What are the functions of the cardiovascular system?
to transport oxygen, nutrients, cell wastes, and hormones to and from cells
What is the size of the heart?
the size of a human fist, weighs less than 1 pound
inferior mediastinum
region in between the lungs/thoracic cavity, location of the heart
Orientation of the apex
directed toward the left hip and rests on the diaphragm
Orientation of the base
points toward the right shoulder
Pericardium
double-walled sac covering the heart
Fibrous pericardium
loose and superficial layer to the pericardium
Two layers of the serous membrane
parietal pericardium, visceral pericardium/epicardium
epicardium
outside layer of the walls of the heart, also called the visceral pericardium
myocardium
middle layer of the heart wall, mostly cardiac muscle
endocardium/endothelium
inner layer
Atria
superior receiving chambers of the heart, blood enters under low pressure
ventricles
discharging chambers, thick-walled pumps of the heart, during contraction blood is propelled into circulation
interartial septum
separates the two atria longitudinally
interventricular septum
separates the two ventricles longitudinally
Arteries
carry blood away from the heart
veins
carry blood toward the heart
double pump
right side works as the pulmonary circuit pump, left side works as the systemic circuit pump
Steps to Pulmonary circulation
-blood flows from the right side of the heart to the lungs and back to the left side of the heart
-blood is pumped out of the right side through the pulmonary trunk, which splits into pulmonary arteries and takes oxygen-poor blood to the lungs
-oxygen-rich blood returns to the heart from the lungs via pulmonary veins
Steps to systemic circulation
-oxygen-rich blood returned to the left side of the heart and is pumped out into the aorta
-blood circulates to systemic arteries and to all body tissues
left ventricle has thicker walls because it pumps blood to the body through the systemic circuit
-oxygen-poor blood returns to the right atrium via systemic veins, which empty blood into the superior or inferior vena cava
Heart valves
allow blood to flow in only one direction, to prevent backflow
atrioventricular valves
between the atria and ventricles
bicuspid/mitral valve
left atrialventricular valve
tricuspid
right atrioventricular valve
semilunar valves
-between ventricle and artery
-closed during heart relaxation
-open during ventricular contraction
pulmonary semilunar valve
between a ventricle and pulmonary arterty
aortic semilunar valve
between a ventricle and aorta
Atrioventricular(AV) valves
-cusps are anchored in place by chordae tendineae to the walls of the ventricles
-opens during heart relaxation, when blood passively fills the chambers
-closed during ventricular contraction
-valves open and close in response to pressure changes in the heart
These valves have prssure put on them by the blood returning to the atria.
AV valves (question)
Blood in the heart chambers does not nourish the _________.
myocardium (question)
Parts of the heart’s nourishing circulatory system
-coronary arteries
-cardiac veins
-coronary sinus
Cardiac Circulation
blood empties into the right atrium via the coronary sinus and does not nourish the myocardium
Coronary arteries
branch from aorta to supply the heart muscle with oxygenated blood
cardiac veins
drains the myocardium of blood
coronary sinus
a large vein on the posterior of the heart; receives blood from cardiac veins
two systems that regulate heart activity:
autonomic nervous system and intrinsic conduction system/nodal system
Sinoatrial node
starts each heartbeat
impulse spreads through the atria to the AV bundle, bundle branches, and Purkinje fibers
ventricles contract; blood ejected from heart
techycardia
rapid heart rate, over 100 beats per minute
Cardiac cycle
refers to one complete heartbeat, when both atria and ventricles contract and relax
Diastole
relaxation
average heart rate
\n 75 beats per minute
Length of cardiac cycle
0.8 seconds
____ transfers blood to tissues and back from the heart
blood vessels in the closed vascular system
arteries and arterioles
vessels that carry blood away from the heart
capillary beds
vessels that are involved in exchanges between blood and tissue
tunica media
smooth muscle and elastic tissue
controlled by the sympathetic nervous system
tunica externa
forms protective outermost covering
mostly fibrous connective tissue
supports and protects the vessel
arteries
heavier, stronger, and stretching tunica media than veins to withstand pressure changes
smaller lumen
veins
thinner tunica media because they operate under low pressure
have valves to prevent backflow
larger lumen
skeletal muscle contracts and pushes blood in veins toward heart
capillaries
one layer thick, tunica intima
exchanges between blood and tissue
form capillary beds, networks that consist of:
vascular shunt and true capillaries
Bradycardia
slow heart rate, less than 60 beats per minutes
intrinsic conduction/nodal system
sets heart rhythm
composed of special nervous tissue
ensures heart muscle depolarization in one direction only (atria to ventricles)
enforces a heart rate of 75 beats per minute
autonomic nervous system
controls voluntary movement
Sinoatrial node
located in the right atrium
serves as the heart’s pacemaker
Atrioventricular node
at the junction of the aria and ventricles
atrioventricular bundle/bundle of his
in the interventricular septum with bundle branches
Purkinje fibers spread within the ventricle wall muscles
Systole
contraction
venules and veins
vessels that return blood toward the heart
tunica intima
layer of the blood vessels that is friction reducing
endothelium
microcirculation
blood flow through a capillary bed