Heart Test 2 Flashcards
how many quarts of blood is in the body
6 quarts
how long does it take to replace the body’s supply of blood?
one day
The atrial cells beat about… per minute
60 times
operation of the AV Valves
- causes heart muscle depolarization in only one direction from the atria to the venticles
AV valve contraction rate
75 beats per min
enables the heart beat as a coordinated unit
when the valves contract what does it do?
effectively ejects blood superiority into the large arteries leaving the heart
what is electrocardiography?
the clinical procedure for mapping the electrical activity of the heart
when atria relaxes…
ventricles contract
systole
contraction
diastole
relaxation
explain the cardiac cycle
- both atria and ventricles contract and then relax
- length of this cycle is 0.8 seconds based on the average heart beating 75 times per minute
three periods of the cardiac cycle
mid-to late diastole
ventricular systole
early diastole
what happens during ventricular systole?
contraction begins
-pressure within the ventricles increases rapidly
- av valves close creating the first heart sound
LUB
What happens during early diastole?
systole ends, ventricles relax
- semilunar valves snap shut and create the second heart sound DUB
What is Cardiac Output?
the amount of blood pumped out by each side of the heart (actually each ventricle) in one minute
cardiac output is the product of the…
heart rate and stroke volume
average adult cardiac output
75 beats/min x 70 ml/beat
5250 ml/min
as the heart beats, blood is propelled into the…
large arteries leaving the heart
what is the tunica interna?
lines the lumen cavity
- interior of the vessels
- thin layer of the endothelium (squamous epithelial cells) resting on a scanty layer of loose connective tissue
what is the tunica media?
bulky middle coat made up of smooth muscle and elastic tissue
- some of the larger arteries have elastic laminae
- complete sheets of elastic tissue in addition to the scattered elastic fibers
what are capillary beds?
the tiny interweaving network of capillaries
microcirculation is
the flow of blood from an arteriole to a venule that is through a capillary bed.
(capillary bed) Vascular shunt
a vessel that directly connects the arteriole to the venule at opposite ends of the bed
Capillary bed - precapillary sphincter
surrounds the root of each true capillary and acts as a valve to regulate the flow of blood into the capillary
two routes blood flowing though a terminal arteriole
- through the true capillaries
- through the shunt
when sphincters are relaxed
blood flows through the true capillaries and takes part in exchanges with tissue cells”
when sphincters are contracted
blood flows through the shunts and bypasses the tissue cells
