Part 1: Structure and Function

Question 1

What are the 3 structural components generally found in vessels?

Answer 1

Tunica intima: endothelium
Tunica media: SM and elastic tissue
Tunica adventitia: CT and elastic tissue

Question 2

How thick are capillaries?

Answer 2

1um thick

Question 3

What are the 3 types of capillaries?

Answer 3

Continuous: uninterrupted lining, only allow small molecules to cross (eg BBB)
Fenestrated: Have pores allow small molecules and protein to diffuse (eg glomerular capillaries)
Sinusoidal: Open pore/discontinuous capillary with large openings. Allow RBC and WBC and larger serum proteins to pass. (located in bone marrow, lymph nodes)

Question 4

Where in the circulation is most blood volume found at rest?

Answer 4

Venules and small veins (capacitance vessels) hold 40-50%. Large veins and VC hold 20%. Pulmonary circulation 8%, heart 8%, capillaries 5%. Arteries and arterioles 16%

Question 5

Describe what happens to blood flow as it travels from LV to RA

Answer 5

Flow drops as cross-sectional area increases from the aorta and large veins down to arterioles. Slowest at capillaries where greatest cross-sectional area exists. Flow slowly increases in venules and veins and cross-sectional area decreases. The IVC and SVC are both similar diameter to aorta and therefore combined twice the c/s area thus flow in IVC/SVC is 0.5 of that in aorta.

Question 6

What is the man site of flow resistance in the vascular system?

Answer 6

Arterioles - thick wall/smooth muscles, able to constrict and increase resistance and thus direct flow to different systems/tissues

Question 7

What is normal cardiac output at rest?

Answer 7

5l/min

Question 8

What can CO increase to in exercise?

Answer 8

15l/min

Question 9

How much cardiac output does brain require?

Answer 9

15% at rest. 50ml/min. Constant rate in rest and exercise (although of course % drops comparatively to increase CO in exercise)