Exchange and the lymphatic system

Question 1

Where do the leaks occur in continuous capillaries?

Answer 1

-Leaky junctions

Question 2

Where can continuous capillaries with no clefts be found?

Answer 2

Brain

Question 3

Where can continuous capillaries with leaky clefts be found?

Answer 3

Muscle (lots of other tissues)

Question 4

Where can fenestrated capillaries be found?

Answer 4

Intestine

Question 5

What are fenestrated capillaries specialised for?

Answer 5

Fluid exchange

Question 6

Where can discontinuous capillaries be found?

Answer 6

Liver

Question 7

Why are discontinuous capillaries found in liver?

Answer 7

Lots of proteins made in liver need to get to blood stream

Question 8

What are the two parts of a clot?

Answer 8

• Platelet plug

- Fibrin clot

Question 9

Why is blood flowing through capillaries at risk of clotting?

Answer 9

Because its super slow

Question 10

What is the basement membrane made of?

Answer 10

-Collagen

Question 11

What happens to platelets when they come into contact with the basement membrane?

Answer 11

-Form a plug

Question 12

What does fibrinogen turn into when clotting?

Answer 12

Fibrin

Question 13

What converts Fibrinogen to fibrin?

Answer 13

-Thrombin

Question 14

How does endothelium stop clotting?

Answer 14

-Acts as a physical barrier between collagen and platelet

Question 15

What does the endothelium produce to stop clotting and how?

Answer 15

• Prostacyclin and NO

- Tissue factor pathway inhibitor

Question 16

What does prostacylin and NO?

Answer 16

-Inhibit platelet aggregation

Question 17

What does TFPI

Answer 17

-Stops thrombin & inactivates it

Question 18

What does endothelium produce to prevent clotting?

Answer 18

• Thrombomodulin

- Heparin

Question 19

What does thrombomodulin do?

Answer 19

-Binds to thrombin & inactivates it

Question 20

What does heparin do?

Answer 20

-Innactivates thrombin

Question 21

What does endothelium produce to digest clot?

Answer 21

Plasminogen activator (t-PA)

Question 22

What does plasmin do?

Answer 22

Converts fibrin to fibrinogen?

Question 23

What are the characteristics of diffusion? (4) between capillary-ECF-cell

Answer 23

• Self-regulating
• non-saturable
• Non-polar substances across membrane
• Polar substances through clefts/channels

Question 24

What requires carrier mediated transport?

Answer 24

-Glucose trasnporter

Question 25

What does non saturable mean in relation to diffusion?

Answer 25

-No Max speed (Unlike a set number of protein pumps)

Question 26

What two forces control bulk flow?

Answer 26

• Hydrostatic pressure

- Osmotic (oncotic) pressure

Question 27

How much plasma is lost due to hydro static forces?

Answer 27

-20L

Question 28

How much plasma is regained by oncotic pressure?

Answer 28

17L

Question 29

How much fluid does lymph move a day?

Answer 29

-3L (blind ended pumps)

Question 30

What is Oedema?

Answer 30

Accumulation of excess fluid

Question 31

When does oedema happen? (4 points)

Answer 31

• Lymphatic obstruction
• Raised CVP
• Hypoproteinemia
• Increased capillary permeability

Question 32

How can lymphatic obstruction come about?

Answer 32

• Filariasis (Tropical disease caused by parastic worms)

- Surgery

Question 33

How does raised CVP come about?

Answer 33

due to ventricular pressure

Question 34

How does hypoproteinemia come about?

Answer 34

Due to nephrosis, liver failure, nutrition

Question 35

How does increased capillary permeability come about?

Answer 35

-Inflammation

EG rheumatism

Question 36

What happens in swelling with a bee sting?

Answer 36

Increases permeability of capillaries so what and proteins are lost which reduces oncotic pressure. Permeability increased to let white t cells out