ch. 45 part 2 Flashcards
what does gonadotropin-releasing hormone from the hypothalamus stimulate
release of FSH and LH
what does corticotropin-releasing hormone from the hypothalamus stimulate
adrenocorticotropic hormone release
what does growth hormone-releasing hormone from the hypothalamus stimulate
growth hormone release
what does thyrotropin-releasing hormone from the hypothalamus stimulate
thyroid-stimulating hormone release
inhibitory neurohormone from hypothalamus of growth hormone
somatostatin
inhibitory neurohormone from hypothalamus of prolactin
dopamine
what happens if thyroid hormone levels drop in blood
- hypothalamus secretes thyrotropin-releasing hormone
- anterior pituitary secretes thyroid-stimulating hormone
- TSH stimulates release of thyroid hormone by thyroid gland
thyroid hormone components
T3 and T4
what does thyroid hormone block
TRH release and TSH release - prevents overproduction of thyroid hormone
only iodine-containing molecule synthesized in body
thyroid hormone
what happens with insufficient levels of iodine
low levels of thyroid hormone
- pituitary continues to secrete TSH
- thyroid gland enlarges (goiter)
goiter
thyroid gland enlarges because of too much TSH
does growth hormone have tropic or nountropic effects
both
major target of GH
liver
- responds by releasing insulin-like growth factors
what do insulin-like growth factors released by liver and GF stimulate
bone and cartilage growth
gigantism
excess of GH during childhood
dwarfism (short stature)
lack of GH during childhood
acromegaly
if high levels of GH continue from childhood to adulthood
- normally caused by tumors on pituitary
what can dwarfism/short stature be treated with
GH injections as long as treatment begins before puberty ends
what does endocrine signaling regulate
homeostasis, development, and behavior
parathyroid hormone (PTH)
released by parathyroid glands when Ca2+ levels fall below a set point in blood
how does PTH increase blood Ca2+ levels
- releases Ca2+ from bone by stimulating osteoclasts
- stimulates reabsorption of Ca2+ in kidneys
- promotes production of vitamin D
calcitonin
decreases level of blood Ca2+
how does calcitonin decrease blood Ca2+
- stimulates Ca2+ deposition by stimulating osteoblasts in bones
- secretion by kidneys
where is calcitonin produced
C-cell (parafollicular cell) of the thyroid
vitamin D
fat-soluble vitamin naturally present in a few foods, added to others, available as supplement, or obtained from ultraviolet rays striking skin
what must vitamin D obtained from sun, food, and supplements undergo
2 hydroxylations in body for activation
- first occurs in liver, converts vitamin D to 25-hydroxyvitamin D (calcidiol)
- second occurs in kidney, forms 1,25-dihydroxyvitamin D (calcitriol)
where are adrenal glands located
atop the kidneys
2 glands in each adrenal gland
- adrenal medulla (inner)
- adrenal cortex (outer portion)
what does the adrenal medulla secrete
epinephrine (adrenaline) and norepinephrine (noradrenaline)
catecholamines
class of compounds that include epinephrine and norepinephrine
what do catecholamines coordinate
set of physiological responses that comprise fight or flight response
epinephrine and norepinephrine functions
- fight or flight
- release of glucose/fatty acids into blood
- increase oxygen delivery to body cells
- direct blood toward heart, brain, skeletal muscles, away from skin, digestive system, kidneys
where does epinephrine bind in liver cells
receptor that activates protein kinase A, which regulates glycogen metabolism
what does epinephrine do in smooth muscle cells lining blood vessels that supply skeletal muscle
leads to vasodilation increasing blood supply
what does epinephrine do in smooth muscle cells lining blood vessels that supply intestines
leads to vasoconstriction, reducing blood flow
when does the adrenal cortex become active
under stressful conditions:
- low blood sugar
- decreased blood volume and pressure
- shock
what does the adrenal cortex produce
family of steroids called corticosteroids
2 types of corticosteroids in humans
- glucocorticoids
- mineralocorticoids
ex. of glucocorticoids
cortisol
glucocorticoids function
influence glucose metabolism and immune system
cortisol function
synthesis of glucose form non-carbohydrates, suppresses immune system
ex. of mineralocorticoid
aldosterone
mineralocorticoid function
salt and water balance
where are most of the sex hormones produced
gonads: testes and ovaries
3 sex hormones
androgens, estrogens, progesterone
- all 3 found in both males and females
what do testes primarily synthesize
androgens (mainly testosterone)
androgens
promote development of male reproductive structures
testosterone
male secondary sex characteristics:
- penis
- scrotum
- hair
- aggression
- musculature
estrogens (most importantly estradiol)
- maintenance of female reproductive system
- female secondary sex characteristics
female secondary sex characteristics
- lack of body hair
- thicker hair on head
- rounded hips/figure
- decreased ability to generate muscle mass at fast rate
- decreased upper body strength
- breasts
- ability to nurse children
- menstrual cycle
- increased body fat composition
progesterone in mammals
preparing and maintaining uterus
what is synthesis of sex hormones controlled by
gonadotropins
gonadotropins
follicle-stimulating hormone and luteinizing hormone
what is gonadotropin secretion controlled by
gonadotropin-releasing hormone from hypothalamus
diethylstilbestrol (DES)
synthetic estrogen prescribed to some pregnant women at risk for complications from 1938-1971
- endocrine disruptor
what are daughters of women treated with DES at higher risk for
reproductive abnormalities:
- miscarriage
- structural changes
- cervical/vaginal cancers
endocrine disruptor
molecule that interrupts normal function of hormone pathway
where is pineal gland located
brain
what does the pineal gland secrete
melatonin
primary functions of melatonin
biological rhythms associated with reproduction and daily activity levels
what is release of melatonin by pineal gland controlled by
group of neurons in hypothalamus called suprachiasmatic nucleus (SCN)
melanocyte-stimulating hormone
group of peptide hormones produced by skin, pituitary gland, and hypothalamus
MSH function in amphibians, fish, and reptiles
controls pigment distribution in melanocytes
MSH function in mammals
- hunger
- metabolism
- coloration
