adrenal gland

Question 1

• How many arteries and veins supply the adrenal glands respectively?
• Where does the left adrenal vein drain into?
• Where does the right adrenal vein drain into?

Answer 1

57 arteries

1 vein

Renal vein

Inferior Vena Cava

Question 2

• What hormone class is produced by the adrenal cortex?

- What hormone class is produced by the adrenal medulla?

Answer 2

Corticosteroids

Catecholamines

Question 3

• What are the three layers of the adrenal cortex?

- What hormone does each of these layers produce?

Answer 3

Zona Glomerulosa

Zona Fasiculata

Zona Reticularis

Zona glomerulosa - Mineralocorticoids (Aldosterone)

Zona Fasiculata - Glucocorticoids (Cortisol)

Zona Reticularis - Sex Steroids (Androgens, Oestrogens)

Question 4

• How is Progesterone formed from Cholesterol?

- How is Aldosterone produced from Progesterone?

Answer 4

Side chain cleavage of cholesterol to produce Pregnenolone
3 beta Hydroxy Steroid Dehydrogenase acts on Pregnenolone to produce Progesterone

21 Hydroxylase acts on Progesterone to produce 11 Deoxycorticosterone
11 Hydroxylase acts on 11 Deoxycorticosterone to produce Corticosterone
18 Hydroxylase acts on Corticosterone to produce Aldosterone

Question 5

• What does Aldosterone do?

- Describe the mechanism of action of Aldosterone

Answer 5

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 and Na+/K+ pumps
This removes Na+ from urine, transporting water with it due to a decrease in water potential in the DCT, 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
This process also occurs in the cortical collecting duct

Question 6

• What are the physiological effects of Cortisol with regards to metabolic, immune and vascular effects? (aka normal stress response)

Answer 6

Metabolic - Increases blood glucose by hepatic gluconeogenesis, lipolysis, proteolysis, and decreased cellular insulin sensitivity, enhance effects of glucagon and catecholamines.

Immune - Decreased intensity of immune inflammatory response

Vascular - Excretion of water load and increased vascular permeability

Question 7

• Describe the negative feedback system of Cortisol

- When would the highest secretion of cortisol be?

Answer 7

CRH produced in hypothalamus stimulates release of ACTH in the anterior pituitary gland

ACTH stimulates production of Cortisol in adrenal gland

Cortisol reduces the production of CRH in hypothalamus and ACTH in the anterior pituitary

morning

Question 8

• What is Addison’s disease?

- Why do patient’s with Addison’s disease tan more?

Answer 8

Primary adrenal failure

Autoimmune disease where the immune system destroys the adrenal cortex

Pituitary starts secreting more ACTH and hence, MSH as these are made from the same precursor (POMC)

Question 9

• What are some of the symptoms of Addison’s disease?

- Why do patient’s with Addison’s disease have low blood pressure?

Answer 9

Hyperpigmentation
    Low blood pressure (Hypotension)
    Salt Loss
    Weight Loss
hypoglycaemia

No cortisol or aldosterone

Question 10

• What is Cushing’s Syndrome?

- List 4 possible causes of Cushing’s syndrome

Answer 10

When ACTH is produced all the time and so is not diurnal

causes excess of cortisol or other glucocorticoid

Taking steroids by mouth → Prednisone (immunosuppresive) or other 
glucocorticoids- most common
Pituitary adenoma
Ectopic ACTH (lung cancer - lung cells start randomly making ACTH)
Adrenal adenoma/carcinoma → increased cortisol

Question 11

• What are the clinical signs of Cushing’s syndrome?

Answer 11

Thin skin
    Proximal myopathy
    Centripetal obesity
    Diabetes, hypertension and osteoporosis
    Immunosuppression
    Moon face
    Striae

Question 12

• What is the cause of stretch marks forming due to Cushing’s syndrome?
• What is the medulla derived from?

Answer 12

Protein cannot be made fast enough to facilitate weight gain and fat deposition

Blood leaks under skin, leaving reddish mark

Ectodermal neural crest

Question 13

• How is Adrenaline formed from its amino acid precursor?

Answer 13

Tyrosine hydroxylated to form Dopa

Dopa decarboxylated to form Dopamine

Dopamine hydroxylated to form noreadrenaline

Noradrenaline methylated to form adrenaline

Question 14

• What is the general role of catecholamines?
• What are adrenaline and noradrenalline bound to when they circulate in the bloodstream?
• What 2 hepatic enzymes can catecholamines be degraded by?

Answer 14

Fight or flight e.g. → Tachycardia, sweating, increased blood glucose, alertness, vasoconstriction

Albumin

Monoamine oxidase
Catechol-O-methyltransferase (COMT)

Question 15

• What is the precursor amino acid for Adrenaline and Noradrenaline?
• Are catecholamines stored before release?

Answer 15

Tyrosine

Yes, unlike corticosteroids

They are stored in cytoplasmic granules and released in response to ACh from preganglionic sympathetic neurones

Question 16

When is renin secreted?

what does renin do?

Answer 16

Decreased renal blood pressure
decreased sodium concentration on top of loop of henle
increased renal sympathetic activity

convert angiotensinogen to angiotensin one
ACE converts angiotensin one to angiotensin two
angiotensin 2 activates the enzymes that produce aldersterone from cholesterol

Question 17

How is cortisol synthesised from progesterone?

Answer 17

17 hydroxylase, converts progesterone to 17 hydroxy progesterone

21 hydroxylase, to 11 -deoxy cortisol

11 hydroxylase, to cortisol

Question 18

what happens during an adrenal crisis? (during Addison’s disease)

how do you treat a adrenal crisis?

Answer 18

fever
syncope (fainting)
convulsions
hypoglycaemia
hyponatremia (low sodium)
vomiting and diarrhoea 

saline- rehydrate
dextrose- prevent hypoglycaemia
hydrocortisone- a glucocorticoid