Pituitary Gland Flashcards
pituitary gland
lies in the sella turcica
connected to the hypothalamus by pituitary stalk
anterior and posterior parts
6 hormones secreted by anterior pituitary
GH
ACTH
TSH
FSH
LH
PRL
Other name of GH, promotes what
also known as somatotropin
promotes growth of entire body by affecting protein formation
cell multiplication, differentiation
ACTH
also known as corticotropin
controls secretion of hormones from adrenal cortex (cortisol), affects metabolism of glucose, proteins, and fats
TSH
also known as thyrotropin
stimulating thyroid gland to control secretion rate of t3 and t4
control the rate of intracellular chemical reaction of entire body
FSH
control growth of gonads and hormonal and reproductive activities
LH
same function as FSH
PRL
promotes mammary gland and milk production
posterior pituitary secretes how many hormones
hypothalamus synthesizes
2
ADH
oxytocin
ADH
control rate of water excretion into urine
help control water concentration in body fluids
maintain BP
oxytocin
help for delivering milk from glands of breast to the nipple during suckling
help baby delivery at the end of gestation
main cell types of the anterior pituitary
5
somatotropes
corticotropes
thyrotropes
gonadotropes
lactotropes
somatotropes
30-40%
secrete GH
corticotropes
20%
secrete ACTH
thyrotropes
3-5%
secrete TSH
gonadotropes
3-5%
secrete LH and FSH
lactotropes
3-5%
secrete PRL
control of post. pit.
nerve signals from hypoothalamus
control of ant. pit.
hormones
hypothalamic releasing and inhibitory hormones
cascade of events of ant. pit. hormone secretion
hypothalamus receives signal from different sensory sources in the nervous system
hypothalamic releasing and inhibitory hormones are synthesized in a special neuron in the hypothalamus
endings of these neurons connect to medial eminence in hypophysial stalk
release from these neurons into tissue fluids
hormones are absorbed into the hypothalamic-hypophysial portal vessels and are carried to the sinuses of the ant. pit.
hormones produced in the hypothalamus that control the release of ant. pit. secretions
GHRH
GHIH
CRH
TRH
GnRH
PIH
GHRH
release of growth hormone
GHIH
inhibits release of GH
CRH
release of ACTH
TRH
release of TSH
GnRH
release of FSH and LH
PIH
inhibits PRL secretion
GH functions
promotes growth of babies
promotes growth of m. in adults
increase the physical size of cells
increase the number of cells
increase the amount of protein inside of a cell
3 main effects of GH
promotes protein synthesis
enhancing fat as a source of energy
decreases the use of glucose for energy
GH secretion rate is promoted by
promoted by malnutrition, starvation (low FA and glucose)
promoted by exercise (after about 2h of strenuous exercise)
promoted by sleep (after 2h)
promoted by trauma (long surgery)
control of GH secretion rate
GHRH short term effect (increase release into the blood bc of Ca)/
GHIH long term effect (increase transcription in nucleus by the genes that causes new GH synthesis
panhypopituitarism
decreased secretion of all ant. pit. hormones
congenital or during life
lack of GH = abnormal growth
multiple of other issues
dwarfism
lack of GH alone
appropriate proportions
no sufficient gonadotropic hormones to develop sexual function (1/3 can)
gigantism
too uch GH cause by tumour in pit.
acromegaly
acidophilic tumor after adolescence
soft tissue continues to grow, bones thicker
aging caused by decreased secretion of GH
accelerates aging process
result from decreased protein synthesis in body tissue and increased deposition of fat
cells composing the post. pit.
pituicytes
post. pit.
supporting structure for nerve fibers and nerve endings
ADH synthesized in supraoptic nuclei of hypothalamus
oxytocin is synthesized in paraventricular nuclei of hypothalamus
hormones bind with neurophysisns and are transported to nerve endings
when are hormones released in the post. pit.
when nerve impulses reach the nerve endings, hormones are released from the vesicles in the nerve endings by exocytosis
oxytocin
cause contraction of pregnant uterus at the end of gestation for helping with the birth of the baby
cause milk to be expressed from the alveoli into the ducts
main purpose of ADH
maintain BP homeostasis
osmosis
movement of solvent molecules through a selectively permeable membrane into a region of higher solute concentration
solvent
liquid things get disolved in
selectively permeable
only allows small molecules through
solute
thing that dissolves in a liquid
dissolve
solid is absorbed by a liquid
concentration
amount of solute in a solvent
regulation of ADH secretion
by osmosis through osmoreceptors in the hypothalamus
cardiovascular reflexes
osmoreceptors
specialized neurons in the hypothalamus that expand when the blood is dilute, contract when the blood in concentrated
cardiovascular reflexes
response to a decrease in BV or BP
barorecpetors in atria can be excited by stretch caused by high BP, transmitted to brain to inhibit ADH secretion
ADH physiological function
retains water by promoting it to go in the direction of urine back into the blood
what separates blood from urine
luminal membrane of tubular cells
vasopressin
ADH but has another type of effect that happens at the same time in the body
pressor response
high concentration of ADH causes constriction of arterioles throughout the body to increase arterial pressure
ADH has effects on arterial resistance
see page 24
