Parathyroid gland

Question 1

How does the skeleton help to buffer serum calcium levels?

Answer 1

Through the release and uptake of calcium phosphate

Question 2

What are the three functions of parathyroid hormone?

Answer 2

1) Stimulate bone resorption 2) Stimulates calcium reabsorption and phosphate excretion in the kidneys 3) Stimulates hydroxylation of VitD3 to its active form calcitrol

Question 3

What are the two effects of calcitrol?

Answer 3

Increased absorption of Ca2+ at the kidneys and GI and increased bone resorption

Question 4

PTH has a serum binding protein. True or false?

Answer 4

False

Question 5

PTH is continuously synthesised but where is it stored?

Answer 5

PTH is not stored

Question 6

Which cells is PTH secreted from?

Answer 6

Chief cells in the parathyroid gland

Question 7

Where is the PTH-CA2+ receptor found?

Answer 7

On chief cells and in the kidney tubules

Question 8

During high Ca2+, PTH degradation is …….

Answer 8

Stimulated

Question 9

High serum phosphate, ….. PTH secretion

Answer 9

Stimulates

Question 10

High serum magnesium, ….. PTH secretion

Answer 10

Inhibits

Question 11

What are the target organs of PTH? (2)

Answer 11

Bone and kidney

Question 12

Osteoclasts are stimulated by PTH. What is the role of osteoclasts?

Answer 12

They break down bone

Question 13

Ca2+ is taken up in the small intestine. In which parts of the small intestine?

Answer 13

The duodenum and the jejenum

Question 14

To activate vitamin D, how many hydroxylation reactions are required?

Answer 14

Two

Question 15

What enzyme catalyses the formation of calcitrol from VitD3?

Answer 15

1a-hydroxylase

Question 16

Where in the body is calcitrol formed?

Answer 16

The kidney proximal convoluted tubules

Question 17

Hypocalcaemia leads to ……-……….. of the neuromuscular junction.

Answer 17

Hyper-excitability

Question 18

What is the possible consequences of chronic hypercalcaemia?

Answer 18

Renal calculi, kidney damage, constipation, dehydration, tiredness and depression

Question 19

What is the usual cause of primary hyperparathyroidism?

Answer 19

Parathyroid adenoma

Question 20

PTH related peptide secreted from various tumours can lead to……

Answer 20

Over secretion of PTH

Question 21

Hypocalcaemia can cause conditions such as rickets and osteomalacia. How?

Answer 21

Serum calcium concentrations is maintained at the expense of bone so bone density decreases

Question 22

Does vitamin D stimulate or inhibit the uptake of phosphate in the gut?

Answer 22

Stimulate

Question 23

Why does parathyroid hormones stimulate the calcium uptake but not phosphate?

Answer 23

It makes the formation of calcium-phosphate stones less likely

Question 24

If serum calcium increases, which hormone is released and from where?

Answer 24

Calcitonin is release from the parafollicullar cells of the thyroid gland

Question 25

Cell signalling is a function of Ca2+ in the body. True or false?

Answer 25

True

Question 26

Parathyroid hormone is an amine hormone. True or false?

Answer 26

False. It is a peptide hormone.

Question 27

Does calcitonin effect the GI tract?

Answer 27

No

Question 28

How does the parathyroid gland sense plasma concentration?

Answer 28

The calcium receptors on the parathyroid gland are G-protein coupled receptors.