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Endocrine #3 > Physiology of Calcium-Regulating Hormones (Toribio) > Flashcards

Physiology of Calcium-Regulating Hormones (Toribio) Flashcards

1
Q

What is the most important calcium regulating hormone?

A

PTH

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2
Q

List the Functions of PTH:

A
  • Increases Blood calcium
  • Reduces blood Phosphorus
  • Activates vitamin D
  • Promotes bone remodeling
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3
Q

Mammals have ______ parathyroid glands
- Parathyroids III (caudal, internal, lower)
- Parathyroids IV (external, cranial, upper)

A

4

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4
Q

What are the 3 cell types of the Parathyroid glands?

A
  • Chief cells
  • Clear cells
  • Oxyphil cells
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5
Q

Fill in the blanks:

______________ produce PTH in response to hypocalcemia (Main cells)
_______________ are less active cells but secrete PTH
_______________ are inactive cells

(PTH = 84 aa, 1-34 is the active domain)

A
  • Chief cells
  • Clear cells
  • Oxyphil cells
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6
Q

(T/F) PTH receptor is present in renal tubular cells and osteoblasts

A

True

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7
Q

What controls PTH secretion?

A
  • Ca2+ concentrations
  • Calcium-sensing receptor
  • Vitamin D (1,25- dihydroxyvitamin D)
  • Phosphate (PO4, Pi) concentrations
  • Mg2+ concentrations
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8
Q

(T/F) Hypercalcemia increases PTH release

A

False, Hypocalcemia

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9
Q

(T/F) Stimulation by Ca2+ inhibits PTH secretion

A

True

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10
Q

(T/F) Vitamin D inhibits PTH synthesis and secretion, decreases parathyroid chief cell proliferation

A

True

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11
Q

(T/F) Hypophosphatemia stimulates PTH secretion

A

False, Hyperphospatemia

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12
Q

(T/F) Mag2+ facilitates Ca2+ homeostasis (PTH secretion and action)

A

True

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13
Q

PTH targets the:

A
  • Kidneys
    - Increases calcium reabsorption (and Mg reabsorption ThickAL)
    - Inhibits phosphate reabsorption (PCT) = increase excretion
    - Increases 1,25(OH)2D synthesis (tubular cells)
  • Bones
    - Increases bone resorption during hypocalcemia
    - PTH interacts with PTH receptors on osteoblasts to secrete factors that activate osteoclasts
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14
Q

PTH actions on bone resorption are indirect via ___________________

A

osteoblasts

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15
Q

Is a decoy receptor for RANKL to balance resorption and avoid excessive bone loss

A

OPG

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16
Q

________________ DO NOT have receptors for PTH but have receptors for calcitonin

A

Osteoclasts

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17
Q

The following is Hyperparathyroidism or Hypoparathyroidism?

Secondary
1. Sepsis (critically ill patients)
2. Hypomagnesemia

A

Hypoparathyroidism

18
Q

The following is Hyperparathyroidism or Hypoparathyroidism:

Secondary
1. Renal
2. Nutritional

A

Hyperparathyroidism

19
Q

Produced by the parafollicular cells (C Cells) of the thyroid gland in response to hypercalcemia

A

Calcitonin (CT)
- 32 aa
- decreases blood calcium
- decreases bone loss/resorption

20
Q

What controls calcitonin secretion?

A
  • Ca2+ concentrations
  • Stimulation by Ca2+ increases CT secretion
  • Gastrin
21
Q

(T/F) Hypocalcemia increases CT release

A

False, Hypercalcemia

22
Q

What is a strong stimulator of CT release?

A

Gastrin

23
Q

List the functions of vitamin D:

A
  • Increases calcium and phosphorus absorption and reabsorption
  • Modulates bone remodeling
  • Inhibits parathyroid cell function / PTH secretion
  • Regulates the immune function
24
Q

(T/F) Vitamin D is important for intestinal absorption and renal reabsorption of calcium

A

False, calcium AND phosphorus

25
Q

(T/F) There is active vitamin D in milk

A

False, it would be a bad idea

26
Q

(T/F) Vitamin D inhibits parathyroid chief cell proliferation, activity, and PTH secretion

A

True

27
Q

Why do animals with chronic kidney disease have increased PTH concentrations?

A

The activation of vitamin D takes place in the Kidneys (the kidney suppresses PTH)

28
Q

(T/F) PTHrP is not important for development of animals

A

False

29
Q

Low calcium stimulates ________________ secretion

A

PTH

30
Q

Vitamin D is activated in the ____________ by ___________________

A

kidney, 1alpha-hydroxylase

31
Q

Osteoclast activation requires PTH binding to _________________

A

osteoblast

32
Q

Vitamin D stimulates renal reabsorption of ________________

A

Calcium and phosphorus

33
Q

Vitamin D stimulates intestinal absorption of ________________

A

Calcium and Phosphate

34
Q

PTH increases paracellular calcium reabsorption by _________________

A

binding to its receptor in the renal tubular cell, specifically in the TAL, by making the lumen more positive

35
Q

If serum PTH concentrations are elevated, what is expected?

A

Increased renal excretion of phosphorus and increased reabsorption of calcium

36
Q

What are some important things about magnesium?

A
  • It is important for the synthesis and action of PTH
  • PTH increases its renal reabsorption
  • Contributes to energy homeostasis
37
Q

(T/F) Unlike calcium, magnesium is minimally stored in bone

A

False

38
Q

(T/F) In the lactating animal, parathyroid hormone-related protein (PTHrP) is produced by the mammary gland to reduce/stop bone resorption

A

False

39
Q

What makes renal tubules electropositive?

A

PTH

40
Q

What binds receptors on osteoclasts?

A

Calcitonin

41
Q

What promotes the absorption of phosphorus?

A

Vitamin D

42
Q

Where is PTHrP secreted?

A

It is secreted by multiple tissues

Endocrine #3 (8 decks)

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