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Biology
7 - Mass transport
7.5 - The cardiac cycle
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Created by
Ivy Young
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Cards (10)
What’s it called when the heart relaxes ?
Diastole
Does diastole occur in all chambers at once ?
Yes
Describe what occurs in the heart during diastole
Left and right
atria
fill with blood from the
vena cava
and
pulmonary veins
Pressure increases in atria
When pressure in atria exceeds ventricular pressure the
atrioventricular valves
open
All walls relax so pressure in
ventricles
is reduced (less than in
aorta
and pulmonary artery)
So
semi-lunar valves
are closed
Describe what happens in the heart during systole
Atrial systole forces blood into
ventricles
and
atrioventricular
valves open, but
ventricles
stay relaxed
A pause allows ventricles to fill, increasing pressure
Causes atrioventricular valves to close which prevents back flow
Ventricular systole occurs, once pressure exceeds the
aorta
and
pulmonary artery
, Semi-lunar valves open
Blood pumped out
What are found in veins that prevent back flow of blood ?
Pocket valves
How are veins squeezed ?
When
skeletal muscles
contract
during movement
What is a valve made of ?
Flexible
,
fibrous
cusp shaped tissue
What are tendinous cords ?
Inelastic cords of
fibrous
connective tissue
that connect muscles to valve, prevent
inversion
What is cardiac output ?
The volume of blood pumped by one
ventricle
in one
minute
Equation for cardiac output (CO) ?
CO =
stroke volume
x
heart rate