Question

Chapter 11 Cardiovascular system   

1. Case Scenario An athlete on completeion of 400 mts relay run experiences a very rapid heart beat and then after sometimes experiences normal heat beat.

a.Which system is responsible for increaing the heart rate?

b.Which system is responsible for decreasing is heart rate?

2. Describe how the valves keep the blood moving in one direction?   

3. Why is the pressure in the pulmonary circulation lower than in the systemic circulation?   

4. Watch this video to explore capillaries and how they function in the body. Capillaries are never more than 100 micrometers away.

a. Describe the structure of the capillary walls.

b. What is the main component of interstitial fluid?

c. What is microcirculation? Name the two types of capillary vessels and name the actual exchange vessels

Answer 1

1 a. sympathetic nervous system is responsible for increasing heart rate.this system releases hormones (catecholamines-epinephrine and norepinephrine) to accelerate the heart rate

b. parasympathetic nervous system is responsible for decreasing heart rate.this system release acetylcholine to slow the heart rate.

2. the heart valves prevent backflow of blood during systole

atrioventricular valves(tricuspid and mitral valves)prevent backflow of blood from the ventricles to the atria during systole , and the semilunar valves (pulmonary and aortic valves) prevent blackfrow from pulmonary and aortic arteries into ventricle during diastole. these valves, for left ventricle close and open passively. that is they close when a backword pressure gradient pushes blood backwards , and they open when a forward pressure gradient forces blood in forward direction.

3. pressure in the pulmonary circulation is lower because of absence of muscular arterioles responsible for high resistance found in systemic circulation.

4 a. structure of capillary wall

the wall is composed of unicellular layer ofendothelial cells and is surrounded by a thin basement membrane on the outside of capillary. the total thickness of capillary wall is only about 0.5 micro meter. the internal diameter iss 4 to 9 micrometers, barely large enough for red blood cells and other blood cells to squeeze through.

b. main component in interstitial fluid is water and it also contains lymph

c.microcirculation is the circulation of the blood in the smallest blood vessels, the micro vessels include arterioles ,venules and capillaries

two types of capillaries includetrue capillaries and sinusoids.

exchange vessels are of three types: continuous capillaries, fenestrated capillaries, sinusoidal capillaries.