Autoregulation And Cap Dynamics

Front 1

The process by which the various organs and tissues of the body self-regulate blood delivery. Blood flow through individual organs is controlled intrinsically in response to local requirements.

Back 1

autoregulation

Front 2

Where does blood flow regulation occur?

Back 2

capillary beds

Front 3

Where does exchanges of materials take place between tissue cells and the blood?

Back 3

true capillaries

Front 4

What regulates the flow of blood into the true capillaries?

Back 4

precapillary sphincter

Front 5

The build-up of certain chemical signals in an area of the body can act as a metabolic control, bringing more blood to the capillaries of the area. What two types of blood vessels do these chemical signals affect and how do they work?

Back 5

the feeder arterioles and precapillary sphincters
feeder arterioles dilate and help relax the precap. sphincters. If precap. sphincters are open, more blood will get through, but if closed less blood gets through.

Front 6

Will the precapillary sphincters open or close in a capillary bed that is high in oxygen? Explain.

Back 6

Close. If the oxygen levels in the tissue cells are already high, no more blood flow is needed in that area until the oxygen levels are lower again.

Front 7

Will the precapillary sphincters open or close in a capillary bed that is high in carbon dioxide? Explain.

Back 7

Open. Carbon dioxide is a metabolic waste product. If it builds up in a capillary bed, then the precapillary sphincters will open to allow it to be removed from the area.

Front 8

Will the precapillary sphincters open or close in a capillary bed that has a high pH? Explain.

Back 8

Close. Typically acids that accumulate must be removed from tissues. So when there is a low pH a lot of acid is present and the precapillary sphincters open.

Front 9

Will the precapillary sphincters open or close in a capillary bed that is high in nutrients? Explain.

Back 9

Close. If nutrients are already present in a capillary bed, precapillary sphincters will close. They open when nutrients are needed.

Front 10

Why would a decreased blood pressure cause precapillary sphincters to open?

Back 10

Decreased blood pressure will cause precapillary sphincters to open, allowing more blood to reach the capillary bed

Front 11

List three ways materials move from the lumen of the capillary into the interstitial spaces.

Back 11

1. Cytoplasmic vesicles
2. Fenestrations
3. Clefts

Front 12

Pore in a capillary endothelial cell that may be open or covered by a delicate membrane; allows for freer passage of fluids and small solutes between capillaries and tissue cells.

Back 12

fenestrations

Front 13

How do clefts differ from fenestrations?

Back 13

Clefts are gaps btwn the capillary endothelial cells, and fenestrations are part of capillary endothelial cells that may be open or have a thin membrane covering it.

Front 14

Explain how materials are moved across an endothelial cell via bulk transport.

Back 14

Through cytoplasmic vesicles.

Front 15

Most solutes move across the capillary wall by diffusion. Define diffusion.

Back 15

The movement of solutes from a region of higher concentration to lower concentration.

Front 16

What types of solutes are able to diffuse though the plasma membranes of the endothelial cells from higher to lower concentration without the help of transport proteins or expenditure of metabolic energy. Give two specific examples.

Back 16

Lipid soluble molecules
Oxygen & Carbon Dioxide

Front 17

What types of solutes are typically transported from the blood to interstitial fluid by exocytosis and endocytosis across endothelial cells?

Back 17

Lipophobic solutes

Front 18

What types of solutes are typically transported from the blood to interstitial fluid through clefts or fenestrations? Give two specific examples.

Back 18

Water soluble solutes
A.A's & sugars

Front 19

What process is responsible for fluid leaving the capillaries at the arterial end and returning to the capillary at the venule end?

Back 19

Bulk fluid flows

Front 20

What happens if more fluid leaves the capillaries than is returned to the capillaries?

Back 20

The fluid is returned to the bloodstream by lymph capillaries of the lymphatic system.

Front 21

What two types of pressures influence fluid exchanges at capillary beds?

Back 21

Hydrostatic
Osmotic

Front 22

Is the pressure exerted by a fluid on the walls of its container.

Back 22

hydrostatic pressure

Front 23

What term is used to denote the blood pressure in the capillaries?

Back 23

HPc

Front 24

What happens to capillary hydrostatic pressure as the blood moves through a capillary bed? Explain.

Back 24

HPc encounters friction in the cap, and thus HPc is lower at the venule end of cap.

Front 25

What term is used to denote the pressure of the fluid in the interstitial fluid?

Back 25

HPif

Front 26

Why is the hydrostatic pressure of the interstitial fluid (HPif) normally low?

Back 26

Because it is quickly picked up the lymphatic capillaries.

Front 27

What is the net hydrostatic pressure in a capillary bed?

Back 27

HPc-HPif = net NP

Front 28

Predict the net movement of water (osmosis) across a membrane permeable only to
water in the following situations:

a. Higher concentration of solute
inside the sac compared to outside
the sac.

b. Higher concentration of solute
outside the sac compared to inside
the sac.

c. Equal concentrations of solute on both sides.

Back 28

a. inside
b. outside
c. no movement

Front 29

When you talk about osmotic pressure in a capillary bed, why is protein the only solute that is considered?

Back 29

Becaue of its high content of plasma proteins leads to having high osmotic pressure.

Front 30

Why is the osmotic pressure of the interstitial fluid typically very low?

Back 30

Because the leak proteins are gathered up by the lymph caps very quickly.

Front 31

What is the difference in the direction of force of net hydrostatic pressure and net osmotic pressure in a capillary bed?

Back 31

HP forces fluid OUT of the capillary blood.
OP pulls fluid INTO capillary blood.

Front 32

If net hydrostatic pressure is higher than net osmotic pressure, in which direction will fluid flow?

Back 32

fluid leaves the capillary

Front 33

If net hydrostatic pressure is lower than net osmotic pressure, in which direction will fluid flow?

Back 33

fluid enters the capillary.