endocrine system Flashcards
the endocrine system uses __; the nervous system uses __
hormones; neurotransmitters
pores in cell membrane allow signaling molecules, nutrients, and electrolytes to move from cell to cell
gap junctions
released from neurons to travel across synaptic cleft to second cell
neurotransmitters
secreted into tissue fluids to affect nearby cells
paracrines
chemical messengers that travel in the bloodstream to other tissues and organs
hormones
glands, tissues, and cells that secrete hormones
endocrine system
study of this system and the diagnosis and treatment of its disorders
endocrinology
organs that are traditional sources of hormones
endocrine glands
chemical messengers that are transported by the bloodstream and stimulate physiological responses in cells of another tissue or organ, often distance away
hormones
pineal gland, hypothalamus, pituitary gland, thyroid gland, thymus, adrenal gland, pancreas, parathyroid gland, trachea, gonads (ovary, testis)
organs of endocrine system
exocrine glands have __; endocrine glands do NOT
ducts
carry secretion to an epithelial surface or the mucosa of the digestive tract “external secretions”
exocrine glands
extracellular effects (food digestion)
exocrine gland
contain dense, fenestrated capillary networks which allow easy uptake of hormones into bloodstream
endocrine gland
“internal secretions” intracellular effects such as altering target cell metabolism
endocrine gland
both nervous and endocrine systems serve for
internal communiication
nervous system reacts __ and stops __
quickly (ms timescale)
endocrine system reacts __, effect may continue for days or longer
slowly (seconds or days)
nervous system adaptation to long-term stimuli
response declines (adapts quickly)
endocrine system adaptation to long-term stimuli
response persists (adapts slowly)
system that is targeted and specific to one organ
nervous system
system that has general, widespread effects (many organs)
endocrine system
what chemicals function as both hormones and neurotransmitters
norepinephrine (NE), dopamine, and antidiuretic hormone (ADH)
both norepinephrine and glucagon cause
glycogen hydrolysis in liver
nervous and endocrine systems have similar effects on target cells and can
regulate each other
neurotransmitters can affect glands, and hormones can affect
neurons
neuroendocrine cells share characteristics with
nervous and endocrine systems
neuron-like cells that secrete oxytocin into blood
neuroendocrine cells
organs or cells that have receptors for a hormone and can respond to it
target organs or cells
some target cells possess __ that convert a circulating hormone to its more active form
enzymes
forms floor and walls of third ventricle of brain
hypothalamus
regulates primitive functions from water balance and thermoregulation to sex drive and childbirth
hypothalamus
functions carried out by pituitary gland
hypothalamus
__ suspended from hypothalamus by a stalk- infundibulum
the pituitary gland
housed in sella turcica of sphenoid bone; size and shape of kidney bean
hypothalamus
hypothalamus is composed of 2 structures with independent origins and separate functions
anterior pituitary (adenohypophysis) and posterior pituitary (neurohypophysis)
constitutes anterior 3 quarters of pituitary
anterior pituitary
linked to hypothalamus by hypophysical portal system
anterior pituitary
primary capillaries in hypothalamus connected to secondary capillaries in adenohypophysis (anterior pituitary) by
portal venules
__ hormones regulate adenohypophysis cells
hypothalamic
constitutes the posterior one-quarter of the pituitary
posterior pituitary (neurohypophysis)
nerve tissue, not a true gland
posterior pituitary
thyrotrpoin-releasing hormone produced by hypothalamus
- corticotropin-releasing produced by hypothalamus
- gonadotropin-releasing
TRH
CRH
(GnRh)
hormones produced by hypothalamus
- growth-hormone releasing
- prolactin-inhibiting
- somastostatin
- oxytocin
GHRH
PIH
OT
__are releasing hormones that promote anterior pituitary secretion of TSH, PRL, ACTH, FSH, LH, and GH
TRH, CRH, GnRH, and GHRH
inhibits secretion of prolactin
PIH
inhibits secretion of growth hormone and thyroid stimulating hormone
somatostatin
hypothalamic hormones stored and released by posterior pituitary
oxytocin (OT) and antidiuretic hormone (ADH)
anterior lobe of the pituitary synthesizes and secretes six principal hormones:
FSH, LH, TSH, ACTH, PRL, GH
stimuates secretion of ovarian sex hormones, development of ovarian follicles, and sperm production (targets gonads)
follicle stimulating hormone (FSH) anterior lobe of pituitary
stimulates ovulation, stimulates corpus luteum to secrete progesterone, stimulates testes to secrete testosterone (target gonads)
luteinizing hormone (LH) anterior lobe of pituitary
stimulates secretion of thyroid hormone
thyroid-stimulating hormone (TSH) anterior pituitary
stimulates adrenal cortex to secrete glucocorticoids
adrenocorticotropic hormone (ACTH) anterior pituiatry
after birth, stimulates mammary glands to synthesize milk
prolactin (PRL) anterior pituitary
stimulates mitosis and cellular differentiation
growth hormone (GH) anterior pituitary
two hormones produced in hypothalamus and transported to the posterior lobe; released when hypothalamic neurons are stimulated
ADH (antidiuretic hormone) and oxytocin (OT)
increases water retention, reducing urine volume and preventing dehydration
ADH (antidiuretic hormone) posterior pituitary
also called vasopressin bc it can cause vasoconstriction
ADH (antidiuretic hormone) posterior pituitary
released during sexual arousal and orgasm, promotes feelings and emotional bonding between partners
oxytocin (OT) posterior pituitary
stimulates labor contractions and flow of milk during lactation; may promote emotional bonding between mother and infant
oxytocin (OT) posterior pituitary
rates of pituitary secretion are
not constant
__ is regulated by hypothalamus, other brain areas, and feedback from target organs
pituitary secretion
__ monitors conditions and influences anterior pituitary accordingly (hypotHALAMIC and cerebral control)
brain
in time of stress, hypothalamus triggers release of
ACTH
during pregnancy, hypothalamus triggers
prolactin secretion
controlled by neuroendocrine reflexes
posterior pituitary
hypothalamic osmoreceptors triggers release of __ when they detect a rise in blood osmolarity
ADH
infant suckling triggers hypothalamic response to release
oxytocin
increased target organ hormone levels inhibit release of hypothalamic and/or pituitary hormones
negative feedback
stretching of uterus increases OT release, causes contractions, causing more stretching of uterus until delivery
positive feedback
growth hormones has many effects on
cartilage, bone, muscle, and fat
__ induces liver to produce growth stimulants
growth hormone
protein synthesis and lipid metabolism increases, carbohydrate metabolism, electrolyte balance are effects of
growth hormones
bone growth, thickening, and remodeling influenced are effects of
growth hormone
levels decline gradually with age
growth hormone
lack of __ contributes to aging of tissues and wrinkling of the skin
protein synthesis
attached to roof of third ventricle beneath the posterior end of corpus callosum
pineal gland
after age 7, it undergoes involution (shrinkage)
pineal gland
plays a role ion 3 systems: endocrine, lymphatic, immune
thymus
bilobed gland in the mediastinum superior to the heart; goes through shrinkage after puberty
thymus
site of maturation of Tcells important in immune defense
thymus
secretes hormones that stimulate development of other lymphatic organs and activity of T lymphocytes
thymus
largest gland that is purely endocrine
thyroid gland
composes of 2 lobes and an isthmus below the larynx
thyroid gland
dark reddish brown color due to rich blood supply
thyroid gland
sacs that make up most of thyroid
thyroid follicles
thyroid follicles contain
protein-rich colloid
secretes thyroxine and triiodothyronine in response to TSH
thyroid gland
cells located in thyroid gland that secrete calcitonin with rising blood calcium
parafollicular cells
stimulates osteoclast activity and bone formation in children
parafollicular cells
increases metabolic rate, 02, consumption, heat production, appetite, growth hormone secretion, alertness, and reflex speed
thyroid gland
usually 4 glands partially embedded in posterior surface of thyroid gland
parathyroid gland
can be found from as high as hyoid bone to as low as aortic arch
parathyroid glands
secretes parathyroid hormone
parathyroid glands
increases blood calcium levels, promotes synthesis of calcitriol
parathyroid gland
- increases absorption of calcium
- decreases urinary excretion
- increases bone resorption
parathyroid hormone
has dual nature acting as an endocrine gland and ganglion of the sympathetic nervous system
adrenal medulla
innervated by sympathetic preganglionic fibers
adrenal medulla
the adrenal medulla consists of modified sympathetic postganglionic neurons called
chromaffin cells
when stimulated, release catecholamines and a trace of dopamine directly into the bloodstream
adrenal medulla
increases alertness and prepare body for physical activity
catecholamines in adrenal medulla
increases blood pressure, heart rate, blood flow to muscles, pulmonary airflow, and metabolic rate
adrenal medulla
decrease digestion and urine production
adrenal medulla
surrounds medulla and secretes several corticosteroids (hormones) from 3 layers of glandular tissue
adrenal cortex
layers of glandular tissue in adrenal cortex
zona glomerulosa (thin, outer layer)
- zona fasciculata (thick, middle layer)
- zona reticularis (narrow, inner layer)
cells arranged in rounded clusters, regulates the body’s electrolyte balance
zona glomerulosa in adrenal cortex
cells arranged in fascicles separated by capillaries
zona fasciculata in adrenal cortex
cells in branching network, secretes sex steroids
zona reticularis in adrenal cortex
from zona glomerulosa
mineralocorticoids
steroid hormones that regulate electrolyte balance
mineralocorticoids
__ stimulates Na+ retention and K+ excretion
aldosterone
water is retained with sodium by __, so blood volume and blood pressure are maintained
osmosis
regulates metabolism of glucose and other fuels, helps body adapt to stress and repair tissues
glucocorticoids in adrenal cortex
release of fatty acids and glucose into blood
glucocorticoids
2 sex steroids
androgens and estradiol
medulla and cortex of adrenal gland are not functionally
independent
medulla atrophies (waste away) without the stimulation of
cortisol
zona glomerulosa secretes
mineralocorticoids
zona fasciculata secretes
glucocorticoids and androgens
secreted by zona fasciculata and zona reticulata in response to ACTH
glucocorticoids
secreted by zona fasciculata and zona reticularis
sex steroids
set libido throughout life; large role in prenatal male development
androgens
important after menopause for sustaining adult bone mass
estradiol
secreted by alpha cells or glucagon cells
glucagon
released between meals when blood glucose concentration is falling
glucagon
in adipose tissue, stimulates fat catabolism and release of free fatty acids
glucagon
provides cells with raw material for gluconeogenesis and promotes amino acid absorption
glucagon
insulin secreted by
beta cells
stimulates cells to absorb these nutrients and store or metabolize them, lowering blood glucose levels
insulin
brain, liver, kidneys, and RBCs absorb glucose without
insulin
somatostatin secreted by
delta cells
inhibits nutrients digestion and absorption which prolongs absorption of nutrients
somatostatin
__ hormones raise blood glucose concentration
hyperglycemic
__ hormones lowers blood glucose
hypoglycemic
ovaries and testes are both
endocrine and exocrine
whole cells-eggs and sperm (cytogenic glands)
exocrine product
gonadal hormones-mostly steroids
endocrine product
estradiol, progesterone, and inhibin are
ovarian hormones
testosterone, weaker androgens, estrogen, and inhibin are
testicular hormones
testes are __ tubules that produce sperm
seminiferous
tubule wall of testes contain sustentacular cells called
Sertoli cells
Leydig cells lie in clusters between __ of testes
tubules
testosterone and other steroids from interstitial cells nestled between the tubules
testicular hormones
stimulates development of male reproductive system in fetus, adolescent, and sex drive
testicular hormones
keratinocytes convert a cholesterol-like steroid into cholecalciferol using UV from sun
skin
secretes angiotensinogen (a prohormone) and converts cholecalciferol into calcidiol
liver
stimulates bone marrow, controls action of growth hormone
liver
promotes intestinal absorption of iron
hepcidin (of liver)
convert calcidiol to calcitriol (vitamin D), secretes renin, produces 85% of erythropoietin
kidneys
atrial muscle secretes 2 natriuretic peptides in response to an increase in blood pressure
heart
__ peptides of heart decrease blood volume and pressure by increasing Na+ and __ output and oppose action of angiotensin 11
natriuretic, H20
stomach and small intesine secrete at lease 10 __ hormones secreted by enteroendocrine cells
enteric
coordinates digestive motility and glandular secretion
stomach and small intestine
adipose tissue secretes at least hormones including __ and slows __
leptin, apetite
osteocalcin secreted by __
osteoblasts
secretes estrogen and progesterone
placenta
regulates pregnancy, stimulates development of fetus and mammary glands
placenta
__ are synthesized in the same way as any protein
peptides
gene is transcribed to mRNA; assembled from amino acids at ribosome
peptides
__ and __ may modify peptide to form mature hormone
rough ER and Golgi
synthesized from the amino acid tryptophan
melatonin (a monoamine)
nerve fibers supply some endocrine glands and elicit the release of their hormones
neural stimuli
the __ nervous system stimulates the adrenal medulla to secrete epinephrine and norepinephrine in situations of stress
sympathetic (neural stimuli)
in childbirth, nerve signals originate from stretch receptors in the uterus, travel up the spinal cord and brainstem to the hypothalamus, and stimulate the release of __
oxytocin (neural stimuli)
hormones from the hypothalamus regulate secretion by the anterior pituitary gland
hormonal stimuli
pituitary hormones stimulate other endocrine glands to release thyroid hormone, sex hormones, and cortisol
hormonal stimuli
refers to blood-borne stimuli
humoral stimuli
rising blood glucose concentration stimulates the release of __ in humoral stimuli
insulin
low blood osmolarity stimulates the secretion of __ in humoral stimuli
aldosterone
low blood calcium levels stimulates the secretion of __ hormone in humoral stimuli
parathyroid
stored in secretory vesicles of the endocrine cell until needed and released by exocytosis when the cells receives stimulus to do so
peptide hormones and catecholamines
are not stored in vesicles or released by exocytosis
steroid hromones
diffuses freely through plasma membranes
thyroid hormone
most monoamines and peptides are __, they mix easily with blood plasma
hydrophilic
steroids and thyroid hormones are __, bind to transport proteins
hydrophobic
__ proteins protect circulating hormones from being broken down by enzymes in plasma and liver
transport
thyroid hormone binds to 3 transport proteins in plasma
albumin, thyretin, thyroxine-binding globulin
steroid hormones bind to
globulins
hormones stimulate only the cells that have __ for them
receptors
receptors are __ or __ molecules
protein or glycoprotein
receptors are on plasma membrane, in the cytoplasm or the
nucleus
peptides and catecholamines cannot __ target cell
penetrate
steroids and thyroid hormones penetrate __ and bind to internal receptors
plasma membrane
estrogen binds to nuclear receptors in cells of
uterus
___ hormone enters target cell by ATP- dependent transport protein
thyroid
most hormones are taken up and degraded by liver and kidney
excreted in bile or urine
excess cortisol secretion
cushing syndrome
insulin is used to treat
type 1 diabetes mellitus
treated with weight loss program and exercise
type 2 diabetes mellitus
cells cannot absorb glucose
pathogenesis
