Cardiovascular System Study Guide

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How things flow through the heart:
blood drains into the right atrium through the superior vena cava, inferior vena cava, and the coronary sinus (drains the heart muscle itself)→Right Ventricle→pulmonary semilunar valves→lungs→pulmonary veins→left atrium→bicuspid valve→left ventricle→aortic semilunar valve→systemic circuit. What the valves do:

Prevent backflow into the atria and ventricles, ensuring that blood only flows one way through the heart. what vessels bring blood to the heart and take blood away, etc... Veins from the systemic circuit bring deoxygenated blood back to the heart, while veins from the pulmonary circuit bring oxygenated blood from the lungs into the left atrium. Heart wall structure:

Epicardium: external layer; smooth slippery texture to outermost surface; includes adipose and coronary blood vessels •Myocardium: middle/muscular layer; the thickest layer
Endocardium: inner layer; smooth lining for chambers of the heart, valves and continuous with the lining of large blood vessels

Pericardial membranes:
1 Parietal Layer: fused to fibrous pericardium in on the inside/deep •2 Visceral layer: also called EPICARDIUM, the outer covering of the heart itself •pericardial cavity: small potential space between the parietal and visceral layers-filled with a small amount of serous fluid secreted by the serous pericardium Coronary circulation

Coronary arteries (L and R) branch from ascending aorta, immediately after the aortic valve •Anastomoses provide alternate routes or collateral circuits •Allows the heart muscle to receive sufficient oxygen even if an artery is partially blocked •Coronary Veins: drain the heart muscle, converge and drain into the coronary sinus, empties into the right atrium. Elements of the conduction system:

1.) The SA node (PACEMAKER) generates impulses
2.) The impulses pause at the AV node
3.) The AV bundle connects the atria to the ventricles
4.) The bundle branches conduct through the interventricular septum •5.) Finally, large diameter Purkinje fibers (subendocardial conducting network) conduct action potential to remainder of ventricular myocardium

Composite record of action potentials produced by all the heart muscle fibers •3 recognizable waves
oP wave: atrial depolarization, followed by atrial contraction oQRS complex: ventricular depolarization, followed by ventricular contraction (masks atrial repolarization) oT wave: relaxation/recovery/ventricular repolarization

Heart sounds:
Lub/S1: AV valves CLOSE
Dupp/S2: SL valves CLOSE

Cardiac output:
Volume of blood ejected from left or right ventricle into aorta (or pulmonary trunk) each minute. •CO= SV x HR
oEX: In a typical resting male; CO= 5.25L/min = 70ml/beat x 75BPM •The entire blood volume flows through pulmonary and systemic circuits each minute Factors that effect stroke volume:
Increased Sympathetic neural stimulation: increase HR, SV, CO • Increased Venous return: HR same, Increase SV, CO
Exercise: Increase HR, SV, CO
Increased Ca2+: HR same, increase SV, CO
Decreased HR: SV same, CO decreased

Know your vessel walls:
Tunica interna (intima): inner layer;
oSmooth lining in direct contact with blood
oEndothelium continuous with endocardial lining of heart
oActive role in vessel- related activities
Tunica Media: Middle layer, smooth muscle
oMuscular and connective tissue layer
oGreatest variation among vessel types
oSmooth muscle regulates diameter of lumen

Tunica Externa: outer layer (connective tissue)
oElastic and collagen fibers
oVasa vasorum: small blood vessels that supply wall of large blood vessels oHelps anchor vessel to surrounding tissue

Know the five types of blood vessels and their differences and functions: •Arteries:
ocarry blood away from the heart
othick tunica media
ohigh compliance: walls stretch and expand in response to pressure without tearing •Arterioles:...
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