The Adrenal Gland Flashcards
Describe the blood supply to the Adrenal glands?
Left adrenal vein drains into renal vein. Right adrenal vein drains into Inferior Vena Cava
Both adrenals have many arteries but only one vein
( Draw a diagram )
What structures make up the Adrenal Cortex?
Zona glomerulosa
Zona fasciculata
Zona reticularis
( Draw a diagram )
What does the Adrenal Medulla do?
Secretes catecholamines e.g. adrenaline/ epinephrine
NoraAdrenaline/norepinephrine
What does the Adrenal Cortex do?
Secrete Corticosteroids e.g.
Mineralocorticoids ( Aldosterone ) Glucocorticoids ( Cortisol ) Sex Steroids ( Androgens, Oestrogen)
What does the Zone Glomerulosa make?
Aldosterone
What do Zones Fasciculata and Reticularis make?
Cortisol ( Androgens and Oestrogen )
What is a Steroid?
Hormone based on a cholesterol molecule.
Adrenal gland secretions precursor is cholesterol
Chemical pathway to get from Cholesterol to Aldosterone?
Cholesterol –> Progesterone –> [21 hydroxylase] 11-deoxycorticosterone –> [11 hydroxylase] corticosterone –> [18 hydroxylase] Aldosterone
Chemical pathway to get from cholesterol to Cortisol?
Cholesterol –> Progesterone –> [17 hydroxylase] 17-OH pregnenolone –> [21 hydroxylase] 11-deoxycortisol –> [11 hydroxylase] cortisol
What does Aldosterone do?
(Maintains blood pressure)
In kidneys: binds to receptor on nucleus = transportes and ATP k+ N+ pump
Stimulates Sodium+ reabsorption in distal convulated tubule and cortical collecting duct
Stimulates K+ and H+ secretion
How is Aldosterone regulated by
Juxtaglomerular apparatus measures blood pressure in arteries indirectly by measuring renal perfusion pressure.
Decreased Na+ load to top of loop of henle
Secrete Renin from JGA cells if Aldosterone low
What are the effects of renin?
Stimulated activation:
With Angiotensinogen from liver it creates Angiotensin I
Angiotensin I becomes Angiotensin II using ACE
Angiotensin II increased ACTH, K+ and lowers Na+ in Adrenal = vasoconstriction
( check diagram )
What are the physiological effects of cortisol?
- Stress response
- Metabolic effects : Protein catabolism, hepatic Gluconeogenesis, increased blood glucose concentration, fat Metabolism, enhances Glucogon and catecholamine effects.
- Weak Mineralcorticoid effects
- Renal and cardio effects ( excretion of water load, Increased vascular permeability )
What is Adenohypophysis?
Cortisol negative feedback to hypothalamus and pituitary, lowers levels of ACTH (and MSH)
Why do Px with Addison’s disease have a good tan?
Pro-opio-melanocortin ( POMC )
is a large precurosr protein which cleaves to form ACTH, MSH and endorphins
So become tanned
Cortisol has a (a) rhythm?
a - diurnal
Tells your body what time of day it is ( circadiam rhythym)
- Cortisol test has to be at 9AM - this is when it is at a high level.
What are the characteristics of Cushing’s disease?
A tumour of the adrenal gland = excess corticol
Tumour of the pituitary = excess ACTH
Too much cortisol = changes metabolism and can put on weight
Why do Px with Addison’s disease have a good tan?
Pro-opio-melanocortin ( POMC )
is the large precurosr protein which cleaves to form ACTH and MSH (and endorphins)
So become tanned
List four possible causes of Cushing’s disease?
- Taking steroids by mouth (common)
- Cushing’s disease (pituitary adenoma)
- Ectopic ACTH (lung cancer)
- adrenal adenoma or carcinoma
How are Catecholamines made?
Precursor for Adrenaline and NA is tyrosine
Dopamine created by Tyrosine –> Dopa –> Dopamine
How are Catecholamines made?
Precursor for Adrenaline and NA is tyrosine
Dopamine created by Tyrosine –> Dopa –> Dopamine –> Norepinephrine –> (+methyl and donor group ) Epinephrine
How are Catecholamines stored and released?
Cytoplasmic granules and released in response to ACh from preganglionic sympathetic neurones.
What are the roles of Catecholamines?
How are they transported and then degraded?
Flight or fight response features
NA and Adr circulate bound to Albumin
Degraded by two hepatic enzymes - monoamine oxidase and catechol-O-methyl transferase
What is the Medulla derived from?
Ectodermal neural crest
