Basic Functions of the Adrenal Gland Flashcards
What causes adrenal insufficiency?
- Glucocorticoid deficiency
- Mineralocorticoid deficiency
- Adrenal androgen deficiency
Can corticosteroids pass through membranes?
Yes, they are lipid soluble
What causes Cushing’s syndrome?
Excess glucocorticoid
Effect(s) of excess glucocorticoid on brain/CNS
- Depression
- Psychosis
Effect(s) of excess glucocorticoid on eyes
Glaucoma
Effect(s) of excess glucocorticoid on pituitary
- Decreased LH/FSH release
- Decreased TSH release
Effect(s) of excess glucocorticoid on GIT
Peptic ulcerations
Effect(s) of excess glucocorticoid on carb/lipid metabolism
- Hepatic glycogen deposition
- Peripheral insulin resistance
- Gluconeogenesis, diabetes
Effect(s) of excess glucocorticoid on adipose tissue distribution
Promotes visceral obesity
Effect(s) of excess glucocorticoid on cardiovascular/renal
- Salt and water retention
- Hypertension
Effect(s) of excess glucocorticoid on skin/muscle/connective tissue
- Protein catabolism/collagen breakdown
- Skin thinning
- Muscular atrophy
Effect(s) of excess glucocorticoid on bone and calcium metabolism
- Decreased bone formation
- Decreased bone mass, osteoporosis
Effect(s) of excess glucocorticoid on growth and development
Decreased linear growth
Effect(s) of excess glucocorticoid on immune system
- Anti-inflammatory action
- Immunosuppression
What percentage of glucocorticoids in circulation are bioavailable?
5%
What are glucocorticoids bound to in circulation (and what percentage bound to each)?
- Corticosteroid-binding globulin (CBG) (90%)
- Albumin (5%)
What happens to CBG levels with inflammation?
They decrease (so more glucocorticoid bioavailable)
What system regulates glucocorticoid synthesis?
Hypothalamic-pituitary-adrenal (HPA) axis
Sequence of the HPA axis
- Hypothalamus releases corticotropin-releasing hormone (CRH)
- Anterior pituitary releases adreno-corticotropic hormone (ACTH)
- Adrenal cortex releases cortisol
What factors cause stress?
- Infection
- Trauma
- Haemorrhage
- Medical illness
- Psychological
- Exercise/exhaustion
What are the main mineralocorticoids?
- Aldosterone
- DOC
What are mineralocorticoids critical to?
Salt and water balance in:
- Kidney
- Colon
- Pancreas
- Salivary glands
- Sweat glands
Why does cortisol need to be deactivated for aldosterone binding?
- The 2 bind the same receptor
- Cortisol has a much higher concentration so will swamp aldosterone
What is the deactivated form of cortisol and what enzyme converts it to that?
- Cortisone
- Enzyme = 11β-hydroxysteroid
What is the most abundant adrenal steroid?
Dehydroepiandrosterone (DHEA)
What are the main sources of androgens in men and women?
- Men = testicles
- Women = adrenal glands
What regulates adrenal androgen production?
ACTH
What is the main site of catecholamine synthesis?
Adrenal medulla
Percentages of different catecholamine productions
- Adrenaline = 80%
- Noradrenaline = 20%
- Dopamine = small amounts
What receptors do catecholamines act through?
Adrenergic receptors
Action(s) of catecholamines on CNS
Increased alertness
Action(s) of catecholamines on respiratory
Increased breathing rate
Action(s) of catecholamines on heart
- Increased contractility
- Increased blood pressure
- Increased heart rate
Action(s) of catecholamines on adipose tissue
Lipolysis
Action(s) of catecholamines on liver
- Gluconeogenesis
- Glucose release
Action(s) of catecholamines on muscles
Gluconeogenesis
