Week 8 - Adrenal

Question 1

What are the roles of the adrenal cortex and the adrenal medulla?

Answer 1

Adrenal cortex = produces steroid hormones

Adrenal medulla = catecholamine secretion

Question 2

What is the structure of the adrenal gland?

Answer 2

• Capsulated
• 3 layered outer cortex
  
  • Zona glomerulosa
  • Zona fasiculata
  • Zona reticularis
• Inner medulla
  
  • Secretion under SNS control

Question 3

Is this a steroid-secreting cell or peptide-secreting cell?

Why?

Answer 3

Steroid-secreting cell

• Has smooth ER
• Has lipid droplets
• Has tubular cristae in mitochondria

Question 4

Is this a steroid-secreting cell or peptide-secreting cell?

Why?

Answer 4

Peptide-secreting cell

• Has RER and Golgi
• Has granules
• Has normal mitochondria

Question 5

What is the innervation of the adrenal medulla?

How does it act?

Answer 5

Sympathetic innervation = sympathetic ganglion

• Secretion = controlled by preganglionic neurons
• Quick release
• Act on adrenergic receptors

Question 6

What are the pathology of adrenal gland?

Answer 6

• Hypoadrenalism
  
  • Addison’s disease
• Hyperadrenalism
  
  • Conn’s syndrome, Cushing’s syndrome, malignant tumour, ectopic syndrome, neuroendocrine lung tumour
• Phaeochromocytoma
  
  • Benign adrenal tumour, neuroectodermal origin
  • • catecholamine oroductino = hypertension

Question 7

What are the symptoms and diagnosis of phaechromocytoma?

Answer 7

Symptoms:

• Headaches
• • sweating
• Palpitations

Diagnosis = urinary catecholamines or metabolites

Question 8

What is the rate-limiting step of steroidgenesis?

Answer 8

Transport of cholesterol from outer to inner mitochondrial membrane

Question 9

What is produced by each of the zona glomerulosa, zona fasciculata, and zona reticularis?

Answer 9

Zona glomerulosa = aldosterone

Zona fasciculata = cortisol

Zone reticularis = androstenedione (testosterone i.e.)

Question 10

How do the steroid hormones aldosterone and androgens act on target cells?

Answer 10

Aldosterone = act on DCT and Cd, promoting Na+ reabsorption and K+ elimination during urine formation (SECRETION STIMULATED BY + K+ CONC. AND RAA)

Androgens = secretion starts age 5-6, + in women, regulated by ACTH

Require transportation via plasma protein carriers

Question 11

What are the metbaolic actions of cortisol?

Answer 11

• Stress hormone
• Elevate ACTH levels
• AVP and CRH action
• Affects sleep / wake cycle
• • in morning, - in evening
• Catabolic in muscle and adipose
• Stimulate gluconeogenesis and glycogen storage in liver
• Inhibit glucose uptake, + glucose production
• Counter-regulation against insulin

Question 12

What are the anti-inflammatory/ immunosppressive effects of cortisol?

Answer 12

• Stimulate lipocortin 1 production = no prostanoids or leukotrienes
• • number and activation of T-lymphocytes
• • cytokine production
• Stabilises lysosomes
• Decrease in NO production

Question 13

What is the role of cortisol in the stress response?

Answer 13

+ CV tone

+ glucose availability

• energy consuming activities

SNS response

Question 14

What are the implications of prolonged elevated cortisol levels?

Answer 14

• Muscle wasting
• Hyperglycaemia
• GI ulcers
• Impaired immune response

Question 15

What is Cushing’s syndrome and what are the primary and secondary causes?

Answer 15

Excessive glucocorticoid activity

Endogenous or exogenouse (Ex = + use of glucocorticoids)

• Primary = adrenal carcinoma or adenoma
  
  • • Negative feedback = + cortisol, - ACTH
• Secondary = pituitary or ectopic ACTH-secreting tumour
  
  • • Tumour cells have impaired negative feedback response

Question 16

What are the symptoms of Cushing’s syndrome and causes of each?

Answer 16

• Truncal obesity and red round face (altered fat deposition)
• Female frontal balding, hirsutism, menstrual irregularities (excessive adrenal androgen production)
• Testicular atrophy, thin arms + legs, muscle weakness, thin skin, purple striae (breakdown of protein)
• Poor wound healing, easy bruising, skin infections (collagen loss)
• Cognitive difficulties, emotional instability, depression, sleep distrubance (mental changes)
• Osteoporosis, hypertension, diabetes (altered bone metabolism, insulin resistance)
• Growth retardation in children

Question 17

How do you diagnose Cushing’s syndrome?

Answer 17

• Cortisol measurements
  
  • • plasma cortisol = Cushing’s
• Tests of loss of diurnal cortisol rhythm
• ACTH levels distinguish primary from secondary
• Dynamic tests
  
  • Suppression test

Question 18

How do you treat Cushing’s disease?

Answer 18

• Localisation of tumour
• Surgery or radiotherapy
• Drugs to inhibit steroidgenesis