Parathyroid Gland Flashcards

1
Q

Outline the calcium pathway in the body

A

Dietary intake
Absorption by digestive tract into plasma
Deposition onto bone via osteoblasts, Resorbtion vis osteoclasts
Filtration by kidneys, reabsorbtion by kidneys
Urinary loss (kidney), faecal loss (digestive tract)

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2
Q

Outline calcium homeostasis

A

Concentration of extracellular (blood) calcium is tightly controlled
Bone is body’s major store of calcium
Immediate adjustments made via rapid bone-blood exchange
Normally balance exists between buildup and breakdown of bone

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3
Q

What three hormones are involved in calcium regulation

A

Parathyroid hormone (PTH)
Calcitriol
Calcitonin

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4
Q

Where are the parathyroid glands located

A

Posterior to the thyroid

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5
Q

What is role of parathyroid

A

Secrete parathyroid hormone (PTH)
PTH is essential for life

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6
Q

Outline the homeostatic response to low calcium

A

Stimulus: low blood calcium concentration
Parathyroid gland secretes PTH
Effects: Kidneys increase calcium reabsorbtion, decrease urinary excretion of calcium. Conversion of vitamin D to calcitriol, in tern increases calcium absorption from food.
Increases bone breakdown, thus release of calcium into blood
Blood calcium levels rise, stimulus decreases, decreases PTH synthesis

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7
Q

Outline what a decrease in plasma [Ca2+] results in
And,
Outline what a increase in plasma [Ca2+] results in

A

Increase in plasma [Ca2+] leads to increase in PTH release
Decrease in plasma [Ca2+] leads to decrease in PTH release

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8
Q

Outline the relationship between the hypothalamus and the calcium regulation pathway

A

Calcium regulation pathway is not controlled by hypothalamus

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9
Q

What prevents exponential increase in Calcitriol in calcium regulatory system

A

Conversion of Vitamin D to Calcitriol, while increasing Ca2+ absorption in kidney, also acts to inhibit further Vitamin D conversion to Calcitriol, preventing exponential uptake of Ca2+

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