Thyroid/Parathyroid/Calcium regulation (lecture)

Question 1

What is the primary function of osteoblasts?

Answer 1

Deposit bone

Question 2

What is the primary function of osteocytes?

Answer 2

maintain bone

Question 3

What is the primary function of osteoclasts?

Answer 3

Digest bone

Question 4

Which of the “bone cell types” is multi-nucliated?

Answer 4

Osteoclasts

Question 5

What is the primary component of thyroid colloid?

Answer 5

Thyroglobulin

Question 6

What is organification as it relates to thyroid and what enzyme is responsible for this?

Answer 6

Adding iodine to thyroglobulin

Thyroid peroxidase

Question 7

What are the two most common forms of thyroid hormone, which is more active, and which is the primary product of the thyroid?

Answer 7

T3 is more active

T4 is the primary product of the thyroid

Question 8

What thyroid cell type monitors serum calcium levels, under what conditions are they activated, their response, and the effect?

Answer 8

Parafollicular cells release calcitonin in response to high serum calcium, resulting in a decreased serum calcium

Question 9

What is released in response to low serum calcium and what cells make it?

Answer 9

PTH

Chief cells

Question 10

What are the three physiological effects of PTH?

Answer 10

Initiate bone resorption, increase active Vitamin D, Increase renal calcium reabsorption

Question 11

How are osteoclasts and osteoblasts linked?

Answer 11

Osteoblasts release RANKL, activating osteoclasts

Question 12

How is estrogen protective against osteoporosis?

Answer 12

Reduces RANKL synthesis, and thereby osteoclast stimulation

Question 13

What are the three target tissues of PTH and it effect on these tissues?

Answer 13

Bone - increase RANKL expression –> osteoclast activation
Kidney - Decrease Ca++ excretion and increase phosphate excretion
Intestines - increase Ca and phosphate absorption