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physio > Q2: Hypothalamus + Pituitary > Flashcards

Q2: Hypothalamus + Pituitary Flashcards

1
Q

which organs are solely endocrine ? whats mixed

A

thyroid, parathyroid, pituitary, adrenal gland

mixed (thymus, heart, liver, stomach, pancreas, duodenum, kidney, adipose tissue, skin, ovaries, placenta, testes)

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2
Q

what is a paracrine hormone

A

it does not enter the bloodstream to reach its target, nearby cells

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3
Q

what is a juxtacrine hormone

A

hormone that acts on ADJACENT cell

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4
Q

how do autocrine cells act on themselves

A

either in cytoplasm or released outside the cell and binnd to membrane..

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5
Q

what are intracrine cells

A

autocrines that work only by binding to receptors IN the cytoplasm. dont leave the cell!

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6
Q

what types of molecules act as precursors for hormones

A

proteins, cholesterol amino acids and fatty acids all act as precursors
-the chemical properties determine the hormones (whether it is membrane bound etc)

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7
Q

where do phow do protein based hormones get formed and where do they attach to target cells

A

peptidases cleave into peptides which act as hormones. these hormones are they are membrane bound!!!! mostly.

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8
Q

what type of compound forms :growth hormone, ACTH, thyroxine, cortisol, 1,25 OHD3, Epinephrine, TRH,retinoic acid, prostaglandin E1

A

Growth hormone = protein

acth = protein (peptide from protein)

thyroxine (protein-type is thyronine)

cortisol= cholesterol (type is steroid)

1,25 OHD3 = cholesterol (type is steroid)

epinephrine = from a modified amino acid

TRH= from amino acids- tripeptide (3 amino acid chain)

retinoic acid = from fatty acid (retinoid)

prostaglandin E1= from fatty acid (eicosanoid)

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9
Q

what are teh types of plasma carrier proteins for steroids

A

albumins and globulins are the two types

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10
Q

what factors impact affinity of a hormone to its carrier and the concentration of the hormone in the blood?

A

age, health, nutrition, drugs and the hormone itself.

-hydrophobic hormones have to bind it and are inactive when bound , but hydrophilic hormones go freely in blood and are always active/can bind their target at any time

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11
Q

what are the features of bound hormones during transport- what type of interactions, half life, affinity

A

bound to either albumins or globulins by NON covalent intreractions.
the affinity varies by age health nutrition drugs and hormones
-being bound INCREASEs their half life!

-inactive while bound

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12
Q

what are free hormones during transport features; relationship to clinical states, feedback inhibition, clearance

A
  • they are active the whole time
  • free hormone correlates with clinical states and dictates the magnitude of feedback inhibition. it also can be cleared from the blood, so bound hormones have a longer half life.
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13
Q

what types of hormones use the cyclic AMP/PKA pathway (examples ) and what is the action?

A
  • LH, FSH, TSH, ACTH, vasopressin, epinephrine , norepinephrine, glucagon, PTH, CRH, GHRH, somatostatin, calcitonin
    action: alters preexisting designated protein

(g protein coupled receptor)

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14
Q

what hormones use the IP3/Ca and DAG/PKC transduction pathway? what is the outcome?

A

TRH, GnRH, oxytocin,

action: alters preexisting designated protein

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15
Q

what hormone uses the tyrosine kinase transduction pathway and whats the outcome

A

insulin, insulin like growth factors (IGf1 and igf 2) use it

ACTION: alters preexisting designated protein

receptor is surface membrane- exerts tyrosine kinase activity

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16
Q

what hormones use JAK/STAT transduction and what does it do

A

turns on gene transcription, leading to synthesis of designated protein

growth hormone and prolactin!!

surface mem receptor is bound to/activates JAK enzymes which phosphorylate stat

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17
Q

what type of hormones use hormone-response elements ON DNA and what do they do

A

all lipophilic hormones; thyroid hormone, cortisol, aldosterone, testosterone, estrogen, progesterone, vitamin D

18
Q

what type of tissue makes up the posterior/anterior pituitarys

A

posteror: (neurohypophysis) ; composted of nervous tissue. connects hypothalamus to neural pathways

anterior (adenohypophysis): composed of grandular epithelial tissue. connects hypothalamus by a vascular linkage

19
Q

where are the cell bodies of the posterior pituitary & where do the axons terminate

A

cell bodies are in the hypothalamus! axons pass through the stalk connecting hypothal and posterior pituitary, and terminate on capillaries in the posterior pituitary (from there hormones enter blood via the capillaries)

20
Q

which hormones are released by the posterior pituitary? how do the hormones travel down the axon and whre are they stored? what triggers the release?

A

vasopressin and oxytocin!!!!!!!!

  • each is made in the cell bodies which are in the hypothalamus. once made, they are packed into secretory granules and transported by molecular motors down cytoplasm of axon. stored at axon terminals in posterior pituitary!
  • release is triggered by synaptic inputs into their cell bodies, which generates an action potential

-the cells are both neurons AND endocrine cells

21
Q

whats the function of vasopressin

what stimulates its release?

A

Antidiuretic hormone

  • conserve water during urine formation. primary hormone for water balance!!!
  • vasoconstriction; contract arteriolar smooth muscle ( note this is a minor role, normal levels dont do much)

regulation:
- - osmoreceptors in the hypothalamus detect raises in osmolarity of CSF , and activate with higher osmolarity
- baroreceptors in the left and right atria trigger activation with severe hypovolemia (low volume of plasma)

22
Q

what are the functions of oxytocin what stimulates its release?

A
  • stimulates contraction of uterine smooth muscle (helps w childbirth and secretion of milk from mammary glands)
  • influence behavior (especially maternal behaviors) may help with human bonding behaviors
  • regulation: reflexes that originate within the birth canal during childbirth
  • reflex that triggered during breast feeding.
  • number of oxytocin receptors increase towards teh end of pregnancy.
23
Q

which hormones do the anterior pituitary release? what type of hormones are they and what si the EXCEPTION?

A 
tropic hormones (GH, TSH, ACTH, FSH and LH) 
EXCEPTION= prolactin (stims milk secretion) - not tropic

LH and fsh= gonadotropins (control secretion of sex hormones by the gonads)
GH= stimulate release of insulin like growth factor (IGF-1 which is also a tropic hormone)
-GH , FSH and LH ALSO target nonendocrine cells

TSH, ACTH, FSH, and LH bind G protein couped receptors that activate cAMP
-GH and PRL act through the JAK/STAT pathway (this one

24
Q

what do each of the following target/cause to occur:

TSH, ACTH, Growth hormone, LH

A

TSH: thyroid gland stimulation to secrete thyroid hormone (t3 and t4) which increases metabolic rate

ACTH - targets adrenal cortex to release cortisol, which triggers stress response

growth hormone: targets liver, adipose tissue and muscle. The liver secretes IGF-1 which acts on bone and soft tissues for growth. all the targets (adipose muscle and liver) have metabolic reactions too

LH: acts on gonads (ovaries/testes) -> causes estrogen and progesterone in females, testosterone in men to be released. also gamete production

25
Q

what are hypothalamic hypophysiotrpoic hormones

A

hormones frmo hypothalamus that trigger the release of anterior pituitary hormnes . these stimulate or inhibit hormone release. the release of the hypothal hypophysiotropic hormones is regulated by homeostatic control, feedback from downstream hormone levels.

-each one may regulate more than one anterior pituitary hormone

26
Q

what is the endocrine axis

A

a three hormone hierarchic chain of command ; hypothalamic hypophysiotropic hormone -> anterior pituitary tropic hormone -> target endocrine gland for release of hormone

27
Q

what do the following trigger release of: thyrotropin releasing hormone, corticotropin releasing hormone, somatostatin, dopamine

A

TRH : stimulates TSH and prolactin from AP

corticotropin releasing (CRH); stims ACTH
somatostatin: growth hormone AND TSH

dopamine: INHIBITS release of prolactin

28
Q

what controls hypothalamic hypophysiotropic hormones ?

what type of feedback ?

A

chemical signals in the blood and the brain/emotions

-negative feedback from target gland hormones supresses secretio nfrom the hypothalamus and from the anterior pituitary also!

29
Q

what is durnal rhythyms?

A

the set point for hormone conecntration in the blood changes as a function of the time of day. NOT merely regulated by negative feedback or it would remain pretty constant

cortisol is low at night and high in the morning

30
Q

what factors impact growth

A
  • genetic (maximum capacity)
  • diet : sufficient amino acids for protein synth
  • health; freedom from chronic disease/stress (cortisol breaks down proteins, inhibits growth of long bones and blocks secretion of GH)
  • levels of other hormones; thyroid , insulin, sex (androgens and estrogen)
31
Q

what stimulates fetal growth

A

stimulated by hormones in the placenta. GH has no role in it at this point!!!!! genetic and environmental factors impact size.
-after birth, GH, genetics, nutrition etc impact growth

32
Q

when are the two growth spurts

A

first two years of life (postnatal) and puberty

33
Q

what are the effects of GH? whats hyperplasia vs Hypertrophy?

A

HYPERPLASIA: increasing the NUMBER of cells

Hypertrophy: increasing the SIZE of cells

  • metabolism: increase fatty acid in blood, increase blood glucose level by decreasing uptake of glucose by musclesm and increasing output by the liver.
    overall: fat used as a major energy source. glucose is conserved for glucose dependent tissues (brain)

-

34
Q

which type of growht do cancerous tumors undergo

A

hyperplasia; number of cells (as opposed to hypertrophy- size of cells)

35
Q

how do organs increase in size during developmenthow does hypertrophy occur- muscle?

A

protein synthesis is stimulated and prevents protein degradation.

most muscle growth is hypertrophy; increase in size is stim by use/stress exercise.

36
Q

What do IGF 1 and 2 do

A

IGF’s induce growth in soft tissue and bone

IGF-1; synthesis is stimulated by GH. major source is the liver. in bone, IGF1 induces growth in length and thickness. (length= proliferatino of epiphyseal cartilage, stimulate osteoblast activity)

IGF 2:
-gh has no influence on synthesis of IGF2.It is important for fetal development.

37
Q

which hypophysiotropic hormones regulate GH?

what else regulates GH

A

growth hormone releasing hormone (GHRH), growth hormone inhibiting hormone (GHIH=somatostatin)

  • these are controlled by feedback loops!!!
  • diurnal rhythym; low gh during the day, increase 5x 1 hour after deep sleep.
  • increase GH in response to exercise, low blood glucose
38
Q

what can cause a reduced GH acvtivity

A
  • pituitary defect (lack of GH, but the receptors are normal)
  • hypothalamic dysfunction )lack of GHRH, GH receptors are normal)
  • lack of IGF-1 - (GH levels and GH receptors are normal)
  • GH receptor defects (GH levels are normal)
39
Q

what are the symtpoms of gh deficeincy in a child

A

short, poor developed muscles, excess subcutaneous fat (dwarfism)

40
Q

what happens wtih GH defiicency after growth

A

reduced muscle mass and bone density, and also increased risk for heart failure

41
Q

what happens with excessive GH activity; what disorders can come of it based on when they start?

A

usually caused by a tumor of the GH producing cells of the anterior pituitary.

  • onset in childhood before epiphyseal plates close. rapid growth in height without distortion of body proportions; gigantism.
  • onset after adolescence: epiphyseal plates are closed — no growth in height, but bones become thicker. soft tissue proliferare (CT and skin) disproportionate growth pattern.

condition ina dutls = ACROMEGALY

42
Q

what is the suprachiasmatic nucleus- describe the process of how it works!

A

aka master biological clock. synthesize clock proteins regulated by melanopsin-containing ganglion cells located in the eye. the ganglion cells are stimulated by light and inhibited by darkness.

  • when stimulated by light the melanopsin containing retina ganglion cells stimulate master bio clock to make clock proteins. clock proteins = made during teh day.
  • -clock proteins are not continuous in the presence of light because clock proteins inhibit their OWN synthesis. nge feedbak inhibition. once made, they begin to naturally degrade. each cycle from high to low amounts takes a day and synchronizes circadium rhythyms in effector organs…

-suprachiasmatic nucleus stimulates the pineal gland to release melatonin in the darkness , and decrease melatonin secretion in the light. this resets circadian rhythym to match the light/dark cycle.

meanwhile suprachiasmatic nucleus also makes clock proteins, these negatively inhibit suprachiasmatic nucleus to make more. the degradation of the clock proteins however, tells the suprachiasmatic nucleus to make mroe!!.
-the clock proteins that are made synchronize circadian rhythyms in effector organs throughout the body

physio (7 decks)

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