Urinary System and Electrolytes

Question 1

How does the kidney regulate blood pressure?

Answer 1

Kidneys are responsible for the regulation of fluids, blood volume and therefore blood pressure.
- The RAAS system is a long term regulation mechanism for the regulation of BP in the kidneys. Renin is released from the kidneys in response to low BP. This activates the release of angiotensin 1 which binds with ACE to form angiotensin 2. This causes vasoconstriction of blood vessels increasing BP and also causes aldosterone to be released from the adrenal glands causing increased sodium and water retention therefore increasing blood volume and BP.

• ADH also has an effect on the kidneys, increasing the amount of aquaporins in the collecting duct of the nephron. This allows more water to be reabsorbed into the blood stream thus increasing BV and BP.
• ANP is released by the walls in the atria of the heart in response to high blood pressure. This hormone stimulates the loss of sodium in urine and peripheral dilation reducing blood pressure.

Question 2

What is the most adundant cations and anions in intracellular fluid and extracellular fluid

Answer 2

Extracellular fluid:

     - Cation: Na+
     - Anion: CI- 

Intracellular fluid:

     - Cation: K+
     - Anion: Proteins

Question 3

How does the Kidney regulate pH balance?

Answer 3

If the pH increases the kidneys reabsorb Na+ into the blood and secrete H+ to be excreted in urine, decreasing the pH
The kidneys also reabsorb more HCO3- (bicarbonate ions) which increases the pH

Question 4

What happens during dehydration?

Answer 4

There is a decrease in water volume and an increase in the concentration of body fluids. The osmolarity of ECF increases causing water to move out of cells, causing them to shrink.

Question 5

What happens during water intoxication?

Answer 5

Where cells swell as a result of water moving into the intracellular fluid via osmosis

Question 6

Angiotensin 2 has what effect on GFR?

Answer 6

GRF will decrease as both afferent and efferent arterioles constrict

Question 7

ANP has what effect on the kidneys?

Answer 7

Decreases blood pressure by increasing the secretion of Na+ and water, and inhibits the effects of ADH and aldosterone