lecture 18: endocrine sys Flashcards
exocrine
glands secrete into ducts that empty onto an epithelium that lines a surface
ex. sweat, sebaceous, mucous, and digestive glands
endocrine
glands secrete into interstitial fluid -> diffuse into blood capillaries
ex. pituitary and thyroid glands
hormones
molecules that alter the physiological activity of other cells in the body
powerful effects even when present in low concentration
hormone path
- endocrine cells release hormones into the interstitial fluid
- hormones diffuse into the bloodstream
- hormones bind to the target cells located far away
nervous sys
neurotransmitters - released locally
close to site of release - postsynaptic membrane
- muscle fibers, gland cells, and other neurons
- release within milliseconds, short term effects
endocrine sys
hormones: delivered globally
far from site of release: target cells located far away
cells throughout the body
seconds, hrs, days, - longer term effects
mediator molecules
nervous sys:
- neurotransmitters released locally in response to nerve impulses
endocrine:
- hormones delivered to tissues throughout the body by blood
site of mediator action
nervous sys:
- close to site of release, at a synapse; bind to postsynaptic membrane
endocrine:
- far from site of release; bind to target cells located far away
types of target cells
time of onset of action
duration of action
nervous sys:
- muscle fibers, gland cells, other neurons
- typ. within milliseconds
- generally short term
endocrine:
- cells throughout the body
- several to hrs or days
- generally longer
what is a space or fluid you would not expect to find in a hormone
duct
hypothalamus
located inferior to the thalamus
neuroendocrine organ
controls pituitary gland
acts as your body’s smart control coordinating center
pituitary gland
pea-shaped; lies in the sella turcica of the sphenoid bone
- master endocrine organ; secretes several hormones that control other endocrine organs
anterior lobe - indirectly: pars distalis (larger bulbar portion), pars tuberalis (sheath around infundibulum)
produces and secretes 7 hormones
posterior lobe - directly
- pars nervosa: larger bulbar portion
- infundibulum: stalk portion, connect to hypothalamus
- stores and releases 2 hormones
- pars intermedia: separates the 2 lobes, size decreases during fetal development, not present in adults
the 2 lobes of the pituitary gland are joined by a mass of tissue called the
pars intermedia
hypothalamic regulation
(direct and indirect control)
- transport 2 hormones to posterior pituitary (direct control)
- secrete releasing and inhibiting hormones to the anterior pituitary (indirect control)
releasing hormone: “turn up”
hypothalamus -> releasing hormone -> anterior pituitary -> hormone 1 to target organ or endocrine glands -> if from endocrine gland its hormone 2
releasing hormones to stim production and release of other hormones in the endocrine system.
inhibiting hormone: “turn down”
hypothalamus -> inhibiting hormone -> anterior pituitary -> hormone 1 rither to target organ or endocrine glands -> hormone 2 -> target organ from endocrine glands
basically just hormones produced and released by specialized cells in various organs throughout the body
ex: somatostatin (inhibits growth hormone and insulin), dopamine (inhibits prolactin)
hypothalamic neurosecretory cells
synthesize hypothalamic hormones
1st capillary bed
at junction of hypothalamus and infundibulum
portal veins
connect 2 capillary plexuses
carry hypothalamic hormones
blood vessel that carries blood from GI, gallbladder, pancreas, spleen, liver
2nd capillary bed
receive hypothalamus hormones and send out hormones secreted by anterior lobe
veins carrying hormones 1
enter general circulation
secreted by the anterior pituitary
hormones of the anterior pituitary
F -> follicle-stim hormone (FSH)
L -> luteinizing hormone (LH)
A -> adrenocorticotropic hormone (ACTH)
T -> thyroid-stim hormone (TSH)
P -> prolactin (PRL)
E -> melanocyte-stim hormone (MSH)
G -> growth hormone (GH)
growth hormone (GH)
target: liver and other tissues (muscle, bone, cartilage)
principle action: stim body growth and increases protein synthesis
thyroid stim hormone (TSH)
target: thyroid gland
principle action: stim the synthesis and secretion of thyroid hormones
follicle stim hormone (TSH)
target: ovaries and testes
principle action: females (initiates oocytes development and induces secretion of estrogens), males (stim sperm production)
luteinizing hormone (LH)
target: ovaries and testes
principle action: females (stim secretion of estrogen and progesterone, ovulation, and formation of corpus luteum), male (stim secretion of testosterone
prolactin (PRL)
targets: mammary gland
principle action: initiates milk production
adrenocorticotropic hormone (ACTH)
targets: adrenal cortex
principle action: stim glucocorticoids (mainly cortisol) secretion
glucocorticoids: widely used for inflammatory and autoimmune diseases
melanocyte-stim hormone (MSH)
target: melanocyte
principle action: excess causes skin darkening
hormones of the posterior pituitary
- antidiuretic hormone (ADH)
- oxytocin (OT)
produced by hypothalamus!!
antidiuretic hormone (ADH) or vasopressin
target: kidney, sweat gland, arterioles
principle action: decrease urine volume, decrease water loss through sweating, constrict arterioles to increase bp
oxytocin (OT)
target: mammary glands
principle action: during childbirth (stim contraction of smooth muscle fibres of the uterus), after childbirth (stim milk ejection from mammary glands)
stim uterine contraction for childbirth and lactation after childbirth
why does alc cause frequent urination
- diuretic
- alc inhibits secretion of ADH
- lack of ADH = increased urine output
normal: 1-2 L/day
- w 4 fl oz beer: 1.25 L/hr
oxytocin (describe the actual hormone not its job, how does it increase)
the “love hormone”
- levels increase when we’re excited by our sexual partner and when we fall in love
- acts to boost oxytocin: giving someone a massage, cuddling with pets, give someone a hug
which of the following are not direct targets of anterior pituitary hormones?
a) mammary glands
b) adrenal cortex
c) thyroid gland
d) kidneys
d) kidneys
