mod 4 Lymphatics

Question 1

describe the fine structure of lymphatic capillaries and relate these to their function.

Answer 1

endothelial cells with blind ending tubes
collagen filaments anchor the endothelial cells to surrounding structures
cells are not fused, simply overlapping
mini valves, pulled open by connective tissue.
valves open when fluid pressure within interstitial space is more than lymphatic capillaries

Question 2

how is the lymph propelled along large lymphatic vessels

Answer 2

ducts
trunks
expansion and contraction
smooth muscle layer contracts rhythmically
physical activity also promotes lymph movement.

Question 3

return of lymphatic fluid to the general circulation…

a) almost all is returned at venous end
b) about 50% returned at lymph nodes
c) about 50% returned via subclavian veins
d) 100% returned via subclavian veins
e) b and c both correct.

Answer 3

b and c

b) about 50% returned at lymph nodes
c) about 50% returned via subclavian veins

Question 4

what is the major force that leads to small but constant net loses of fluid from plasma to the interstitium
a) high hydrostatic pressure of blood arriving at the capillary bed.

Answer 4

a) high hydrostatic pressure of blood arriving at the capillary bed.

Question 5

what is the blood pressure in the large veins

Answer 5

low, often near zero mmHg

Question 6

lymph nodes

a) return tissue fluid to the blood
b) filter tissue fluid and monitor infections
c) generate crucial components of hte immune response
d) can become enlarged when fighting infection
e) all of the above

Answer 6

e) all of the above