by: – Preload: ventricular end diastolic volume and pressure – Afterload: resistance or impedance to ejection of blood from the LV (aortic systolic pressure) – Myocardial contractility – Heart Rate Influence of the ANS Influence Resting Heart Rate (about 70bpm) Resting heart rate under the influence of parasympathetic nervous system Parasympathetic effects: through vagus nerve → acetylcholine → decrease HR Sympathetic effects: in SA node increase HR Myocardial Cells Myocardial Transmit A.P. faster than skeletal cells Synthesize more ATP than skeletal cells Readier access to ions in the interstitium Myocardial cells work constantly Cardiac Contraction facilitated by: – – – Actin/myosin cross bridging Calcium channels Calcium­troponin complex interaction Peripheral Circulation Peripheral Structure of Blood Vessels Structure Three layers: Tunica Intima Tunica Media Tunica Externa Endothelium (tunica intima) of Blood Vessels Blood Fine lining of cells called endothelial cells Functions: – Filtration and permeability – Vasomotion – Clotting – Inflammation Factors Affecting Blood Flow Factors Pressure: depends on the difference in pressure between the arterial and venous systems Resistance: opposition to force Velocity: directly related to blood volume Laminar vs. Turbulent Flow in the vessel Vascular compliance: ability to accommodate an increase in blood volume Blood Pressure Regulation Blood MAP: average pressure in the arteries throughout the cardiac cycle Baroreceptors: aorta and carotid stretch receptors reduce BP by ↓ C.O. Arterial Chemoreceptors (aortic and carotid arteries); sensitive to pH, C02 and PO2) ADH, renin­angiotensin system, and natriuretic peptides Venous Pressure Venous Regulated by: ­Volume of fluid in the vein ­Compliance of the vessel wall ...
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