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endocrine lecture3 Flashcards

1
Q

what kind of hormone is glucagon?

A

peptide

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2
Q

what cells release glucagon?

A

alpha cells of the islets of langerhans

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3
Q

main stimulus for glucagon release?

A

drop in blood glucose

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4
Q

what is the GLUT found on pancreatic alpha cells?

A

GLUT4 (insulin dependent)

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5
Q

how does diabetes get exacerbated by glucagon?

A

low insulin –> no block on glucagon –> more and more glucagon –> higher blood glucose

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6
Q

what is the main glucagon receptor?

A

G protein receptor (Gs) (stimulates adenlyl cyclase)

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7
Q

glucagon’s main role occurs where in the body?

A

the liver, it has very few effects in the periphery and is not in appreciable concentrations there either

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8
Q

what does glucagon do in the liver?

A

activates the enzymes responsible for the reversal of insulin’s actions

  • glycogen breakdown
  • gluconeogenesis
  • beta oxidation of fatty acids –> acetyl CoA –> ketones
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9
Q

what GLUT occurs on liver cells?

A

GLUT2 (insulin independent)

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10
Q

structure of thyroid hormone?

A

2 tyrosine residues linked together by an ether, and iodonated

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11
Q

Is thyroid hormone water soluble?

A

no, but its not super hydrophobic either.

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12
Q

what cell type produces thyroid hormones?

A

follicular cell

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13
Q

iodo residue are generally in the ___ and ___ position on thyroid hormone?

A

3 and 5

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14
Q

which is the active thyroid hormone? T3 or T4?

A

T3 (3,5,3-triiodothyronine)

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15
Q

How does iodide get into the cell?

A

an Na+/iodide symporter, then Na+ is pumped out (REQUIRES ATP)

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16
Q

what is thyroperoxidase?

A

enzyme that converts iodide to active iodide, and attaches it to thyroid hormone. Also catalyzes the ether link between tyrosine residues

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17
Q

what is thyroglobulin?

A

protein made by follicular cell, which has tyrosine residues. Secreted INTO THE LUMEN of the follicle

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18
Q

what is “luminal colloid” made of?

A

thyroglobulin

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19
Q

does the lumen of the follicle have any free thyroid hormone?

A

NO, they are all bound up in thyroglobulin molecules. Must be endocytosed and processed in lysosomes to become free hormone

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20
Q

what does thyroid hormone do once its in the blood?

A

99% is bound up 1% is free

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21
Q

what does thyroid hormone do at its target cells?

A
  • binds to intracellular receptors in the nucleus
  • change gene expression
  • primary controller of basal metabolic rate
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22
Q

does T4 have any function?

A

yes, it is de-iodonaated in the target cells into the active form T3

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23
Q

will increased thyroid hormone cause higher or lower metabolic rate?

A

higher

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24
Q

what are the “permissive effects” of T3?

A

basically it means that Thyroid hormone is essential for the proper function of many other hormones (GH, epi, catecholamines)

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25
how is thyroid hormone regulated?
hypothalamus (TRH-->thyrotropes-->TSH)
26
what kind of molecule is TSH?
peptide
27
what receptors does TSH use?
G protein receptors
28
how does TSH affect the thyroid gland?
regulates the number of follicle cells, levels of enzymes, levels of thyroglobulin, and iodide transport
29
what is "organification of iodide"?
taking inorganic iodide and putting it into the organic molecule
30
What causes HYPO-thyroidism?
- endemic (water doesnt have enough iodide) - pituitary dysfunction - autoimmune (Hashimotos thyroiditis)
31
what is the result of HYPO-thyroidism?
- Cretinism (mental retardation) - enlarged thyroid gland - goiter
32
levels of T3/T4, and TSH in case of endemic HYPO-thyroidism (low iodide)?
- low T3/T4 | - high TSH (disinhibited)
33
levels of T3/T4, and TSH in case of panhypopituitarism HYPO-thyroidism
- low T3/T4 | - low TSH (since the problem is at the pituitary
34
levels of T3/T4, and TSH in case of autoimmune HYPO-thyroidism?
- low T3/T4 | - high TSH
35
What can cause HYPER-thyroidism?
tumor of thyroid tumor if pituitary graves disease (antibodies mimic TSH)
36
what is the mechanism of graves disease?
antibodies simulate TSH. these are called TSI's (thyroid stimulating immunoglobulins)
37
levels of T3/T4, and TSH in case of thyroid tumor?
``` T3/T4 = high TSH = low ```
38
levels of T3/T4, and TSH in case of in case of pituitary tumor?
``` T3/T4 = high TSH = high ```
39
levels of T3/T4, and TSH in case of graves disease?
``` T3/T4 = high TSH = low ```
40
overall symptoms of HYPO-thyroidism?
low BMR, lethargy
41
overall symptoms of HYPER-thyroidism?
high BMR, agitated
42
adrenal gland is located where?
on top of kidney
43
what are the 2 parts of the adrenal?
Cortex (steroids) | medulla (epinephrine)
44
what are the 3 parts of the adrenal cortex?
``` zona glomerulosa (mineralocortocoids) zona fasciculata (gluccocortocoids) zona reticularis (sex steroids) ```
45
what is the main mineralocortocoid?
aldosterone
46
what is the main gluccocortocoid?
cortisol
47
what are the main sex steroids?
androgens
48
what controls the level of aldosterone?
renin angiotensin system
49
why is cortisol important?
it regulates the stress response
50
how is cortisol carried in the serum?
cortisol binding globulin (90% bound)
51
what does cortisol do when it reaches its target?
enters cell, binds to receptor, goes to nucleus - counters the action of insulin - potentiates effects of epinephrine - increases gluconeogenesis - stimulates glycogen breakdown - protein breakdown in skeletal muscle - stimulates FFA breakdown - antiinflammatory effect
52
what happens in HYPER-cortisol?
- redistribute fat (buffalo hump, moon face, centripetal redistrubutions of fat) - inhibits fibroblasts in the skin (thin skin, easy bruising) - increases heart rate/contractility (upregulates B adrenergic receptors thereby potentiating epinephrine - controls RBC production (polycythemia / anemia) - antagonizes Vit D
53
how does cortisol have an antiinflammatory effect?
-inhibits prostaglandin synthesis, therby preventing vascular permeablity increaes
54
how does cortisol have immunosupressive effects?
inhibits T-cells
55
what is the cortisol synthesis pathway?
hypothalamus --> CRH--> ant. pituitary (POMC) --> ACTH --> zona fasciculata--> cortisol -->negative feedback
56
what does ACTH do to the adrenal cortex?
- regulates number of cells | - regulates enzyme activity
57
what regualtes ACTH production?
only cortisol levels
58
what can cause HYPO-cortisol?
-Addison's disease (autoimmune destroction of cortex)
59
levels of cortisol, ACTH, and aldosterone in addisons disease?
cortisol down ACTH up aldosterone down
60
levels of cortisol, ACTH, and aldosterone in hypo-pituitarism?
low cortisol ACTH down aldosterone normal
61
what can cause HYPER-cortisol?
adrenal tumor pituitary problem (cushings disease) exogenous cushings
62
what is addisons?
HYPO-cortisol
63
what is cushings DISEASE
HYPER-cortisol cause by pituitary dysfunction
64
levels of cortisol, ACTH, and aldosterone in adrenal tumor HYPER-cortisol
high cortisol low ACTH high aldosterone
65
levels of cortisol, ACTH, and aldosterone in pituitary dysfunction HYPER-cortisol?
high cortisol high ACTH normal aldosterone
66
levels of cortisol, ACTH, and aldosterone in exogenous cushings HYPER-cortisol?
high cortisol low ACTH normal aldosterone
67
general symtoms of HYPER-cortisol?
immune supression | hyperglycemia
68
what is cushings SYNDROME?
the constellation of problems caused by HYPER-cortisol in general

physiology test5 (6 decks)

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