Lecture 36 Flashcards
(5 cards)
explain how the body responds to a change in the osmolarity of the blood.
example dehydration during sporting.
- an increase in blood (ECF) osmolarity
- detected by osmoreceptors in hypothalamus
- increases release of ADH from the posterior pituitary into the blood
- increased aquaporins in apical membrane of distal tubule cells
- increased water reabsorption decreased urine volume
- ECF osmolarity returns to normal
- water moves out of the cells
- cells shrink
explain how the kidney helps to restore ECF volume after loss of isosmotic fluid
isosmotic fluid loss
- no gradient for water to move in or out of the cells
- only a change in ECF and therefore blood volume and pressure
- decrease in blood volume/ loss of isosmotic fluid.
- detected by pressure receptors in the kidney
- increased release of aldosterone form the adrenal cortex
- increased sodium channels in apical membrane of distal tubule cells.
- increased sodium reabsorption.
- blood volume returns to normal
what is the greatest risks during exercise?
dehydration or hyperhydration and why?
hyponatremia- lack of sodium. this occurs when being overhydrated during training or competition. + feedforward ADH release at the start of exercise this will lead to the body containing too much water
what is ADH?
control of water reabsorption in the distal tubule .
the water moves by osmosis form a high water concentration to a low one
(water moves to where there is more solutes/ higher osmolarity)
the tight epithelia cause the trans- cellular movement of water.
what is aldosterone
control of Na+ reabsorption in the distant tubule
sodium moves trough the electrochemical gradient. high outside and low inside, so sodium can diffuse easier into the bloodstream
