18.4: Capillaries and Tissue Perfusion

Question 1

What is tissue perfusion? is the blood flow through a capillary bed to a tissue.

Answer 1

Tissue perfusion is the blood flow through a capillary bed to a tissue.

Question 2

Substances may be exchanged across capillary walls by osmosis, diffusion through the endothelial cells, diffusion through small pores, and transcytosis.

Question 3

There are three types of capillaries, ordered from least to most leaky:

Answer 3

There are three types of capillaries, ordered from least to most leaky:

• continuous capillaries, fenestrated capillaries, and sinusoidal capillaries.

Question 4

The ___________ is the total blood flow that takes place within the capillary beds.

Answer 4

The microcirculation is the total blood flow that takes place within the capillary beds.

Question 5

Tissue perfusion in most tissues is largely autoregulated to ensure that blood flow meets the cells’ needs.

The myogenic mechanism involves reflexive vasoconstriction and vasodilation in response to stretching of smooth muscle in blood vessels.

Arterioles dilate when the concentration of O2 decreases and the concentrations of CO2 and H+ increase. They constrict in the opposite conditions.

Answer 5

Tissue perfusion in most tissues is largely autoregulated to ensure that blood flow meets the cells’ needs.

• The myogenic mechanism involves reflexive vasoconstriction and vasodilation in response to stretching of smooth muscle in blood vessels.
• Arterioles dilate when the concentration of O2 decreases and the concentrations of CO2 and H+ increase. They constrict in the opposite conditions.

Question 6

Tissue perfusion in the heart decreases during ventricular systole and increases during ventricular diastole.

Question 7

The brain, skeletal muscle, and skin have their own autoregulatory systems for tissue perfusion.

Question 8

What type of capillaries have large pores within their endothelial cells and are the leakiest?

continuous capillaries

sinusoidal capillaries

closed capillaries

fenestrated capillaries

Answer 8

What type of capillaries have large pores within their endothelial cells and are the leakiest?

continuous capillaries

sinusoidal capillaries

closed capillaries

fenestrated capillaries

Question 9

Under what conditions will the myogenic mechanism slow blood flow into a capillary bed?

rising carbon dioxide levels

rising arteriolar pressure

dropping arteriole pressure

rising hydrogen ion levels

Answer: B

Answer 9

Under what conditions will the myogenic mechanism slow blood flow into a capillary bed?

rising carbon dioxide levels

rising arteriolar pressure

dropping arteriole pressure

rising hydrogen ion levels

Question 10

True or False: Fenestrations in capillaries are small pores that allow water and small substances to move freely through these pores.

Answer 10

Fenestrations in capillaries are small pores that allow water and small substances to move freely through these pores.

True

False