Endocrine 2: Hormones and the Hypothalamus Flashcards
the mechanism of thyroxine is a ___feedback loop
negative
when thyroxine is high in the blood, negative feedback is sent to the brain which stops the production of ___ and therefor stops the production of thyroxine
RH
when iodine is completely absent from the diet, ___ cannot be made
thyroxine
what causes a Goiter?
iodine not present in the blood so thyroxine cannot be made, so when the pituitary continues to secrete TSH, it builds up and forms the loiter
breastfeeding is a ____feedback loop that will result in the continuous secretion of ____ until the baby stops feeding
positive; oxytocin
where is the hypothalamus located?
at the base of the brain, just below the thalamus and above the pituitary
the hypothalamus is attached to the pituitary by the __
infundibulum
the _____ senses any unbalance in the body and secretes hormones into the blood to maintain homeostsatisi
hypothalamus
there are two groups of ____ cells in the hypothalamus
neuroendocrine
stimulating and inhibitory hormones are secreted by the ___ pituitary
anterior
anti-diuretic hormone and oxytocin are secreted by the ___ pituitary
posterior
the anterior and posterior pituitary secrete hormones in response to
signals from the hypothalamus
the anterior pituitary is also called the ___
Adenhypophysis
the posterior pituitary is also called the ___
neurohypophysis
secretion from the anterior pituitary is controlled by the ___ hormones secreted by the hypothalamus and reach the pituitary through the ____ vessels
hypothalamic releasing and inhibitory; portal
secretion from the posterior pituitary is controlled by ___ that start in the hypothalamus and terminate in the posterior pituitary
nerve signals
between the two lobes of the pituitary, there is a small vascular zone called the ___
pars intermedia
the pars intermedia is almost ___ in humans, but is much more ___ in other animals
absent; large/functional
t/f the two lobes of the pituitary secrete different hormones and have different functions
t
the ____ pituitary is vital to fertility and contributes significantly to a variety of critical functions ranging from growth and development to general well being
anterior
the ___ pituitary is important for the body osmoregulation and breastfeeding
posterior
the ___ pituitary is often referred to as the master gland bc it controls the activity of most other hormone-secreting glands
anterior
the posterior pituitary is actually an extension of the ___ of the hypothalamus
neurosecretory cells
the cell bodies of the neurosecretory cells rest in the __ and their axons can be found in the ___
hypothalamus; posterior pituitary
does the posterior pituitary make hormones?
no!
the function of the posterior pituitary is to store and release 2 neurohormones that act on ___ target tissues
non-endocrine
what are the 2 neurohormones secreted by the posterior pituitary?
antidiuretic hormone, oxytocin
what is the function of the ADH?
acts on kidney to promote water reabsorption
what is the function of oxytocin?
stimulates smooth muscle contractions in uterine and mammary tissue regulate labor and milk production and letting
plasma osmolarity is maintained within a narrow range by employing mechanisms that regulate both ___ and ___
water intake and output
____ sense changes in plasma osmolarity and changes of ___mOsm/kg induce action
hypothalamic osmoreceptors; 2-3
the control os plasma osmolarity involves control of the blood water level, which is secrete by the __ hormone
antidiuretic
control of hormone synthesis in the hypothalamus is at the level of ___
gene transcription
what is the hormonal response to thirst?
hypothalamic osmoreceptors stimulate secretion of ADHand turn on gene machine to increase ADH expression on mRNA in magnocellular neurons
ADH hormones are first made as large ___, then are enzymatically processed to produce the ___ and 2 ___
preprohormones; mature hormone and 2 byproducts
what ae the 2 byproducts of ADH synthesis?
neurophysin and glycopeptide
the mature form of ADH is transported by ___ to the posterior pituitary along ___ tracks
neurosecretory vesicles; microtubule
ADH vesicle transport increases when synthesis is ___ and stops when stimulus is __
stimulated; removed
ADH activates ____receptors, leading to ____mediated activation of __, which will phosphorylate ___and lead to their insertion in the cell membrane
V2 GPCR; cAMP; PKA; Aquaporin 2
what is the function of inserting AQ2 channels in the cell membrane ?
reabsorb water
tropic neurohormones are carried from the hypothalamus to the anterior pituitary by ___
portal vessels
tropic hormones from the hypothalamus act on ___ cells in the anterior pituitary which will then release ___ into a second set of capillaries for distribution through the body
endocrine; peptides
what are the 5 types of cells that secrete hormones in the anterior pituitary and what are the hormones they secrete? and what % of AP cells are they?
- somatotropes–> human growth hormone (GH) 30-40%
- thyrotropes–>TSH 3-5%
- Corticotropes–> adrenocorticotropin hormone (ACTH) 20%
- gonadotropes –> gonadotropic hormones (LH, FSH)
- lactotropes –> prolactin (PRL) 3-5%
with the exception of ____, all anterior pituitary hormones are collectively referred to as tropic hormones bc they turn on/off the function of other hormones
GH
which AP hormone is not tropic?
GH
all AP hormones act on ____ receptors except GH
GPCR
the GH is also called ___ or ____
somatotropin hormone; somatotropin
GH is a small protein of around ___aa
200
unlike tropic hormones, GH does not function on a ___, but rather exerts its effects by ___
acting directly on all (or almost) tissues of the body
GH also acts through an intermediate substance called ___ or ___
insulin-like growth factor or somatomedin
which of the 2 (GH/IGF) attaches weakly to transporters for a short time and which attaches strongly for a long time?
GH weak and short, IGF strong and long
IGF-1 is activated by ___ and supports the ___, ___ and ___ of many tissues, ranging from muscle and immune cells to nervous and immune systems
GH; bioenergetic prossesses, metabolism, and growth
IGF-1 regulates GH through negative feedback loops at the level of the ___, where it activates the release __
hypothalamus; growth hormone inhibitory hormone (GHIH)
GH binds to GH receptors which undergo___ and then interact with ___ that activate the receptor by the phosphorylation of ___ on GH receptors
dimerization; janus kinase (JAK), tyrosine residues
the GH JAK complex interacts with the ____- that gets phosphorylated by JAK causing its dimerization and movement into the nucleus where it induces the transcription and production of ___
signal transducer and activator of transcription (STAT); IGF-1
list some things that may cause abnormalities in GH secretion
GH deficiency, GH receptor mutation, IGF deficiency, IGF receptor mutation, TH deficiency, insulin/insulin receptor defects, nutrition deficiency
hyper secretion of GH before puberty causes
giantism
hyper secretion fo GH acter puberty causes
acromegaly
what is the treatment for hypersecetion of GH?
somatostatin analogues (Octreotide)
