endocrinology - exam 3 Flashcards
what do endocrine systems consist of
cells that secrete long-distance signaling molecules into the blood
what are the signaling molecules called
hormones
nervous system communication
short & voluntary
rapid response
endocrine communication
slow & involuntary
travels further but lasts longer
1st endocrinology experiment
remove testes on roosters –> not masculinized
remove & replace back into body cavity –> typical male
remove & transplant into body cavity –> typical male
1st experiment conclusion
must secrete something & must circulate whole body
testosterone from gonads
hormone
chemical messengers
released into bloodstream
act on distant target cells
glucose example
glucose is low
endocrine cell in pancreas releases GLUCAGON into bloodstream
acts on target cell = LIVER
response = glucose becomes available
endocrine system
consists of all hormone-secreting cells
access to entire body
some parts of endocrine system
hypothalamus & pituitary gland
thyroid gland
adrenal glands
what surrounds endocrine glands
blood vessels
why do hormones only affect certain cells
hormones bind to target cells
where are hormone receptors located
can be in the plasma membrane or inside the cell
synaptic signaling
neurotransmitters diffuse across synapses & trigger responses in target tissues
neurons, muscles, glands
endocrine signaling
secreted molecules diffuse into the bloodstream & trigger responses in target cells anywhere in the body
3 major classes of hormones
amines
peptides/proteins
steroids
peptide/protein/amine
water soluable
travel well through blood not lipids
where are water soluable hormones stored
vesicles
secreted through exocytosis
where do water soluble hormones bind
receptors in the plasma membrane
activate signal transduction pathways
rapid responses
water soluble hormone example
glucagon (peptide)
steroid
lipid soluble
travel well through lipids not blood
where are lipid soluble hormones stored
not stored
made on demand
how are lipid soluble hormones transported
through blood by transport proteins
where do lipid soluble hormones bind
receptors in cytoplasm or nucleus
slow gene transcription effects
can have rapid effects too
lipid soluble hormone example
testosterone
what structure is key for the brain to interact with the endocrine system
pituitary gland
neurosecretory cells
neurons that release chemicals (hormones) into blood vessels
neuroendocrine signaling
neurohormones diffuse into the bloodstream & trigger responses in target cells anywhere in the body
how is post pituitary connected to the brain
directly connected to the brain
how is ant pituitary connected to the brain
connected by vessels
what 2 hormones are secreted by the post pituitary
ADH & oxytocin
oxytocin
regulates maternal activities
- stimulates uterine contractions –> receptors appear in uterus at time of birth = upregulation
- stimulates milk ejection –> positive feedback
- promotes bonding
oxytocin from bloodstream does not readily enter the brain
receptor upregulation
makes tissue more sensitive to a signaling molecule
receptor downregulation
makes tissue less sensitive
ADH
antidiuretic conserves body water (decreases urination)
alc & caffeine disrupt – they are diuretics
acts on kidney
ant pituitary gland
neurosecretory cells in the hypothalamus release releasing hormones
portal vessels
releasing hormones
inhibiting
release ant pituitary hormones
tropic effects
cause other endocrine cells to release hormones
thyroid hormone pathway
cold
TRH released from neurosecretory cells of hypothalamus
move through portal vessels into ant pituitary gland
bind to TRH receptors – stimulates release of TSH
move into thyroid gland
bind to TSH receptors – stimulated release of Thyroid hormones T3 & T4
T3 & T4 move to target cells & bind to receptors –T3 & T4 receptors in most body cells
warm up
negative feedback in thyroid hormone pathway
increased levels of hormones signal the hypothalamus to stop secreting TRH & the ant pituitary to stop synthesizing TSH
hyperthyroidism
too much thyroid hormone
feel hot, lose weight, irritable
cause of hyperthyroidism
graves’ disease - immune system stimulates TSH receptors causing thyroid hormone release
hypothyroidism
not enough thyroid hormone
feel cold, gain weight, tired
cause of hypothyroidism
lack of iodine in diet
goiter
enlarged thyroid gland
where are steroid hormones secreted from
adrenal cortex of adrenal gland
slow response
where are amine hormones secreted from
adrenal medulla of adrenal gland
fast response
adrenaline
which hormones & pathways are involved in fight or flight
adrenal medulla
amine hormones
provides energy for quick response
adaptive responses of adrenaline
increase blood glucose
increase blood pressure
increase breathing rate
increase blood flow to brain, heart, muscles
decrease digestive processes
What happens to “fight or flight” hormones in students before, during, and after an
exam
before - up & down, overall up
during - spikes
after - immediate decrease then gradual
long term stress response
stress
hypothalamus releases CRH through portal vessel into ant pituitary
stimulates release of ACTH from ant pituitary through portal vessels into adrenal cortex
adrenal cortex releases glucocorticoids
negative feedback
glucocorticoids
break down proteins & fats & convert to glucose – increase blood glucose
suppress immune system
inhibit growth & reproduction
main glucocorticoid released in humans
cortisol
main glucocorticoid released in birds & rats
corticosterone
how is stress response adaptive
makes glucose available & moving it to critical regions
increases alertness
“brakes” immune system
decreases investment in long term “expensive” projects
why is stress considered harmful
when stressors last longer than they were evolved for
no energy for immediate use - fatigue
problems w reporduction
immune system suppression - sick
can affect memory
