Stress and metabolism 4 Flashcards
2 divisions of adrenals?
Cortex and medulla
Where are the adrenal glands embedded?
Adrenal glands embedded above each kidney in a capsule of fat
Of the adrenal glands which is the inner and which is the outer part?
Cortex is the outer part
Medulla is the inner part
What does the adrenal cortex have similar origin to?
What group of hormones does it make?
What are the types of hormones in outer gland, middle and inner glands give examples:
Similar origin to gonads
Make steroids hormones
Mineralocorticoids (outer gland) – aldosterone
Glucocorticoids (middle gland) – cortisol (corticosterone)
Androgen sex steroids (inner gland) – DHEA (dehydroepiandrosterone)
What is the adrenal medulla composed of?
Where does it originate from?
What group of hormones are here give the 2 examples:
Chromaffin cells
Originates from sympathetic nervous system
Catecholamines
– epinephrine (adrenaline)
– norepinephrine (noradrenaline)
What are the 3 layers/zones that the adrenal cortex consists of?
Zona glomerulosa – outermost layer
Zona fasciculata – middle and largest portion
Zona reticularis – innermost zone
Categories of adrenal steroids?
Mineralocorticoids
Glucocorticoids
Sex hormones
Mineralocorticoids is mainly and what balance does it influence?
Aldosterone
Influence mineral balance, specifically Na^+ and K^+ balance
Glucocorticoids are primarily? and what is the major roles?
Primarily cortisol
Major role in glucose metabolism as well as in protein and lipid metabolism
Sex hormones in adrenal glands are identical or similar to those produced by gonads - which is the most abundant and physiologically important?
Most abundant and physiologically important is dehydroepiandosterone (male “sex” hormone)
Aldosterone is major mineralocorticoid and maintains electrolyte balance - explain the 4 steps of feedback:
- low plasma Na++ or high K+
- activates renin-angiotensin system
- Angiotensin II increases aldosterone release from adrenal glands
- acts on distal renal tubules
* increase Na++ & water retention
* increase excretion of K+ & H+ ions
What is another name for the major glucocorticoid in humans: cortisol?
In what rhythm is cortisol secretion regulated?
Hydrocortisone
Secretion is regulated by diurnal rhythm
What does cortisol play a role in?
What does it do to blood glucose?
What does it do to blood fatty acids?
What does it do for water and electrolyte balance?
Does it create an inflammatory/anti-inflammatory response?
Plays role in stress
Increase blood glucose
Increase blood fatty acids
Control water and electrolyte balance
Anti-inflammatory/immunosuppressive
What feedback does cortisol have and on what?
Negative feedback on hypothalamus (CRH) & anterior pituitary (ACTH)
Adrenal cortex - secretes both male and female
sex hormones in both sexes what is the only hormone that has any biological importance ?
Dehydroepiandrosterone (DHEA)
What is DHEA overpowered by in males?
Overpowered by testicular testosterone in males
What about DHEA in females what happens?
Physiologically significant in females where it governs
– Growth of pubic and axillary hair
– Enhancement of pubertal growth spurt
– Development and maintenance of female sex drive
Primary stimulus of epinephrine and norepinerphrine?
Primary stimulus: activation of sympathetic nervous
system by stress
Where is adrenaline secreted into?
In response to?
What does it maintain?
What does it do blood glucose?
What does it do fat metabolism?
– Secreted into blood
– “fight-or-flight” responses
– Maintenance of arterial blood pressure
– Increases blood glucose
– Increases fat metabolism (increase blood fatty acids)
4 glucocorticoids?
Hydrocortisone, prednisolone, dexamethasone, betamethasone
When is replacement therapy used for glucocorticoids?
In adrenal failure (Addison’s disease)
What do these glucocorticoids try to do in anti-inflamatory/immunosuppressive disorders?
Reduce T cell proliferation, release of IL2, TNF-a, IL1
Glucocorticoids therapy for:
asthma?
eczema?
arthritis?
ulcerative colitis?
transplant?
cancer patients?
– asthma (inhaler)
– eczema (topical cream)
– arthritis (systemic injections)
– ulcerative colitis (rectal suppositories)
– prevent graft rejection of the transplant
– cancer patients (anti-emetic; reduce oedema in brain tumours)
Is the benefit greater than the risk of glucocorticoid use or no?
Benefit > Risk of glucocorticoid use
Why is the benefit > Risk of glucocorticoid use? What are lots of the risks assoicated?
– Immune system limited (delay tissue repair, gastric/peptic ulcers)
– Cushing’s symptoms
– Osteoporosis (alter function of bone cells osteoblasts/osteoclasts)
– Adrenal insufficiency due to sudden withdrawl (patient card – ”do not stop my steroid treatment abruptly”)
What does the drug fludrocortisone have in it?
What is it used in and give an example?
Fludrocortisone has glucocorticoid and mineralocorticoid activity
Used in mineralocorticoid replacement therapy (eg) in Addison’s disease
What are the main targets of mineralcorticoids?
Kidneys, bladder and colon are the major targets of mineralocorticoids
Addison’s disease is one of low corticoids - which ones?
low glucocorticoid (cortisol) & mineralocorticoid
(aldosterone)
Primary and secondary causes of Addison’s disease?
Primary Addison’s: damage adrenal gland (TB or autoimmunity)
Secondary Addison’s: low ACTH release
JFK had Addison’s disease
Symptoms of Addison’s disease? 10
hypoglycaemia, decreased liver glycogen, fatigue, anorexia, nausea, weight loss, dizziness, hypotension, psychiatric, death if untreated
Treatment of Addison’s disease?
Steroid replacement therapy
What is Cushing’s disease?
Causes?
Treatment? 3
High glucocorticoids - excess glucocorticoids (cortisol)
ACTH secreting tumor in pituitary
Treatment involves removing tumor, using antiglucocorticoids or surgical adrenalectomy
Symptoms of Cushing’s disease? 7 main points
- hyperglycemia
- elevated blood pressure
- obesity (abdominal fat, thin arms & legs)
- muscle wasting, osteoporosis, cataracts
- poor wound healing
- buffalo hump, moon face, red cheeks
- psychiatric symptoms (depression, euphoria, hallucinations)
a. What is Conn’s syndrome?
b. Primary and secondary causes?
c. Symptoms? 4
d. Treatment? 2
a. High mineralocorticoids - excessive mineralocortocoids (aldosterone)
b. primary - tumour
secondary - excessive renin-angiotensin action in kidney disease, cirrhosis of liver, congestive heart failure
c. sodium and water retention, increase in extracellular fluid and hypertension
d. antagonist of aldosterone (spirono-lactone) and unilateral adrenalectomy
Stress and depression: Hypothalamus-Pituitary-Adrenal Axis
During a generalised stress response - What is secreted from adrenal medulla?
What does mobilises metabolic resources?
What raises blood glucose and fatty acids?
What systems and hormones maintains blood volume and blood pressure?
↑ epinephrine secretion from adrenal medulla
(chromaffin cells)
↑ CRH-ACTH-cortisol (HPA axis) that mobilises
metabolic resources
↓ insulin & ↑ glucagon secretion to raise blood
glucose & fatty acids
↑ renin-angiotensin-aldosterone system &
vasopressin secretion to maintain blood volume
and blood pressure
What diseases does chronic stress cause?
Heart disease, hypertension, atherosclerosis, immune-suppression
What does prolonged release of CRH- Corticotropin releasing hormone cause?
Anxiety and depression
What drugs may treat anxiety, depression, drug dependence and IBS?
CRF1 receptor antagonists
What is the action of a stressor on the body?
A stressor is put on the body and then 2 responses occur:
1. Specific response characteristic of type of stressor
2. Non specific generalised response regardless of type of stressor- stress response
What change occurs to adrenaline during the stress response and what purpose does this serve?
Adrenaline is increased
Reinforces the sympathetic nervous system to prepare the body for “fight or flight”
Mobilises carbohydrate and fat energy stores which increases blood glucose and blood fatty acids
What change occurs to CRH-ACTH-Cortisol during the stress response and what purpose does this serve?
CRH-ACTH-Cortisol is increased which mobilises energy stores and metabolic building blocks for use as needed, this increases blood glucose, blood amino acids and blood fatty acids
ACTH facilitates learning and behaviour
What change occurs to glucagon and insulin during the stress response and what purpose does this serve?
Glucagon increases and insulin decreases
Acts in concert to increase blood glucose and blood fatty acids