Endocrine 2 - physiology > Phys - Endo Intro/Hypothalamus > Flashcards

Phys - Endo Intro/Hypothalamus Flashcards

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1
Q

What is the function of the endocrine system

A
  • secrete messengers that regulate organ system function

- coordinates with neural regulation

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2
Q

List the 6 gland with endocrine function

A
  • pituitary
  • thyroid
  • parathyroid
  • adrenal glands
  • pineal
  • thymus
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3
Q

List the four organs with endocrine function

A
  • gonads
  • pancreas
  • kidneys
  • heart
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4
Q

List the three hormone types

A
  1. Steroid
  2. Peptide/protein
  3. Amine
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5
Q

Steroid hormones

  • synth from what
  • produced by what
  • bind to what
A
  • synthesized from cholesterols
  • produced by gonads, placenta, and adrenal glands
  • usually bind to intracellular receptor (can cross cell membrane)
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6
Q

Where do peptide hormones usually bind?

A

surface receptor on a target cell

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7
Q

Amine hormones

  • synth from what
  • produced by what
  • bind to what usually
A
  • synth from tyrosine
  • produced by adrenal medulla (and thyroid)
  • usually bind to intracellular receptor
  • somewhat similar to proteins
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8
Q

Peptide hormone

  • synthesis
  • storage
  • release
A
  • via protein synthesis
  • synthesized as preprohormones
  • cleaved in ER to prohormone
  • cleaved in secretory vesicles to active hormone
  • stored in cytoplasmic granules
  • exocytosis to release hormone when stimulated by specific signal
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9
Q

What regulates peptide hormone production (overall)

A

secretory pathway

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10
Q

Steroid hormone synthesis

  • synth from what
  • regulation
  • constitutive or pulsatile production?
A
  • synth from cholesterol
  • regulated by production of key enzymes in synthesis pathway
  • constitutive
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11
Q

Peptide/amine hormone transport

A

free or bound

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12
Q

Steroid hormone transport

A
  • insoluble = must have carriers
  • Most carriers made in liver, called steroid binding proteins (SBP)
  • when arrive at target cell, hormone is released from carrier
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13
Q

Steroid hormone binding to a carrier

  • prevents what
  • allows for what
A
  • prevents elimination

- allows for hormone reserve

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14
Q

What cells to hormones reach? How to they act?

A
  • hormones reach all cells

- act specifically on target cells that contain specific receptors

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15
Q

What does hormone receptor binding rely on?

A
  • blood level of hormone
  • number of receptors
  • affinity of receptor for substrate
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16
Q

How do hormones alter target cell activity?

A
  • change in membrane permeability or membrane potential
  • synthesis of protein or regulatory molecule
  • enzyme activation/deactivation
  • induction of secretory activity (secrete another hormone or cell product)
  • stimulation of mitosis
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17
Q

What do protein and amine hormones use to cause intracellular change? why do they need this?

A
  • second messengers

- because they bind to the cell surface but need to make an internal change

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18
Q

What are 2 common second messengers

A
  • cAMP

- IP3 & DAG

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19
Q

cAMP MoA

A
  • common secondary messenger
  • Hormone receptor is G protein coupled receptor
  • binds GTP which dissociates subunits
  • Activates/inhibits adenylate cyclase cleavage of ATP to cAMP
  • cAMP activates protein kinases which phosphorylate a regulatory protein
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20
Q

what degrades cAMP

A

phosphodiesterase

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21
Q

IP3 and DAG MoA

A
  • GPCR binds hormone
  • activation splits PIP2 into DAG and IP3
  • DAG activates protein kinases
  • IP3 increases ICF calcium which binds calmodulin or activates enzymes
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22
Q

Define
PIP2
DAG
IP3

A
  • PIP2: phospatidylinositol
  • DAG: diacylglycerol
  • IP3: inositol triphosphate
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23
Q

Steroid hormone MoA

A
  • bind intracellular receptors (bc lipid can cross cell membrane)
  • attach to chromatin
  • Alter gene transcription (increase/decrease protein synthesis)
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24
Q

Feedback control of hormones

A
  • target cell response to hormone sends signal to hormone source
  • positive feedback increases the hormone
  • negative feedback decreases hormone (MC)
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25
Hypothalamus - describe - role
- homeostatic center for chemistry and temp or internal environment - acts with limbic system as a unit that regulates emotional and instinctual behavior - controls release of hormones from pituitary gland
26
How is the hypothalamus able to control chemistry/temp of the body?
- "sips" full strength blood all the time to test | - no/less blood brain barrier so exposed to blood
27
Hypothalamic-hypophyseal tract | - define
- neural connection between hypothalamus and posterior lobe of the pituitary gland - hypothalamic nuclei produce hormones - hormones are sent by fibers via infundibulum to posterior pituitary
28
Hypothalamic-hypophyseal tract | - What two hypothalamic nuclei are involved and what do they produce
- Supraoptic nuclei (ADH) | - Paraventricular nuclei (oxytocin)
29
Hypophyseal portal system
- vascular pathway from hypothalamus to anterior lobe of pituitary gland - ventral hypothalamus neurons release hypophysiotropic (releasing) hormones to primary capillary plexus of infundibulum - drained by hypophyseal portal vein to secondary capillary plexus at anterior lobe
30
List the 7 hypophysiotropic hormones
- corticotropic-releasing hormone (CRH) - thyrotropin-releasing hormone (TRH) - growth hormone-releasing hormone (GRH) - growth hormone-inhibiting hormone (GIH/somatostatin) - Gonadotropin-releasing hormone (GnRH) - prolactin-releasing hormone (PRH) - prolactin-inhibiting hormone (PIH)
31
What does CRH stimulate the release of?
adrenocorticotropic hormone (ACTH)
32
What does TRH stimulate the release of?
thyroid stimulating hormone (TSH)
33
What does GRH stimulate the release of?
growth hormone
34
What does GRH inhibit the release of?
Growth hormone
35
What does GnRH stimulate the release of?
gonadotropins - LH - FSH
36
What does PRH stimulate the release of?
prolactin
37
What does PIH inhibit the release of?
prolactin
38
Name the two parts of the hypophysis
- neurohypophysis (posterior) | - Adenohypophysis (anterior)
39
Anterior pituitary | - two cells types
1. secretory cells ("-trope"): granulated | 2. Folliculostellate cells: regulate growth and function of secretory cells (assistants)
40
What are the five types of secretory cells in the anterior pituitary, what do they release, and what percent are they
- somatotrope: growth hormone (50%) - Lactotrope: prolactin (10-30%) - Corticotrope: ACTH (10%) - Thyrotrope: TSH (5%) - Gonadotrope: FSH, LH (20%)
41
What is the process to produce ACTH
corticotropes produce POMC (pro-opiomelanocortin) which are cleaved into many things including ACTH and endorphins
42
ACTH - released by - in response to - target cell - action - inhibited by
- corticotropes - hypothalamic CRH - adrenal cortex - stimulate release of glucocorticoids including cortisol - feedback inhibition by cortisol
43
what does cortisol do?
increase blood sugar
44
Growth hormone - released by - in response to - inhibited by
- somatotropin of anterior pituitary - GHRH - somatostatin (from hypothalamus), GH, somatomedin, cortisol
45
How variable is the genetic coding for GH?
located on 5 diff genes with variable processing = how important it is to have GH!!
46
GH transport
50% bound to extracellular GH receptor
47
At what frequency/pattern is GH released?
pulsatile over lifetime and daily
48
GH actions
- stimulates cellular uptake of aa - stimulates protein synthesis - stimulates uptake of sulfur needed to make chondroitin sulfate - increased production of cartilage matrix - increased lipolysis and FA in blood - decreased cellular glucose uptake, maintains blood sugar levels - increases somatomedin (ILG) production
49
Somatomedins - made where - describe - action
- produced by liver - insulin-like growth factors (ILG-1 and ILG-2) * enhances insulin-like activity which is contrary to most GH which decreases - GH mediated anabolic effect on skeleton and muscle
50
TSH - released by - in response to - target cell - action - inhibited by
- thyrotropes - hypothalamic TRH - thyroid gland follicle cells - stimulates production/release of thyroid hormone, stimulates iodine uptake - somatostatin, circulating thyroxine
51
What is release pattern of TSH?
constitutive (not pulsatile)
52
Gonadotropins - released by - in response to - target cell - inhibited by
- gonadotropes - hypothalamic GnRH - target gonads - estrogen in female, testosterone and inhibin in male
53
FSH | - action in male
Testes | - stimulates spermatogenesis in seminiferous tubules and sperm maturation in epididymis
54
FSH | - action in female
Ovaries - stimulates estrogen production by granulose cells - follicle maturation
55
LH | - action in male
Testes | - testosterone production via cells of Leydig
56
LH | - action in female
- estrogen production - ovulation - corpus lute conversion and progesterone secretion
57
Prolactin - released by - in response to - action - target cell - inhibited by
- lactotropes - hypothalamic PRH - estrogen/progesterone primed mammary glands - production of milk, initiates lactation post-birth, takes a few days - hypothalamic PIH
58
Oxytocin - released from - in response to - target cell - inhibited by
- posterior pituitary - cervical and nipple stretch, infant suckling, oxytocin - uterus, alveolar glands - stimulates: milk release, uterine contractions (OUCH), bonding/empathy/trust - lack of neural stimulus
59
ADH - aka - released from - target organ
- vasopressin - posterior pituitary - kidneys: increase number or size of water channels in CD to retain water
60
What stimulates the release of ADH
- increased blood osmolarity (water loss dt dehydration, sweating, diarrhea, reduced blood volume/pressure) - low-pressure receptors in great veins, LA, RA, PV - also continuously released at low level
61
What inhibits ADH release
- decreased blood osmolality - increased blood volume - increased blood pressure
Endocrine 2 - physiology
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