Physiology 534 Final: Capillary Exchange

Front 1

Continuous capillaries found?

Back 1

Found in skeletal and cardiac muscle, skin, connective tissue, exocrine glands

Front 2

Continuous capillaries made of?

Back 2

1. Endothelium
2. Basal lamina
3. Pericytes

Front 3

How do the continuous capillaries allow for exchange of materials?

Back 3

-allows exchange of lipid soluble material and gases through the plasma membrane of endothelial cells.

-Water soluble substances don't go through the plasma membrane. These go through the intercellular clefts

Front 4

Special type of capillaries in the brain: The blood brain barrier

How do small molecules pass through?

What is its function?

Back 4

Has no interruptions in tight junctions so small water-soluble substances go through via facilitated diffusion.

Function of blood brain barrier: seals the brain off in certain areas from undesirable water-soluble.

Front 5

What are 2 pathways for macromolecules to pass through the blood-brain barrier?

Back 5

1. Large clefts
2. Pinocytosis

Front 6

Fenestrated capillaries found?

function?

Back 6

Endocrine glands, GI tract, kidney.

Contain large openings covered by a thin diaphragm.

Allow macromolecules and solutes to easily pass through.

Front 7

Sinusoidal or discontinuous capillaries found?

Back 7

Liver, bone marrow, lymph nodes, some endocrine glands

Large gaps between endothelial cells

Front 8

Why are capillaries suited for diffusion?

Back 8

1. Large total surface area
2. thin walls
3. short distances

Front 9

What determines rate of diffusion?

Back 9

1. Concentration difference between capillary blood and tissue
-capillary blood flow
-rate of tissue metabolism
2. Permeability & SA of capillary walls

Front 10

Capillary blood flow: what would happen if flow slowed down too much?

Back 10

All oxygen would be extracted very quickly and the concentration difference would equalize.

CO would also build-up in the capillaries

Front 11

Ultrafiltrate

Back 11

Plasma without the plasma proteins

Front 12

What are the four forces that affect filtration and reabsoprtion?

Back 12

1. Capillary hydrostatic pressure
2. Interstitial hydrostatic pressure
3. Plasma colloid osmotic pressure
4. Interstital colloid osmotic pressure

Front 13

Capillary hydrostatic pressure

Back 13

Pushes fluid out of the capillary

Front 14

Capillary hydrostatic pressure is increased by:

Back 14

1. Arteriolar dilation: bc more blood is allowed
2. Increased venous pressure caused by venous constriction
3. Increased arterial pressure

Front 15

Capillary hydrostatic pressure is decreased by:

Back 15

1. Arteriolar constriction

Arterial pressure upstream of the constriction may increase, while downstream falls

Front 16

What is the relationship between tissue hydrostatic pressure and interstitial volume?

Back 16

The higher the interstitial volume, the higher the tissue hydrostatic pressure

Front 17

Interstitial fluid volume is increased by

Back 17

1. Inc. filtration of fluid out of capillaries
2. Dec. reabsorption of fluid into capillaries
3. Dec. lymph flow

Front 18

What is the difference between colloid osmotic pressure and protein concentration?

Back 18

As protein concentration increases, colloid osmotic pressure increases

Front 19

What determines the protein concentration?

Back 19

[protein] = mass/volume

Front 20

How is mass concentration changed?

Back 20

-dec. by protein leaving in lymph

-inc. by protein coming from plasma

Front 21

How is volume changed?

Back 21

-Net capillary filtratin

-Lymph flow

Front 22

Lymph flow

Back 22

Proteins steadily move down their concentration gradient so it cannot get back into the capillaries.

Lymphatics return ISF back into circulation

Front 23

What would occur in the absence of lymphatics?

Back 23

COPi = COPp

concentration of proteins on both sides of the capillary barrier will quickly become equal.

The only thing left to cuonteract the tendency for filtration will be an increase in the interstitial hydrostatic pressure.

Front 24

Edema

Back 24

Clinically noticeable accumulation of excess interstitial fluid.

Front 25

3 safety mechanisms that limit the formation of edema

Back 25

1. Inc. Pi (interstitial pressure)-->reduces filtration
2. Inc. lymph flow-->restores lymph flow
3. Dec. COPi

Front 26

How does a dec. in COPi prevent edema

Back 26

Inc. in ISF (in absence of inc. in protein)-->dec. COPi (dilution)-->red. filtrate bc more proteins in capillaries than in interstital fluid. So water follows solutes.

Front 27

Kwashiorkor

Back 27

Adequate calorie intake, but not adequate protein intake.

dec. plasma protein-->dec. COPp (bc less of it)-->so more pressure in the plasma which inc. filtration

inc. ISF-->inc. hydrostatic pressure ISF-->dec. filtration & inc. lymph flow

Front 28

Elephantiasis

Back 28

Destruction of the inguinal lymph nodes by a parasite.

Dec. lymph flow-->inc. ISF volume-->inc. ISF pressure-->dec. filtration-->inc. colloid osmotic pressure-->inc. capillary filtration

Bc no pathway for protein to leave, the [protein] will be equal in the interstital fluid and in the capillary.

Front 29

How does the body stop increase in filtration caused by Elephantiasis?

Back 29

COPi = COPp and inc. ISF is only limited by hydrostatic pressure intersital fluid = hydrostatic pressure capillary.

pi = pc