Pituarity And Adrenal Glands Flashcards
(23 cards)
Where is the pitaurity gland located?
At the base of brain, and is suspended from the hypothalamus by a stalk.
What are the features of the blood supply to the pituarity gland?
It has a portal suste, (where there is a vessel connecting two capillary beds) one is in the hypothalamus and one is in the anterior pituarity. It is also supplied by the internal carotid artery , directly by the superior and inferior nypoissed arteries.
How does the pitaury gland develop?
There is a fusion of cells from the primitive pharynx (which forms the anterior lobe) and a down growth of neural tissue from the hypothalamus that forms the posterior lobe.
What are the parts the adrenal gland is split into?
A connective tissue capusle, then a cortex and then a medulla
What are the 3 areas of the a rdrenal cortex and the hormones they are responsible for producing?
The zona glomerulosa, ( secretes minerocorticoids ), the zona fasiculta which produces glucocorticoids and the zona reticularis which secrete glucortocids and a small amount of androgens.
What does the adrenal medulla produce?
Adrenaline
How is the secretion of cortisol controlled?
Adrencorticotropic hormone is released from anterior pituaruty, which is under the control of corticotropin realising factor that is released from the hypothalamus, and the release of this is triggered by chemical triggers such as hypoglycaemia, physical triggers such as temperature and pain and some level of negative feedback on the pituarity and hypothalamus.
What are sp,e key features of the hormone ACTH?
It is a 39 amino acid single chain polypeptide, with a short half life in circulation, is hydrophilic and so connects with high affinity receptors on the plasma membrane of target cells, is synthesised from propiomelanoccortin (pomc) which is a 250 amino acid molecule and it undergoes post translational modification.
Whtat is the mechanism of action of corrisol?
As a steriod hormome it passes through the plama membrane and binds cytoplasmic receptors, it enters the nucleus and interacts with a specific region of plasma DNA proteins, changes the rate of gene transcription.
What are some of the actions of cortisol on a cell?
There is a decrease in amino acid uptake and protein synthesis, an increase in proteolysis and an increase in hepatic gluconeognesis and glycogenlysis, an increase in lipolysis in adipose tissue and a decrease in peripheral uptake of glucose and insulin.
What are the actions of adrenaline?
Increase in cardiac output and blood supply to muscles, increase in motor attention, increased gluconeogensis and glycogenlysis in muscle snd a increase f lipolysis in adipose tissue.
What bones are the pituarity gland surrounded by?
In the deep recesses of the spehoid bone ( the pitaurity fossa), surrounded by a small bone cavity ( the sella turcia).
What is congenital adrenal hyperplasia?
This is caused by a defect in enzymes that synthesise cortisol. Leading to hyperplasia and enlargement of the adrenal cortex.
What causes addissions disease?
Decreased activity of the adrenal cortex, either autoimmune destruction that causes a decrease in the release of gluccocrtocods and mineralocorticoids, or a problem in the pituarity which affects glucocortcoids only.
What are the clinical affects on addissions?
Increase pigmentation, due to melanocyte stimulation by ACTH, decreased blood pressure due to sodium, hypoglycaemic episodes on fasting, non specific symptoms such as tiredness, muscle pain, anorexia, weight loss, extreme muscular weakness and dehydration.
What are the causes of cushings syndrome?
Over secretion of cortisol, Disorders in secretion, ectopic secretion of ACTH, or pituarity adrenal cortex.
What are the clnical affects of excessive cortisol secretion?
Immunosuppression of inflammatory and antiallergic reactions, purple striae due to catabolic affects on skin and easy bruising, increase in lipogenesis, deposition of fat in the abdomen neck and face p, mon shaped face and central weight gain, muscle proteolysis and wasting of proximal muscles to give thin arms and legs, and increased proteolysis and gluconeogensis can lead to hyperglycaemia, polydipisia and polyuria.
What can precipitate an addission crisis and how would you treat it?
It is precpitated by extreme stress and you would teat with intravenous cortisol and fluids, to help avoid patient death.
What is the dexamethanisone test?
Dexamethasome suppression of plasma cortisol by greater than 50% is indicative of cushings, (is a synthetic steroid), as the pitaurity gland has become relatively insenstised but can still be affected by strong steroids.
What is a suthacen test?
This would naturally increase plasma cortisol by 200mg, and a normal response would help exclude addissions.
What does aldestrone do?
na+ reabsorption in the kidneys in exchange k+, and over excretion can lead to hypertension.
What do androgens do?
These are the male hormones, and encourage the growing of the male gential tract, contributing to height, body shape and body hair.
What does oestrogen do?
Causes development of the female genital tract, is partly anabolic and an increase in criculating cholestrol
