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Ch 21 Anatomy of the Cardiovascular System

Terms in this set (51)

location of the heart
lies in the mediastinum behind the body of the sternum between the points of attachment of ribs two through six
pericardium
heart coverings; provides protection against friction; has three layers:

fibrous pericardium
serous pericardium
pericardial space
fibrous pericardium
tough, loose fitting inextensible sac
serous pericardium
parietal layer lies inside the fibrous pericardium, and visceral layer (epicardium) adheres to the outside of the heart
pericardial space
lies between visceral and parietal layers and contains 10 to 15 ml of pericardial fluid
wall of heart
three layers make up this structure:

epicardium
myocardium
endocardium
epicardium
out layer of heart wall
myocardium
thick, contractile middle layer of heart wall; compresses the heart cavitites, and the blood within them, with great force
endocardium
delicate inner layer of endothelial tissue
atria
two superior chambers known as "receiving chambers" because they receive blood from veins and then contract to push blood into ventricles
auricle
earlike flap protruding from each atrium
ventricles
two lower chambers known as "pumping chambers" because they push blood into the large network of vessels
ventricular myocardium
thicker than the myocardium of the atria because great force must be generated to pump the blood a large distance
atrial myocardium
not very thick because little pressure is needed to move blood such a small distance
heart valves
mechanical devices that permit the flow of blood in one direction only
atrioventricular valves (AV)
prevent blood from flowing back into the atria from the ventricles when the ventricles contract
tricuspid valve (right AVE valve)
guards the right atrioventricular orifice; free edges of three flaps of endocardium are attached to papillary muscles by chordae tendineae
bicuspid or mitral valve (left AV valve)
similar in structure to tricuspid valve except has only two flaps
semilunar valves (SL)
half moon shaped flaps growing out from the lining of the pulmonary trunk and aorta; prevent blood from flowing back into the ventricles from the aorta and pulmonary trunk
pulmonary valve
at entrance of the pulmonary trunk
aortic valve
at entrance of the aorta
coronary arteries
first branches to come off the aorta; ventricles receive blood from branches of both the left and right of these.
cardiac veins
these follow the course that closely parallels that of coronary arteries; blood flows through here then enters the coronary sinus to drain into the right atrium
cardiac plexus
located near the arch of the aorta, made up of the combination of sympathetic and parasympathetic fibers
sympathetic nerves
accelerator nerves
vagus fibers
inhibitory or depressor nerves
angiogenesis
formation of new blood vessels
arteries
carry blood away from the heart; all of these except pulmonary carry oxygenated blood
elastic arteries
(conducting) largest in body; able to stretch without injury; accommodate surge of blood when heart contracts and able to recoil when ventricles relax; examples: aorta and its major branches
muscular arteries
(distributing) smaller in diameter than elastic arteries; examples: brachial, gastric, superior mesenteric
arterioles
(resistance vessels) smallest arteries; important in regulating blood flow to end organs
metarterioles
short connecting vessel between true arteriole and 20 to 100 capillaries
capillaries
primary exchange vessels; microscopic vessles; carry blood from arterioles to venules--together, arterioles, capillaries and venules constitute the microcirculation
true capillaries
receive blood flowing from metarteriole with input regulated by precapillary sphincters
continuous capillaries
continuous lining of endothelial cells
fenestrated capillaries
have both intercellular clefts and "holes", or fenestrations, through plasma membrane to facilitate exchange functions
sinusoids
large lumen and tortuous course; absent or incomplete basement membrane; very porous
veins
carry blood toward the heart; act as collectors and as reservoir vessels
collagen fibers
exhibit woven appearance; function to strengthen and keep lumen of vessel open
elastic fibers
composed of insoluble protein called elastin; play important role in creating passive tension to help regulate blood pressure throughout the cardiac cycle
layers of blood vessels
these layers make up the structure of blood vessels:

tunica externa
tunica media
tunica intima
systemic circulation
blood flows from the left ventricle of the heart through blood vessels to all parts of the body (except gas exchange tissues of lungs) and back to the right atrium
pulmonary circulation
venous blood moves from right atrium to right ventricle to pulmonary artery to lung arterioles and capillaries, where gases are exchanged; oxygentated blood returns to left atrium by way of pulmonary veins; from left atrium, blood enters the left ventricle
fetal circulation
two umbilical arteries, placenta, umbilical vein, ductus venosus, foramen ovale, ductus arteriosus
two umbilical arteries
extensions of the internal iliac arteries; carry fetal blood to the placenta
placenta
attached to the uterine wall; where exchange of oxygen and other substances between the separated maternal and fetal blood occurs
umbilical vein
returns oxygenated blood from the placenta to the fetus; enters body through the umbilicus and goes to the undersurface of the liver where it gives off two or three branches and then continues as the ductus vesosus
ductus venosus
continuation of the umbilical vein and drains into inferior vena cava
foramen ovale
opening in septum between the right and left atria
ductus arteriosus
small vessel connecting the pulmonary trunk with the aortic arch
atherosclerosis
blockage or weakening of critical arteries
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