Steroid Hormones Flashcards
(17 cards)
Where is the adrenal gland located?
Above the kidney
What gland produces steroid hormones?
The adrenal gland
What part of the adrenal gland produces steroid hormones?
The adrenal cortex
What type of steroid hormones does the G zone of the adrenal cortex produce and what do they effect?
Mineralcorticoids e.g aldosterone, effect salt and water balance
What type of steroid hormones does the F zone of the adrenal cortex produce and what do they effect?
Glucocorticoids e.g cortisol, effect glucose metabolism, blood pressure, immune system
What type of steroid hormones does the R zone of the adrenal cortex produce?
Androgens (sex hormones)
What layer of the adrenal cortex produces aldosterone?
Zona glomerulosa
What is the action of aldosterone?
Stimulates Na+ reabsorption from the distal convoluted tubules of the kidney in exchange for K+ or H+
Describe the synthesis of aldosterone.
Renin-angiotensin system: renin cleaves angiotensinogen in the plasma to angiotensin 1, which is converted to angiotensin II in the lungs by converting enzyme, which acts on the adrenal gland to synthesize aldosterone
What system controls the synthesis of aldosterone?
The Renin-angiotensin system (RAAS)
What stimuli signal the release of renin from the kidney to ultimately cause the synthesis of aldosterone?
- Decreased renal perfusion pressure
- Na+ loss or restriction
- Neural stimuli
What stimuli signal the adrenal gland to produce aldosterone?
Angiotensin II, ACTH, and raised plasma K+
What is the general action of cortisol?
Regulates carbohydrate, protein, and lipid metabolism
What are the 4 metabolic effects of cortisol?
- Catabolic - protein breakdown in muscle
- Catabolic - lipolysis in adipose tissue
- Immune system - suppresses function
- Anabolic - gluconeogenesis in the liver
How does cortisol increase blood glucose?
Stimulates gluconeogenesis in the liver by increasing sysnthesis of enzymes involved in gluconeogenesis
Describe the different cortisol binding proteins.
80% of cortisol is bound to cortisol binding globulin which has low capacity but high affinity
15% of cortisol is bound to albumin which has high capacity but low affinity
5-10% of cortisol is free and biologically active
Describe the capacity of cortisol binding globulin?
Low capacity but high affinity = once capacity is full then free cortisol builds up in the plasma
