Pituitary and Hormones Flashcards
what 2 systems to the hypothalamus and pitutary gland link?
Nervous and Endocrine system
decribe the structure and location of the pitutary gland?
size of a pea and sits beaneath the hypothalamus in a socket of the bone at the base of the skull “sella turcica”
describe formation of each gland (embylogical origin)
-Anterior (adenohypophysis)
arises from oral ectoderm (Rathke’s Pouch), which is primitive gut tissue, it grows UP to meet the posterior pituatry gland.
-Posterior (Neaurphypohyis)
originated from the neuroactroderm. (primitive brain tissue)
which of the pituitary gland is not an actual gland? why?
Posterior (Neaurphypohyis) bc it doesn’t really make the hormones, it only STORES them
Describe the function of posterior and anterior pituitary glands and the routeof how their hormones r synthesized & released
Posterior Gland
Oxytocin & ADH r produced by neurosecretory cells in the
Supraoptic and paraventricular nuclei in hypothalamus, they r transported down the neurons into the posterior gland where they r STORED there.
Anterior gland
Hormones r made in hyothalamus
travel down axons & r stored in the Median eminence. (lower part of hypothalamus)
then theyre released into the Hypopheseal Portal system
these hormones then stimlaute the neurosecretory cells in the A. gland and these cells will talk to each other via paracrine or autocrine.
describe formation of each gland (embylogical origin)
-Anterior (adenohypophysis)
arises from oral ectoderm (Rathke’s Pouch), which is primitive gut tissue, it grows UP to meet the posterior pituatry gland.
-Posterior (Neaurphypohyis)
originated from the neuroactroderm. (primitive brain tissue)
where is ADH synthesized?
what is its function?
in neurosecretory cells in the hypothalamus (mostly supraoptic)
recepterd fro ADH r in the collecting duct of kidneys
what is a portal system?
linkage of 2 capillary beds
The hormones produced by nerve cells in the hypothalamus act via TWO distinct neurocrine pathways
describe them
Oxytocin & ADH released from hypothalamus> go to posterior> act on target tissues
Anterior shway 7osa….
Hormones secreted by the hypothalmu go down to the median eminence, then goes via the hypophyseal portal system then they STIMULATE the synthesis of the actual hormones in the Anterior lobe.
Hormones of the pOsterior and their function
Oxytocin> milk release & uterus contractions
ADH“vasopressin”> regulation of body water volume nad causes vasoconstriction too
REMInDER ALAA:
they r made in the supra and paracentricular nuclei of the hypothalamus, but stored in the Posterior gland.
ok?
what r tropic hormones?
Name the tropic hormones of the hypothalamus
Tropic hormones effect the release of other hormones in target tissue.
there r 7 in the hypothalmaus (which r stored in the median eminence) wich will effect the release of anterior pituatry hormones
TRH
PIH (dopamine)
PRH
CRH
GnRH
GHRH
GHIH (somatostatin)
these 7 hormones will leave the hyopothalamus and control the release of the 5 types of anterioir pituatry hormones
ALaa if u know ur anterior pitautry hormones, u know these!
what is another name for Dopamine?
PIH
which hormone is known as Somatostatin?
GHIH
what r the hormones of the Anterior pituatry glands?
what is the Pars intermedia
layer of cells located in btw the anterior and posterior lobe of the pitatury gland.
must know this alaa
ok
explain the Hypothalamic pitautry -adrenal axis with its feeback mechanisms! mention the triggers of release as well
ACTH can also inhibit hypothalamus too (short loop)
describe the terms
Hyperplasia
Atrophy
Hypertrophy
apoptosis
Hyperplasia> increase in cell #
Atrophy> decrese in cell size & #
Hypertrophy>increse in cell size
apoptosis> programmed cell death
is GH orally active? explain
No, because it is a protein and will be degraded.
Describe the role of GH in bone growth in kids and adults.
what is the epiphiseal plate?
epiphiseal plate: is a hyaline cartilage plate in the metaphysis at each end of a long bone. It is the part of a long bone where new bone growth takes place.
GH stimulates long bone growth
B4 epiphyseal closes= increases WIDTH & LENGTH of the bone
after epiphyseal closes= growth in WIDTH ONLY
what controls GH secretion?
when does it peak?
- main control is in hypothalamus via GHRH and GHIH (somatostatin)
- After onset of DEEP SLEEP
why is interuptted sleep in kids not good for them?
bc the levels of GH PEAK after onset of DEEP SLEEP.
so sleep is important for their growth
Pituatary tumors r Benign/malignant?
How do patients Clinically present?
what r the reasons that causes the symptoms?
Benign, they ain’t gunna kill ya
Either bc of the effect of the tumor mass on local structures
-Headache
-visual loss
OR
abnormality in pituitary function!
Hypo-hyper secretion
Explain the strucutres located around the pituitary gland.
Superiorly= optic chiasm
sides= Internal carotid artery, cavernous sinus
Inferiorly=
Describe what happens if u get an upwards growth of pituitary tumor?
Lateral growth?
up= it’ll squash the optic chiasm (where optic nerve cross over)= vision losss!
Bi-temporal heminopia
Lateral= effect nerves that control eye movement and pain
and cavernous sinus> they get 3rd nerve pasly and ptosis (droopy eye)
if u have a damage to ur pituary gland, what happens to your Prolactin levels?
goes up, bc usually the pituatry gland sends a negative control on prolactin.
so if its damaged> no negative control> high prolactin
when u get a pituatry tumor, what is the first hormone to be effected?
List in order the deficiencies in the hormones!
Growth hormone!
GH
LH/ FSH
TSH
ACTH
PRL
those with Gonadotropin deficiency, how to they present clinically? (men & women)
Men= got women feautures, no hair, wrinkly skin
Women= period stops ( women present earlier than men)
what happens if u get TSH and ACTH deficiency?
u get feautures of Hypo-thyrodism
cold,weight gain, tiredness, slow pulse, low T4 and non elevated TSH
Bc u need TSH>TRH> to stimulate thyroid hormone!
ACTH deficiency
low cortisol, tired, dizzy, low BP, low NA,
can be life threatening!
what things should u test for in pituatry disease?
Blood tests to check for hormones!
Thyroid axis
fT4, TSH
Gonadal axis
LH, FSH
testosterone - men
oestradiol - women
Prolactin axis
Serum prolactin
HPA axis
cortisol
GH axis
measure it throughout the day
measure it in response to GLUCOSE
bc it causes gluconeogenesis during hypogylcemia
when your hyperglycemic, GH levels______
drop
(opposite of insulin)
what procedure can u do to test for pituatry disease? (2)
MRI-magnetic resonance imaging
Assessing visual fields
when assessing someone with pituiatary disease, what 4 procedures/test do u do?
- -clinical*
- -biochemical*
- -Imaging*
- -Visual fields*
- -imaging-MRI*
- -visual fields*
if youve got a lesion in the pituaitary that sqaushes the optic chiasm, how will your vision look like?
Bitemporal heminopia
what r some pituitary tumour conditions? (4)
Prolactinoma
NFPA
acromegaly
cushing’s disease
what is the term used to describe a large tumour? small tumour? what size determines the names
Large tumour = macro-adenoma (> 1cm)
Small tumour = micro-adenoma (< 1cm)
the larger the tumour in the pituatary, the ______ the Prolactin levels.
Why?
what is this condition called?
treatment?
symptoms?
PROLACTINOMA-Hyperprolacinemia
HIGHER, bc there is a colonal proliferation of the lactotropes (cells producing prolactin) and so the more** the cells available, the **more prolactin is made.
Symptoms: (men present much later bc they dont have periods)
- amenorrhea (cessation of periods)
- Fertility problems
- Galactorrhoea (unexplained milk production)
- gynecomastia (hard breast tissue)
- erectile dysfunction
Treatment
TABLETS containing dopamine (Dopamine agonists)>it will shrink the prolactinoma
Bromocriptine & Cabergoline
NO OPERATION NEEDED
NEVER SEND A PATIENT FOR SURGERY UNTIL U FIND OUT WHAT THE PROLACTIN LEVELS R!
effects of dopamine?
inhbits prolactin
so DOPE ;)
inhibits milk (milk mu zain a9lan for u)
what is the condition used to describe someone with large extremities? what causes this? how do they present (symptoms)?
what r the long term complications?
Diagnosis?
Treatments?
Any therpies available?
Acromegaly
is a disorder that results from excess GH in adults
Clinical findings
Large extremeties: Hands, feet, lower Jaw
Deep voice, large tongue w/ deep furrows
diaphoresis (excessive sweating)
impaired glucose tolerance (insulin resistence)
Long term complications:
- CVS death
- increased colonic cancer
- increased risk of thyroid cancer
- hypertension
- Diabetes
Diagnosis
- Oral glucose tolerance test (OGTT) w/ GH response
(Give glucose>> GH will not supress>> “failure to supress”
- Elevated serum IGF-1 levels (insulin like Growth factor)
Treatment?
Surgical removal of tumor! “trans-sphenoidal hypophysectomy” from nose
Tumours in cavernous sinus>> need additional treatment
1) reduce GH secretion
Dopamine agonists
Somatostatin analogs (octeroides)
2) blocks GH recepter
Pigvesomant
Radiotherapy
external beam
Gamma knife
what is the Cavernous sinus?
is a true dural venous sinus creating a cavity bordered by the temporal bone of the skull and the sphenoid bone, lateral to the sella turcica.
What is cushings disease?
symptoms & findings?
Diagnosis?
Treatment?
Cushings>>Cortisol
increased cortisol
can be due to (ACTH-secreting pituitary tumour)
symptoms & findings
MOON face (we use cushion at night..lol)
Pink face, round abdomen
skinny weak arm and legs
thinning skin >Abdominal Striae (red stretch marks)
buffalo hump
Hypertension
Osteoporosis
describ ethese clinicnal findings, what can they be indication of?
Buffalo hump
Abdominal Striae (red strech marks)
Cushing disease!
cushings disease vs cushing syndrome
- *Cushing’s disease** is due to a pituitary tumour
- *Cushing’s syndrome** may be caused by other pathologies
Adrenal tumour, ectopic ACTH, steroid medication
what is the difference btw diabetes insipidous and diabetes Mellitus?
diabetes insipidous = caused by problems with a hormone called vasopressin (ADH). water is reabsorbed, pee alot!
pale”insipid” urine
diabetes Mellitus=occurs due to insulin resistance or insulin deficiency and subsequent high blood glucose levels.
“sweet urine”
Diabetes means “Siphon” is greek
it means water goes in (thirsty) and water goes out (pee alot)
just for fun guys
this is a siphon :P
coolio
what is diabetes insipidous?
r the 2 types of diabetes insipidous?
what r the consequences of untreated DI?
treatment?
Central diabetes insipidus
damage to the pituitary gland or hypothalamus. This damage disrupts the normal production, storage and release of ADH.
Nephrogenic diabetes insipidus
defect in the kidney tubules — This defect makes your kidneys unable to properly respond to ADH.
consequences of untreated DI
Severe dehydration
high Na levels (hyoernatremia)
reduce consciousness
coma & death
Treatment
Give Vasopressin (ADH) spray
How does vasopressin ADH work?
what inhibits it releases from the pitautry gland?
what controls the amount of ADH released?
it binds to Vasopressin recepter in kidneys
this facilittes TRASLOCATION of aquaporin channels allowing water reabsoeption into the blood.
Vasopressin= mean vasoconstrciton effects too on BV> ^ BP
OSMORECEPTERS in the hypothalamus detect changes in plasma osmolarity and control the amount of ADH released and thirst.
ALCOHOL
makes sense why drunk ppl wanna be so much ;p
IMPRTANT FACT:
Standard pituitary tumors only effect the anterior Pituitatary
so someone with a pituitary problem and theyve got diabetes insipidous (ADH problem), thats weird, there has to be something else going on!
cuz pituitary tumors only effect the anterior Pituitatary
could be due to other patholgy:
inflammation
infiltration
malignancy
what is a pituitary Apoplexy?
Clinical presentation? symtoms?
‘Apoplexy’ is the old-fashioned word for stroke
Sudden vascular event in a pituitary tumour
Bleeding within tumour ‘haemorrhage’
Blood supply cut off ‘infarction’
Clinical presentation
- sudden onset Headache
- double vision (3rd nerve palsy)
- Visual feild loss
- hypopituitarism (cortisol deficiency!)
what triggers oxytocin release?
suckling of breast> neurons from breast to hypothalamus> oxytocin released>gors to oxytocin recepters on myoepithelial cells surroundong mammalary alveoli>causes them to contract> squeeze milk into duct system.
childbirth>pressure on cervix and uterine wall> neurons to hypothlalamus>oxytoxin release> same shit but on uterine smooth muscle cells.
***Syntheic oxytocin (pitocin) is usually given after birth to increase uterine tone and control bleeding.***
Functions of prolactin
how is is regualted?
initiate and maintain lactation and prolactin secretion from lactotroped in the anterior pitautry
via PRH & PIH
BUT PIH (dopamine) DOMINATES THE MOST
where exactly r the posterior hormones made?
ADH>> Supraoptic nucleus
Oxytocin>> paraventricular nucleus
nucleus in the hypothalamus
(ADH is super alaa! cuz its the one used the most!) get it? supra? super? haha no.
which one has a longer half life and why?
GH or Somatomedians?
SM bc it is bound more tightly with the Plasma protein, making it survive longer in the circulation!
unlike GH which bind weakly
How is GH secreted?
How is its secretion regulated or controlled?
GHRH released from the hypothalamus and stimulates the anterior pitutary somatotrope cells to release GH.
1) it is regulated metabolically by plasma Glucose and FFA.
Decrease in glucose or FFA= MORE GH SECRETION
2) CNS= via inputs into the hypothalamus effecting GHRH and somatosatin levels
(remember lalls, GH 3aks insulin ok?)
______released from the hypothalamus stimulates release of GH
______released from the hypothalamus inhibits release of GH
GHRH
GHIH (somatostatin)
Is GH orally active? why?
No, bc its a protein, and it’ll be degraded by peptidases!
ex: insulin
explain the long loop & short loop feedback mechanisms involved in the regulation of GH. and explain what mediates each loop?
describe how GH exerts its effects on cells both Directly and indirectly through Insulin -like Growth factors?
describe the types of IGF’s? where r they mainly produced? which one is mediates the majority of the effects in adutls? what is the function of each
GH act directly through its own recepter, or indirectly through induced production of IGF-1.
GH bind to GH “cytokine recepter”, this is then coupled w/ intracellular enzymes “JAK” Janus kinases. this phosphorylates target proteins.
1) activates transcription factor>turns on production of IGFs, go to bloodstream bound to pp, and act on target cells, IGFs act through IGF receptors (distinct from GH receptors) to modulate:
- Cell growth (Hypertrophy)
- Cell number (Hyperplasia)
- Increase in the rate of protein synthesis
- Increase in the rate of lipolysis in adipose tissue (fat)
Decrease in glucose uptake
2 forms:
IGF-1 & IGF-2 >>mainly in liver and skeletal muscle
(also other tissues like bone, kindey, CNS)
- IGF-1>>majority of the effects in adults
- IGF-2>>crucial during Growth and development B4 birth
what happens if u have excess of GH in kids and adults?
Kids>> gigantism (rare, caused mostly by pituatry adenoma)
Adults>> acromegaly (large extremeties)
what happens if u have GH deficiency as a kid? how can this be treated?
in childhood it results in>> pituatry Dwarfism
height below the 3rd percentile!
this will result in delayed or no sexual development in teen yrs
responds well to GH supplements!
fucntions of GH in kids and adults?
1) KIDS>> stimulates Long bone growth
length and width>> b4 epiphiseal plate closes
Width only!>> after epiphiseal plates close
2) ADULTS>> helps maintain muscle and bone mass + promotes healing and tissue repair and modulates metabolism and body composition
***Epiphyseal plates “growth plate” >>is a hyaline cartilage plate in the metaphysis at each end of a long bone.is the area of growth in LENGTH in a long bone.
functions of cortisol!
- stimulates Gluconeogeneis
- bind to recepters on fat cells
- Supresses immune system
- increases liver pp
- depresses cartilgae and bone fomrmation
Adrenal gland hormones?
what term is used to describe a sudden vascular event (bleeding into or impaired blood supply) in a pituitary tumour?
Pituitary apoplexy!
role of LH in men
acts on Leydig cells of the testis>> control production of testosterone!
name procedure that can be used to remove pituatry tumor by inserting an endoscope through the nose
transsphenoidal surgery
