12 The Adrenal Glands Flashcards
What are the sections of the adrenal cortex?
Zona glomerulosa
Zona fasiculata
Zona reticularis
What is released from the Zona glomerulosa?
Mineralcorticoids
E.g. aldosterone
What does the Zona fasiculata release?
Glucocorticoids
E.g. CORTISOL, corticosterone, cortisone
What does the Zona reticularis release?
Glucocorticoids + Androgens-sex hormones
How are steroid hormones synthesised?
From cholesterol
In adrenal glands and gonads
Are steroid hormones lipid or water soluble?
Lipid soluble
Adrenal gland structure
Capsule
Cortex
Medulla
What cells produce adrenaline and nor adrenaline?
Chromaffin cells
What hormones are released in the medulla?
Adrenaline
Noradrenaline
How to remember what is secreted by the layers of the cortex?
The deeper you go the sweeter it gets
Salt sugar sex
What is the main glucocorticoid?
Cortisol
What do steroid hormones regulate?
Gene transcription
What is aldosterone and where is it released form?
Mineralcorticoid
Zona glomerulosa - outer layer of cortex
How is aldosterone transported?
Steroid hormone so by carrier proteins:
Serum albumin mainly
Transcortin
Aldosterone function
- regulation of plasma Na+, K+
- regulation of arterial BP
- promotes expression of Na+/K+ pump - NA+ in, K+ out - influences water retention, blood volume and BP
How does aldosterone exert its actions?
Regulating gene transcription
Actions of angiotensin II
- vasoconstriction
- stimulation of adrenal cortex - aldosterone released causing increased expression of Na+/K+ so increased water reabsorption
- stimulation of posterior pituitary - ADH released causing more aquaporins in nephron so increased water reabsorption
How is cortisol transported?
Carrier protein- transcortin
How does cortisol exert its actions?
Regulating gene transcription
Actions of cortisol
- increased protein breakdown in muscles
- increased lipolysis in fats
- increased gluconeogensis in liver
- resistance to stress
- anti-inflammatory effects
- depression of immune response
Effects of glucocorticoids on metabolism
- increased glucose production (in liver)
- breakdown of protein (in muscle)
- redistribution of fat
Effects of cortisol in liver
- increased gluconeogensis
- increased glycogen storage due to increased glucose production
Effects of cortisol of muscle
What does it inhibit?
Increased protein degradation
Inhibits insulin induced GLUT 4 translocation - prevents glucose uptake
Where is the GLUT 4 transporter found?
Striated muscle and adipose
Effects of cortisol on adipose
Increased lypolysis
Decreased glucose utilisation
What is the only source of oestrogen for women after menopause?
Adrenal androgens converted in oestrogen
What do chromaffin cels act as?
Postganglionic nerve fibres
What do chromaffin cells lack?
Axons
Hormonal action of adrenaline on the heart, lungs + blood vessels including the receptors involved
Heart - increased HR and contractibility (B1)
Lungs - bronchodilation (B2)
Blood vessels - vasoconstriction in high level (a1) + vasodilation in circulating level (B2)
How to remember which receptors are in heart and lungs
1 heart 2 lungs
Heart B1
Lungs B2
How is noradrenaline converted to adrenaline
Enzyme N-methyl transferase
What is POMC a precursor of?
a-MSH
ACTH
B-endorphins
Outline QISS receptors
- Q : a1: stimulates DAG + IP3
- I : a2: inhibits adenylyl cyclase > reduces cAMP + PKA
- S : B1: activates adenylyl cyclase > increases cAMP > activates PKA
- S : B2: activates adenylyl cyclase > increases cAMP > activates PKA
