Calcium Homeostasis

Question 1

What effect does PTH have on the kidneys?

Answer 1

Stimulates increased reabsorption of calcium.

Reminder: the parathyroid glands are four small glands behind the corners of thyroid gland.

Question 2

What effect does PTH have on the bones?

Answer 2

Stimulation of osteoblasts to release RANKL, which stimulates osteoclasts precursors to proliferate, which increases bone breakdown and calcium release in to the blood stream.

Question 3

What effect does PTH have on the intestines?

Answer 3

Increased calcium absorption from the contents of the intestine.

Question 4

How does calcium act within neutrons?

Answer 4

Once AP meets a synapse the VG-Ca channels open, release calcium in to the cleft, and stimulate the vesicles to bind with the presynaptic membrane, releasing neurotransmitters.

Question 5

How does calcium act within muscles?

Answer 5

Calcium needs to be present for tropomyosin crossbridges in order for effective contraction.

Question 6

How does calcium act within the myocardium action potential?

Answer 6

The calcium is necessary for the sustained AP during the plateau period.