Parathyroid gland

Question 1

Stimuli for PTH secretion

Answer 1

a decrease in calcium ion
activated vitamin D
decrease in magnesium ion
an increase in phosphate ion in plasma

Question 2

Which pathway does low calcium inhibit to cause increased PTH secretion

Answer 2

Gq- PLC pathway

Question 3

What are the 2 pools of calcium in bone

Answer 3

Exchangeable pool and stable pool

Question 4

PTH acts on which portion of the kidney for phosphate secretion

Answer 4

proximal convoluted tubule

Question 5

PTH acts on which portion of the kidney for calcium reabsorption

Answer 5

Distal convoluted tubule

Question 6

PTH activates which enzyme during the synthesis of vitamin D

Answer 6

1 alpha hydroxylase

Question 7

1 alpha hydroxylase works on which organ to make vitamin D

Answer 7

Kidneys

Question 8

25-hydroxylase converts cholecalciferol to 25-hydroxycholecalciferol in which organ

Answer 8

liver

Question 9

PTH and Vitamin D inhibit ______ and activate _______ to cause bone resorption

Answer 9

Inhibit osteoprotegrin

Activate RANK L and M-CSF

Question 10

The kidney hydroxylation enzyme to make vitamin D is stimulated by which factors

Answer 10

PTH

Low plasma ionized calcium

Low plasma ionized phosphate

Prolactin (during pregnancy & lactation)

Question 11

Functions of Vitamin D

Answer 11

1. Increases total body calcium by increasing intestinal absorption of calcium
2. Increases ECF ionized calcium by enhancing response of bone to PTH (increases resorption)

Question 12

Actions of calcitonin

Answer 12

• Calcitonin decreases movement of ionized calcium from exchangeable pool of bone to ECF
• It decreases bone resorption by inhibiting activity of osteoclasts.