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19 Cards in this Set
- Front
- Back
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The right side of the heart pumps deoxygenated blood to the... |
lungs |
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The left side of the heart pumps oxygenated blood to the... |
whole body |
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Why does the left ventricle of the heart have a thicker, more muscular wall than the right ventricle? |
Needs to contract powerfully to pump blood all the way around the body Right side pumps only to lungs |
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Why do ventricles have thicker walls than the atria? |
They have to push blood out of the heart whereas areas just push blood short distance to ventricles |
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What is the function of the atrioventricular (AV) valves? |
Link atria to ventricles Stop blood flowing back into atria when ventricles contact |
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What is the function of the semi-lunar (SL) valves? |
Link ventricles to pulmonary artery and aorta Stop blood flowing back into heart after ventricles contract |
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What is the function of the cords? |
Attach the atrioventricular valves to ventricles to stop them being forced up into atria when the ventricles contract |
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Why does blood only flow in one direction through the heart? |
Valves only open one way Depends on pressure behind valve (relative pressure of heart chambers) |
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Step 1 of cardiac cycle |
Ventricles relax, atria contract |
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When atria contract, what happens to pressure and volume inside the chamber? Where does blood go because of this? |
Pressure increases Volume decreases Blood pushed/ejected into ventricles |
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Step 2 of cardiac cycle |
Ventricles contract, atria relax |
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When ventricles contract, what happens to pressure and volume inside the chamber? Where does blood go because of this? What happens to AV valves? What happens to SL valves? |
Ventricular pressure increases Ventricular volume decreases Pressure higher in ventricles than atria, so AV valves forced shut to prevent back-flow Pressure in ventricles higher than in aorta and pulmonary artery, forcing SL valves open, forcing blood into those arteries |
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Step 3 of cardiac cycle |
Ventricles relax, atria relax |
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How does the higher pressure in the pulmonary artery and aorta affect the SL valves? |
It results in the SL valves closing to prevent back-flow into the ventricles |
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What does the higher pressure in the vena cava and the pulmonary vein result in? |
Blood returns to the high and atria fill again |
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How does this affect the pressure of the atria? |
It increases the pressure of the atria |
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As ventricles continue to relax, their pressure falls below the pressure of the atria. How does this affect the AV valves? |
They open |
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This allows blood to flow passively into the ventricles from the atria. What does this mean? |
The blood isn't being pushed by atrial contraction |
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Next, the atria contract... |
...and the whole process begins again |
