Adrenal glands Flashcards
The adrenal gland is made up of…
- capsule
- outer cortex
- medulla
all of seperate embyrological origins
What are the layers of the cortex?
zona glomerulosa
zona fasciculata
zona reticularis
The adrenal cortex contains triglyceride droplests, what is the purpose of this?
they are used for steroid production
The cortex is regulated by…
hypothal and pituitary hormones
What are the characteristics of the adrenal medulla?
- made up of chromaffin cells
- no lipids
- stimulated by sympathetic nervous system
What hormones are produced in the zona glomerulosa? What is the function of these hormones
- mineralcorticoids- aldosterone
- regulate electrolyte homeostasis; kidney- blood pressure
What hormones are produced in the zona fasciculata? What is the function of these hormones
- glucocorticoids cortisol
- regulates glucose homeostasis
What hormones are produced in the zona reticularis? What is the function of these hormones
- androgens
- regulates male characteristics
secondary sex hormones
What hormones are produced in the adrenal medulla? What is the function of these hormones?
catecholamines- adrenaline, noradrenaline
fight or flight response
Why is cortisol able to stimulate mineralcorticoid receptors?
this is because they share similar strutures and all cells in the adrenal glands start with the base raw material of cholesterol
Aldosterone is stimulated by the ______ pathway
RAA - renin- angiotensin aldosterone pathway
What is the function of aldosterone?
- increases sodium reabsorption at the kidney (therefore water reabsorption)
- promotes potassium exctretion at kidney
- increases blood volume and thus blood pressure
Briefly describe the RAA pathway
- renin released by kidneys when there is a drop in blood pressure and volume
- renin acts on angiotensinogen to form angiotensin I
- ACE released from the lungs converts angiotensin I to angiotensin II
- angiotensin II has a direct impact on the blood vessels, stimulating vasoconstriction; increasing blood pressure
- angiotensin II acts on adrenal glands and stimulated release of aldosterone from ZG; aldosterone acts on distal convoluted tubules and increased Na2+, Cl- reabsorption; thus increases water reabsorption and causes an increase in blood volume
The production of cortisol in the ZF is stimulated by… produced by the __________
Adrenocorticotrophic hormone (ACTH)
anterior pituitary gland
The functions of cortisol are __________ and __________
- metabolic and immunologic (immunosuppresant, anti-inflammatory)
What are the functions of cortisol ?
- promote fat breakdown- adipose tissue
- cortisol counteracts insulin to increase blood glucose levels- pancrease
- decreases amino acid uptake by muscle
- glucose generation in the liver
- reduces bone formation
Plasma cortisol vary according to a diurnal rhythm, briefly describe normal plasma cortisol levels throughout the day?
- plasma cortisol levels are greatest in the morning
- lower at night
The purpose of cortisol is…
to help the body cope with emotional and physical stress
Briefly outline the substrates used in production of mineralcorticoids
Cholesterol —> Prenenolone —>progesterone –> 11 deoxy-corticosterone –> corticosterone –> 18-OH corticosterone –> aldosterone
Briefly outline the substrates used in production of glucocorticoids
Cholesterol –> prenenolone –> 17-hdroxyprenenolone –>17-hydroxyprogesterone –> 11-deoxycortisol —> cortisol
Briefly outline the substrates used in production of sex hormones
Cholesterol –> Prenenolone –> 17-hydroxyprenenolone–> DHEA –>androstenedione –> testosterone –> dihydrotestosterone (DHT)
What is the main androgen in men?
testosterone
_________ are precursors to oestrogen in women
Androgens
What is the function of androgens?
development and maintenance of male charatceristics
The release of catecholeamines from the adrenal medulla is stimulated by …
sympathetic preganglionic neurones
What is the function of catecholamines released by adrenal medulla?
- increases plasma glucose- glycogen broken down by liver, stimulates glucagon release, inhibition of insulin releae
- promotes lipolysis in adipose tissue
- increases metabolic rate
- increases cardiac output (increases contractility and HR; inotropy)
- relaxation of peripheral smooth muscles (bronchodilation, increased muscle blood glow, decreased GIT activity)
bronchodilation- lungs more open; allows breathing
GIT- gastrointestinal tract
What is the effect of the stress response on visceral effector tissue ?
- increased heart rate and force of beat
- constriction of blood vessels most near the skin and viscera
- dilation of blood vessels of heart, brain, lungs and skeletal muscles
- contraction of spleen
- conversion of glycogen into glucose in liver
- dilation of airways
- decrease digestive activities
- water retention and elevated blood pressure
What is Cushings disease?
a disease of the pituitary gland; pituitary tumour, usually benign
leads to excess secretion of ACTH
What is the consequence of cushings disease ?
increased cortisol production
What is cushings syndrome?
usually an issue in adrenal gland
signs and symptoms associated with excess cortisol
increased cortisol
decreased ACTH (due to negative feedback effect)
What are the potential causes of cushings syndrome?
- adenoma
- adenocarcinoma
- hyperplasia
of the adrenal gland
can also be caused by therapeutic steroid use e.g. prednisolone
Outline the presentation of Cushings (disease/syndrome)
- moon face
- central obesity; peripheral wasting
- flushing
- buffalo hump
- stretch marks
- menstrual irregularity (uterus cannot maintain its weight)
- hypertension (cortisol acts on MRs)
- diabetes- blood glucose levels
- osteoporosis- stops synthesis of bone
- acne
- depression
- decreased libido
- hisrsuitism
MR- mineralcorticoid receptors
What are the risk factors for cushings (disease/syndrome)
- pituitary oedema
- exogenous steroid use
- Female
- adrenal adenoma
- lung cancers- produce hormones that mimic cortisol
What is the management of cushings disease?
- surgical resection of offending tumour
- post surgical hormone replacement (hydrocortisone)
Synthetic cortisol is…
hydrocortisone
What is the management of cushings syndrome?
rationalise the use of steroids
decrease steroids in reducing regime
What is addisons disease?
autoimmune disease that wipes out the adernal cortex
autoantibodies in the adrenal cortex
What is the consequence of addisons disease?
reduced or absent release of cortisol and aldosterone
hypotension
hypoglycaemia
What is the cause of hyperpigmentation in addisons disease?
- lack of negative feedback
- leads to release of a hormone called pro-opiomelanocortin (has similar effects to ACTH and MSH)
- results in hyperpigmentation
MSH- melanocyte stimulating hormone
What is the presentation of addisons disease?
- fatigue
- anorexia
- weight loss
- hyperpigmenation of mucosa and sun exposed areas - includes mouth
- nausea
- postural hypotension
- vomiting
What are the first line therapies of addisons disease?
- oral glucocorticoud and mineral corticoid replacement for life
What is the hormone replacement therapy for aldosterone?
fludrocortisone acetate
During periods of stress, trauma, infection and pregnancy; how should you adjust your hormone replacement therapy in addisons disease
glucocorticoid replacement should be increased
What is the cause of acute adrenal insufficiency?
usually due to suddenly stopping exogenous steroids
adrenal hypotrophy as they are no longer used to producing steroids
What are the symptoms of acute adrenal insufficiency?
Hypotension (aldosterone)
vomiting
hyperkalaemia (lack of aldosterone)
hyponatraemia (lack of aldosterone)
hypoglycaemia (lack of cortisol)
seizures
confusion
What is the management of an acute adrenal insufficiency?
ABCD resuscitation
IV hydrocortisone
IV fluids
What are the dental considerations for addisons and cushings syndrome?
poor wound healing
mucosal hyperpigmentation in addisons
consider steroid replacement if on long term steroids
quality of bone implants
What is a pheochromocytoma?
tumour of the adrenal medulla
can be isolated or with MEN2 syndrome
MEN- multiple endocrine neoplasia
What is the consequence of a pheochromocytoma?
secretion of large amounts of catecholamines- adrenaline and noradrenaline
What is the clinical presentation of a pheochromocytoma?
hypertension
sweating
headaches
tachycardia
tremours
anxiety
headaches
sweating
palpitations
