L6 Adrenal Cortex Physiology Flashcards
Name a glucocorticoids
Cortisol
Name a Mineralocorticoids
Aldosterone
What does cholesterol go on to form [3]
Aldosterone
Cortisol
Testosterone
What can stimulate the secretion of ACTH?
stress
How are steroids secreted if they are not water soluble?
in the liver, they are glucuronidated to form water soluble forms which are then excreted in the urine
What does cortisol do?
Cortisol opposite to insulin, i.e.
- Antagonizes the effects of insulin on cellular uptake of glucose
- Stimulates glycogenolysis
- Stimulates hepatic gluconeogenesis.
- stimulate lipolysis
- in excess, fat synthesis in novel sites
- vasoconstriction
How do Glucocorticoids influence defence systems
immunosuppresion
suppress lymphoid tissue, so reduce antibody production
stabilize leucocyte membranes and reduce the release of proteolytic enzymes
they inhibit phospholipase A2 and reduce synthesis of the inflammatory mediators
How does aldosterone influence sodium concentration?
stimulates the reabsorption of sodium ions in the distal tubule of the kidney, with some lesser effects in the collecting duct, proximal tubule and ascending loop of Henlé, and in the colon, sweat and salivary glands.
What are Mineralocorticoids used for?
-give an example
only for replacement therapy
due to its short plasma half-life
-fludrocortisol
E.g Addisons
Name 3 adverse effects of steroid hormones
- suppress wound healing and exacerbate infections due to their immunosuppresant effects.
- Long term use in children may inhibit growth, and in adults may result in osteoporosis.
- The development of diabetes mellitus and other symptoms of Cushing’s syndrome also often accompanies steroid therapy.
What is the effect of steroids on HPA
Suppresses HPA
adrenal cortex atrophies due to lack of ACTH
Hydrocortisone (Cortisol)
CORE DRUG
- secreted by adrenal cortex
- influence gene expression
- hormone replacement theory
- anti-inflammatory agent
good oral bioavailability
side effects include hyperglycaemia, osteroporosis and Cushings
What happens to the cortisol levels in pregnant women?
increase in SBG so increase in circulating plasma cortisol concentration to compensate for this
the amount of free cortisol remains the same
In general terms, how do steroids work?
because they are lipid soluble they exert their effects by acting on intracellular receptors and therefore altering gene expression
this means there is a delay up to hours/days
How does cortisol act in the liver?
Stimulates amino acid uptake leading to enhanced gluconeogenesis
