Homeostatic control

Question 1

Regulation of pH of the blood

Explain how the regelation of the pH in the blood.

Answer 1

When the blood pH become to low, the excess h+ ions in the blood are removed so the pH can increase and return back to normal

When the Blood pH rises to high (too alkaline), fewer H+ ions are secreted from the blood to the tubules and more bicarbonate ions are secreted from the blood into the tubles, making the amount of H+ ions higher in the blood to increase the pH in the blood back to normal

Question 2

Regulation of salt concentration of the blood

Explain the regulation of the salt concentration in the blood.

Answer 2

• when the sodium concetration (salt) becomes too low, the adrenal cortex is stimulated to secrete more aldosterone.
• More sodium ions are reabsorbed from the kidney into the blood.
• The concentration of sodium ions in the blood increases and fewer sodium ions are excreted in the urine.
• When the sodium concentration in the blood becomes too high, less aldosterone is secreted by the adrenal cortex.
• Fewer sodium ions are reabsorbed from the kidney.
• The concentration of sodium ions in the blood decreases and more sodium ions are excreted as part of the urine.

Question 3

Regulation of water content in the blood

What is the hormone secreted that regulates the water content in the blood?

Answer 3

ADH

Question 4

Regulation of water content in the blood

What secretes the hormone that regultates the water content in the blood?

Answer 4

the Hypophysis

Question 5

Regulation of water content in the blood

What detects the decrease or increase of water content in the blood?

Answer 5

The osmorecepters in the Hypothalmus

Question 6

Regulation of water content in the blood

Explain the Regulation of water content in the blood when it decreases.

Answer 6

• When the water content in the blood decreases, the osmoreceptors in the hypothalamus in the brain are stimulatd and more ADH is secreted by the hypophysis into the bloodstream
• ADH makes the walls of the distal convaluted tuble and collecting ducts more permeable to water
• Therefor more water is reabsorbed into the blood
• Urine becomes more concentrated and its volume decreases
• The osmoreceptors also stimulate the thirst centre in the brain and more fluid is taken in
• Water content increases back to normal

Question 7

Regulation of water content in the blood

Explain the Regulation of water content in the blood when it increases.

Answer 7

• when the water content in the blood increases, the osmoreceptors in the hypothalamus are not stimulated
• Less ADH is secreted by the hypophysis
• The distal convaluted tubules and collecting ducts become less permeable to water
• less water is reabsorbed
• urine is less concentrated and its volume increases
• large amounts of water are excreted in the urine
• water content decreases back to normal.