Exchange and the Lymphatic System

Question 1

Capillaries are specialised for

Answer 1

exchange

Question 2

What cell type are capillaries composed of?

Answer 2

Endothelial

Question 3

What feature of capillaries presents a small diffusion barrier?

Answer 3

Thin walls (one cell)

Question 4

Other than thin walls, what feature of capillaries allows fast diffusion?

Answer 4

Large surface area

Question 5

Give a distinguishing factor of fenestrated capillaries

Answer 5

Presence of large pores

Question 6

What is the function of endothelial cell junctions?

Answer 6

To control which molecules leave the capillary

Question 7

What type of capillary allows larger structures such as proteins and cells to leave?

Answer 7

Discontinuous

Question 8

Capillaries are composed of one endothelial layer and

Answer 8

it’s concordant basement membrane

Question 9

In what type of capillary are there no clefts or channels?

Answer 9

Continuous

Question 10

In what type of capillary are there clefts and channels? (not massive channels)

Answer 10

Fenestrated

Question 11

Fibrin monomers are cleaved from

Answer 11

fibrinogen

Question 12

Fibrin monomers are cleaved by

Answer 12

thrombin

Question 13

When the lining of a blood vessel breaks and endothelial cells are damaged, what fibres are exposed?

Answer 13

Collagen fibres

Question 14

What component of the blood adheres to damaged endothelium?

Answer 14

Platelets

Question 15

What is formed in the adherence of platelets to damaged endothelium?

Answer 15

Platelet plug

Question 16

What is haemostasis?

Answer 16

The process of keeping blood inside a damaged blood vessel to stop bleeding

Question 17

What happens to platelets when they stick together and to the proteins in the vessel wall which stimulates further platelet activation?

Answer 17

Platelets degranulate

Question 18

If platelets alone are not enough to stop the bleeding from a vessel, what protein is released to strengthen the platelet plug?

Answer 18

Fibrin

Question 19

What two substances act as chemical messengers and inhibit platelet aggregation and formation of the platelet plug?

Answer 19

Prostacyclin and nitrous oxide

Question 20

What substance stops thrombin production?

Answer 20

Tissue factor pathway inhibitor (TFPI)

Question 21

What substance binds and inactivates thrombin?

Answer 21

Thrombomodulin

Question 22

What substances are expressed by TFPI to inactivate thrombin?

Answer 22

Thrombomodulin and Heparin

Question 23

What is the function of plasmin?

Answer 23

To degrade blood clots

Question 24

Why do cells have a lower concentration of oxygen than capillaries?

Answer 24

As cells are constantly respiring and using oxygen

Question 25

What is the order of the concentration gradient for oxygen, from highest to lowest, between cells, capillaries and ECF?

Answer 25

Capillary, ECF, cells

Question 26

What effect will increased usage of oxygen by cells have on the concentration gradient, meaning diffusion is non-saturable?

Answer 26

Concentration gradient will increase as will the volume of oxygen diffusing

Question 27

Do polar or non-polar substances cross the cell membrane in diffusion?

Answer 27

Non-polar

Question 28

What substances pass through clefts/channels in cell membranes?

Answer 28

Polar substances

Question 29

What is the carrier mediated transport system used in the brain?

Answer 29

Glucose transporter

Question 30

What is the trend in hydrostatic pressure from arteriole to venule through capillaries?

Answer 30

Hydrostatic pressure decreases

Question 31

What is the trend is osmotic pressure from arteriole to venule through capillaries?

Answer 31

Osmotic pressure increases

Question 32

Approximately how many litres of water is pushed into the lymph capillaries every day?

Answer 32

3 litres

Question 33

What pressure draws more water into the capillaries?

Answer 33

Osmotic pressure

Question 34

What causes the fluid in lymph vessels to be pushed back towards the CVS?

Answer 34

Lymph vessels pass through contracting muscle which squeeze the lymph vessel and push fluid towards the CVS

Question 35

What is an oedema?

Answer 35

Accumulation of excess fluid

Question 36

What effect does oedema have on central/mean venous pressure?

Answer 36

Causes a rise in CVP

Question 37

Other than raised CVP, give an effect of oedema

Answer 37

• lymphatic obstruction
• hypoproteinemia
• increased capillary permeability