Adrenal glands Flashcards
Where do the adrenal glands lie in relation to the kidneys?
Supramedially
What are the 3 layers of the cortex and what do they all produce?
Zona glomerulosa
Zona fasiculata
Zona reticularis
All produce corticosteroids
What does the zona glomerulosa produce?
Mineralocorticoids eg aldosterone
What does the zona fasiculata produce?
Glucocorticoids eg cortisol
What does the zone reticularis produce?
Androgens (sex hormones) eg DHEA
What is the precursor for all corticosteroids?
Cholesterol
Properties of corticosteroids (4)
- lipid soluble - can pass through membranes
- bind specific intracellular receptors
- alter gene expression directly/ indirectly
- function is depended on specific shape
What does the adrenal medulla produce?
Catecholamines eg adrenaline, noradrenaline
What triggers release of aldosterone from the zona glomerulosa?
Renin release from the JGA in afferent arterioles of kidneys
Problems of the pituitary/hypothalamus WON’T affect the secretion of which hormone?
Aldosterone (kidney problems will)
What is stress? Give examples
Real/ perceived threat to homeostasis
eg physical trauma, shock, sleep deprivation
How does stress affect the body?
- Stress detected by hypothalamus - CRH released
- CRH carried by hypothalamic-hypophyseal portal vessles to ANT pituitary - ACTH hormone
- ACTH stimulates adrenal cortex to release cortisol
Cortisol has -ve feedback on CRH and ACTH production
How much cortisol is “free?”
5% is bioavailable
What hormone other than cortisol increases in response to stress?
Vasopressin (ADH)
Stimulates ANT pituitary to stimulate ACTH
What are the normal/ non-stress functions of cortisol?
Maintain homeostasis - blood glucose levels, dampen immune system, maintains bp
What are the stress functions of cortisol? (4)
- Metabolism
- Circulation
- Reduces inflammatory response
- Inhibits non-essential functions (growth & reproduction)
What type of androgens does the zona reticularis release?
Weak androgens eg DHEA and androstenedione
How are androgens made stronger?
Converted in the peripheral tissues
What regulates androgen production?
ACTH secreted by the ANT pituitary
What does the adrenal medulla produce?
Catecholamines (dependent on high cortisol levels - permissive effect)
What 3 catecholamines does the adrenal medulla produce?
- Adrenaline (80%)
- Noradrenaline (20%)
- Dopamine (small amounts)
What are actions of the sympathetic nervous system?
- increase gluconeogenesis
- increase lipolysis
- tachycardia
- redistribution of circulating volume
- increase lung ventilation
