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Block 3 Week 5 Meg > Izuora: Intro to Endocrinology > Flashcards

Izuora: Intro to Endocrinology Flashcards

1
Q

Role of the endocrine system

A

maintain homeostasis by regulating body functions through coordination of cellular activity

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2
Q

Key roles of the endocrine system

A

Regulation of salt/water balance, blood volume/pressure
Regulation of calcium and phosphate
Regulation of energy balance
Regulate response to stress
Regulation of reproduction, development, growth

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3
Q

Releases hormones GHRH, CRH, TRH, GnRH

A

Hypothalamus

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4
Q

Inhibitory hormones somatostatin, dopamine, vasopressin, and oxytocin

A

hypothalamus

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5
Q

releases T3, T4, and calcitonin

A

thyroid gland

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6
Q

releases estrogen and progesterone

A

ovaries

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7
Q

releases growth hormone, prolactin, ACTH, MSH, TSH, FSH, and LH

A

pituitary gland

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8
Q

releases testosterone

A

testes

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9
Q

a molecule functioning as a message to convey information; from the greek work Horman “set in motion”

A

hormone

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10
Q

mounts response to a given hormone

A

target organ

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11
Q

cellular protein that binds specific hormones to effect their actions

A

receptor

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12
Q

intracellular molecules that translate the message conveyed by hormones acting on the cell surface receptors

A

second messenger

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13
Q

Action on receptor in same cell; give an example

A

autocrine; insulin inhibiting its own release

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14
Q

Action in neighboring cell; give an example

A

paracrine; estrogen acting on the ovaries

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15
Q

Action at distant organs/tissues

A

endocrine

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16
Q

Secretions outside body, into ducts

A

exocrine

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17
Q

List the organization of the endocrine system

A

Hypothalamus
Pituitary
Target organ

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18
Q

Six hormones released from the anterior pituitary

A 
ACTH
GH
TSH
FSH
LH
Prolactin
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19
Q

What does ACTH act on?

A

cortisol

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20
Q

What does GH act on?

A

insulin-like growth factors

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21
Q

What does TSH act on?

A

thyroxine

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22
Q

What does FSH act on?

A

ovulation; spermatogenesis

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23
Q

What does LH act on?

A

estrogen, progesterone, testosterone

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24
Q

What does prolactin act on?

A

breast–>lactation

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25
Q

What kind of hormones travel free in plasma? What kind cannot move through plasma to effector sites except if bound to a plasma transport protein (globulins)?

A

protein (hydrophillic); hydrophobic

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26
Q

Hormones bound to transport proteins serve as reserves, ensure easy distribution, and protect the hormone from (blank).

A

rapid degradation/clearance

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27
Q

Are bound hormones active when they are bound?

The relationship between free and bound hormone is a dynamic equilibrium.

A

No, not active until they are free

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28
Q

Four hormone binding proteins (globulins)

A

corticosteroid binding globulin (CBG)
thyrotropin binding globulin (TBG)
sex hormone binding globulin (SHGB)
albumin

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29
Q

This hormone is bound to TBG and has a half life of 7 days. In pts with hypothyroidism, a missed dose can be taken the next day. A total weekly dose can be taken once a week.

A

throxine (T4)

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30
Q

This hormone is not protein bound and has a half life of 2-4 minutes and can be measured during surgery to confirm removal of a hyperfunctioning parathyroid gland adenoma

A

PTH

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31
Q

How do hormones act?

A

Hormones bind to receptor sites.
Binding promotes allosteric changes within receptor.
This translates the signal into biologic activity

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32
Q

T/F: receptors could be on the cell surface or within the cell

A

True

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33
Q 
Located on target cell membrane
Have ligand (hormone) recognition domains exposed on the surface
Integral proteins penetrate through membrane with cytoplasmic effector domain
A

Cell surface receptors

34
Q

Hormone binding to cell surface receptors initiates (blank)

A

an intracellular signaling cascade through second messengers resulting in a specific biologic response

35
Q

3 types of cell surface receptors

A

GPCRs
Receptor tyrosine kinase
Ligand gated ion channels

36
Q

Insulin acts on which type of surface receptor? Discuss what happens when insulin binds

A

tyrosine kinase; insulin binds, cross-phosphorylation occurs, sends glucose transporter to cell surface to let glucose into cell

37
Q

Epi, norepi, glucagon, angiotensin, GnRH, SS, GHRH, FSH, LS, TSH, and ACTH all act on which type of surface receptor?

A

GPCR

38
Q

In this condition, there is lack of response of PTH receptors to PTH from defect in the G-protein. PTH levels are elevated but patient presents with symptoms of hypoparathyroidism

A

pseudohypoparathyroidism

39
Q

How do you confirm a diagnosis of pseudohypoparathyroidism?

A

Measure amounts of cAMP in urine after administration of exogenous PTH

40
Q

Mediate action of steroid hormones, vitamin D, and thyroid hormones (can penetrate lipid membrane).
Can also serve as means for communication with surface receptors through second messengers

A

Intracellular (nuclear) receptors

41
Q

What occurs when hormones bind to the promoter area of trx factor of nuclear receptors?

A

altered transcription and gene expression

42
Q

Discuss steroid hormone action

A
  1. steroid hormone enters target cell
  2. binds to receptor, induces conf. change
  3. hormone-receptor complex binds to DNA and induces trx
  4. RNA transcripts produces, amplify signal
  5. transcript amplified, signal amplified
43
Q

(blank) and (blank) hormones bind to surface receptors; (blank) and (blank) hormones bind to nuclear receptors

A

peptide and amine; steroid and thyroid

44
Q

Proteins synthesized through gene transcription
Synthesized as pre-hormones and undergo post-translational processing
Stored in secretory granules before released by exocytosis

A

peptide hormones

45
Q

Peptide hormones travel free in plasma and have short (blank). Peptide hormones bind to surface receptors and act through (blank)

A

half lives; second messengers

46
Q

Examples of peptide hormones

A

insulin, glucagon, ACTH, PTH, glycoproteins (FSH, LH, TSH, HCG)

47
Q

Amino acid derived hormones are synthesized from (blank). Give two examples.

A

tyrosine; catecholamines and thyroid hormones

48
Q

These types of hormones are synthesized from cholesterol in the adrenal cortex, gonads, and placenta. They are lipid soluble and require binding to proteins to circulate in plasma to target organs.

A

steroid hormones

49
Q

Steroid hormones have longer (blank) and are able to cross cell membranes and act inside of cells. Also includes (blank)

A

Vitamin D

50
Q

3 patterns of hormone secretion

A
  1. pulsatile
  2. episodic
  3. diurnal (daily)
51
Q

Hormone released in regular pulses varying in amplitude and frequency from minutes to hours.
Several pulses result in episodic variations in hormone level limiting reliance on the direct measurement of these hormones.
Continuous release can limit hormone action through desensitization

A

Pulsatile pattern of releases

52
Q

Examples of hormones released in a pulsatile pattern

A

growth hormone and gonadotropin releasing hormone (GnRH)

53
Q

When does GH spike in serum?

A

sleepy time (9pm - 9am)

54
Q

Why use pulsatile administration of GnRH with a pulsing device to treat infertility?

A

Continuous admin of GnRH results in suppression of FSH and LH (infertility)

55
Q

Hormone secretion determined by the sleep-wake cycle which is set by pacemaker in the hypothalamus (SCN).
Follows a 24 hour pattern with low hormone levels at night that peak in the waking hours, then decline as the day progresses.
Affected mainly by alterations in the sleep-wake cycle

A

Diurnal hormone release

56
Q

What is an example of a hormone that follows a diurnal release pattern?

A

cortisol

57
Q

Normally we wake up in the morning because of a surge in hormones. These hormones result in increase in blood glucose (among other effects).
The body responds by producing appropriate amounts of insulin. What is this?

A

Dawn phenomenon

58
Q

In diabetes, the dawn phenomenon can be manifested as elevated (blank)

A

fasting blood glucose

59
Q

What happens once hormones are released into circulation?

A
  1. they bind to a receptor in target organ
  2. they undergo metabolic transformation in the liver
  3. they undergo urinary excretion
60
Q

3 types of regulation of hormone release

A
  1. hormonal
  2. nutrient/ion regulation
  3. neural
61
Q

Most common control of hormone release; protects against excess hormone production

A

negative feedback

62
Q

When is positive feedback appropriate? Give two examples

A

Child birth: oxytocin increases contractions

Lactation: oxytocin increases as suckling increases

63
Q

A situation in which there is no feedback; mainly refers to control of hormone secretion by CNS stimulation. An example of a hormone that works this way.

A

open loop; epinephrine

64
Q

Example of a clinical correlation of open feedback

A

primary hypothyroidism–> failure of thyroid glands to make thyroxine
use TSH level to determine the correct dose of levothyroxine

65
Q

Anterior pituitary releases TSH which acts on the thyroid to produce (blank), which acts on the anterior pituitary

A

T3/4

66
Q

How to measure hormones?

A

direct measure of hormone level in plasma
can measure product of hormone action
can stimulate or suppress hormones in diagnosing disease states

67
Q

Used to evaluate adrenal insufficiency
Give exogenous ACTH (to stimulate cortisol production)
Measure serum cortisol

A

ACTH stimulation test

68
Q

Evaluation for Cushings disease (excess cortisol).
Give exogenous steroid (to suppress cortisol production).
Measure serum cortisol

A

Dexamethasone suppression test

69
Q

Uses immunogenicity to determine hormone levels in a solution (serum)

A

radioimmunoassay

70
Q

Steps in radioimmunoassay

A

Step 1: Mix known amount of radio-labeled antigen (hormone) with antibody (they bind).
Step 2: Add patients serum containing hormone to compete with bound, radio-labeled hormone
Step 3: Precipitate antigen/antibody complex and measure radioactivity

71
Q

Similar to RIA except detection is based on enzyme catalyzing color change (not radiation)

A

ELISA

72
Q

T/F: cross-reactivity of hormones binding to same antibody can result in errors. Give an example of this.

A

True; in pregnancy, high HCG can lead to high TSH, too

73
Q

Patient with very high hormone levels with clinical manifestations. However, assay shows normal or only mildly elevated hormone levels.
Caused by overwhelming of the antibody by very high levels of antigen preventing detection of actual concentration

A

The hook effect

74
Q

How do you avoid the hook effect?

A

dilute the sample

75
Q

T/F: hormone levels are interpreted using reference ranges defined for a demographic group

A

true

76
Q

Interpretation of hormone levels assumes a (blank) distribution exists

A

normal

77
Q

Normal hormone levels can vary with (blank). Patterns of hormone release, illness, and (blank) affect hormone levels. Look for (blank) while interpreting hormone levels.

A

age/gender; nutrition; regulatory factors

78
Q

3 types of endocrine disorders

A
  1. hormone deficiency
  2. hormone resistance
  3. hormone excess
79
Q 
Autoimmune destruction (Type 1 DM)
Deficiency of precursor (Iodine/hypothyroidism)
A

hormone deficiency

80
Q 
Receptor mutations (Psuedohypoparathyroidism)
Functional (Type 2 DM)
A

hormone resistance

81
Q 
Tumors/mutations (Acromegaly)
Autoimmune activation (Grave’s disease)
A

hormone excess

Block 3 Week 5 Meg (8 decks)

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