Endocrine: Thyroid/Adrenal Systems Flashcards
HPA
Hypothalmus Pituitary Axis
Types of hormones
3
- Steroid: receptor in cytoplasm
- Thyroid: receptor in nucleaus
- Peptide: receptor on cell membrane
The 4 F’s
- Feeding
- Fighting
- Flight
- F-ing
Stress>HPA>Endocrine system> Altered behavior
Median Eminence
What hormones
- CRH: corticotropin-releasing hormone (releasing)
- TRH: thyrotropin-releasing hormone (releasing)
- SS: somatostatin (Inhibiting)
- DA: dopamine (Inhibiting)
Anterior Pituary makes what?
ACTH: Adrenocorticotropic hormone
TSH: Thyroid-stimulating hormone
Anterior Pituitary
Structures, pathway, hormones
- Neurons: Parvicellular (hypothalamus)
- Median eminence: DA, SS, CRH, TRH
- Ant Pituitary: ACTH, TSH
- Systemic circulation
Posterior Pituitary makes what?
- OT: Oxytocin
- AVP: Arginine Vasopressin (same as ADH)
Posterior Pituitary
Structures, pathway, hormones
- Neurons: Magnocellular (hypothalmus)
- Magno Produces: OT, AVP
- Stored: in synaptes of Post Pit
Neurohormones
Releasing Hormones
- Hypothalmic Secretions
- Target Ant Pit
- TRH, CRH
Tropic Hormones
- Ant pit secretions
- Target endocrine glands
- TSH, ACTH
Trophic?
Induce growth of the target endocrine gland
i.e. TSH during a goiter
Non-tropic Hormones
- Endocrine gland secretions
- Targets cells not glands
- i.e. Cortisol, Epi, NO, T3, T4
Primary verse Secondary
Primary: Dysfuntion of gland itself
Secondary: Dysfuntion elsewhere in the pathway
Stimulation and Supression Tests
- Stim: determines gland ability to respond to control mechanism
- Supress: Determine if negative feedback is working
what is the thyroid glands secretory functional unit?
follicle
what does the thyroid follicle include?
cuboidal cells (follicular cells)
colloid (lumen)
c-cells (parafollicular cells)
cuboidal cells function
TG synthesis
(I2) iodine
TG: Thyroglubulin
colloid cell function
TG storage
T4/T3 storage
c cells function
Parafollicular or Parathyroid cells
calcitonin
lowers calcium in plasma
Hyptothamus-Pituitary-Thyroid Axis Regulation
HPTA / Stimulation and Inhibition
- Stimulation
* TRH: Thyrotropin Releasing Hormone
* TSH: Tyroid Stimulating Hormone
* TBG: Thyroid Binding Globulin (T3/T4/ bind to this)
* TSI: Thyroid Stimulating Immunoglobulin (Attaches to TSH receptor) - Inhibits
* T4/T3 (Inhibits Ant Pit and Hypothamlus)
* Decrease TBG lvls (liver disease)
TSH
Thyroid Stimulating Hormone
Precursor: TRH
TSI
Thyroid-stimulating immunoglobulin
TBG
Thyroid binding globulin
Binds to T3/T4
what are the 8 steps to synthesis of t3/t4
TNOOCEHD
1 TG synthesis and transport to lumen
2 Na/I cotransport into membrane
3 oxidation of I by peroxidase
4 organification of I into MIT and DIT on tyrosine on TG by peroxidase
5 coupling of MIT and DIT into t3/t4 by peroxidase
6 endocytosis of TG
7 hydrolysis and entering circ of t3/t4 by proteases
8 deiodination of MIT and DIT, recycle I and tyrosine
Tyrosine precurser for TG sythesis / TG = Thyroglobulin
T3 Coupling
MIT+DIT
DIT+MIT doesn’t do anything
T4 coupling
DIT+DIT
what are the 4 B’s of normal T3 function?
basal metabolic rate
beta adrenergic effects
brain maturation
bone turnover– bone growth
what is hashimotos thyroiditis?
levels of T4, TSH, TRH, Goiter?
chronic lymphocytic thyroiditis
(primary HYPOthyroidism)
T4- decrease
TSH- increase
TRH- increase
Goiter? possible
what is pituitary hypothyroidism?
levels of T4, TSH, TRH, Goiter?
secondary hypothyroidism
T4- decrease
TSH- decrease
TRH- increase
Goiter? no
what is graves disease? BUG EYES
levels of T4, TSH, TRH, Goiter?
TSI autoimmune primary HYPERthyroidism
T4- increase
TSH- decrease
TRH- decrease
Goiter? possible
does the thyroid make more t4 or t3?
t4 90%
t3/rt3 10% (made mostly by other tissues deiodinizing)
in the circulation are t3/t4 free or bound?
bound 70% to TBG
bound 29% to albumin
does birth control increase or decrease TBG?
increase
does liver failure increase or decrease TBG?
decrease
to have a goiter what do you need?
activation of TSH receptor, by TSH or TSI
does t3 or t4 have greater affinity for the THR?
THR: Thyroid Hormone Replacement
t3
when would you have an increased likelihood of fracture? hypo or hyper thyroidism?
BOTH
what is a good starting point to test thyroid function?
TSH
Is Iodine deficiency hypo or hyper? TSH?
hypo, TSH increase
is HPA depression hypo or hyper? TSH?
hypo, TSH decrease
is pituitary adenoma hypo or hyper? TSH?
hyper, TSH increase
what are the clinical manifestations of thyroid storm?
DAFT-NV
diarrhea
arrhythmias
fever
tachycardia
nausea
vomit
what pts are most likely to have thyroid storm?
graves disease
thyroid tumor
high dose thyroid meds
subclinical hyperthyroidism
Subclinical: no clinical symptoms of disease yet, but still has disease
what are the treatments for thyroid storm?
PTU (inhibit t4/t3)
potassium iodide (wolff-chaikoff effect, too much iodine)
beta blocker (also slow t4-t3 conversion)
once thyroid hormones are transported to tissue cells what happens?
bind to hormone receptors that bind DNA and alter gene transcription
what are the two functional glands of the adrenal cortex?
cortex (3 layers that surround the medulla)
medulla (functions as modified sympathetic ganglion)
what are the 3 layers of the cortex
G-F-R
glomerulosa
fasciculata
reticularis
Primary Regulator: ANGII/⬆K+
Cortex: Zona Glomerulosa
Hormone: Aldosterone
Mineralcorticoid (salts)
Primary Regulatory: ACTH
Cortex: Zona fasciculata
Hormone: Cortisol
Glucocortisol (regulate sugar)
Primary Regulatory: ACTH
Cortex: Zona reticularis
Hormone: Androgens
DHEA and androstenedione (sex hormones)
Primary Regulator: ACTH/Cortisol
Pre-ganglionic SNS (Ach)
Crommafins
Medulla
Hormone: Epi
from stress
Synthesis of NE and EPI in chromaffin cells
Adrenal medulla / 10 steps
- Tyrosine
- TH (Tyrosine Hydroxylase)
- L-DOPA
- AADC
- DA: Dopamine
- DBH: Dopamine B-hydroxylase
- NE (20%)
- PNMT (80%)
- EPI
- Pre-gang sympathtetic Ach releases EPI/NE
T-T-L-A-D-D-N-P-E-P (bolded answers enchance rxn)
17alpha-OH deficient, ACTH? BP? aldosterone? androgen?
ACTH- increase
BP- increase
Aldosterone- increase
androgen- decrease
21beta-OH deficient, ACTH? BP? aldosterone? androgen?
ACTH- increase
BP- decrease
Aldosterone- decrease
androgen- increase
11beta-OH deficient, ACTH? BP? aldosterone? androgen?
ACTH- increase
BP- increase
Aldosterone- increase
androgen- increase
what in cortisol production causes skin pigment changes?
MSH
Melanocyte-stimulating hormone
how much of cortisol is protein bound?
CBG 92% (less available)
albumin 8%(bioavailable)
when is cortisol highest in the day
morning
what are the critical effects of cortisol? BIG FIB
BIG
increase in BP
increase in Insulin resistance
increase in Glucose
FIB
decrease in Fibroblasts (stretch marks)
decrease in Inflammation and immunity
decrease in Bone formation
BONUS:
impaired learning/mem
what things make cortisol anti inflammitory
CHILL-PW
A
stabilizes lysosomal membranes
decrease capillary permi
decrease WBC migration
decrease lymphocyte prolif
decrease in interleukin, histamine, prostaglandin
if you are fasting and have acute stress what are the results?
liberation of all forms of energy: increase EPI/NE
liver- glycogen to glucose
sm- protein breakdown, glycogen to glucose
adipose- fat breakdown
if you are overfed and chronically stressed
muscle wasting/ IR/ weight gain: decrease EPI/NE
CNS- increase appetite
liver- increase glycogen synthesis
sm- protein breakdown, decrease glucose uptake
adipose- decrease fat breakdown, TG synthesis, decrease glucose uptake
what is cushings syndrome usually caused by
ACTH secreting tumor
adrenocortical hyperplasia
excess cortisol
what does cushings disease look like?
HUMID-BSB
unusual obesity
striae
bone loss
muscle wasting
buffalo hump
diabetes
HTN
Infection Risk
HUMID-BSB
what can increase aldosterone?
mostly RAAS = ANGII
increases serum K+
increases ACTH
what does aldosterone do to Na and K?
increases Na reabsorption
increases K secretion
what is the half life of aldosterone?
20min
how do corticoid receptors fx?
hormone binds to receptor in cytosol and sends regulatory proteins that allow the hormone-receptor complex to bind to DNA and alter transcription
does aldosterone bind MR or GR?
MR
does cortisol bind MR or GR?
MR and GR
what is addisons disease caused by?
autoimmune attack on adrenal cortex
decreased cortisol and aldosterone
what are the symptoms of addisons disease?
HIHH-HID
hypoglycemia
increased lymphocytes
hypoNa
Hypotension
hyperK
increase ACTH (increase MSH, why JFK had tan)
decrease vascular response to adrenergics
short term stress response
adrenal medulla releases EPI
increase BP, HR, blood sugar, metabolic rate
changes in blood flow to vital organs
dilate bronichioles
long term stress response
Adrenal cortex release Aldosterone and Cortisol
Increase in Na and water retention
Increase in blood volme = HTN
Protiens and fat brokedown or converted to glucose
Increased blood sugar
Supression of immune system
