Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Physiology > Lecture 15: Calcium Balance > Flashcards

Lecture 15: Calcium Balance Flashcards

1
Q

What is the most abundant element in body

A

Calcium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the forms of Ca2+ in the blood

A

40-45% protein bound
55-60% ultrafilterable
- 5-10% complexed to anions
- 50% ionized Ca2+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What form of calcium is physiologically active

A

Ionized Ca2+ in blood

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

describe blood coagulation test and role of ca2+

A

Stage 1: injured blood vessel and release of prothrombin activator (PTA)
2. Ca2+ and PTA interact to form thrombin
3. Thrombin—> fibrinogen which forms blood clots

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is hydroxyapatite

A

Biological apatite that makes mineral bone (lots of phosphate)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How can plasma ionized calcium be altered

A

Increase in plasma proteins, increase in anions, acid base refluxes, hormonal exchange between intestine, bone and kidney

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How does increase in plasma proteins affect ionized calcium

A

Increase total bound calcium but minimal change to ionized calcium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How does an increase in anions (PO4^3-) affect ionized calcium

A

Decrease ionized Ca2+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How does acid base refluxes affect ionized calcium

A

Protons complete with calcium for albumin binding sites

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How does acidemia affect ionized calcium levels

A

Increases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How does alkalemia affect ionized calcium levels

A

Decreases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How is Ca2+ balance maintained in body

A

Slowly, between ECF/bone and intestine and kidney

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How is Ca2+ balance maintained in ECF

A

Rapid, between ECF/bone fluid, regulated by hormonal control

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

When is the extracellular pool in equilibrium

A

When mg of calcium removed from serum by bone growth= mg of calcium liberated from bone and returned to blood

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What hormones primarily regulate calcium and phosphate

A

parathyroid hormone and vitamin D

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

When does parathyroid hormone activate

A

Low plasma Ca2+, high plasma PO4^3-

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the main regulator of Ca2+ metabolism

A

Parathyroid hormone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

When does Vitamin D get activated

A

Low plasma Ca2+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the mechanism in which vitamin D increases Ca2+

A

Increases absorption of Ca2+ through the intestine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

When does calcitonin get activated

A

High plasma Ca2+, corrects symptoms of hypercalcemia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Ca2+ intake=

A

Absorbed-secreted (=calcium excretion)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Why kind of hormone is parathyroid hormone

A

Peptide hormone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are chief cells

A

Majority cell type in the parathyroid gland that detect extracellular Ca2+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Describe the mechanism in which chief cells detect increased Calcium and what is the response

A

Increased calcium enters chief cell, cellular signaling activates PKC which inhibits release of PTH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

low Serum Ca2+ drives release of what hormone

A

PTH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Osteoblast

A

Bone builders, deposit the matrix

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Osteocytes

A

Former osteoblasts that are now internalized in the bone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

osteoclasts

A

Bone demolition, reabsorb the matrix

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What are osteoclasts derived from

A

Macrophages

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What are labile calcium pools

A

Ca2+ in bone fluid that allows rapid exchange of calcium with blood

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What are stable calcium pools

A

Ca2+ in bone matrix that allow storage and slow exchange of Ca2+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Where is the site of bone reabsorption

A

Stable pools

33
Q

Describe the mechanism of fast exchange of Ca2+

A

Osteoblasts and osteocyte network has labile reserve of Ca2+, PTH activates membrane bound Ca2+ pumps to take in Calcium and then transfer to central canal and into blood

34
Q

What happens to phosphate during fast exchange of Ca2+

A

Gets left behind

35
Q

Where are PTH receptors located

A

Osteoblasts

36
Q

Describe the mechanism of slow exchange of calcium

A

Osteoclast enters mineralized bone with stable pool of Ca2+, and causes bone dissolution through PTH mediated mechanism

37
Q

PTH inhibits bone formation activity of ___

A

Osteoblasts

38
Q

PTH stimulates osteoblasts to release ___

A

RANKL

39
Q

What does RANKL do

A

Binds RANK on nearby macrophage causing them to differentiate into osteoclasts

40
Q

What do osteoclasts release to dissolve the matrix and release calcium and phosphate

A

HCL and hydrolytic enzymes

41
Q

What two direct effects does PTH have in kidney

A
  1. Conserves calcium
  2. Eliminates phosphate
42
Q

How does PTH conserve calcium in kidney

A

Increases activity of Na+ Ca2+ cotransport in distal tubule of kindey

43
Q

When PTH is increased what happens to urine calcium

A

Decreases

44
Q

How does PTH eliminate phosphate

A

Inhibits Na+/ PO4^3- contransport in the proximal convoluted tubule of the kidney

45
Q

What happens to urine phosphate when PTH is stimulated

A

Increases

46
Q

Why is PO4^3- elimination necessary

A

To avoid cation-anion complexes and apatite formation in the blood

47
Q

How does PTH activate vitamin D

A

By stimulating 1alpha hydroxylase converting precursor to active form

48
Q

What is 25-hydroxycholecalciferol

A

Vitamin D in the liver

49
Q

What is 1,25 dihydroxycholecalcerfol

A

Vitamin D in kidney

50
Q

What are the effects on Ca2+ and PO4^3- on increase vitamin D

A

Increase Ca2+ and PO4^4- absorption in intestine

51
Q

What are the three steps of vitamin D synthesis

A
  1. UV dependent proteolysis of 7-dehydrocholesterol to Vitamin D3
  2. Activation: in liver CYP27A1 adds OH group to carbon 25
  3. PTH dependent activation: in kidney CYP27B1 adds OH group to carbon 1
52
Q

What are 3 sites of action for Vitamin D and what is the main one

A

Small intestine (main)
Kidney
Bone

53
Q

How does vitamin D impact the small intestine and what is the mechanism

A

Increases calcium and phosphate absorption by increasing expression of calcium binding protein, calbindin, Ca2+ goes into cell, binds calbindin and then is actively pumped out via Ca-ATPase into blood

same mechanism for phophsate

54
Q

How does vitamin D impact the kidney

A

Vitamin D promotes calcium reabsorption in DT and phosphate reabsorption in PT

55
Q

How does vitamin D impact bone

A

Synergizes with PTH to stimulate resorption and bone remodeling

Stimulates mobilization of Calcium and phosphate

56
Q

What is Ricket’s disease

A

Vitamin D deficiency that results in insufficient calcium and phosphate.

Present as growth failure or skeletal abnormalities

57
Q

What is osteomalacia

A

Vitamin D deficiency in adults that is a result of impaired ability to absorb calcium and phosphate in intestine

Causes bones to become demineralized and soft, resulting in frequent fractures

58
Q

What could cause osteomalacia

A

Usually a result of intestinal surgery

Also malabsorption syndrome, malnutrition, renal failure and Celia disease

59
Q

What directly regulates phosphate

A

Vitamin D in intestines by increase phosphate absorption

60
Q

What indirectly regulates phosphate

A

Inverse relationship between plasma phosphate and plasma calcium levels. A fall in phosphate will increase Ca2+ resulting in decrease PTH

61
Q

A decrease in PTH has what affect on phosphate

A

Increases renal absorption

62
Q

Where is calcitonin produced

A

Parafollicular C cells in thyroid gland

63
Q

What stimulates release of calcitonin

A

Hypercalcemia

64
Q

What is the job of calcitonin

A

Decrease ECF Ca2+, decrease bone resorption, inhibit Ca2+ and PO4^3- reabsorption in kidney

65
Q

Does calcitonin have an effect on vitamin D

A

No

66
Q

In general, calcitonin opposes ___ system

A

PTH

67
Q

Humoral hypercalcemia of malignancy causes release of

A

PTH related peptide and binds to PTH receptor

68
Q

What are the mechanisms of action of PTH-rp (calcium and phosphate)

A

Increased bone resorption, increased renal calcium reabsorption, inhibition of renal phosphate reabsorption

69
Q

What is the most common cause of hypercalcemia in dogs and cats

A

Humoral hypercalcemia of malignancy

70
Q

Are PTH levels low or high in humoral hypercalcemia of malignancy

A

Low inhibited by hypercalcemia

71
Q

PTH hyper secretion caused by primary hyperparathyroidism results in excess PTH which does what to calcium and phosphate levels

A

Hypercalcemia and hypophosphatemia

72
Q

What are urine levels of calcium and phosphate in cases of primary hyperparathyroidism

A

Increase in both

73
Q

Horses lack 1alpha hydroxylase and therefore are susceptible to what type of toxicity

A

Vitamin D

74
Q

in horses, intestinal absorption of calcium is independent of

A

Vitamin D signaling

75
Q

Equine renal failure may be indicated by

A

Hypercalcemia due to decreased excretion

76
Q

Equine hypervitaminosis D is caused by what and what happens to calcium and phosphate levels

A

Iatrogenic or by ingestion of calcinogenic plants

Causes hypercalcemia and hyperphopphatemia

77
Q

How does hypoparathyroidism impact PTH, calcium and phosphate levels

A

Low PTH, hypocalcemia, hyperphosphatemia

78
Q

How are PTH, calcium and phosphate levels effect in pseudophypoparathyroidism

A

Elevated PTH, hypocalcemia, hyperphosphatemia

Physiology (10 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions