adrenal gland Flashcards
Adrenal glands: where are they?
Above the kidney, Ad RENAL- protected by the ribs
how many arteries do they have- right and left
lots
how many veins for the left and right adrenal glands
1
where does the left adrenal vein drain into
renal vien
right adrenal vein
into inferior vena cava
draw the adrenal gland and the adjacent structure
draw
name the 2 main regions of the adrenal glands
adrenl cortex
adrenal medulla
what does the adrenal cortex relese
Secretes Corticosteroids
adrenal medulla
Secretes catecholamines
name the 3 regions of teh adrenal cortex
Zona glomerulosa
Zona fasciculata
Zona reticularis
draw it
draw it
what regions makes Catecholamines
Adrenal medulla (neuroendocrine/chromaffin cells)
Adrenal cortex
Corticosteroids
what is the origine of adrlaline and noradrelaline
dpoamine
nora
no meythl group
examples of Catecholamines
Adrenaline/epinephrine (80%)
Noradrenaline/norepinephrine (20%)
[Dopamine]
examples of Corticosteroids
Mineralocorticoids (Aldosterone) Glucocorticoids (Cortisol Sex steroids (Androgens, oestrogens)
what does the Zona glomerulosa make
Aldosterone
what do teh Zona fasciculata
Zona reticularis
cortisol
what is a significance of one vein
all hormones released will travel through same vein
what are steriods
Steriod is an hormone based on a cholesterol/ comes from cholestrol
Adrenal gland secretions precursor
cholesterol
how many carbons in cholestrol
27
What is an enzyme?
Protein that catalyses a specific reaction
Protein that catalyses a specific reaction
1
what precourous do all steriods make
pregnenolone- basic steriod
first step to form aldestron (mineralocorticoid)
Side chain cleavage
–> Pregnenolone
next
3 beta Hydroxy Steroid Dehydrogenase
–> Progesterone
what positions are oxidised by hrdoxylases (OH group added)
name the enzymes
21 Hydroxylase
11 Hydroxylase
18 hydroxylase
how to form glucocorticoid
same until forming Progesterone
what are hydroxled (OH group added)
17 hydoxylase
21 hydoxylase
11 hydoxylase
final product
CORTISOL
cholesterol to aldosterone with all intermediates
cholesterol progesterone 11-deoxy corticosterone corticosterone aldosterone
to make cortisol
cholesterol progesterone 17-OH prog 11-deoxy deoxycortisol cortisol
to make S steroids
cholesterol progesterone 17-OH prog Sex steroids (androgens) (oestrogen)
What does aldosterone do?
Major net effect is to conserve body sodium by stimulating its reabsorption
Increased sodium reabsorption water reabsorption,
raising blood volume, regulating blood pressure
how does it work
Stimulates Na+ reabsorption in distal convoluted tubule and cortical collecting duct in kidney (and in sweat glands, gastric glands, colon)
Stimulates K+ and H+ secretion, also in distal convoluted tubule and cortical collecting duct
switches on ATPase
what is released when blood pressure fails
Renin release when blood pressure falls
what releases renins
Juxtaglomerular apparatus
when bp is high
Blood pressure high suppress renin
when bp is low
Blood pressure low suppresses renin secreated
How is aldosterone regulated?
low bp
renin relased
what do the renins do
convert angiotensinogen (from liver) to Angiotensin I
next
A1 concerted by ACE to angiotensin 2
affects of a2
vasoconstriction
acts on adrenals
what happens in the adrenal glands
Activation of the following enzymes Side Chain Cleavage 3 Hydroxysteroid dehydrogenase 21 hydroxylase 11 hydroxylase 18 hydroxylase to make aldetsrone
summary of Aldosterone
Summary of aldosterone action:
Controls blood pressure, sodium and lowers potassium
How is cortisol secretion regulated?
ACTH
Physiological effects of cortisol
Normal stress response Metabolic effects peripheral protein catabolism hepatic gluconeogenesis increased blood glucose concentration fat metabolism (lipolysis in adipose tissue) enhanced effects of glucagon and catecholamines Weak mineralocorticoid effects Renal and cardiovascular effects excretion of water load increased vascular permeability
how is increased cortisol suprresed
Cortisol feedbacks negatively
how is it released
CRH –> ACTH –> cortisol
draw a HPA axis
Remember to add backwards arrow wwhen cortisol negatively effects pit and hyp
Effects of ACTH on the adrenals
Activation of the following enzymes Side Chain Cleavage 3 Hydroxysteroid dehydrogenase 21 hydroxylase 11 hydroxylase 17 hydroxylase cortisol
what sort of variation does cortisol
Cortisol has diurnal rhythm
Tells youre tissue/hormone what time of day it is
Peaks at 8 30
Low at midnight
This is cortisol, and the only difference between prednisolone and cortisol is this double bond here. What this does is it gives prednisolone a longer half life, more potency, and a binding affinity of over twice that of cortisol
This is cortisol, and the only difference between prednisolone and cortisol is this double bond here. What this does is it gives prednisolone a longer half life, more potency, and a binding affinity of over twice that of cortisol
what is Addison’s disease
Primary adrenal failure
Autoimmune disease where the immune system decides to destroy the adrenal cortex (UK)
most common cause
Tuberculosis of the adrenal glands (commonest cause worldwide)
sympotoms/sign
hyperpigmentation low bp weakness weight loss diahorrea vomitting vitilago
adrenal crisis signs/sypm
fever syncope convulsion hypoglecemia hyponatremia severe vomiting and diarrhea
what affect does it have on other hormones
Pituitary starts secreting lots of ACTH and hence MSH
why low blood pressure
No cortisol or aldosterone
Why do patients with Addison’s disease have a good tan?
POMC is a large precursor protein that is cleaved to form a number of smaller peptides, including ACTH, MSH and endorphins
Thus people who have pathologically high levels of ACTH may become tanned
main dangers of addisons
Cortisol deficiency Aldosterone deficiency Salt loss Low blood pressure Eventual death
how to prevent death
Rehydrate with normal saline
Give dextrose to prevent hypoglycaemia which could be due to the glucocorticoid deficiency
Give hydrocortisone or another glucocorticoid
What happens if you have too much cortisol?
Your metabolism changes and you put on weight…
What can cause too much cortisol?
A tumour of the adrenal
-Excess cortisol
A tumour of the pituitary
-Excess ACTH
what is Cushing’s syndrome
Cushing’s syndrome is a condition caused by having too much of a hormone called cortisol in your body. It can be serious if it’s not treated.
signs/symptoms
big torso/fat but skinny arms and legs Red cheeks Easy bruising Thin skin Red Striae (stretch marks) Poor wound healing Adrenal gland gets bigger Interscapular fat Diabetes, hypertension and osteoporosis Immunosuppression (reactivation of TB Proximal myopathy weak muscle
hormone cause
Occurs due to an excess of cortisol or other glucocorticoid
List four possible causes of Cushing’s syndrome
Taking steroids by mouth (common) (glucocorticoid)
pituitary dependent Cushing’s disease (pituitary adenoma)
Ectopic ACTH (lung cancer)
adrenal adenoma or carcinoma
§
examples of Catecholamines
Adrenaline/epinephrine (80%)
Noradrenaline/norepinephrine (20%)
what is the precoursor for adr and na sythesis
tyrosine
where is it stored
in cytoplasmic granules & released in response to ACh from preganglionic sympathetic neuronesq
Role of catecholamines
Fight or flight response’ e.g. tachycardia, sweating, increased blood glucose, alertness, vasoconstriction
how do adr and na circulate the blood
NA & Adr circulate bound to albumin
how do they get degraded
Degraded by two hepatic enzymes: monoamine oxidase & catechol-O-methyl transferase
