The Pituatary Adrenal Axis (week 2) Flashcards
what class of hormones does cortisol belong
Glucocorticoid
Where is cortisol synthesised
The adrenal cortex
What is the adrenal gland
It is a hybrid gland consisting of a cortex and a medulla. The hormones of the adrenal gland are important regulators of metabolism and serve an important role in adaptation of stress
What can a deficiency in cortisol result in
Hypoglycaemia (level of glucose in the blood drops below what is normal)
Why are synthetic analogs widely used in the treatment of disorders ranging from skin rashes to arthritis
Because of the anti-inflammatory and immunosuppressive actions of adrenal corticosteroids
What is aldosterone and what does it do
It is a mineralcorticoid and it promotes salt and water retention by the kidney, it is critical for salt/water balance
Where is the adrenal gland located
On top of both kidneys
What else does the adrenal cortex synthesise and secrete
Androgenic steroids which may be converted by peripheral tissue to testosterone
Where are chromaffin cells located and what do they secrete
They are located in the medulla and secrete epinephrine which are catechlomines
What are the 3 parts of the adrenal cortex and what do they secrete
Zona glomerulosa -aldosterone
Zona fasciculata- cortisol
Zona reticularis- weak androgens
These are all steroid hormones
How is the adrenal medulla signalled
Nerve impulses
How is the adrenal cortex signalled
Hormonal signals
What are the effects of epinephrine and norepinephrine
Glycogen gets broken down to glucose; increased blood glucose
Increased blood pressure
Increased breathing rate
Increased metabolic rate
Change in blood flow patterns, leading to increased alertness
What are the effects of mineralcorticoids
Retention of sodium ions and water by kidneys
Increased volume and blood pressure
What are the effects of glucocorticoids
Proteins and fats broken down and converted to glucose
Partial suppression of the immune system
Where do all steroid hormones derive from
Cholesterol and differ only in the ring structure and side chains attached to it
All steroid hormones are lipid soluble, what does this mean
They are freely permeable to membranes so are not stored in cells; they leave cells shortly after synthesis
Steroid hormones are carried in the blood to specific binding globulins, give an example
Corticosteroid binding globulin transports cortisol
Where are enzymes that produce steroid hormones from cholesterol located
In the mitochondria and SmER
How is cholesterol converted into all other steroid hormones
A series of enzymatic steps in the mitochondria and Er of steroidogenic tissues
What is the rate limiting step in steroid hormone synthesis and hou is it carried out
The transport of free cholesterol from the cytoplasm into mitochondria, carried out by the steroidogenic acute regulatory protein (star) moving cholesterol from the over membrane to the inner membrane
What is cholesterol converted into before it becomes a steroid hormone
Pregnenolone
What de the three steroid hormones that can be made from prognenolone
Mineralcorticoids (aldosterone)
Glucocorticoids (cortisol)
Androstenedione
What determines which pathway is taken
Each step of the pathway is regulated by a specific enzyme.
Different zones of the adrenal cortex have different relative activities of enzymes, resulting in different chemical reactions
