endocrine

endocrine system

acts with the nervous system to coordinate and integrate activity of body cells, communicates to target cells via hormones

hormones

chemicals secreted into the blood, released by endocrine glands

slower, longer

hormones have a ….. response than the CNS but ….. response

lipid soluble

pass through cell membrane and bind to intracellular receptors

lipid soluble

is thyroid hormone lipid soluble or lipid insoluble

water soluble

bind to receptors on the cell membrane, amino acid based hormones

receptors

hormone binds to target cells via specific

lipid soluble

hormone diffuses into cell, binds to receptor protein, receptor complex enter nucleus, receptor complex binds to DNA, binding initiates transcription, mRNA directs protein synthesis

lipid insoluble

act via second messenger pathway, G protein couple receptors, hormone binds receptor, G protein activated, G protein activates adenylate cyclase, adenylate cyclase converts ATP to cAMP, cAMP activates protein kinases

inside the cell

receptors for steroid hormones are commonly located

second messenger

interaction with a membrane-bound receptor will transduce the hormonal message via

nervous system stimulation, humoral stimuli, other hormones

what stimulates glands to release hormones?

hypothalamic

……… hormones control the release of pituitary hormones

down regulation

target cells lose receptors in response to high hormone levels

up regulation

target cells gain receptors in response to low hormone levels

permissiveness

in order for a hormone to have its full response, another hormone must be present in adequate amounts

synergism

combined effect of several hormones is greater than sum of separate effects

antagonism

one hormone reduces effectiveness of another hormone (opposed actions of another hormone)

hypothalamus

sends projections to posterior pituitary, synthesize oxytocin or ADH

pituitary gland

when hypothalamic neurons fire oxytocin or ADH are released

oxytocin

lipid insoluble, stimulated by cervical stretching or suckling of infant at breast, inhibited by lack of stimuli

ADH

lipid insoluble, stimulated by decreased blood volume, high blood solute concentration, low blood pressure, inhibited by hydration and alcohol

kidneys

ADH main target organ

ADH

if …. levels increase water absorption and blood volume increases, concentrated and small volume of urine

ADH

if ….. decrease, water absorption and blood volume decreases, urine is dilute with large volume

hyposecretion of ADH

a patient is displaying high volumes of urine output and severe dehydration, the most likely cause is

hypophyseal portal system

the anterior pituitary and hypothalamus are connected via

TRH, TSH, thyroid hormones

hypothalamus releases …., anterior pituitary releases …., and thyroid gland releases …. ……

GH

also known as somatropin, secreted by anterior pituitary, targets muscle, bone cartilage, and soft tissues, has growth-promoting effects

increased GH

……… ….. leads to lipolysis in adipose tissues → increased fatty acids in the blood, increased blood glucose levels

indirect effect of GH

stimulates liver, skeletal muscle, cartilage, and bone to secrete hormones called IGFs into blood

IGF

has growth promoting effects

IGF

protein synthesis in skeletal muscle, lengthening of bones, increased mitosis/growth in soft tissues

GH

GHRH → …. release and is triggered by low blood GH or glucose

GH

GHIH → inhibits … release

gigantism

GH excess pre puberty

acromegaly

GH excess post puberty

pituitary dwarfism

GH deficiency pre puberty

TSH

thyroid hormones

ACTH

glucocorticoids and androgens

FSH

estrogens

LH

estrogens

PRL

lacatation

follicular cells

…… ….. produce thyroid hormones

parafollicular cells

produce calcitonin

TH

body’s major metabolic hormone, found in two forms T4 and T3

TH

enters target cells and binds to intracellular receptors, required for normal development of nervous system, promotes BMR = energy necessary to maintain body functions at rest, promotes glucose catabolism, ***promotes normal skeletal growth, promotes normal cardiac functions***, increases heat production

hyperthyroidism

excess T3/T4, speeds up BMR, increased heat production, anxious, weight loss, palpitations

hypothyroidism

T3/T4 deficiency, overall decrease in BMR, weight gain, lethargic, increased cold sensitivity, swelling of face hands and feet

parathyroid gland

secretes PTH

PTH

secreted in response to blood levels of Ca+, target organs skeleton, kidney, intestine

PTH

stimulates osteoclasts to digest bone matrix and release Ca+ to blood, enhances reabsorption of Ca+ and secretion of phosphate by kidneys, promotes activation of vit D by kidneys which leads to increased absorption of Ca+

hyperparathyroidism

bones soften and deform

hypoparathyroidism

tetany, respiratory paralysis, and death

adrenal cortex

secretes corticosteroids (mineralocorticoids, glucocorticoids, and androgens)

mineralocorticoids

regulate electrolyte concentration in ECF

aldosterone

main mineralcortocoid, targets kidneys, increases plasma Na+ and decreases plasma K+, humoral release

glucocorticoids

influence metabolism of most cells and help us resist stressors, keep blood glucose relatively constant

cortisol

main glucocorticoid, helps keep nutrient pools at homeostatic levels, increases blood glucose, fatty acids, and blood amino acids

CRH

corticotropin releasing hormone

ACTH

adrenocortotropic hormone

cortisol

main hormone that allows body to adapt to stress

rise

in response to long term stress cortisol levels ……

adrenal androgens

main site of androgen production in females, growth of underarm and pubic hair, development of libido in females

hypersecretion

adrenal abnormalities: depresses cartilage/bone formation and immune system, inhibits inflammation, disrupts neural, cardio, and GI function

hyposecretion

adrenal abnormalities: decrease in plasma glucose and Na+ levels, weight loss, severe dehydration, and hypotension are common