mass transport Flashcards
Although the speed of blood flow in an arteriole is greater than speed of blood flow in a capillary, blood does not accumulate in the arterioles.
Explain why.
Many / more capillaries (than arterioles);
Cross-sectional) area of capillaries (much) greater (than of arterioles
Other than causing slow blood flow, explain one advantage of capillaries being narrow.
Short pathway / short distance between blood and outside of capillary;
Large surface area (of blood) in contact with walls of capillaries;
Fast exchange / fast diffusion / fast osmosis.
What factor limits the minimum internal diameter of the lumen of a capillary?
Width / size / diameter of blood cell.
The volume of blood leaving the capillary network into the veins is less than the volume of blood entering from the arteries.
Explain why.
Width / size / diameter of blood cell.
A principle of homeostasis is the maintenance of a constant internal environment. An increase in the concentration of carbon dioxide would change the internal environment and blood pH.
Explain the importance of maintaining a constant blood pH.
Named protein / enzyme (in blood) sensitive to / affected by change in pH;
(Resultant) change of charge / shape / tertiary structure;
Described effect on named protein or enzyme.
The hydrostatic pressure falls from the arteriole end of the capillary to the venule end of the capillary. Explain why.
Loss of water / loss of fluid / friction (against capillary lining).
High blood pressure leads to an accumulation of tissue fluid. Explain how.
High blood pressure = high hydrostatic pressure;
Increases outward pressure from (arterial) end of capillary / reduces inward pressure at (venule) end of capillary;
(So) more tissue fluid formed / less tissue fluid is reabsorbed.
The water potential of the blood plasma is more negative at the venule end of the capillary than at the arteriole end of the capillary. Explain why.
High blood pressure = high hydrostatic pressure;
Increases outward pressure from (arterial) end of capillary / reduces inward pressure at (venule) end of capillary;
(So) more tissue fluid formed / less tissue fluid is reabsorbed.
Use information from the figure to explain how the pressure in the dog’s ventricle is related to blood flow into the aorta
Ventricle pressure rises then blood starts to flow into aorta because pressure causes (aortic / semilunar) valve to open;
Ventricle pressure starts to fall so blood flow falls;
Use information from the figure to explain how the pressure in the dog’s ventricle is related to the thickness of the ventricle wall.
Thickness of wall increases because ventricle (wall) contracts;
Contraction causes the increase in pressure;
The scientists used the percentage change in the mean resting heart rate after the exercise programme to compare the results for males and females.
Explain why they used percentage change in the resting heart rate.
(Carry) oxygen / glucose;
Accept: oxygenated blood
(To) heart muscle / tissue / cells / myocytes.
The rise and fall in blood pressure in the aorta is greater than in the small arteries.Suggest why.
(Aorta) (is) close / directly linked to the heart / ventricle / pressure is higher / is very high; (Aorta has) elastic tissue; Accept elasticity Ignore reference to muscle (Aorta has) stretch / recoil.
