Microcirculation

Question 1

Define: Microcirculaltion

Answer 1

where exchange of oxygen and nutrients occurs in the tissues

arterioles and capillaries

Question 2

What happens if things aren’t working properly in the microcirculation?

Answer 2

it can cause excess fluid in the tissue space → edema

Question 3

What role do the lymphatic channels play in microcirculation?

Answer 3

They pick up excess fluid and protein from the interstitial space and bring it back to the vasculature

Question 4

What are the parts of microcirculation?

Answer 4

Arterioles

Capillaries

Lymphatic system

Question 5

What controls microcirculation?

Answer 5

sympathetic nervous system

Question 6

What type of muscle do arterioles have alot of?

Answer 6

smooth muscle

Question 7

What innervates the arterioles?

Answer 7

sympathetic nerves

Question 8

Define: Precapillary Sphincters

Answer 8

smooth muscle that regulates blood flow through capillaries (constrict and dilate)

open and close based on metabolic activity

Question 9

What are the two types of blood flow?

Answer 9

Nutrient blood flow

Nonnutrient blood flow

Question 10

Define: Nutrient Blood Flow

Answer 10

blood that flows through capillaries

provides nutrients to tissues

Question 11

Define: Nonnutrient blood flow

Answer 11

blood doesn’t flow through capillaries

blood goes from arterioles to venule through AV shunt

Question 12

What is the purpose of nonnutrient blood flow?

Answer 12

primarily present in the skin for temperature regulation

goes to venule near surface of the skin that disapates heat

Question 13

What type of flow do vessels 20 microns in diameter or larger experience?

Answer 13

laminar flow

Question 14

What type of flow do vessels less than 20 microns in diameter experience?

Answer 14

turbulent flow with cells in a somewhat single file line

Question 15

What factors influence vessel diameter?

Answer 15

O₂

Circulating E and NE

Tissue metabolites

BP

Sympathetic nerves

Endothelial cells

Question 16

What factors constrict vessel diameter?

Answer 16

O₂

Circulating E and NE

BP

Sympathetic nerves

Endothelial cells → endothelin

Question 17

what factors relax vessel diameter?

Answer 17

Tissue metabolites

Endothelial cells → Nitric Oxide

Question 18

What happens to vessel diameter when you increase BP?

Answer 18

local vessel constriction

Question 19

How do different endothelial cells effect fluid movement?

Answer 19

they pose dif limitations

tight junction → little fluid can move across the membrane → Blood brain barrier

Discontinuous endothelium → gaps in endothelium allow fluid to move freely → intestines

Question 20

What are the two types of transport seen in cells?

Answer 20

flow-limited transport

diffusion limited transport

Question 21

Define: Flow-limited transport

Answer 21

some substances are able to leave the capillary and enter ISF but some cannot

the amount of a substance allowed to leave the capillary is determined by concentration gradient in the capillary

Question 22

What establishes the concentration gradient of a capillary?

Answer 22

the amount of flow carrying a substance to a capillary

increase flow bringing substances to the capillary → increase concentration gradient → more diffuse to cell

Question 23

When is diffusion most efficient?

Answer 23

when you have the largest surface area, high concentration, and short distance

Question 24

What is diffusion dependent on?

Answer 24

large cross sectional area and high concentration

Question 25

Define: Diffusion limited transport

Answer 25

Large ISF → greater diffusion distance → fewer substances permeate cell

Question 26

What can cause an increase in the ISF?

Answer 26

edema

Question 27

What factors help control amount of fluid across capillary membrane?

Answer 27

P_c, P_i, *π_p, π*_i, k Fluid movement = k[(P_c + *π*_i) - (P_i + *π_p*)]

Question 28

Define: P_c (capillary hydrostatic pressure )

Answer 28

pressure inside capillary

Question 29

Define: P_i (interstitial fluid hydrostatic pressure)

Answer 29

pressure in interstitial space normally negative

Question 30

Define: *π_p* (plasma protein oncotic pressure)

Answer 30

proteins retained in capillary pull fluid back into venous end

Question 31

Define: *π*_i (interstitial fluid oncotic pressure)

Answer 31

caused by proteins in the interstitial fluid

Question 32

Define: filtration

Answer 32

occurs when the algebraic sum is positive from capillary to interstitial space

Question 33

Define: reabsorption

Answer 33

occurs when the value is negative movement of fluid from interstitial space to capillary

Question 34

What factors make up primary filtration?

Answer 34

P_c and *π*_i

Question 35

What factors make up primary reabsorption?

Answer 35

P_i and *π_p*

Question 36

What would happen to the P_c (capillary hydrostatic pressure) if you increase resistance by constricting artery going into the capillary?

Answer 36

P_c would decrease velocity flow would increase volume flow would decrease

Question 37

What would happen to the P_c (capillary hydrostatic pressure) if you increase resistance by constricting the veins going into the capillary?

Answer 37

P_c would increase increase venous constriction or pressure → increase P_c

Question 38

What happens to pressure as fluid flows from the arterial end of the capillary to the venous end of the capilary?

Answer 38

Pressure gradually drops as you move from arterial to venous side of capillary P_c gradually decreases no net gain or loss of fluid

Question 39

If the flow of movement is equal to 14 on the arterial side and -1 on the venous side; is the capillary mostly filtering or reabsorbing?

Answer 39

filtering

Question 40

If the flow of movement is equal to 14 on the arterial side and -1 on the venous side; what is the next effect across the capillary?

Answer 40

mostly filtering pushing more fluid into the interstitial space than being reabsorbed by the veins

Question 41

If the flow of movement through a capillary is primarily being filtered out, what would happen if the lymphatic channels are not taking up the extra fluid?

Answer 41

the capillary would promote edema

Question 42

Which side of the capillary mainly works in filtration?

Answer 42

arterial

Question 43

Which side of the capillary mainly works in reabsorption?

Answer 43

venous