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Endocrine Physiology > VePHY M4 Part 2 > Flashcards

VePHY M4 Part 2 Flashcards

1
Q

True or False. PTHrP expression is increased when smooth muscle is relaxed and
PTHrP induces contraction

A

False. PTHrP expression is increased when smooth muscle is stretched and it induces relaxation of smooth muscles and reduce contraction.

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2
Q

functions as a paracrine regulator of vascular tone causing vasodilation and modulating vasoconstriction

A

PTHrP

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3
Q

These species PTHrP gene is more closely related to the human PTHrP gene

A

Canine

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4
Q

Calcitonin (CT) other name

A

thyrocalcitonin (TCT)

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5
Q

second calcium-regulating hormone secreted in response to hypercalcemia responsible for the reduction of the plasma concentration of calcium

A

Calcitonin

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6
Q

These cells are distinct from the follicular cells of the thyroid gland that are responsible for the secretion of
thyroxine (T4) and triiodothyronine (T3)

A

C-cells

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7
Q

Name the distinctive feature of the C-cell of the thyroid gland

A

Presence of numerous small membrane-limited secretory granules in the cytoplasm

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8
Q

True or False. In man and other adult mammals, C-cells often remain more
numerous near the hilus and the point of fusion with the ultimobranchial body.

A

True.

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9
Q

Precursor molecule of Calcitonin

A

preprocalcitonin

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10
Q

In which cell compartment is preproPTH is converted to procalcitonin?

A

Golgi apparatus

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11
Q

Give other humoral factors secreted by C-cells derived from neural crest under pathologic conditions

A
  1. serotonin
  2. bradykinin
  3. ACTH
  4. prostaglandins
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12
Q

the neuropeptide that participates in nociception, ingestive behavior, and modulation of the nervous and endocrine systems

A

Pre-procalcitonin gene-related peptide

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13
Q

True or False. Structure of calcitonin differs considerably between species. But, , the amino terminal portion of the calcitonin molecule is similar in all species.

A

True.

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14
Q

most potent in lowering blood calcium than any of the other calcitonins when administered to mammals & man

A

Salmon calcitonin

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15
Q

principal physiologic stimulus for the secretion of calcitonin by C-cells

A

Concentration of Ca2+ in plasma and ECF

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16
Q

Calcitonin is secreted continuously under conditions of?

A

normocalcemia

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17
Q

Under normal conditions C-cells store substantial amounts of calcitonin in their cytoplasm in the form of?

A

membrane-limited secretory granules

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18
Q

Once hypercalcemia occurs, stored Calcitonin is discharged to?

A

Interfollicular capillaries

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19
Q

important in triggering the early release of calcitonin to prevent the development of hypercalcemia following the ingestion of a high calcium meal

A

Gastrointestinal hormones

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20
Q

The effects of calcitonin on plasma
calcium and phosphorus are most evident in which animals

A

young or older animals with increased rates of skeletal turnover

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21
Q

In which cells calcitonin exerts its function?

A

bone, kidney, intestinal cells

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22
Q

Both PTH and Calcitonin decrease the renal tubular reabsorption of this ion

A

Phosphorus

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23
Q

develops from a direct action of calcitonin on increasing the rate of movement of
phosphate out of plasma into soft tissue and bone

A

Hypophosphatemia

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24
Q

True or False. Calcitonin is not dependent on Vitamin D.

A

True.

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25
Q

A tumor in bulls and humans associated with low rates of skeletal turnover and densely mineralized bone

A

Calcitonin-secreting C-cell neoplasms

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26
Q

act in concert to provide a negative feedback mechanism to maintain the concentration of calcium in extracellular fluids within narrow limits

A

Calcitonin and PTH

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27
Q

Major factor concerned with the minute-to-minute regulation of blood levels of calcium and protects against the development of hypocalcemia

A

PTH

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28
Q

True or False. There is only low incidence of calcitonin-secreting neoplasms and metabolic disorders resulting from abnormal levels of calcitonin

A

True.

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29
Q

The vitamin D family

A
  1. vitamin D3 (cholecalciferol)
  2. vitamin D2 (ergocalciferol or irradiated
    ergosterol)
  3. 1,25-dihydroxycholecalciferol (calcitriol;
    1,25-dihydroxyvitamin D)
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30
Q

Cholecalciferol is ingested in small amounts in the diet, it is synthesized in?

A

Epidermis

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31
Q

A high-affinity vitamin D-binding protein in the serum transports cholecalciferol from its site of synthesis in the skin to the?

A

liver

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32
Q

Cholecalciferol is synthesized from _________ in the skin by a photochemical reaction caused by ultraviolet irradiation

A

7-dehydrocholesterol

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33
Q

Cholecalciferol obtained from dietary
resources or produced endogenously binds to an ______ in the blood for transport to the
liver

A

alpha2-globulin

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34
Q

First step in the metabolic activation of vitamin D

A

Conversion of cholecalciferol to 25-
dihydroxycholecalciferol

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35
Q

Where does first step of metabolic activation of Vit. D occurs?

A

liver

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36
Q

Enzyme which converts cholecalciferol to 25-dihydroxycholecalciferol

A

calciferol-25-hydroxylase

37
Q

Primarily serves as a precursor for the formation of the more active metabolites of vitamin D

A

25-OH-CC

38
Q

High circulating levels of ______ serve as a reservoir of vitamin D for the synthesis of the active forms of vitamin D by the kidney

A

25-OH-CC

39
Q

(25-OH-CC) conversion to 1,25-(OH)2- CC takes place in which tissues

A

renal epithelial cells (PCT)

40
Q

Enzyme that converts (25-OH-CC) to 1,25-(OH)2- CC

A

25-hydroxycholecalciferol-1α-hydroxylase

41
Q

True or False. Conversion of 25-OH-CC to 1,25-(OH)2-CC is the rate-limiting steps in vitamin D metabolism

A

True.

42
Q

The main control for the final step of metabolic activation of vitamin D

A

Concentration of calcium in the plasma

43
Q

increases the conversion of 25-OH-CC to 1,25-(OH)2-CC

A

PTH

44
Q

Inhibits conversion of 25-OH-CC to 1,25-(OH)2-CC under certain conditions

A

Calcitonin

45
Q

A low concentration of phosphorus in the blood _______ the rate of formation of 1,25-(OH)2-CC

A

Increases.

46
Q

High phosphorus concentration
_______ the formation of active hormone 1,25-(OH)2-CC

A

suppresses

47
Q

Major biologically active metabolite of cholecalciferol that interacts with target cells in the intestine and bone

A

Dihydroxyvitamin D3 (1,25-(OH)2-CC)

48
Q

Vitamin D and its metabolites function to increase the absorption of these 2 ions in the intestine

A

Calcium, phosphorus

49
Q

act in such a way as to cause the retention
of sufficient mineral ions to ensure that the mineralization of bone matrix is adequate

A

Vitamin D

50
Q

These hormone and its ‘permissive effect’ of vitamin D maintains the proper ratio of calcium to phosphorus in the extracellular fluids

A

PTH

51
Q

major target for (1,25-(OH)2-CC)

A

absorptive cells of the mucosa of the small intestine

52
Q

In proximal part of SI, (1,25-(OH)2-CC) increases the active transcellular transport of?

A

calcium

53
Q

In distal part of SI, (1,25-(OH)2-CC) increases the active transcellular transport of?

A

Phosphorus

54
Q

What is the role of the hormone-receptor complex in the mechanism of action of 1,25-(OH)₂-CC in the nucleus?

A

Stimulate gene expression and synthesize Calcium-binding protein

55
Q

In response to 1,25 dihydroxycholecalciferol, the absorptive cells of the intestine synthesize?

A

calcium-binding protein (CaBP)

56
Q

True or False. The absorptive capacity of the intestine for calcium is a direct function of the amount of calcium-binding protein that is present.

A

True.

57
Q

required for the orderly growth of bone and mineralization of cartilage in the growth plate in young animals

A

Vitamin D

58
Q

Young animals fed diets deficient in vitamin D and housed indoors without exposure to ultraviolet irradiation develop?

A

Rickets

59
Q

also result in rickets because of the failure to maintain an adequate ion product of serum calcium and phosphorus at the zones of mineralization in bone

A

Phosphorus deficiency

60
Q

necessary for osteoclastic resorption and calcium mobilization from bone

A

Vitamin D

61
Q

Necessary to permit osteolytic cells to respond to PTH (“permissive effect”) under physiologic conditions

A

Small amounts of vitamin D or its active metabolite

62
Q

enzyme that is essential for metabolic activation of precursor molecules

A

renal 1α-hydroxylase

63
Q

True or False. Active metabolites of vitamin D also have a direct effect on the parathyroid gland

A

True.

64
Q

directly interact with parathyroid cells to diminish the secretion of PTH

A

Vitamin D metabolites

65
Q

useful to evaluate the potential for a dietary deficiency of vitamin D or the excess intake of vitamin D

A

Measurement of serum levels of 25-hydroxyvitamin D

66
Q

Increases the rate of intestinal calcium and phosphorus absorption and produces hypercalcemia and hyperphosphatemia in cattle

A

Solanum malacoxylon

67
Q

a plant that contains substantial amounts of 1,25-(OH)2-CC and has caused a debilitating disease in cattle and horses

A

Cestrum diurnum (‘day-blooming jessamine’)

68
Q

metabolic disorder in which excessive amounts of PTH secreted by
pathologic parathyroid glands cause disturbances of mineral and/or skeletal homeostasis

A

Hyperparathyroidism

69
Q

characterized by increased bone resorption, decreased radiographic density, and incomplete fractures

A

osteodystrophy (osteitis fibrosa)

70
Q

This disease is encountered more frequently in older dogs but is less common than secondary hyperparathyroidism of either renal or nutritional origin

A

primary hyperparathyroidism

71
Q

Primary or Secondary Hyperparathyroidism?

Mineralization of renal tubule and formation of multiple
calculi.

A

primary hyperparathyroidism

72
Q

form of hyperparathyroidism is a metabolic disease characterized by an excessive, but not autonomous, rate of PTH secretion caused by chronic renal failure

A

secondary renal hyperparathyroidism

73
Q

Type of hyperparathyroidism encountered most frequently in dog but also occurs in cats and other animal species

A

Renal Hyperparathyroidism

74
Q

End results as response to compensatory mechanisms to increase hormonal synthesis and secretion in response to hypocalcemia

A

Cellular hyperplasia

75
Q

Condition due to the accelerated rate of resorption that bones become
softened and are readily pliable and the jaws fail to close properly

A

rubber-jaw disease

76
Q

Dietary mineral imbalances of etiologic importance in the pathogenesis of nutritional hyperparathyroidism

A

(a) a low content of calcium
(b) excessive phosphorus with normal or low levels of
calcium
(c) inadequate amounts of vitamin D3

77
Q

does not stimulate the parathyroid gland directly but does so indirectly, by virtue of the ability to lower blood calcium

A

Hyperphosphatemia

78
Q

In horses, the most frequent nutritional imbalance involves the ingestion of excessive amounts of _______

A

phosphorus

79
Q

Horses develop nutritional hyperparathyroidism after pasturing on grasses with a high _______ content

A

oxalate

80
Q

appear to form insoluble complexes with calcium in the intestine resulting in an elevated fecal calcium; phosphorus ratio

A

oxalates

81
Q

results from the secretion of subnormal amounts of parathyroid hormone by
pathologic parathyroid glands

A

Hypoparathyroidism

82
Q

usually associated with diffuse lymphatic parathyroiditis resulting in extensive degeneration of chief cells and partial replacement by fibrous connective tissue

A

idiopathic hypoparathyroidism

83
Q

Malignancies commonly associated with hypercalcemia

A

(i) adenocarcinoma of the anal glands in dogs
(ii) T-cell lymphomas
(iii) miscellaneous carcinomas in cats and horses

84
Q

2 examples of hypocalcemic syndromes of major economic and veterinary significance

A

Parturient hypocalcemia is dairy cows and puerperal tetany of bitches

85
Q

metabolic disease of high-producing dairy cows characterized by the
development of severe hypocalcemia and hypophosphatemia

A

Parturient hypocalcemia

86
Q

may increase reciprocally as calcium levels decline during parturient hypocalcemia

A

Serum magnesium

87
Q

Increased or suppressed?

Concentration of glucose in the blood in response to hypocalcemia

A

Increased due to interference with the secretion of insulin from the beta cells of the pancreas

88
Q

true or false. adequate level of ionized calcium in the extracellular fluid is required for insulin secretion in
response to glucose

A

True.

89
Q
A

Endocrine Physiology (5 decks)

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