Cardiovascular System: Heart Structure

Epicardium = The inner visceral layer Endocardium = The outer layer that includes compartments, heart valves, and continues with the lining of blood vessels Myocardium = Consists of involuntary striated muscles arranged in spirals/whirls, maintains twists & division of heart Pericardium = Surrounds the heart by a serous sac (pleura & peritoneum)

SA node = Located at the junction of superior vena cava & the rt.atrium AV node = Pathway connecting SA node to ventricles Bundle of HIS = Consists of main lt. & rt. branches Purkinje network = Terminal ramifications in the sub-endocardial muscle

Mitral valve = Between left atrium and left ventricle Tricuspid valve = Between right atrium and right ventricle Aortic semilunar valve = At the junction of left ventricle and aorta Pulmonary semilunar valve = At the junction of pulmonary artery and right ventricle

<p>Depolarization = Cell is stimulated, membrane permeability to Na+ increases while Ca2+ decreases Repolarization = Follows depolarization, restores the cell to its resting state Action potential = Differences in cell membrane permeability to Na+ and K+ leading to cell activation Rhythmic contraction of Heart = Controlled by electrical activity initiated by pace making cell</p> Signup and view all the answers

<p>Chordae tendineae = Attaches free margins of the atrio-ventricular valves Papillary muscles = Maintains tension by shortening ventricular wall during systole Pericardium = Covers the entirely free apex of the heart Atrium = Receives blood from veins</p> Signup and view all the answers

<p>Pulmonary arteries = Carrying deoxygenated blood to the capillaries of respective lung for gas exchange Pulmonary veins = Returning oxygenated blood from the lungs to the lt.atrium Aorta = Passing oxygenated blood to different body parts including heart and lungs themselves Superior vena cava = Junction location of SA node</p> Signup and view all the answers

<p>Pulmonary artery = Carries low oxygen blood to the lungs Pulmonary trunk = Divides into right and left branches beyond pulmonary semilunar valve Cranial vena cava = Returns un-oxygenated blood to the right atrium Caudal vena cava = Returns un-oxygenated blood to the right atrium</p> Signup and view all the answers

<p>Heart block = Interruption in impulse pathway from atria to ventricles Active pace making cells = ↑ permeability of Na+ and K+, progressively depolarized until threshold level is reached Overshoot = Occurs when rate of rise of upstroke is less and peak is more due to Na+ and K+ permeability changes Interatrial systole = Impulse spreading throughout atria causing contraction</p> Signup and view all the answers

<p>Systole = Contraction phase of the heart muscle Diastole = Relaxation phase of the heart muscle Semilunar valves = Prevent blood from flowing back into the respective ventricles Atrio-ventricular valves = Located between atrium and ventricle of each side</p> Signup and view all the answers

<p>Craniodorsal = Direction towards the base of the heart Ventral = Direction towards the apex of the heart Dorsal = Back side of the heart Caudal = Direction towards the tail end of the heart</p> Signup and view all the answers