Normal adrenal function: adrenal gland and steroid hormones

what is the outer adrenal cortex derived from

• mesoderm

what is the role of the adrenal cortex

producing steroid hormones

what controls the adrenal medulla

anterior pituitary

what is the inner adrenal medulla derived from

neural crest

what is the role of adrenal medulla

consists of cells which secrete catecholamines

is adrenal medulla under neural or hormonal control

nervous control

what enzyme is foetal cortex responsive to

ACTH

what week of development are adrenals developped

week 20

what structures do neural crest cells form

• adrenal medulla

• ganglia

• melanocytes

• schwann cells

• meninges

• pharyngeal arch cartilage

• odontoblasts

• parafollicular c cells

• aorticopulmnary septum

• endocardial cushions

• fascial skeleton and other aspects of head

what substances are neural crest cells sensitive to

• alcohol

• retinoic acid

describe vasculature of adrenal gland

• one vein→ left adrenal vein and right adrenal vein

• three arteries→ inferior phrenic artery, aorta and left/right renal artery

what does left adrenal vein drain into

left renal vein

what does adrenal vein drain into

IVC

what does lymphatic drainage of adrenal gland drain into

para aortic nodes

describe nerve supply of adrenal gland

• myelinated preganglionic sympathetic fibres from splanchnic nerves via aortic and renal plexuses

what do myelinated preganglionic sympathetic fibres in adrenal gland synapse with

medullary cells

what are secreted from zona glomerulosa

mineralocorticoidsgi

give an example of a mineralocorticoid

aldosterone

what is secreted from zona fasciculata

glucocorticoids

give an example of a glucocorticoid

cortisol

what is secreted from zona reticularis

gonadocorticoids

give example of gonadocroticoids

androgens

what are the 3 section of adrenal cortex

• zona glomerulosa

• zona fasciculata

• zona reticularis

what are the 2 main parts of the adrenal gland

• cortex

• medulla

what is secreted from adrenal medulla

• adrenaline

• noradrenaline

what cells is the adrenal cortex composed of

• columnar of ovoid cells

describe structural feature of zona fasciculata

• sinusoids between columns of cells

describe structural feature of zona reticularis

• cells arranged in cords by sinusoids

what’s different about cells from adrenal medulla vs. cortex

• medullary cells exhibit chromaffin reaction

• contain cytoplasmic granules which are coloured brown by chromium salts

where do preganglionic fibres from splanchnic nerve pass to

cells of suprarenal medulla

what does activation of cells of suprarenal medulla cause

adrenaline released

how does vasomotor supply reach suprarenal gland

postganglionic fibres from regular relay in coeliac ganglion

what are adrenal steroid hormones derived from

cholesterol

where can cholesterol be obtained from

• blood as LDL

• synthesised de novo as needed (from acetyl Co-A)

what is the rate limiting step in steroidgenesis

transport of cholesterol from outer to inner mitochondrial membrane

what facilitates cholesterol movement from outer to inner mitochondrial membrane

steroidogenic acute regulatory protein (StAR)

where is aldosterone synthase found

zona glomerulosa

what hormones are involved in hypothalamus-pituitary-adrenal axis

• corticotropin-releasing hormone (CRH)

• adrenocorticotropic hormone (ACTH)

• cortisol

what is secretion of aldosterone stimulated by

raised [K+]

raised Angiotensin II

raised ACTH

what are androgens regulated by

ACTH

what can contribute to a stress stimulus

• emotional→ anxiety, fear

• Physiological→ pain, fever, hypoglycaemia, injury, fluid deprivation, surgery

what 2 hormones act synergistically to elevate ACTH levels

CRH and ADH

how is steroid hormone transported

in circulation bound to plasma proteins

effects of cortisol

• elevate plasma glucose levels

• anti-inflammatory/immunosuppressive effects

• role in adaptation to stress

how does cortisol have anti-inflammatory/immunosuppressive effects

• stimulate production of lipocortin→ inhibits PLA2 (generates arachidonic acid)

• decreased number and activation of T lymphocytes

• decreased production of cytokines

• stabilises lysosomes

• decreased NO production→ reduce vasodilation

anti-inflammatory uses of glucocorticoid analogues

• asthma, COPD

• ulcerative colitis, Crohn’s disease

• rheumatoid arthritis

• skin conditions