Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
14 Cards in this Set
- Front
- Back
|
How many chambers are there in a mammalian heart? |
Four. Right atrium, left atrium, right ventricle, and left ventricle. |
|
|
Why is an amphibian heart regarded as "less efficient"? |
Because they only have three chambers, which means that the freshly oxygenated blood from the lungs is mixed with the deoxygenated blood returning from the body. |
|
|
Describe the epicardium. |
Layer forming the outer surface of the heart (visceral pericardium). |
|
|
Describe myocardium and the structures it forms. |
The muscular wall of the heart that forms the atria and ventricles. The myocardium is responsible for the pumping of the heart. |
|
|
Describe the endocardium. |
Layer covering the inner surfaces of the heart, maintaining a smooth surface. |
|
|
Describe the systole phase of the cardiac cycle. |
Contraction phase, pushing the blood out. |
|
|
What is a key difference between the cardiac action potential and the skeletal action potential? |
The cardiac action potential and resulting contraction is extended (sustained duration) by the involvement of calcium ions. |
|
|
Describe the process of rapid depolarisation within the cardiac action potential. |
The result of the opening of voltage gated sodium channels, causing an influx of sodium ions to enter the cell. The depolarisation lasts 3-5 milliseconds, and ends with the closure of the fast sodium channels. |
|
|
Describe the diastole phase of the cardiac cycle. |
Relaxation allowing the chamber to fill with blood. |
|
|
Describe the process of repolarisation in the cardiac action potential. |
The fast sodium channels close. The voltage gated potassium channels open. So, there is a sudden loss of potassium ions to the outside causing rapid repolarisation. The process lasts 75 milliseconds, and ends with the closure of the slow potassium channels.
|
|
|
Do all the chambers of the heart contract/relax at the same time? |
No. If the entire heart contracted/relaxed at once there would be no movement of blood. |
|
|
What is responsible for monitoring systolic pressure? |
Arterial baroreceptors in the aortic arch and carotid sinus. |
|
|
Describe how the sympathetic nervous system can increase heat loss. |
Sympathetic nervous system activity maintains vasoconstriction by stimulation of the smooth muscle of arterioles supplying blood to the skin. To increase heat loss the system shuts off, resulting in vasodilation and increased blood supply to the skin. |
|
|
Describe how coffee (caffeine) influences heart rate. |
Increases the rate of depolarisation, thus increasing heart rate. |
