Endocrine System Continued Flashcards Preview

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Flashcards in Endocrine System Continued Deck (47)
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1
Q

how is the endocrine system controlled

A

negative feedback systems

  • increase hormone effects on target organs can inhibit further hormone release
  • levels vary only within narrow, desirable range
2
Q

hormone release is triggered by what two things

A

endocrine gland stimuli

nervous system modulation

3
Q

what three stimuli does endocrine glands respond to

A

endocrine glands are stimulated to synthesize and release hormones in response to:
humural stimuli
neural stimuli
hormonal stimuli

4
Q

hurmoral stimuli is stimulated by…

A

changing blood level of ions and nutrients directly stimulate secretion of hormones

5
Q

whats an example of calcium in the blood for humoral stimuli

A

declining blood calcium concentration stimulates parathyroid glands to secrete PTH(parathyroid hormone)
-PTH causes calcium concentrations to ride, and stimulus is removed

6
Q

describe neural stimuli

A

nerve fibers stimulate hormone release

- sympathetic nervous sytem fibers stimulate adrenal medulla to secrete catecholamines

7
Q

what does hormonal stimuli stimulate

A

hormones stimulate other endocrine organs to release their hormones

8
Q

in hormonal stimulli what does hypothalamic hormones stimulate

A

hypothalamic hormones stimulate release of most anterior pituitary hormones

9
Q

what do anterioir pituitary hormones stimulate in hormonal stimuli

A

anterior pituitary hormones stimulate targets to secrete still more hormones

10
Q

what occurs in hypothalamic-pituitary-target endocrine organ feedback

A

hormones from final target organs inhibit release of anterior pituitary hormones

11
Q

what can make adjustments to the endocrine systems hormone levels

A

the nervous system can make adjustments to hormone levels (called modulation) when needed. It can modify stimulation or inhibition of endocrine glands. the nervous sytem can also override normal endocrine controls

12
Q

whats an example of the nervous system overriding the endocrine system

A

under stress, hypothalamus and sympathetic nervous system override insulin to allow blood glucose levels to increase
-prepare for “fight or flight”

13
Q

a target cell must have what specific sturucture?

A

target cells must have specific receptors to which hormone binds
ex: ACTH receptors are found only on certain cells of adrenal cortex, but thyroxin receptors are found on nearly all cells of the body

14
Q

what three factors does target cell activation depend on

A
  • blood levels of hormone
  • relative number of receptors on/in target cell
  • affinity(strength) of binding between receptor and hormone
15
Q

up-regulation

A

target cells form more receptors in response to low hormone levels

16
Q

down-regulation

A

target cells lose receptors in response to high hormone levels

17
Q

what can influence the muber of receptors for that hormone

A

the amount of hormone can influence number of receptors for that hormone

18
Q

what does down-regulation desensitize

A

the target cells to prevent them from overreacting to persistently high levels of hormone

19
Q

how do hormones circulate in blood

A

either free or bound.

  • steroids and thyroid hormone are attached to plasma proteins
  • all others circulate w/o barriers
20
Q

what does the concentration of circulating hormone reflect

A

rate of release

speed at which it is inactivated and removed from body

21
Q

how can hormones be removed from blood

A

by degrading enzymes, kidneys, or liver

22
Q

whats half life

A

time required fro level of hormone in blood level to decrease by half
-varies anywhere from fraction of a minute to a week depending on hormone

23
Q

describe the three different response times

A
  • some responses are immediate
  • some, especially steroid, can take hours to days
  • some are inactive until they enter target cells
24
Q

the durcaion of response times for hormones are usually

A

limited.

  • ranges from 10 secs. to several hours
  • effects may dissappear rapidly as blodd levels drop, but some may persist for hours at low levels
25
Q

what is half-life, onset and duraction of hormone activity dependent on

A

whether the hormone is water or lipid soluble

26
Q

can multipule hormones act on the same target at the same time?

A

yes

27
Q

permissiveness

A

one hormone can’t exert it effects w/o another hormone being present
ex: reproductive hormones need thyroid hormone to have effect

28
Q

synergism

A

more than one hormone produces same effect son target cell, causing amplification
ex: glucagon and epinephrine both cause liver to release glucose

29
Q

antagonism

A

one or more hormones oppos(s) action of another hormone

ex: INSULIN AND GLUCAGON

30
Q

what does the posterior pituitary consists of

A

axon terminals of neuron form hypothalamic neurons

  • paraventricular neurons produce oxytocin
  • supraoptic neurons produce antidiuretic hormone (ADH)
31
Q

Oxytocin and ADH

A

-each composed of nine amino acids

almost identical but differ in two amino acids

32
Q

describe 4 things about oxytocin

A
  • stong stimulant of uterine contractions released during childbirth
  • also acts as hormonal trigger for milk ejection
  • both are positive feedback mechanisms
  • acts as neurotransmitter in brain. uses PIP2 calcium second messenger system
33
Q

describe antiduretic hormone

A
  • hypothalamus contains osmoreceptors that monitor solute concentrations
  • if concentration too high, posterior pituitary triggered to secrete ADH
  • targets kidney tubules t reabsorb mor ewater to inhibit or prevent urine formation
  • release also triggered by pain, low BP, and drugs
  • inhibited by alcohol, diuretics
  • high concentrations cause vasoconstriction, so also called vasopressin
34
Q

describe anterior pituitary hormones

A

-All 6 hormones are peptide hormones
-all but growth hormone activate target cells via cAMP second-messenger system
all but teo are tropic hormones(tropins) that regulate secretion of other hormones

35
Q

name the tropic hormones

A

thyroid stimulating hormone(TSH)- tropic
Adrenocorticotropic hormone(ACTH)-Tropic
Follicle-stimulating hormone(FSH)-tropic
Lutenizing hormone(LH)-tropic

36
Q

what are the two hormones that aren’t tropins

A

growth hormone

prolactin

37
Q

what are the indirect actions on growth

A

GH triggers liver, skeletal muscle, and bone to produce insulin like growth factors ICFs

38
Q

what do IGFs then stimulate

A

cellular uptake of nutrients used to synthesize DNA and proteins needed for cell division
-formation of collagen and deposition of bone matrix

39
Q

what does GH stimulate most cells

A

what does GH stimulate most cells to enlarge an ddivide, but major targets are bone and skeletal muscle

40
Q

describe the regulation of secretion

A

GH release or inhibition chiefly regulate by hypothalamic hormones on somatotropic cells

41
Q

describe growth-hormone releasing hormone(GHRH)

A

stimulate GH release

-triggered by low blood GH or glucose, or high amino-acid levels

42
Q

Growth hormone-inhibiting hormone (GHIH)

A

(somatostatin)
inhibits release
-triggered by increase in GH and IGF levels
-ghrelin (hunger hormone) also stimulate GH release

43
Q

describe Regulation of secretion

A

GH release or inhibition chiefly regulated by hypothalamic hormones on somatotropic cells

44
Q

growth hormone-releasing hormone (GHRH)

A

stimulates GH release

triggered by low blood GH or glucose, or high amino acid levels

45
Q

growth hormone-inhibiting hormone (GHIH)

A

(somatostatin) inhibits release

- triggered by increase in GH and IGF levels

46
Q

what does ghrelin(hunger hormone) stimulate

A

GH release

47
Q

What is hypersecretion of GH usually caused by

A

anterior pituitary tumor.

-in children results in gigantism