Capillaries I - Solute Exchange

Question 1

What does metabolism create?

Answer 1

The need to transport solutes and fluids

Question 2

Which molecules can get through the cell membrane and which need help?

Answer 2

Non polar molecules can get through easily and larger polar molecules need help

Question 3

What are the four passive transport processes?

Answer 3

Diffusion
Convection
Osmosis
Electrochemical flux

Question 4

What does diffusion rely on?

Answer 4

Concentration gradient

Question 5

What does convection rely on?

Answer 5

Pressure gradient

Question 6

What does osmosis rely on?

Answer 6

Osmotic pressure gradient

Question 7

What does electrochemical flux rely on?

Answer 7

Electrical and chemical gradients

Question 8

Give an example of convection transport

Answer 8

Blood flow from heart to blood vessels

Question 9

Give an example of electrochemical flux

Answer 9

Ion flow across cell membranes

Question 10

Where does solute and fluid exchange occur?

Answer 10

At capillaries

Question 11

Where are capillaries in higher density?

Answer 11

In highly active tissues (muscles, liver, heart, kidney, brain)

Question 12

What three things does rate of solute transport depend on?

Answer 12

Properties of passive diffusion, solutes and membranes and capillaries

Question 13

What are the properties of passive diffusion?

Answer 13

Concentration, rate and distance

Question 14

What are the properties of solutes and membranes described by?

Answer 14

Ficks law

Question 15

What properties of the solute affect transport?

Answer 15

Concentration gradient, size of solute and lipid solubility of the solute

Question 16

What are the properties of the membrane that affect transport?

Answer 16

• membrane thickness/ composition
• aqueous pores in the membrane
• carrier mediated transport
• active transport mechanisms

Question 17

What is ficks law? (Description)

Answer 17

A mathematical concept that shows the properties of solutes and membranes affecting transport

(Essentially how much of a substance is transported per unit time)

Question 18

What are the three types of capillaries called?

Answer 18

Continuous, fenestrated and discontinuous

Question 19

What are the features of a continuous capillary?

Answer 19

• moderate permeability; tight gaps between neighbouring cells; constant basement membrane

Question 20

What are the features of a fenestrated capillary?

Answer 20

• high water permeability, fenestration structures and modest disruption of membrane

Question 21

What are the features of a discontinuous capillary?

Answer 21

• very large fenestration structures and a disrupted membrane

Question 22

Give some examples of a continuous capillary

Answer 22

Blood-brain barrier

Muscle, skin, fat and connective tissue

Question 23

Give some examples of a fenestrated capillary

Answer 23

High water turnover tissues like salivary glands, kidneys, eyes and gut mucosa

Question 24

Give some examples of a discontinuous capillary

Answer 24

When movement of cells is required; RBCs in liver, spleen and bone marrow

Question 25

What are the layers of a capillary?

Answer 25

(From inside out) | Cellular membrane, single layer of endothelial cells, a cellular basement membrane made of connective tissue

Question 26

How do you get into the capillary?

Answer 26

Either go through the cells or between them

Question 27

What are the three main properties of capillaries?

Answer 27

Intercellular cleft, caveolae and vesicles and glycocalyx

Question 28

How wide are the intercellular clefts?

Answer 28

10-20nm wide

Question 29

What are caveolae and vesicles?

Answer 29

It’s a large pore system (exo and endocytosis)

Question 30

What is the glycocalyx?

Answer 30

Covers endothelium and its negatively charged. Blocks solute permeation and access to transport mechanisms, it’s highly regulated

Question 31

What is permeability?

Answer 31

The rate of solute transfer by diffusion across unit area of membrane per unit concentration difference

Question 32

How does blood flow control diffusion rate?

Answer 32

More blood brings more solutes. Increased blood volume means less time for equilibration to occur across capillaries

Question 33

How does a fall in interstitial concentration control diffusion rate?

Answer 33

During metabolism more solute is used up, which means there is a bigger concentration difference. Metabolism increases blood flow

Question 34

How does capillary recruitment control diffusion rate?

Answer 34

Dilation of arterioles leads to increased number of capillaries per fused which increases total surface area for diffusion.