Calcium dysregulation

Question 1

What hormonal methods does the body use to increase serum calcium

Answer 1

-Vitamin D
-Parathyroid hormone

Question 2

What hormonal methods does the body use to decrease serum calcium

Answer 2

Calcitonin

Question 3

Where is calcitonin released from.

Answer 3

Parafollicular cells

Question 4

Describe calcitonins effects on bones and kidney

Answer 4

-In bones decreases osteoclast activity
-In kidney increases calcium excretion

Question 5

What can be used as a good indicator of vitamin D levels and why is it a good indicator.

Answer 5

Serum 25(OH)cholecalciferol, it is the major circulating form of vitamin D.

Question 6

What form of vitamin D regulates its own synthesis, and how does it do this.

Answer 6

-1,25(OH) cholecalciferol
-By decreasing the transcription of 1 alpha hydroxylase in the kidneys

Question 7

Describe the effects of calcitriol on bones gut and kidneys.

Answer 7

-On bones increases osteoblast activity
-On gut increases calcium and phosphate absorbtion
-On kidneys increases calcium and phosphate reabsorbtion.

Question 8

Describe the effects of PTH on the bones gut and kidneys.

Answer 8

-Increases calcium resorption from the bone
-Increases calcium and phosphate absorbtion from the gut.
-Increase calcium absorption and phosphate excretion from the kidneys. And increase 1-a hydroxylase activity

Question 9

Explain how serum phosphate absorption is regulated in the kidneys.

Answer 9

FGF23 gets produced by osteocytes which:
-Inhibits Na+/PO43- transporter and thus inhibits phosphate reabsorption in kidney.
-Inhibits formation of calcitriol and its effects.

Question 10

How does a HIGH serum calcium affect membrane excitability.

Answer 10

Calcium ions block NA+ influx which means LESS membrane excitability.

Question 11

How does a LOW serum calcium affect membrane excitability.

Answer 11

Enables greater NA+ influx which means GREATER membrane excitability.