Adrenal gland

Question 1

Where is the adrenal gland

Answer 1

Located above the kidney at the back of the abdomen and is protected by ribs

Question 2

Blood supply to the adrenal glands

Answer 2

57 arteries by only one vein which supplies the adrenal gland

Question 3

Left adrenal gland blood supply

Answer 3

Left adrenal vein drains into renal vein . Many arteries

Question 4

Right adrenal gland

Answer 4

Right adrenal vein drains into IVC. Many arteries but only one vein

Question 5

3 parts of the adrenal cortex

Answer 5

Zona glomerulosa
Zona Fasiculata
Zona reticularis

Question 6

What does the adrenal cortex secrete

Answer 6

Corticosteroids ( cortisol)

Question 7

What does the adrenal medulla secrete

Answer 7

Catecholamines ( adrenaline )

Question 8

Catecholamines

Answer 8

Adrenaline / epinephrine ( 80%)
Noradrenaline / norepinephrine (20%)
[Dopamine]

Question 9

Corticosteroids

Answer 9

Mineralocorticoids ( aldosterone) 
Glucocorticoids ( Cortisol)
Sex steroids ( Androgen, Oestrogens)

Question 10

Where do set steroids come from

Answer 10

Most come from ovaries and testes but a bit comes from the adrenal gland ( e.g. in children before puberty)

Question 11

Where is aldosterone released

Answer 11

Zona glomerulosa

Question 12

What does aldosterone do

Answer 12

Controls sodium and potassium ion channels ( controls blood pressure )

Question 13

Where is cortisol and a bit of the sex steroids ( androgens and oestrogen) produced

Answer 13

Zona fasciculata and zona reticularis

Question 14

Which is produced in the adrenal gland / is present in the blood stream more , aldosterone or cortisol

Answer 14

Aldosterone - measured in picomol

Cortisol - measured in nanomol

Question 15

What is a steroid

Answer 15

A hormone that is based on a cholesterol molecule - so the adrenal cortex secretions precursor is cholesterol

Question 16

What is an enzyme

Answer 16

Proteins that catalyse a specific reaction
Various enzymes are present in cells
Specific enzymes catalyse the synthesis of particular alterations to the molecule

Question 17

How is aldosterone ( a mineralocorticoid ) produced in the zona glomerulosa

Answer 17

Cholesterol - pregnenolone ( side chain cleavage ) - progesterone( 3 beta Hydroxylase steroid dehydrogenase) - 11 deoxycorticosterone ( catalysed by 21 Hydroxylase) - Corticosterone ( catalysed by 11 Hydroxylase) - aldosterone ( catalysed by 18 Hydroxylase )

Question 18

How is glucocorticoid/ cortisol made in zona fasicularis

Answer 18

Cholesterol (side chain cleavage)- pregnenolone - progesterone ( 3 beta Hydroxy steroid dehydrogenase ) - 17 Hydroxy progesterone ( catalysed by 17 Hydroxylase) - 11 deoxy-cortisol ( catalysed by 21 Hydroxylase) - cortisol ( catalysed by 11 deoxyhydroxylase)

Question 19

What does aldosterone do

Answer 19

Stimulates Na+ reabsorrption 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 the cortical collecting duct

Increased sodium reabsorption water reabsorption , raises blood volume

SO WORKS ON K+/Na+ ION CHANNEL TO KEEP BLOOD PRESSURE

Question 20

How is aldosterone regulated

Answer 20

When blood pressure falls, Renin is released,

Decreased renal perfusion pressure is normally associated with decreased arterial BP .

Increased renal sympathetic activity ( direct to Juxtaglomerular apparatus)

Decreased Na+ load to top of the loop of Henle ( macula dense cells)

Question 21

Renin and aldosterone release

Answer 21

Cells of macula densa sense the sodium load delivered to the distal tubule and regulate levels of circulating renin according to the body’s sodium requirements

If the sodium concentration in the tubular fluid is low, the juxtoglomerular cells increase secretions of renin

Renin acts on protein angiotensin ( secreted by liver) to convert it to angiotensin 1

ACE catalyses conversion of angiotensin 1 to angiotensin 2

Angiotensin 2 regulates aldosterone release and so now increased sodium reabsorption by distal tubule

Question 22

What other hormone can regulate aldosterone

Answer 22

ACTH but to a lesser extent that angiotensin 2

Question 23

Effects of angiotensin 2 on adrenals

Answer 23

Activation of the following enzymes 
Side chain cleavage 
3 hydroxysteroid dehydrogenase
21 Hydroxylase
11 Hydroxylase
18 hydroxylase

Question 24

Summary of action of aldosterone

Answer 24

Controls blood pressure, sodium and lowers potassium

Question 25

How is cortisol secretion regulated

Answer 25

ACTH

Question 26

Physiological effects of cortisol

Answer 26

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 - may maintain BP and has an effect on heart Renal and cardiovascular effects ; excretion of water load , increased vascular permeability

Question 27

Effects of ACTH on the adrenal gland

Answer 27

``` Activation of the following enzymes Side chain cleavage 3 hydroxysteroid dehydrogenase 21 Hydroxylase 11 Hydroxylase 17 Hydroxylase ```

Question 28

What rhythm does cortisol have

Answer 28

Diurnal - peaks in the morning and then decreases during the night- cortisol is released in pulses

Question 29

Cortisol and circadian rhythm

Answer 29

ACTH simulates cortisol and so the ACTH cycle is slightly ahead of the cortisol cycle

Question 30

Addison’s disease

Answer 30

Primary adrenal failure Autoimmune disease where the immune system decides to destroy the adrenal cortex Tuberculosis of the adrenal glands ( commonest cause worldwide - TB bacteria destroy adrenal gland) Pituitary starts secreting lots of ACTH and hence MSH and so become tanned

Question 31

Addison’s disease

Answer 31

Adrenal glands do not produce sufficient steroid hormone Adrenal crisis; fever, syncope, convulsion , hypoglycaemia, hyponatremia, severe vomiting and diarrhoea ``` Hyperpigmentation of skin Low bp Weakness Weight loss Gastric problems Vitiligo ```

Question 32

Why do patients with Addison’s disease have a good tan

Answer 32

POMC is a large precursor protein that is cleaved to form a number of smaller peptides , including ACTH , MSH and endorphins So people who have pathologically high levels of ACTH may become tanned

Question 33

Summary of Addison’s disease

Answer 33

``` Cortisol deficiency Aldosterone deficiency Salt loss Low bp Eventual death ```

Question 34

Urgent treatment of Addisonian crisis

Answer 34

Rehydrate with normal saline Give dextrose to prevent hypoglycaemia which could lead to the glucocorticoid deficiency Give hydrocortisone or another glucocorticoid or cortisol or give pregnenolone ( analogue of cortisol)

Question 35

What happens if you have too much cortisol

Answer 35

Metabolism changes and you put on weight

Question 36

What can cause too much cortisol

Answer 36

A tumour of the adrenal - excess cortisol | Tumour of pituitary - excess ACTH

Question 37

Symptoms of Cushing’s syndrome

Answer 37

``` Mental changes ( depression) Red cheeks Fat pads Moon face Easy brusining Red stretch marks Poor wound healing Thin skin Impaired glucose tolerance High blood pressure Proximal myopathy - muscle weakness . Diabetes , hypertension and osteoporosis Immunosuppression ```

Question 38

Catecholamines

Answer 38

Medulla derived from ectoderm album neural crest Precursor for ADR and NA synthesis = tyrosine Catecholamines stored in cytoplasmic granules and released in response to ACh from preganglionic sympathetic neurones

Question 39

Role of catecholamines

Answer 39

Fight or flight response Tachycardia, sweating , increased blood glucose , alertness, vasoconstriction NA and ADR circulate bound to albumin Degraded by two hepatic enzymes ; monoamine oxidase and catecholamines-O-methyl transferase

Question 40

What controls aldosterone release

Answer 40

Angiotensin 2

Question 41

What 4 things can cause an increase in cortisol and so possible Cushings Syndrome

Answer 41

prolonged steroid use - can often be be used to treat autoimmune conditions as glucocorticoids can suppress immune system pituitary adenoma ectopic ACTH (lung cancer) adrenal ademona or carcinoma

Question 42

difference between cushings disease and syndrome

Answer 42

cushings disease= excess cortisol as a result of a pituitary tumour. cushings syndrome = anyone who has excess cortisol