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Bio Lab Exam 2

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function of cardiovascular system
transportation
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
epicardium
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
pericarditis
inflammation of the pericardium; causes painful adhesions between the serous parietal layers; the adhesions interfere with heart movements
myocardium
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
chambers
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
valves
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
myocardium
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
mediastinum
superior heart chambers
atria
inferior heart chambers
ventricles
visceral pericardium
epicardium
"anterooms" of the heart
atria
equals cardiac muscle
myocardium
provide nutrient blood to the heart muscle
coronary arteries
lining of the heart chambers
endocardium
actual "pumps" of the heart
ventricles
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