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cell bio > Final (New content) > Flashcards

Final (New content) Flashcards

1
Q

Thyroid hormones are derived from the amino acid ________

A

Tyrosine

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2
Q

True or False
T3 and T4 are hydrophilic

A

False - hydrophobic

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3
Q

Catecholamines bind to _______ _______ receptors and thyroid hormones bind to ________ ________

A

cell membrane; nuclear receptors

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4
Q

Which of the following describes catecholamines?
a) Amino acid derived thyroid hormone
b) Hydrophilic
c) Circulate unbound in the blood
d) all of the above

A

d) all of the above

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5
Q

Which of the following is true of thyroid glands?
a) Follicular cells synthesize the thyroid hormones
b) Multiple layers of epithelium
c) Absence of blood capillaries
d) all of the above

A

a) follicular cells synthesize the thyroid hormones

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6
Q

What is true of colloid?
a) Viscous rich protein
b) Rich in glycoprotein thyroglobulin
c) Main storage of active TH’s
d) all of the above

A

d) all of the above

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7
Q

What allows mammals to withstand iodine deprivation without effecting production of thyroid hormones?
a) Colloid storage
b) Secretion of calcitonin
c) Conversion of iodine to iodide
d) none of the above

A

a) Colloid storage

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8
Q

Colloid is found within the _____ and is created by _____ _____

A

lumen; glandular cells

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9
Q

What cells are responsible for calcitonin secretion?
a) C-cells or parafollicular cells
b) Follicular cells
c) Colloid
d) None of the above

A

a) C-cells or parafollicular cells

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10
Q

What is synthesized within the follicle epithelial cell and secreted into the colloid?

A

Thyroglobulin

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11
Q

What is the substrate that helps form thyroid hormones?

A

Tyrosine

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12
Q

True or False
Iodide is converted to iodine to be transported in the blood

A

False
Iodine is converted to iodide to be transported in the blood

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13
Q

Iodine (I2) comes from the ____ and is converted to ______ in the intestinal tract and is transported to the ______ _____ _____

A

Iodine comes from the diet and is converted to iodide in the intestinal tract and is transported to the thyroid follicle cells

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14
Q

What type of transport do thyroid follicle cells use to trap iodide?

A

Active transport (Na/I cotransporter)

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15
Q

What provides the driving force to bring Iodide into the cell?

A

Sodium - provides concentration gradient via Na/K ATP-ase

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16
Q

True or False
Iodide has highest concentration in the blood

A

False - higher concentration outside of the cell (25-200x higher)

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17
Q

What facilitates the synthesis of thyroid hormones?
a) Thyroxine
b) Thyroid peroxidase
c) Tyrosine
d) Iodothyronine deiodinase

A

b) Thyroid peroxidase

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18
Q

What are the two steps involved in thyroid synthesis?
a) Organification
b) Oxidation of iodide to iodine plus tyrosine iodination
c) Coupling of iodinated tyrosines
d) all of the above

A

d) all of the above
a and b are the same process

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19
Q

True or False
Only small amounts of T4 are produced by the thyroid gland

A

False
Small amount of T3!

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20
Q

What is the main source of T3?
a) Coupling of DIT and MIT
b) Deiodination of T4
c) T3 synthesized by the thyroid gland
d) Lysosomes

A

b) Deiodination of T4

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21
Q

Thyroid hormones are transported into plasma via what transport proteins?
a) Thyroxine-binding globulin and Albumin
b) Corticoglucoid binding globulin and albumin
c) Albumin and transcortin
d) none of the above

A

a) TBG and albumin

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22
Q

True or False
It is difficult to shift the equilibrium between free and bound hormone in the blood plasma due to the availability of receptors

A

False
Equilibrium is easily shifted because of physiological or pharmacological situations (ie. increase of estrogen during pregnancy)

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23
Q

Which of the following statements regarding hormone clearance is false?
a) Rate of removal of hormone from the blood can not be measured
b) The MCR interferes with hormone concentrations
c) MCR = rate of disappearance from plasma / concentration of hormone
d) The rate of removal can be measured

A

A is the false answer

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24
Q

Which of the following is not a method of clearance for T3 and T4?
a) Conjugation (formation of sulfates and gluconuronides)
b) Deiodinatio
c) Excretion by liver into bile
d) Excretion by kidney into urine
e) All of the above

A

e) All of the above

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25
Q

True or False
Thyroid hormones are the primary factors for the control of cellular metabolism

A

True

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26
Q

Which of the following statements about thyroid hormones are correct?
a) Bind to nuclear receptors and initiate transcription of mRNA
b) Increase the rate of ATP formation
c) Increase basal metabolic rate
d) All of the above

A

d) all of the above

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27
Q

Which of the following describes thyroid hormone effects on carbohydrate metabolism?
a) Facilitates the movement of glucose into fat and muscle tissues
b) Decreases lipolysis
c) Causes hypolipidemia
d) Decreases HR, blood flow and cardiac output

A

a) is the only correct statement

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28
Q

True or False
Thyroid hormones increase GI motility

A

True

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29
Q

If the thyroid is removed from an amphibian, what would be the effect on that animal’s growth?
a) Normal growth
b) It would not fully develop
c) It would develop but more slowly
d) It would develop but would be deformed

A

b) It would not fully develop

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30
Q

Where is the parathyroid gland typically located?

A

Usually at the poles of the 2 lobes of the thyroid glands

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31
Q

What species only have 1 pair of parathyroid glands?

A

Pigs and rats

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32
Q

What type of hormone is PTH?
a) Steroid
b) Protein/Peptide
c) Amine
d) None of the above

A

b) Protein/peptide hormone

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33
Q

What are the 2 types of parathyroid hormones?

A

Chief cells and Oxyphil cells

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34
Q

Which of the following is a correct statement?
a) Chief cells produce PTH and are the larger of the 2 parathyroid cells
b) Oxyphil cells produce PTH and are the larger of the 2 parathyroid cells
c) Chief cells produce PTH while Oxyphil cells have unknown function despite being larger
d) None of the statements are correct

A

c) Chief cells produce PTH while Oxyphil cells have unknown function depsite being larger

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35
Q

Parathyroid cells are very sensitive to decline in blood ______ ______

A

ionic calcium

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36
Q

What stimulates PTH release?
a) Decrease in iCa
b) Increase in iCa
c) Calcitriol release
d) Decrease in phosphate

A

a) Decrease in iCa

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37
Q

What is the main gland involved in Calcium and Phosphate metabolism?
a) Thyroid gland
b) Adrenal gland
c) Parathyroid gland
d) Adrenal medulla

A

c) parathyroid gland

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38
Q

Where is majority of Phosphate and calcium found?
a) Muscles
b) Heart
c) Bones
d) Intracellular

A

c) bones

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39
Q

What is the biologically active form of calcium?
a) Ionized calcium
b) Calcium bound to albumin
c) Calcitriol
d) Calcium in bones

A

a) iCa

40
Q

What form is calcium in the bone?
a) iCa
b) Intracellular calcium
c) hydroxyapatite crystals
d) Calcidiol

A

c) hydroxyapatite crystals

41
Q

50% of calcium is ______ and 40% is _______ to ______

A

50% of calcium is ionized and 40% is bound to proteins (albumin)

42
Q

Which of the following is not a form of calcium?
a) iCa
b) Bound to protein
c) Combined with other anions
d) Combined with other cations

A

d) Combined with other cations

43
Q

Which of the following is the most important pool for physiological control of calcium concentration in the blood?
a) Calcitriol
b) Calcidiol
c) iCa
d) All of the above

A

d) iCa

44
Q

True or False
Increased intracellular calcium is indicative to increased cell activity

A

True

45
Q

What hormones are involved in the regulation of calcium?
a) PTH
b) Active Vit D (Calcitriol)
c) Calcitonin
d) All of the above
e) None of the above

A

d) All of the above

46
Q

True or False
PTH has direct effect on calcium metabolism in the GI tract and indirect effect in the bones and kidneys.

A

False
PTH has direct effect on bone and kidney metabolism of calcium, and indirect effect on GI (via Calcitriol)

47
Q

Which of the following are correct statements regarding PTH direct effect on bones?
a) Promotes the transfer of iCa across the osteoblast-osteoclast membrane
b) Osteocytes pump iCa into ECF and eventually the blood
c) Binds to receptors on bone osteoblast cells and stimulates production of osteoclast-activating factor
d) all of the above are correct

A

d) all of the above are correct

48
Q

What action releases iCa and PO4 into the blood?
a) Organification
b) Binding of PTH to osteoblast cells
c) Binding of PTH to osteoclast cells
d) Activation of oestoblasts

A

b) binding of PTH to osteoblast cells

49
Q

True or False
Vit D must be transformed by liver and kidneys to become biologically activated

A

True

50
Q

Which of the following statements are true?
a) Calcitonin increases calcium absorption in GI tract
b) Calcium enhances PTH effects on bone metabolism
c) PTH stimulates a kidney enzyme which converts calcidiol to calcitriol
d) All of the above are correct

A

c) PTH stimulates kidney enzyme which converts calcidiol to calcitriol
Explanation:
a) is not correct b/c CALCITRIOL increases calcium absorption
b) is not correct b/c PTH enhances effects of PTH on bone metabolism of calcium

51
Q

What feature allows calcitriol to be carried in plasma by transcalciferin?
a) Hydrophobic
b) Hydrophilic
c) Lipophobic
d) None of the above

A

a) Hydrophobic

52
Q

_______ stimulates the active transport of dietary calcium across the intestinal epithelium

A

Calcitriol

53
Q

Which of the following explains how hindgut fermenters regulate blood calcium levels?
a) Intestinal mechanisms to absorb calcium at all times
b) Calcitriol stimulates active transport across the intestinal epithelium
c) Regulates blood Ca2+ by increasing/decreasing urinary loss
d) All of the above
e) None of the above
f) More than one of the above

A

f) More than one of the above - both A and C are correct

54
Q

By regulating ______ animals can regulate ____ entering the blood from the diet

A

By regulating calcitriol animals can regulate iCa entering the blood from the diet

55
Q

Increase in iCa _____ PTH secretion
Decrease in iCa _____ PTH secretion

A

Increase in iCa stimulates PTH
Decrease in iCa inhibits PTH

56
Q

What is produced by parafollicular cells or c-cells in the thyroid gland?
a) Calcitriol
b) Calcium
c) Calcitonin
d) All of the above

A

c) Calcitonin

57
Q

Increase in blood iCa stimulates ______ release

A

Calcitonin

58
Q

True or False
Calcitonin release counterbalances the effects of PTH

A

True

59
Q

True or False
Calcitonin increases the movement of calcium from the bone

A

False - it decreases the movement of calcium

60
Q

Which of the following does NOT stimulate calcitonin secretion?
a) Gastrin
b) Secretin
c) CCK
d) Pepsinogen

A

d) Pepsinogen

61
Q

Increased iCa ______ calcitonin secretion

A

Stimulates

62
Q

What is the main factor regulating production and secretion of PTH and calcitonin?
a) Free calcium levels in the blood
b) Calcium in bones
c) Phosphate levels in blood
d) Phosphate levels in bone

A

a) Free calcium levels in the blood

63
Q

Calcitonin ______ calcium levels while PTH _____ calcium levels

A

Calcitonin decreases calcium levels while PTH increases calcium levels

64
Q

Which of the following is true in the case of Hyperparathyroidism?
a) Leads to persistent hypercalcemia
b) Negative feedback control is lost
c) Secretion of PTH is not suppressed
d) All of the above

A

d) All of the above

65
Q

Which of the following are symptoms of hyperparathyroidism?
a) PU/PD
b) UTI
c) Tachycardia
d) all of the above

A

d) All of the above

66
Q

What disease process correlates with hypocalcemia, hyperphosphatemia, and decreased calcitriol?
a) Hyperparathyroidism
b) Hypothyroidism
c) Hypoparathyroidism
d) Hyperthyroidism

A

c) Hypoparathyroidism

67
Q

Where are adrenal glands located?

A

Next to the cranial pole of the kidneys

68
Q

Which of the following are maintained by the adrenal gland?
a) Potassium
b) Sodium
c) Water
d) All of the above

A

d) All of the above

69
Q

Which of the following is an action of the adrenal gland?
a) Regulate body’s response to stress
b) Control blood pressure
c) Is the site for steroidogenesis
d) All of the above

A

d) all of the above

70
Q

Which of the following statements are correct?
a) Glucocorticoids are synthesized in the Zona glomerulosa
b) Estrogen and testosterone are synthesized in the Zona reticularis
c) Epinephrine and Norepinephrine are synthesized in the Zona fasciulata
d) All of the above are correct

A

b) Estrogen and testosterone are synthesized in the Zona reticularis

71
Q

Where are catecholamines (epinephrine and NE) synthesized?
a) Adrenal cortex
b) Zona glomerulosa
c) Adrenal medulla
d) HPA axis

A

c) Adrenal medulla

72
Q

Which of the following statements are false?
a) ACTH stimulates the Fascicular zone more strongly than the reticular and glomerulosa
b) ACTH stimulates the adrenal medulla more strongly than the cortex
c) ACTH stimulates the reticularis zone more strongly than the glomerulosa zone
d) Potassium and angiotensin stimulate the glomerular zone

A

b) is the incorrect statement

73
Q

Where does the conversion of cholesterol to pregnenolone take place?
a) Cytosol
b) Nucleus
c) Mitochondria
d) Cell membrane

A

c) Mitochondria

74
Q

What is the rate limiting step in steroidogenesis?

A

Conversion of cholesterol to pregnenolone, regulated by ACTH

75
Q

True or False
Cholesterol is carried in the blood plasma by VLDL

A

False - LDL

76
Q

Which of the following statements regarding steroidogenesis are correct?
a) Enters the cells via endocytosis
b) ACTH limits the rate of synthesis
c) Steroid hormones are secreted immediately by diffusion across the membrane
d) all of the above

A

d) All of the above are correct

77
Q

True or False
Aldosterone is largely bound to transcortin for transport

A

False - Aldosterone is bound mostly to albumin, Cortisol is mostly bound to transcortin

78
Q

Androgen hormones can bind to cell surface receptors triggering a rapid response via….
a) Nuclear receptors
b) Ligand gated channels
c) GPCR
d) All of the above
e) More than one of the above

A

e) More than one
b and c allow for more rapid response.
They do bind to nuclear receptors but that is much slower

79
Q

True or False
Only unbound hormones can diffuse into the cell

A

True

80
Q

What corticosteroids influence salt and water balance?
a) Glucocorticosteroids
b) Mineralocorticosteroids
c) Corticotropins
d) Catecholamines

A

b) Mineralocorticosteroids

81
Q

What characteristics allows steroids to become more water-soluble for passage in the urine?
a) Lipophilic
b) Hydrophobic
c) Conjugation of sulfates and gluconuronides

A

C) Conjugation of sulfates and gluconuronides

82
Q

What is the primary mineralocorticoid?
a) Androgens
b) Aldosterones
c) Catecholamines
d) Glucocorticoids

A

b) Aldosterone

83
Q

True or False
ACTH has little effect in aldosterone synthesis

A

True

84
Q

True or False
There are many receptors for ACTH located in the cells of the zona glomerulosa

A

False
There are FEW receptors for ACTH which is why it has little effect in aldosterone synthesis

85
Q

Which of the following situations stimulate RAAS?
a) Hypertension
b) Hyponatremia
c) Hypokalemia
d) All of the above

A

b) Hyponatremia

RAAS is stimulated by hypotension and hyponatremia

86
Q

Production of aldosterone is mainly regulated by what?
a) ACTH synthesis
b) RAAS
c) Blood pressure
d) All of the above

A

b) RAAS

87
Q

What detects hyponatremia in renal filtrate?
a) Macula densa
b) Baroreceptors
c) B1 andrenoreceptors
d) RAAS

A

a) Macula densa

88
Q

What detects reduced BP in the kidneys?

A

Baroreceptors in the afferent arteriole

89
Q

Which of the following stimulate renin secretion?
a) Hyponatremia in renal filtrate
b) Reduced BP in kidneys
c) Sympathetic stimulation of juxtaglomerular apparatus
d) All of the above

A

d) All of the above

90
Q

What are the effects of stimulation of renin secretion (RAAS)?
a) Increase in [Na+]
b) Increased water absorption
c) Increased blood pressure
d) All of the above

A

d) All of the above

91
Q

If there is a decrease in renal perfusion (juxtraglomerular apparatus) what is the effect on renin?
a) Stimulates renin secretion
b) Inhibits renin secretion
c) Stimulates sodium channels to open
d) Increases the blood pressure of the kidneys

A

a) Stimulates renin secretion

92
Q

Increase in concentration of potassium directly stimulates _________ ________ to secrete aldosterone

A

Zona glomerulosa

93
Q

Aldosterone acts on ______ _____ of the kidneys to assist in active reabsorption of sodium

A

distal tubules

94
Q

What is the result of aldosterone action on the kidney’s distal tubules?
a) Decreased Na and K reabsorption
b) Increased Na reabsorption and K secretion
c) Increased Na reabsorption and decreased K secretion
d) Increased Na reabsorption but no effect on K

A

b) Increased Na reabsorption and K secretion

95
Q

Which of the following drive the action of Na and K within the distal tubules of the kidney?
a) GPCR
b) Simple diffusion
c) Na/K ATP-ase
d) Ligand gated channels

A

c) Na/K ATP-ase

96
Q

What is true of aldosterone?
a) Hormone-receptor complex initiates transcription in the nucleus resulting in new protein channels/pumps
b) Aldosterone induced proteins modify existing proteins
c) Aldosterone combines with cytoplasmic receptor
d) All of the above

A

d) All of the above

97
Q

True/False
PTH increases reabsorption of calcium via distal convoluted tubules, and decreases renal reabsorption of phosphate via Proximal convoluted tubules

A

True

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