Chapter 16 - Endocrine System

passes thru membrane

binds to receptor protein

receptor-hormone complex enters nucleus

complex binds to specific DNA

triggers cell response

maintains homeostasis/controls autonomic function

connects hypothalamus to pituitary

communicates with other endocrine glands

anterior - stimulated by hormones from hypothalamus

posterior - made of neurons from hypothalamus

trigger release of other hormones

connects hypothalamus/anterior pituitary by capillary system

FLAT PeG

FSH, LH - ovaries/testes

ACTH - adrenal cortex

TSH - thyroid

PRL (prolactin) - breasts

GH - liver, bone, cartilage

*first 4 tropic hormones

Powerful Anti-Oxidants

ADH (antidiuretic hormone) - kidneys (retain H2O, sodium)

Oxytocin (positive feedback loop) - uterus, breasts

hormones travel on axons from hypothalamus to posterior pituitary through infundibulum

*largest endocrine gland

growth/metabolism

calcitonin - bone homeostasis (parafollicular)

follicles filled w/colloid (protein-rich gel)

maintains Ca ions

band connecting R/L lobes of thyroid

3 iodine atoms

half-life 24 hours

amino-acid based but acts like steroid hormone (lipid soluble)

more activity than T4

4 iodine atoms (colloid + iodine)

half life 7 days

more T4 than T3 in body, can change into T3

amino-acid based but acts like steroid hormone (lipid soluble)

regulate metabolic rate/thermoregulation

growth/development

synergism with sympathetic nervous system

Graves disease

T3/T4 increased

TSH/TRH decreased

weight loss, heat intolerance, elevated BP, goiter, exophthalmus

Hashimoto thyroiditis, Cretinism (child)

destruction thyroid gland by immune sys

iodine deficiency

T3/T4 decreased

TSH/TRH increased

weight gain, cold intolerance, decreased BP, goiter

steroid hormones

catecholamines

adrenal cortex (outer)

adrenal medulla (inner) - neuroendocrine organ, secretes neurohormones

zona glomerulosa - outer/dense (mineralorticoids)

zona fasciculata - middle/stacked (glucocorticoids)

zona reticularis - inner/loose (gonadocorticoids/androgens)

*regulated by hypothalamic-pituitary-adrenocortical (HPA) axis

fluid, electrolyte homeostasis

*aldosterone

maintain/regulate extracellular Na/K (hold/elim) ions

maintain BP

maintain acid-base homeostasis

inhibited by atrial natriuretic peptide (ANP)

hypernatremia - inc BP, ph blood alkaline

hyperaldosteronism = hypokalemia

mediate body response to stress

*cortisol (hydrocortisone)

gluconeogenesis in liver

keep blood sugar constant

release amino acids from muscle tissue

release fatty acids from adipose tissue

anti-inflammatories = corticosteroids

CRH-ACTH-cortisol

Cushing disease

oversecretion of adrenal cortex (tumor)

long-term corticosteroids

90% cases

moon facies, buffalo hump

Addison disease

low cortisol/aldosterone

sex hormones

most produced by gonads

increased sex drive

chromaffin cells - derived from nerve tissue

release catecholamines - epinephrine/norepinephrine

inc HR

dilate bronchioles

inc blood glucose

constrict blood vessels, skin, dig/urin organs, skeletal muscles, pupils

dec dig/urin functions

coord response between endo/nerv sys (sympathetic nerv sys)

head, body, tail

endocrine and exocrine

islets of Langerhans (endo)

acinar cells (exo - digestive)

alpha (A cells) - glucagon

beta (B cells) - insulin

delta - somatostatin (like hypothalamus)

liver, muscle tissue, adipose tissue

*increase glucose

break down glycogen to glucose = glycogenolysis

form new glucose in liver

protein break down in muscle tissue to rel amino acids

release fats from adipose tiss

form ketone bodies in liver from fatty acids

*ketacidosis = inc ketones/dec pH blood

liver, cardiac/skeletal muscle, parts of brain

*decrease glucose

promote uptake of nutrients to decrease blood glucose

lipid, amino acid, glucose uptake

synthesize glycogen in liver/skeletal muscle

synthesize fat from lipids/carbs

promote satiety

low glucose

weak, dizzy, rapid breathing, nausea, sweats

DM type 1/2

maturation site WBCs (T lymphocytes)

thymosin (dev T lymphocytes)

thymopoietin

(testes)

testosterone -

anabolic effect = stimulate bone growth/increased muscle mass

androgenic effect = develop secondary sex characteristics

(ovaries)

estrogen -

stimulate secondary sex characteristics

regulate menses cycle

progesterone - prep body for pregnancy, breast development

sleep-regulation centers in brainstem

*melatonin

neurons in hypothalamus that control feeding

*leptin (protein) - crosses blood brain barrier

induceses satiety (hunger)

small muscle cells lining blood vessels, kidney tubules

*ANP (atrial natriuretic peptide)

natriuresis = increase H2O excreted in urine, decrease blood volume

vasodilation = relax small muscle cells

both lead to decreased BP

erythropoietin (EPO) - stimulate erythrocytes, increase O2-carrying capacity of blood

renin secretion - enzyme converts plasma protein angiotensin to angiotensin I

converts vitamin D from active form (calcitriol)

rest/fasting - thyroid detects basal metabolic rate, stim gluconeogenesis, inc blood glu, triggers glucacon, inc GH

rest/feeding - insulin secretion inc, prot in meal rel GH/IGF-1, prot stims glucagon release, ends with ins/leptin

exercise - catecholamines control met rate/glucagon secretion inc

ADH, adlosterone, ANP

baseline - dec ADH, adlosterone continues

dec plasma volume/inc plasma solute - ADH/aldo inc, dec urine output

inc plasma vol/dec plasma solute - ADH/aldo dec = inc urine output

CRH, ACTH

adrenal steroid hormones from HPA axis

GH from anterior pituitary

catecholamines from adrenal medulla

glucagon from pancreas

bone/skeletal musle

promotes protein synthesis, fats to fuel

dwarfism (kids) - hyposecretion - 4 ft, norm body proportions

gigantism (kids), acromegaly (adults) - hypersecretion

thyroid gland

release thyroid hormones

adrenal cortex

stimulates adrenal cortex, release cortisol

growth/development adrenal cortex

ovaries/testes

gonadotropin

men - sperm production

women - maturation of follicle/egg production

ovaries/testes

gonadotropin

men - testosterone production

women - estrogen production, ovulation

breasts

causes milk production

blood levels increase end pregnancy

suckling stimulates PRH release/continued milk production

**most important hormone for Ca homeostastis

stimulates osteoclast ativity

remove Ca for bone release back to blood

osseous tiss, kid, intestine

prod by parafollicular cells (thyroid)

antagonist to PTH

dec blood Ca level

when blood Ca level inc, inhibits osteoclast activity/releases Ca from bone matrix

stimulates Ca uptake/incorporates into bone matrix

regulated by humoral (blood) negative feedback mechanics

low blood Ca

neurons excitable, tingly sensations

tetany (muscle twitch)

convulsions

progress to paralysis/death

weakening bones (Ca loss)

release too many neurotransmitters = decrease neuro function

increase Ca level = depressed nervous system

form kidney stones

produced by placenta

maintains uterine thickness

maintains corpus luteum

elevates progesterone level

permissiveness - one can't effect without another (FSH/LH)

synergism - 1+ hormones produce same effect on target cell (amplification)

antagonism - 1+ hormones oppose action of another (calcitonin & PTH)