endocrine system Flashcards
autocrine
chemicals that exert effects on same cells that secrete them (ex. prostaglandins)
paracrine
locally acting chemicals that affect cells other than those that secrete them (ex. histamine)
hormone
long-distance chemical signals that travel in blood/lymph
can be either AA or steroid based
AA hormones
water-soluble (ex. proteins, AA’s, and peptides)
steroid hormones
lipid-soluble (ex. cholesterol and sex hormones)
signal transduction of proteins/peptide hormones
- hormone binds to receptor
- receptor activates G-protein
- adenylate cyclase converts ATP to cAMP
- cAMP activates protein kinases
*amplify signals due to activation of multiple substrates, resulting in many activated proteins and a large response
signal transduction of steroid hormone
- steroid hormone diffuses through PM and binds to an intracellular receptor
- receptor/hormone complex enter nucleus
- receptor/hormone complex binds to specific DNA region
- transcription of gene to mRNA
- mRNA directs protein synthesis
pineal gland
secretes melatonin (sleep)
thyroid gland
secretes TH (metabolism)
thymus
secretes thymosin (immune response)
pancreas
secretes insulin (regulates blood glucose levels)
adrenal glands
secretes E/NE (flight/fight response)
kidneys
secretes renin (controls BP)
ovaries
releases estrogen (regulation of menstrual cycle)
testes
release testosterone (sperm production)
hypothalamus
CRH, GnRH, TRH
drained by the hypophyseal portal system
anterior pituitary gland
MSH (melanin production)
FSH (production of egg in ovary)
LH (release of egg from ovary)
ACTH (regulates cortisol levels)
TSH (TH production)
prolactin (breast milk production)
GH (stimulates growth)
posterior pituitary
oxytocin (childbirth/releases breast milk)
ADH (inhibits urine production and raises BP)
hypersecretion of ADH
can result in edema (water retention)
hyposecretion of ADH
can result in dehydration
hypersecretion of GH
can result in acromegaly (gigantism)
can cause type II diabetes
hyposecretion of GH
can result in dwarfism
hypersecretion of prolactin
inappropriate lactation
lack of menses
infertility in females
impotence in males
endocrine system
delayed response
prolonged effects
humoral stimuli
changing blood levels of ions and nutrients directly stimulate secretion of hormones
nerve stimuli
nerve fibers stimulate hormone release
adrenal medulla secretes catecholamines
hormonal stimuli
hormones stimulate other endocrine organs to release their hormones (ex. hypothalamic and pituitary hormones)-> trophic hormones
PIP2-calcium signaling mechanism
- phospholipase C splits PIP2 into DAG and IP3
- DAG activates protein kinase
- IP3 releases Ca2+
phosphodiesterase 5 inhibitors
sildenifil (viagra)
tadalafil
thyroid gland
anterior to trachea
2 lateral lobes separated by medial isthmus
follicular cells produce TH (T3 and T4) via TSH or low iodine levels
parafollicular cells secrete calcitonin
increases metabolic rate and heat production
regulates tissue growth and development
maintains BP
hyperthyroidism
can cause graves disease
hypothyroidism
can cause myxedema/goiter due to lack of iodine
can cause cretinism in infants
parathyroid glands
posterior aspect of thyroid gland
PTH increases Ca2+ levels by stimulating osteoclast activity
calcitonin decreases Ca2+ levels by inhibiting osteoclast activity
hyperparathyroidism
can soften and deform bones
can depress NS
can form kidney stones
hypoparathyroidism
can result in tetany
can result in respiratory paralysis
can result in death
adrenal glands
superior portion of kidneys
adrenal medulla release E and NE
adrenal cortex releases aldosterone, cortisol, and androgens
aldosterone
stimulates Na+ resorption and water retention
eliminates K+
aldosteronism
hypersecretion of aldosterone
can cause hypertension and edema
can cause hypokalemia (results in abnormal func. of neurons and muscle)
cortisol
gluconeogenesis= formation of glucose from fats and proteins
increases BG, fatty acids, and AA levels
ACTH released in response to CRH
hypersecretion of cortisol
can result in cushing’s syndrome (depression of cartilage and bone func., depression of immune system, inhibition of inflammatory response, disruption of CV, neural, and GI func.)
hyposecretion of cortisol
can result in addison’s disease (decreased BG and Na+ levels, weight loss, severe dehydration, hypotension)
pancreas
contains islet of langerhans
contains alpha, beta, delta, epsilon, and upsilon cells inside islet of langerhans
alpha cells secrete glucagon (increase BG)
beta cells secrete insulin (decrease BG)
DM
type 1= insulin-dependent; treated via insulin
type 2= not insulin-dependent; treated via medication, diet, exercise, or insulin
MOA of insulin
increased glucose levels trigger insulin release, which then triggers increased glucose uptake into muscle and fat cells via GLUT4
adrenal medulla
releases E as a result of SNS’s fight/flight response
increases HR, BP, sweating, bronchodilation, blood flow to skeletal muscle, and BG
when released into blood, E acts as a hormone
when released by nerve axons to act on other neurons or glands, E acts as a neurotransmitter
hashimoto’s thyroidism
hypothyroidism
decreased T3 and T4/increased TSH= primary
decreased T3 and T4/decreased TSH=secondary
hGH
increases glucose and AA uptake
increases protein synthesis
zones of adrenal gland
zona glomerulosa= secretes aldosterone
zona fasciculata= secretes cortisol
zona reticularis= secretes androgens
adipose tissue
leptin= appetite control
resistin= insulin antagonist
adiponectin= enhances sensitivity to insulin
enteroendocine cells
gastrin= releases HCl
secretin= stimulates liver and pancreas
cholecystokinin= stimulates pancreas, gallbladder, and hepatopancreatic sphincter
serotonin= acts as paracrine
ANP
decreases BP
kidneys
secrete erythropoietin and renin
thymus
secretes thymulin, thymopoietins, thymosins
development of T cells in immune response
act as paracrines
skin
cholecalciferol (precursor of vit. D)
skeleton
osteocalcin= secretes more insulin, restricts fat storage, improves glucose handling, reduces body fat
T3
more biologically active and potent
T4
more present than T3 (90%)
insulin
peptide hormone
promotes anabolism of glycogen, fats, and proteins
cortisol
steroid hormone
TH
lipid-soluble
chief cells
secrete PTH
chromaffin cells
secrete E (80%) and NE (20%)
prolactin
inhibited via dopamine
osmoreceptors in the hypothalamus stimulate the release of
ADH from the hypothalamus in response to high osmotic pressure
TSH
increases the uptake of iodine by the thyroid gland
increases the growth of the thyroid gland
thyroxine
tyrosine + iodine
somatostatin
inhibits the secretion of other hormones, mainly glucagon and insulin
secreted by delta cells in pancreas
also secreted by hypothalamus
protein anabolism is promoted by
insulin
somatotropin
cortisol
triiodothyronine
erythropoietin
secreted by kidneys
increase hematopoiesis
Ach
increases secretion of insulin
renin
secreted in response to low BP
trophic hormones
MSH
FSH
LH
ACTH
TSH
GH
glycogenolysis
glycogen->glucose
gluconeogenesis
synthesis of glucose from lactic acid and noncarbohydrates
