3 Feedback Mechanisms Flashcards
origin of hormones
glands
hormones to target cells
via blood
negative feedback
increase leads to less hormones
positive feedback
increase leads to more hormones
examples positive feedback loop
oxytocin
lactation
childbirth
regulation of hormones
production
secretion
metabolism
patterns of secretion
pulsatile
acute
cyclic
pulsatile
constant level
acute
rapid increase
cyclic
predictable pattern
pineal gland
produces melatonin
pancreas
produces insulin and regulatory hormones
adrenal gland
aldosterone cortisol sex hormones norepinephrine epinephrine
pituitary gland / hypothalamus
gonadotropic corticotropic growth hormones oxytocin arginine vasopressin
gonads
estrogen
progesterone
testosterone
exocrine
digestive enzymes and alkaline
pancreatic fluid
endocrine
hormones regulating carbs, lipids and protein metabolism
endocrine location
Islet of Langerhand
= islet cells
Islet of Langerhand cell types
10% alpha cells
70% beta cells
5% sigma cells
alpha cells
secrete glucagon
raise blood glucose
beta cells
secrete insulin
lowers blood glucose
sigma cells
secrete somatosin
GHIH
neural regulation
e. g. norepinephrine
from adrenal glans
endocrine regulation
hormones bind to endocrine cells
e.g. FSH stimulates estrogen
neuroendocrine interaction
???
adrenal glands compartments
salt
sugar
sex
sympathy
zona granulosa
aldosterone
increase Na+ reabsorption
zona fasiculata
cortisol
long term blood glucose
zona reticulaire
androgens and estrogens
medulla
norepinephrine
and epinephrine
a modified sympathetic ganglion
medulla and cortex
stress mediated
two glands of the adrenal
cortex
medulla = core
cortisol peaks
early morning
stress
cortisol effects
lipolysis
increase blood glucose
suppressed immune function
facilitates catecylamines
deficient cortisol
poor processing of stress during injury
regulation of ACTH
???
ovary
theca cells
corpus lute
granulosa cells
theca cells
estrogen
corpus luteum
progesterone
granulosa cells
inhibition and activation
testis
Leydig
Sertoli
Leydig cells
testosterone
Sertoli cells
sperm development
LH
luteinizing hormone
FSH
follicle stimulating
controlled by inhibit
stimulates estrogen
anterior pituitary
LH
FSH
gonadotropic releasing hormone
major effect on LH
LH pulses
biphasic
every minute
large pulse at 1 hour
humoral factors
other factors in circulation
e.g. glucose
FSH
uniphasic
LH and FSH over life
more during puberty
LH in females
surge at ovulation
LH in males
constant
produces testosterone
follicular phase
maturing follicle secretes E2
P is low
preovulatory surge
follicle makes enough E2 switches to PFB LH/FSH surge ovulation corpus luteum is formed
luteal phase
c. luteum secretes P for NFB
c. luteum demises
decrease in P
menstruation
positive feedback LH and FSH
estradiol
at high plasma concentration in late follicular phase
stimulates GnRH and LH
stimulates ovulation
negative LH and FSH
inhibin by testis / ovaries
???
prolactin
inhibits GnRH release
creates post-partum contraception
amenorrhea
???
testosterone and LH
feeds back to pituitary
inhibits LH
HPA axis complications
???
follicular phase
maturing follicle secretes E2
P is low
Preovulatory surge:
Luteal phase
corpus luteum secretes P for NFB on HPG axis,
low LH]allows corpus luteum demise
decrease in P
menstruation