7.7 Adrenal Glands, Adrenaline & Cortisol Flashcards
What TYPE of hormones does the adrenal cortex produce? What about the adrenal medulla?
Cortex: Steroid (Androgens, Glucocorticoids, Mineralocorticoids)
What are the three zones of the adrenal cortex, from the outside to the inside?
- Zona Reticularis
- Zona Fasciculus
- Zona Glomerulosa
Where in the adrenal glands are catecholamines secreted from? Which catecholamines are secreted?
- Secreted from adrenal medulla
- Noradrenaline and andrenaline are secreted
What hormones are released from the adrenal medulla? What stimulates this? What is the result?
- Catecholamines (mainly adrenaline)
- Sympathetic stimulation
- Helps resist stress
What hormones are released from the zona reticularis? What stimulates this? What is the result?
- Androgens (mainly dehydroepiandrosterone)
- Adrenocorticotropic hormone
- Mostly male sex hormone
What hormones are released from the zona fasciculata? What stimulates this? What is the result?
- Glucocorticoids (cortisol)
- Adrenocorticotropic hormone
- Helps cope with stress; increases metabolic rate
What hormones are released from the zona glomerulosa? What stimulates this? What is the result?
- Mineralocorticoids (aldosterone)
- Angiotensin
- Regulates Na+, K+ and water concentration in blood
Which cells in the adrenal medulla release adrenaline and noradrenaline?
Chromaffin cells
In fundamental terms, what is the adrenal medulla? What does this make chromaffin cells?
- Modified sympathetic ganglions
- Therefore chromaffin cells are modified postganglionic neurons with no axons
How much adrenaline and noradrenaline is released from the adrenal medulla upon acetylcholine release from the preganglionic fibre?
Five times more adrenaline than noradrenaline
Why do neurons release noradrenaline, but NOT adrenaline?
Neurons lack the necessary enzyme to convert noradrenline to adrenaline; the adrenal medulla does not
Recall the five types of stress
- Physical
- Chemical
- Psychological
- Physiological
- Social
Outline Hans Selye’s GAS
- Alarm reaction
- Resistance stage
- Exhaustion (depletion of resources)
Outline the revised GAS
- Alarm reaction (sympathetic response); varies depending on sex, and the stressor itself
- Resistance stage: persist and adapt
- Allostatic overload: Chronic problems arise due to stress mediators themselves
Describe the two main components of the alarm reaction of GAS
- Noradrenaline release from sympathetic nerve terminals (some spillage into blood)
- Release of adrenaline and nor-adrenaline from adrenal medulla
Describe the actions of catecholamines on the heart
- Increased heart rate and contractility
Describe the actions of catecholamines on the lung
Bronchodilation
Describe the actions of catecholamines on the kidneys
- Vasoconstriction
- Increased renin release (leads to water retention)
Describe the actions of catecholamines on skeletal muscle
Vasodilation
Describe the actions of catecholamines on the liver
- Increased gluconeogenesis
- Glycogenolysis
Describe the actions of catecholamines on adipose tissue?
Increased lipolysis
Describe the actions of catecholamines on the pancreas
- Increased glucagon, decreased insulin
Draw the Feedback mechanism of cortisol from the hypothalamus to four target areas
What is the relationship between cortisol and insulin? Why does this make sense? Therefore, what can be the long term effect of elevated stress?
- Antagonistic
- Makes sense; cortisol wants the body to show its cards, which involves release of glucose
- Long term, this can lead to insulin resistance and therefore type 2 diabetes
In terms of cardiovascular function, which hormones is cortisol permissive to? What are the results of this?
- Adrenaline, Noradrenaline, Angiotensin II
- Maintains contractility, vascular tone and blood pressure
HOW does cortisol maintain cardiovascular function?
- Increased beta receptors
- Decreased nitric oxide
- Increases catecholamine and Na/K pump synthesis
How does aldosterone increase sodium reabsorption? What effect does this have on one other ion? IGNORE THIS CARD
- Uses sodium potassium pumps
- Therefore excretion of potassium also increases
Other than aldosterone production, what is a function of angiotension II?
Vasoconstrictor
Draw a diagram of the RAAS system, including the roles of renin and ACE. What area of the adrenal gland is acted on? Include the negative feedback mechanism.
Draw a diagram of the hormonal response to stress. Compare to 7.7.doxc. What is missing from that diagram?
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What is a pheochromocytoma?
Adrenal tumour:
Pheo: Dusky
Chromo: Colour
Cytoma: Tumour
Describe the primary and secondary forms of Conn’s syndrome
- Primary: aldosterone-secreting tumour in zona glomerulosa
- Secondary: Hyperactivity of RAAS system due to low renal blood flow
What is the name for too-low levels of potassium? What can this cause?
- Hypokalaemia
- Muscle weakness & cardiac toxicity
Why is sodium concentration not greatly impacted by conn’s syndrome? What is the main issue, then?
- Cardiac muscle stretches, resulting in ANP secretion from the heart
- Main problem is hypokalaemia
Cushing’s Syndrome vs Cushing’s disease + other secondary one
Syndrome: Primary, adenoma of adrenal cortex (20-25%)
Disease: Secondary, Pituitary tumour increases ACTH release
Other: ectopic secretion of ACTH (e.g. in lung cancer)
What is a common cause of cushing’s syndrome/disease?
Large doses of glucocorticoids
What hormones are in excess during Cushing’s disease?
- Cortisol
- Dehydroepiandrosterone
Derive as many effects of cushing’s disease as you can think of
- Gluconeogenesis (hyperglycemia -> adrenal diabetes)
- Fat mobilisation into thorax, abdomen and face
- Protein loss (weakness, osteoporosis)
- Weakened immune system
- Acne + facial hair (DHEA)
Draw the logical permutations of primary, secondary, and tertiary adrenal insufficiency
How can Addison’s disease lead to hyperpigmentation?
- Overproduction of alpha melanocyte stimulating hormone in response to pituitary hyperstimulation
What is Addison’s disease?
Primary adrenal insufficiency; autoimmune destruction of adrenal glands
How can secondary adrenal insufficiency arise?
Negative feedback suppression of HPA axis due to steroid medications
What are some consequences of cortisol deficiency?
- Decreased stress tolerance
- Hypoglycaemia
- Decreased gluconeogenesis
- Decreased fuel mobilization
- Hyperpigmentation
What are the consequences of aldosterone deficiency?
- Hyperkalemia
- Acidosis
- Hyponatremia
- Decreased plasma volume and blood pressure
- Tachycardia
- Hypotension
