pituitary gland Flashcards
what is the pituitary gland also known as ?
hypophysis
what does this gland act as ?
the chemical co-ordinator of most of the endocrine glands
know as master gland
where is the pituitary gland situated ?
attached to the hypothalamus at the base of the brain by a short stalk
in the small bone cavity in the floor of the cranium ( turkish saddle )
how is the pituitary made up?
two glands
large anterior lobe
small posterior lobe
how is the large posterior lobe made up ?
purely glandular
made up of secretory cells
how is the small posterior lobe made up ?
it develops from the base of the brain
made mainly of neurons
what are the hormones that the anterior lobe secretes ?
STH
TSH
ACTH
FSH
LH
ICSH
prolactin
growth hormone / STH
somatrophic hormone
promotes skeletal/ muscular growth
( stimulates the synthesis of proteins )
TSH/ thyroid stimulating hormone
TSH stimulates the thyroid gland to secrete thyroxin
ACTH/ adrenocorticotrophic hormone
ACTH stimulates the adrenal cortex to secrete
cortisone + aldosterone
FSH/ follicle stimulating hormone
in females - stimulates oogenesis in ovaries
(formation of eggs in the ova)
in males - stimulates spermatogenesis in testes
(sperm formation)
LH/ lutenizing hormone
in females - stimulates ovulation
release of an egg from ovary
ICSH/ interstitial cell stimulating hormone
chemically similar to LH
produced in males to stimulate testes to secrete testosterone
prolactin
stimulates the production of milk
in the female mammary glands after the birth of the baby as long as baby continues to suckle
responsible for maternal instinct
what are the growth disorders?
hypersecretion
hyposecretion
what is hypersecretion of growth hormone ?
overdevelopment of skeleton (tall stature)
condition: gigantism
caused by tumor in the pituitary gland
extremely rare
what is different about hypersecretion in adults ?
enlarged hands, jawbone + brows
(terminal skeletal structure)
condition: acromegaly
in adults, bones only thicken
as growth points in the long bones are no longer active
what is hyposecretion of growth hormone ?
underdevelopment of the skeleton (short stature)
condition: pituitary dwarfism
causes by disease in the anterior lobe of pituitary
what are the effects of hyposecretion?
height is reduced
body proportions are normal
not mentally retarded
sexually immature
how can hyposecretion be treated ?
can be treated by injections of synthetic growth hormone (STH)
produced by genetically engineered bacteria
what are the two types of dwarfism?
pituitary dwarfism-
lack of growth hormone
perfectly proportion
small, midge
defective gene-
a dwarf looks malformed
arms/legs are short vs torso/head normal size
what happens in the posterior lobe ?
osmoreceptors in the hypothalamus detect an increase in osmolarity of blood
nerve impulses stimulate the posterior lobe to release ADH
what is the role of ADH in the posterior lobe ?
help to conserve water if body is dehydrated
by causing more water to be reabsorbed back into the blood from the collecting ducts of the kidneys
(less water lost in urine)
what are the occurring disorders related to the pituitary lobe ?
diabetes insipidus -
lack of ADH secretion
condition characterised by the loss of large quantities of dilute urine
5-10L per day
