A&P 2 Heart

mediastinum

mediastinum

where the heart is located; cavity between the lungs

pericardium

serous membranes that enclosed and hold in place the heart; two layers: visceral and parietal; has cavity filled with serous fluid

epicardium

outer layer of the heart; fused with the visceral layer of the pericardium

myocardium

middle layer of the heart; contains cardiac muscle; used to contract the walls to insinuate blood flow; thicker on the left side of the heart

endocardium

inner layer of the heart; smooth on inside to reduce friction with blood

right atrium

receives blood from the superior & inferior vena cava and the coronary sinus

right ventricle

receives blood from the right atrium and sends blood to the lungs through pulmonary arteries

left atrium

receives oxygenated blood from the pulmonary veins leaving the lungs

left ventricle

receives blood from the left atrium and sends blood all over the body through the aorta

fibrous skeleton

part of the heart that forms the foudnation for which the heart valves attach; serves as a point of insertion for cardiac muscle bundles; prevents overstretching of the heart valves; acts as an electrical insulator

atrioventricular valves

valves that prevent back flow from the ventricles into the atria; bicuspid and tricuspid; open when SL are closed

semilunar valves

valves that prevent the backflow from the arteries into the ventricles; pulmonary and aortic; open when AV are closed

coronary arteries

arteries on the heart that deliver oxygenated blood and nutrients to the myocardium

coronary veins

veins on the heart that remove carbon dioxide and wastes from the myocardium

cardiac muscle cells

cells that are self-excitable and autorhythmic; repeatedly generate spontaneous action potentials that then trigger heart contractions; form the conduction system

conduction system of the heart

the route for propagating action potentials through the heart muscle; 1) sinuatrial node, 2) atrioventricular (AV) node (spreads signal), 3) atrioventricular bundle, 4) right and left bundle branches, 5) subendocardial conducting network

sinuatrial (SA) node

natural pacemaker of the heart; first step in conduction system of the heart;

EKG

aka electrocardiogram; a recording of the electrical changes that accompany each heart beat

systole

depolarization and contraction phase of the heart

diastole

repolarization and relaxation phase of the heart

cardiac cycle

cycle that consists of systole and diastole of both atria, rapidly followed by the systole and diastole of both ventricles

S1

the first sound heard when ventricular systole occurs (hearing vibrations against wall & valves as blood slosh)

S2

the second sound heard when ventricular diastole occurs (semilunar closing)

cardiac output

the volume ejected from the left or right ventricle into the aorta or pulmonary trunk each minute

stroke volume

the amount of blood pumped out of the ventricle in one beat

CO = SV x HR

the equation for cardiac output

preload, contractility, afterload

factors affecting stroke volume

preload

amount of blood pumped back into the atria

contractility

the ability (ease @ which) heart is able to contract

afterload

the amount of pressure that the heart needs to exert to eject the blood during ventricular contraction

factors regulating heart rate

autonomic nervous system; hormones; ions; age; gender; physical fitness; and temperature