Exchange and the lymphatic system Flashcards Preview

CVS physiology > Exchange and the lymphatic system > Flashcards

Flashcards in Exchange and the lymphatic system Deck (19):
1

what are the 3 different structures of capillaries?

continuous
fenestrated
discontinuous

2

describe continuous capillaries.

may have no clefts or channels
may have no channels but clefts only

3

where is a continuous capillary with no channels or clefts found?

brain

4

where is a continuous capillary with clefts found?

muscle

5

describe fenestrated capillaries.

contain clefts and channels

6

where can a fenestrated capillary be found?

intestine

7

describe a discontinuous capillary.

clefts and massive channels

8

where can a discontinuous capillary be found?

liver

9

what is the action of thrombin?

thrombin converts fibrinogen into fibrin
(fibrin is involved in clot formation)

10

does prostacyclin increase or inhibit platelet aggregation?

prostacyclin inhibits platelet aggregation

11

does NO inhibit or increase platelet aggregation?

inhibits platelet aggregations

12

what are the different anti-clotting mechanisms of the endothelium?

stops blood contacting collagen
produces prostacyclin and NO
Produced tissue factor pathway inhibitor (TFPI)
expresses thrombomodulin
expresses heparin
secretes tissue plasminogen activator (t-PA)

13

what is the role of tissue plasminogen activator?

activates plasminogen.
activated plasminogen is converted to plasmin which lyses and breaks down clots

14

what is the role of tissue factor pathway inhibitor?

stops thrombin production

15

what are the benefits of diffusion?

self regulation
non-saturable
non-polar substances can cross membrane
polar substances can travel through clefts and channels

16

as you go along from arteries to venules, does the hydrostatic pressure increase or decrease?

decreases because pressure is higher in arteries thus higher hydrostatic pressure

17

does the oncotic pressure increase or decrease as you move from arteriole to venules?
and why?

increases
as the water is lost due to increasing hydrostatic pressure, the proteins remain in the capillaries therefore increasing the concentration.
the increase in concentration builds up the oncotic pressure which draws more water into the capillaries.

18

what is the volume of fluid lost and gained each day through the capillaries?

20l lost
17l regained
remaining 3l drained by lymphatic system

19

what can increase capillary permeability?

inflammation e.g rheumatism