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function of cardiovascular system


what does cardiovascular system carry

using blood as the transport vehicle, the system carries oxygen, digested foods, cell wastes, electrolytes, and many other substances vital to the body's function to and from the body cells

cardiovascular system's propulsive force

the contracting heart

the contracting heart

muscular/circulatory pump that has one way valves

what happens when heart contracts

when the heart contracts, it forces blood into a closed system of large and small plumbing tubes (blood vessels) within which blood is confined and circulated

structure of the heart

heart is a cone shaped organ, approximately the size of a fist

location of the heart

it is located within the mediastinum, or medial cavity of the thorax; it is flanked laterally by the lungs, anteriorly by the sternum, and posteriorly by the vertebral column

heart's apex

it points slightly to the left, rests on the diaphragm at the level of the 5th intercostal space

heart's base

from which the great vessels emerge, lies beneath the 2nd rib and points toward the right shoulder

apical pulse

the apical pulse may be heard in the 5th intercostal space at the point of maximal intensity (PMI)

double-walled sac

the heart is enclosed in a double-walled fibroserous sac called pericardium


the thin epicardium, or visceral pericardium is closely applied to the heart muscle

parietal pericardium

the epicardium reflects downward at the base of its heart to form its companion serious membrane, the outer, loosely applied parietal pericardium which is attached at the heart apex to the diaphragm

serous fluid

the serous fluid produced by the membranes allows the heart to beat in a frictionless environment

fibrous pericardium

the serous parietal pericardium, in turn, lines the loosely fitting superficial fibrous pericardium composed of dense connective tissue


inflammation of the pericardium; causes painful adhesions between the serous parietal layers; the adhesions interfere with heart movements


the walls of the heart are composed primarily of cardiac muscle -- the myocardium -- which is reinforced internally by a dense fibrous connective tissue network

fibrous skeleton of the heart

is more elaborate and thicker in certain areas, such as the valves and at the base of the great vessels leaving the heart


two superior chambers called the atria (atrium); two inferior chambers called ventricles, each lined by serous endothelium (endocardium)

interatrial/interventricular septum

the septum that divides the heart longitudinally depending on which chamber it partitions

function of atria

atria are the receiving chambers and are ineffective as pumps

blood flow in atria

blood flows into the atria under low pressure from the veins of the body

right atrium

receives oxygen-poor blood from the superior venae cavae, inferior venae cavae, and the coronary sinus

left atrium

the four pulmonary veins deliver oxygen-rich blood from the lungs to the left atrium

function of ventricles

the inferior thick-walled ventricles form the bulk of the heart; are the discharging chambers

blood flow in ventricles

they force blood into the large arteries that emerge from its base

right ventricle

pumps blood into the pulmonary trunk, which routes the blood to the lungs to be oxygenated

left ventricle

discharges blood into the aorta, from which all systemic arteries of the body diverge to supply the body tissues


four valves; two atrioventricular valves (AV), two semilunar valves (SV)

atrioventricular valves

located between the atrial and ventricular chambers on each side prevent backflow into the atria when the ventricles are contracting

left atrioventricular valve

the mitral or bicuspid valve, consists of two cusps, or flaps, of endocarium

right atrioventricular valve

the tricuspid valve, has three cusps

chordae tendinae

tiny while collagenic cords (heart strings), anchor the cusps to the ventricular walls

where do chordae tendinae originate from

from small bundles of cardiac muscle, called papillary muscles, that project from the myocardial wall

av valve during diastole

when blood is flowing passively into the atria and then into the ventricles during diastole (ventricular filling), the AV valve flaps hang limply into the ventricular chambers and then are carried passively toward the atria by the accumulating blood

av valve during systole

when the ventricles contract (systole) and compress the blood in their chambers, the intraventricular blood pressure rises, causing the valve flaps to be reflected superiorly, which close the AV flaps

chordae tendinae during ventricular contraction

the chordae tendinae, pulled taut by the contracting papillary muscles, anchor the flaps in a closed position that prevents bakcflow into the atria during ventricular contraction

semilunar valves (SL)

the pulmonary and aortic vavlves

pulmonary and the aortic valve

each composed of three pocketlike cusps, that guards the bases of the two large arteries leaving the ventricular chambers

SL valves during systole

the valve cusps are forced open and flatten against the walls of the artery as the ventricles discharge their blood into the large arteries during systole

Sl valves during diastole

when the ventricles relax, blood flows backward toward the heart and the cusps fill with blood, closing the semilunar valves and preventing arterial blood from reentering the heart

pulmonary circulation

the ride side of the heart serves as the pulmonary circulation pump, shunting the CO2-rich blood entering its chambers to the lungs to unload CO2 and pick up oxygen, and then back back to the left side of the heart

function of the pulmonary circulation

to provide gas exchange

systemic circulation

2nd circuit, which carries oxygen-rich blood from the left heart through the body tissues and back to the right side of the heart

function of the systemic circulation

provides the functional supply to all body tissues

coronary circulation

even though the heart chambers are almost continually bathed with blood, this contained blood does not nourish the myocardium; the function blood supply of the heart is provided by the coronary arteries

right and left coronary arteries

issue from the base of the aorta just above the aortic semilunar valve and encircle the heart in the coronary sulcus at the junction of the atria and ventricles; then they ramify over the heart's surface

right coronary artery

supplies the posterior surface of the ventricles and the lateral aspect of the right side of the heart, largely through its posterior interventricular and right marginal artery branches

left coronary artery

supplies the anterior ventricular walls and the laterodorsal part of the left side of the heart via its two major branches, the anterior interventricular artery and the circumflex artery

coronary arteries during systole and diastole

coronary arteries and their branches are compressed during systole and filled when the heart is relaxed


largely drained by the great, middle, and small cardiac veins, which empty into the coronary sinus; the coronary sinus, in turn, empties into the right atrium; in addition, anterior cardiac veins empty directly into the right atrium

flow of blood through the heart

right atrium -> right ventricle -> pulmonary arteries -> lungs -> pulmonary veins -> left atrium -> left ventricle -> aorta -> body tissues -> back to the right atrium

cardiac muscle

found only in the heart; the heart acts as a vascular pump, propelling blood to all tissues of the body; cardiac muscle is thus very important to life

function of cardiac muscle

involuntary, ensuring a constant blood supply

structure of cardiac cells

invested in connective tissue, arranged in spiral of figure - 8 shaped bundles; when the heart contracts, its internal chambers become smaller, forcing the blood into the large arteries leaving the heart

branching cells and intercalated discs

these two structural features provide a continuity to cardiac muscle no seen in other muscle tissues and allow close coordination of heart activity

brachiocephalic trunk

splits to form the right carotid and subclavian arteries, which supply the right side of the head and right forelimb

ligamentum arteriosum

fat between the pulmonary trunk and the aorta

ductus arteriosus

in the fetus, the ductus arteriosus allows blood to pass directly from the pulmonary trunk to the aorta thus bypassing the nonfunctional fetal lungs

pectinate muscles

comblike ridges of muscle throughout most of the right atrium

coronary sinus

returns venous blood of the coronary circulation to the right atrium

fossa ovalis

oval depression in the interatrial septum

foramen ovalis

in the fetal heart; allows blood to pass from the right to the left atrium, thus bypassing the lungs

trabeculae carnae

pitted and ridged appearance of the inner ventricular muscle

moderator band

septomarginal band; a bundle of cardiac muscle fibers connecting the interventricular septum to anterior papillary muscles; it contains a branch of the atrioventricular bundle and helps coordinate contraction of the ventricle

what if the function of the fluid that fills the pericardial sac

to reduce friction during heart activity

location of the heart in the thorax


superior heart chambers


inferior heart chambers


visceral pericardium


"anterooms" of the heart


equals cardiac muscle


provide nutrient blood to the heart muscle

coronary arteries

lining of the heart chambers


actual "pumps" of the heart


drains blood into the right atrium

coronary sinus

what is the function of the valves found in the heart

they enforce a one-way flow of blood through the heart

what is the role of the chordae tendinae

they anchor the AV valve flaps during ventricular systole, thus preventing backflow of blood into the atria

blood flow

right atrium through the tricuspid valve to the right ventricle, through the pulmonary semilunar valve to the pulmonary trunk, to the left and right pulmnoary arteries, to the capillary beds of the lungs, to the pulmonary veins to the left atrium of the heart, through the mitral/bicuspid valve to the left ventricle through the aortic semilunar valve to the aorta, to the sytemic arteries, to the capillary beds of the tissues, to the systemic veins, to the superior venae cavae, inferior venae cave, and coronary sinus entering the right arium of the heart

if the mitral valve does not close properly, which circulation is affected

systemic circulation

which might a thrombus in the aterior-descending branch of the left coronary artery cause sudden death

this artery supplies blood to the interventricular septum and the anterior walls of both ventricles; ventricular damage (mainly left ventricle) is serious

how would you distinguish the structure of cardiac muscle from that of skeletal muscle

skeletal muscles are long, cylindral cells with many peripherally located nuclei per cell; cardiac cells have 1 or 2 centrally located nuclei per cell, their branched ends fit together at tight junctions called intercalated discs, which are not seen in skeletal muscles

describe the unique anatomical features of cardiac muscle

the cardiac cells are arranged in spirals or figure - 8 bundles

what role does the unique structure of cardiac muscle play in its function

when the heart contracts, blood if forced into the anterior leaving the heart; the cardiac cells are branched and the disc shaped which allows the heart to have a coordinated activity

what differences can you observe in the two ventricles

the left ventricles is thicker and has a more dense feel to it than the right ventricle, which is thinner and softer

why is the left ventricle thicker

because the left ventricle pumps blood through the high-resistance systemic circulation, therefore, it has to be stronger than the right ventricle, which pumps blood through the short low-resistance pulmonary circulation

semilunar valves prevent backflow into the ____......

semilunar valves prevent backflow into the ventricles; mitral and tricuspid valves prevent backflow into the atrium

different operations of SL and AV valves

when the ventricle was compressed (systole), the AV flaps moved superiorly into the closed position; when water was poured (as when blood backflows) into the semilunar valves, the cusps filled and closed the valves

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