Parathyroid gland Flashcards

1
Q

How does the skeleton help to buffer serum calcium levels?

A

Through the release and uptake of calcium phosphate

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2
Q

What are the three functions of parathyroid hormone?

A

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

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3
Q

What are the two effects of calcitrol?

A

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

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4
Q

PTH has a serum binding protein. True or false?

A

False

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5
Q

PTH is continuously synthesised but where is it stored?

A

PTH is not stored

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6
Q

Which cells is PTH secreted from?

A

Chief cells in the parathyroid gland

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7
Q

Where is the PTH-CA2+ receptor found?

A

On chief cells and in the kidney tubules

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8
Q

During high Ca2+, PTH degradation is …….

A

Stimulated

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9
Q

High serum phosphate, ….. PTH secretion

A

Stimulates

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10
Q

High serum magnesium, ….. PTH secretion

A

Inhibits

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11
Q

What are the target organs of PTH? (2)

A

Bone and kidney

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12
Q

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

A

They break down bone

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13
Q

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

A

The duodenum and the jejenum

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14
Q

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

A

Two

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15
Q

What enzyme catalyses the formation of calcitrol from VitD3?

A

1a-hydroxylase

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16
Q

Where in the body is calcitrol formed?

A

The kidney proximal convoluted tubules

17
Q

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

A

Hyper-excitability

18
Q

What is the possible consequences of chronic hypercalcaemia?

A

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

19
Q

What is the usual cause of primary hyperparathyroidism?

A

Parathyroid adenoma

20
Q

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

A

Over secretion of PTH

21
Q

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

A

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

22
Q

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

A

Stimulate

23
Q

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

A

It makes the formation of calcium-phosphate stones less likely

24
Q

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

A

Calcitonin is release from the parafollicullar cells of the thyroid gland

25
Q

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

A

True

26
Q

Parathyroid hormone is an amine hormone. True or false?

A

False. It is a peptide hormone.

27
Q

Does calcitonin effect the GI tract?

A

No

28
Q

How does the parathyroid gland sense plasma concentration?

A

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