Exchange and the Lymphatic System Flashcards

1
Q

Capillaries are specialised for

A

exchange

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2
Q

What cell type are capillaries composed of?

A

Endothelial

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3
Q

What feature of capillaries presents a small diffusion barrier?

A

Thin walls (one cell)

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4
Q

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

A

Large surface area

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5
Q

Give a distinguishing factor of fenestrated capillaries

A

Presence of large pores

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6
Q

What is the function of endothelial cell junctions?

A

To control which molecules leave the capillary

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7
Q

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

A

Discontinuous

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8
Q

Capillaries are composed of one endothelial layer and

A

it’s concordant basement membrane

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9
Q

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

A

Continuous

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10
Q

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

A

Fenestrated

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11
Q

Fibrin monomers are cleaved from

A

fibrinogen

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12
Q

Fibrin monomers are cleaved by

A

thrombin

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13
Q

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

A

Collagen fibres

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14
Q

What component of the blood adheres to damaged endothelium?

A

Platelets

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15
Q

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

A

Platelet plug

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16
Q

What is haemostasis?

A

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

17
Q

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

A

Platelets degranulate

18
Q

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

19
Q

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

A

Prostacyclin and nitrous oxide

20
Q

What substance stops thrombin production?

A

Tissue factor pathway inhibitor (TFPI)

21
Q

What substance binds and inactivates thrombin?

A

Thrombomodulin

22
Q

What substances are expressed by TFPI to inactivate thrombin?

A

Thrombomodulin and Heparin

23
Q

What is the function of plasmin?

A

To degrade blood clots

24
Q

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

A

As cells are constantly respiring and using oxygen

25
What is the order of the concentration gradient for oxygen, from highest to lowest, between cells, capillaries and ECF?
Capillary, ECF, cells
26
What effect will increased usage of oxygen by cells have on the concentration gradient, meaning diffusion is non-saturable?
Concentration gradient will increase as will the volume of oxygen diffusing
27
Do polar or non-polar substances cross the cell membrane in diffusion?
Non-polar
28
What substances pass through clefts/channels in cell membranes?
Polar substances
29
What is the carrier mediated transport system used in the brain?
Glucose transporter
30
What is the trend in hydrostatic pressure from arteriole to venule through capillaries?
Hydrostatic pressure decreases
31
What is the trend is osmotic pressure from arteriole to venule through capillaries?
Osmotic pressure increases
32
Approximately how many litres of water is pushed into the lymph capillaries every day?
3 litres
33
What pressure draws more water into the capillaries?
Osmotic pressure
34
What causes the fluid in lymph vessels to be pushed back towards the CVS?
Lymph vessels pass through contracting muscle which squeeze the lymph vessel and push fluid towards the CVS
35
What is an oedema?
Accumulation of excess fluid
36
What effect does oedema have on central/mean venous pressure?
Causes a rise in CVP
37
Other than raised CVP, give an effect of oedema
- lymphatic obstruction - hypoproteinemia - increased capillary permeability