Microcirculation

Question 1

What are the functions of microcirculation?

Answer 1

• Transport nutrients
• Remove waste

Question 2

What are the smallest vessels in the CV system?

Answer 2

Capillaries

Question 3

What are capillaries comprised of?

Answer 3

A single layer of endothelial cells

Question 4

Can capillaries constrict or dilate?

Answer 4

No

Question 5

What do arterioles do?

Answer 5

Regulate TPR, regulate blood moving from arterial side through venous side

Question 6

What regulates the distribution of blood flow among the capillaries?

Answer 6

Terminal arterioles and in some tissues, precapillary sphincters

Question 7

Postcapillary venules are devoid of

Answer 7

smooth muscles

Question 8

Postcapillary venules are an important area of

Answer 8

exchange

Question 9

Alterations in postcapillary resistance and pressure can significantly influence

Answer 9

capillary hydrostatic pressure

Question 10

Density of exchange vessels is proportional to the

Answer 10

metabolic requirements of the tissue

Question 11

Arterial-venous anastomoses form

Answer 11

anatomical shunts

Question 12

Arterial-venous anastomoses are only present in special areas such as

Answer 12

skin

Question 13

What types of “pores” are in capillaries of the brain?

Answer 13

Tight junctions, which limit what can pass

Question 14

What type of “pores” are in capillaries of the kidney?

Answer 14

Fenestrated glomerular capillaries

Question 15

Sympathetics have little influence over the

Answer 15

terminal arterioles and precapillary sphincters

Question 16

Describe metabolic local control of blood flow

Answer 16

Byproducts of tissue metabolism can cause vascular smooth muscle to relax and vessels to dilate.

Provides coupling mech between local tissue need and local blood flow

Question 17

Describe myogenic local control of blood floq

Answer 17

Degree of ctx of smooth m cells surrounding arterial microvessels in influenced by changes in transmural pressure

Question 18

Increasing the transmural pressure cause the vessels to

Answer 18

constrict

Question 19

Decreasing the transmural pressure causes vessels to

Answer 19

dilate

Question 20

Describe endothelial cell local control of blood flow

Answer 20

Endothelial vessels release both vasoconstrictors and vasodilators

Question 21

In general, terminal arterioles are predominantly influenced by

Answer 21

metabolic and myogenic mechanims

Question 22

Terminal arterioles are less influenced by

Answer 22

neural control than are the small arteries and arterioles

Question 23

What are the primary site of exchange across the circulation

Answer 23

capillaries and postcapillary venules

Question 24

How does the majority of dissolved gas and nutrient molecules move across the capillaires?

Answer 24

By diffusion

Question 25

What is Fick's Law?

Answer 25

J = - Perm * A *(conc in - Conc out)

Question 26

Diffusion of lipid-insoluble molecules is restricted to ______ in capillaries

Answer 26

"pores"

Question 27

The amount of fluid filtered is important in the regulation of

Answer 27

blood and interstitial fluid volume

Question 28

What is te magnitude of filtration and absorption by the capillaries determined by?

Answer 28

Hydrostatic and osmotic pressures across the capillary wall

Question 29

What are factors that influence tissue ydrostatic pressure?

Answer 29

- Interstitial volume - Compliance of interstitial space

Question 30

What does the osmotic pressure gradient across the capillary depend on?

Answer 30

-Plasma protein concentration - Tissue protein concentration

Question 31

What are factors involving filtration?

Answer 31

- Capillary hydrostatic pressure - Tissue colloid pressure

Question 32

Because the capillaries are relatively impermeable to proteins, the concentration of protein in plasma is ______ than the conc in interstitial fluid

Answer 32

greater

Question 33

The higher the conc of protein molecules in plasma causes the plasma osmotic pressure to be approx ____________ than interstitial fluid osmotic pressure called the oncotic or colloid osmotic pressure

Answer 33

25mmHg higher

Question 34

In areas where capillaries have low hydrostatic pressure, interstitial fluid pressure may actually be

Answer 34

negative

Question 35

An increase in arterial or venous pressure ________ capillary hydrostatic pressure

Answer 35

elevates

Question 36

A decrease in arterial or venous pressure ______ capillary hydrostatic pressure

Answer 36

reduces

Question 37

An increase in arteriolar resistance or closure of arteries ______ capillary pressure

Answer 37

reduces

Question 38

Greater resistance in venules and veins _________ capillary pressure

Answer 38

increases

Question 39

What are factors that influence capillary hydrostatic pressure?

Answer 39

- Systemic arterial pressure - Precapillary resistance - Postcapillary resistance - Venous pressure

Question 40

An imbalance between forces causing filtration and those causing absorption may result in what?

Answer 40

edema

Question 41

When edema occurs, _______ can occur in interstitium

Answer 41

bulk flow of fluid

Question 42

What is the major function of lymphatics?

Answer 42

Return interstitial fluid and plasma proteins into the blood

Question 43

Lymph flow can be increased 20 fold in order to compensate for

Answer 43

increase in filtration

Question 44

Interstitial fluid is collected by

Answer 44

terminal lymphatic capillaries

Question 45

How is lymph propelled through the lymphatic system?

Answer 45

By spontaneous contractile activity of lymph vessels and by intermittent skel m ctxs