Adrenal Glands Flashcards
Where are adrenal glands
Above kidneys
How many arteries and veins does each adrenal gland have
Lots of arteries but only one vein each
Where do the left and right adrenal veins drain into?
Left adrenal vein drains into renal vein which drains into IVC
right adrenal vein drains into IVC(inferior vena cava)
What are the three layers of the adrenal cortex
Zona Glomerulosa
Zona Fasiculata
Zona Reticularis
What hormone class is produced by the adrenal cortex?
Corticosteroids
What hormone does each of the adrenal cortex layers produce?
Zona glomerulosa - Mineralocorticoids (Aldosterone)
Zona Fasiculata - Glucocorticoids (Cortisol)
Zona Reticularis - Sex Steroids (Androgens, Oestrogens)
How is Progesterone formed from Cholesterol?
Side chain cleavage of cholesterol to produce Pregnenolone
3 beta Hydroxy Steroid Dehydrogenase acts on Pregnenolone to produce Progesterone
How is Aldosterone produced from Progesterone?
21 Hydroxylase acts on Progesterone (by adding OH) to produce 11 Deoxycorticosterone
11 Hydroxylase acts on 11 Deoxycorticosterone to produce Corticosterone
18 Hydroxylase acts on Corticosterone to produce Aldosterone
How is Cortisol produced from Progesterone?
17 hydroxylase adds OH group to carbon 17 of progesterone to form 17 hydroxy-progesterone
21 hydroxylase adds OH group to carbon 21 to form 11 deoxy-cortisol
11 hydroxylase adds OH group to carbon 11 to form cortisol
What hormone class is made by adrenal medulla
Catecholamines (produced by neuroendocrine/chromaffin cells of the medulla)
Eg - Adrenaline aka epinephrine (80%)
- Noradrenaline aka norepinephrine (20%)
- Dopamine
Where are catecholamines stored and how are they released
- Stored in cytoplasmic granules
- Released in response to ACh from preganglionic sympathetic neurones
Role of catecholamines
Fight or flight response e.g. tachycardia, sweating, increased blood glucose, alertness, vasoconstriction
What are adrenaline and noradrenaline bound to when circulating in bloodstream
Albumin
What two hepatic enzymes degrade them
Monoamine oxidase
Catechol o methyl transferase
Precursor amino acid for adrenaline and noradrenaline
Tyrosine
Where is adrenal medulla derived from
Ectodermal neural crest
Aldosterone
Major net effect is to conserve body sodium by stimulating its reabsorption
Aldosterone enters cells of Distal Convoluted Tubule (DCT) via bloodstream and increases expression of Na+ transporters (on apical) and Na+/K+ pumps (on basolateral)
Which helps you reabsorb sodium and lose potassium (cells K+ is pumped out into urine)
Na+/K+ pump transports this Na+ into the bloodstream and water with it due to lower water potential in the blood
This increases blood volume and pressure (so ultimately aldosterone controls blood pressure)
How is aldosterone regulated
- In kidney, the juxtaglomerular apparatus is always monitoring blood pressure
- When there’s decreased renal perfusion pressure (associated with low BP), this leads to increased renal sympathetic activity to JGA cells, the JGA cells release renin into blood
- Renin converts angoiotensinogen (protein made in the liver) into Angiotensin I
- Then angiotensin converting enzyme (ACE) converts Angiotensin I into Angiotensin II
- Angiotensin II increases Aldosterone production by increasing the activation of the enzymes needed to convert Cholesterol into Aldosterone, (ang II also has other effects like vasoconstriction)
ACE made in lungs
What are the physiological effects of Cortisol with regards to metabolic, immune and vascular effects?
Metabolic - Increases blood glucose conc. by hepatic gluconeogenesis, lipolysis, proteolysis, and decreased cellular insulin sensitivity
Immune - Decreased intensity of immune inflammatory response
Vascular - Excretion of water load and increased vascular permeability
How is cortisol secretion regulated
CRH produced in hypothalamus stimulates release of ACTH in the anterior pituitary gland
ACTH stimulates production of Cortisol in adrenal gland
Increased cortisol means less ACTH and CRH secreted from hypothalamus and anterior pituitary and vice versa (in a negative feedback system)
What rhythm does cortisol have
when you wake up it’s at its highest
Addison disease
- Primary adrenal failure happens
- Autoimmune disease where immune system destroys adrenal cortex→ cortisol and aldosterone deficiency
- Salt loss
- TB of the adrenal glands is the commonest cause worldwide
- Primary starts secreting lots of ACTH and hence MSH
Symptoms of Addison
Hyperpigmentation(tanned skin) due to - POMC (pro-opio-melanocortin) is a large precursor protein that is cleaved to form a number of smaller peptides including ACTH, MSH and endorphins
- People who have pathologically high levels of ACTH will also have high MSH levels and may become tanned
- MSH stands for melanocyte-stimulating hormone
Low blood which leads to death as they have no cortisol or aldosterone
Adrenal crises
Nausea
Weight loss
Weakness
Treatment of Addison as
Saline
Dextrose to prevent hypoglycemia
Hydrocortisone
Cushing syndrome
Excess cortisol or glucocorticoid
Caused by taking steroids orally,pituitary adenoma where lots of ACTH is made,ectopic ACTH secretion (lung cancer cells randomly make ACTH),adrenal adenoma
Symptoms of Cushing
Striae (stretch marks) as protein can’t be made fast enough to facilitate weight gain and fat deposits
Centripetal obesity
Poor wound healing and easy bruising
Fat pads on neck
Thin skin
Diabetes
Moon face
Weakness of upper limbs
