22. The adrenal gland

Question 1

What are the three different types of hormones?

Answer 1

Amine
Peptide
Steroid

Question 2

Where can an endocrine hormone have an effect in a cell?

Answer 2

At the cell surface
In the cell cytoplasm
In the nucleus of the cell

Question 3

What are different effects mediated by endocrine hormones?

Answer 3

Increased hormone production
Release of stored hormone
Cell multiplication

Question 4

Where is the adrenal gland located?

Answer 4

Superiorly to the kidney at the posterior abdominal wall

Question 5

What are the divisions of the adrenal gland and what do they produce?

Answer 5

Inner medulla

Outer cortex divided into three zones:
Zona glomerulosa - mineralcorticoid hormones e.g. aldosterone
Zona fasciculata - glucocortoid hormones e.g. cortisol
Zona reticulosa - andorgenic steroids e.g. testosterone

Question 6

What are the forms of stress that the adrenal gland responds to?

Answer 6

Physiological states of stress:
Starvation
Infection
Severe volume loss

Question 7

Where are mineralcorticoids released from?

Answer 7

From the zona glomerulosa of the adrenal cortex

Question 8

How can the adrenal cortex produce so many different hormones?

Answer 8

Via the expression of different enzymes and cofactors in the individual cells of the different zones

E.g. cells of the zona glomerulosa will contain aldosterone synthase

Question 9

What is the main mineralocorticoid and how does this have an effect in the body?

Answer 9

Aldosterone

RAAS system - activation of which increases the blood pressure via increased Na+ reabsorption via up-regulation of ENaC channels, H20 reabsorption via increased ADH

Question 10

How does aldosterone lead to an increased Na+ reabsorotion

Answer 10

Aldosterone binds to Na+/K+ ATPase and activates these transporters
This results in the upregulation of ENaC channels

Question 11

Where is the mineralcorticoid receptor (activated by aldosterone) located?

Answer 11

Located in the nucleus

Question 12

What is Conn’s syndrome?

Answer 12

Hyperaldosterone - excess production of aldosterone

Question 13

What are the effects of hyperaldosterone?

Answer 13

Hypertension
Decreased plasma renin activity
Increased aldosterone secretion

Question 14

Why might someone develop hyperaldosteronism?

Answer 14

Aldosterone producing adenoma in the zona glomerulosa

Bilateral adrenal hyperplasia

Question 15

How can you recognise this for diagnosis?

Answer 15

In investigations, should have a high aldosterone level and a low renin level
CT scan of the adrenal gland - is a tumour present? (this can be removed)

Question 16

How can cortisol lead to hyperaldosteronism?

Answer 16

Cortisol (glucocorticoid) also binds to the mineralcorticoid receptor
SO is normally converted to the inactive form cortisone which does not bind to the receptor
Some food types can inactivate the enzyme that converts cortisol to cortisone and so the cortisol binds to the mineralcorticoid receptor and results in a mineralcorticoid excess

Question 17

How is cortisol released?

Answer 17

Corticotropin releasing hormone (CRH) is released from the hypothalamus
Causes the release of ACTH from the pituitary gland
Leads to the production of cortisol from the zona reticulosa of the adrenal glnad

Question 18

How is the release of cortisol (glucocorticoids) controlled?

Answer 18

Many feedback loops:
Glucocorticoid production will inhibit CRH production from the hypothalamus and can also inhibit ACTH production from the anterior pituitary gland

ACTH production itself can also feedback on the hypothalamus and inhibit CRH release and ACTH can also feedback onto itself and inhibit it’s own release from the anterior pituitary

Question 19

What is the effect of glucocorticoids on the immune system?

Answer 19

Inhibits the immune system

Question 20

What are the actions of glucocorticoids (cortisol)?

Answer 20

In starvation - tissue breakdown for fuel
In infection - immunosuppression
In hypotension - increased blood pressure

Question 21

What is Cushing’s syndrome?

Answer 21

Where there is too much cortisol produced
All the process i.e. tissue breakdown, immunosuppression, increase in BP will be increased - myopathy and osteoporosis will result from an increased breakdown of muscle and of bone

Question 22

How can Cushing’s syndrome occur?

Answer 22

Corticotroph adenoma of the pituitary

ACTH secreting tumour

Question 23

What is Addison’s disease?

Answer 23

Primary adrenal cortex failure, generally due

SO have problems producing adrenal androgens, glucocorticoids and mineralcorticoids

Question 24

Why is Addison’s disease dangerous?

Answer 24

The body is unable to respond to stress due to the lack of cortisol - an addisonian criss can occur:
Low BP
Low blood glucose
Low sodium and high potassium

Question 25

What is adrenal hyperplasia and what are the signs of this?

Comes up in exams

Answer 25

Various different forms of this - when various enzymes do not work at birth e.g. 21-hydroxylase deficiency and means that the hormones of the adrenal gland are not produced

Salt-losing
Adrenal insufficiency
Virilisation i.e. female babies born with male genitalia
Adrenal hyperplasia

Question 26

What hormones are produced by the adrenal medulla?

Answer 26

Catecholamines - adrenaline and noradrenaline

Question 27

What is the importance of the roles of the catecholamines in the stress response?

Answer 27

Noradrenaline - important in the stress response to low blood pressure
Adrenaline - important in the stress response to low blood sugar

Question 28

Which cells secrete adrenaline and noradrenaline?

Answer 28

Chromaffin cells

Question 29

What occurs following the activation of the following adrenoreceptors?

Alpha 1
Beta 1
Beta 2

Answer 29

Alpha 1 - stimulates smooth muscle contraction i.e. vasoconstriction
Beta 1 - Positive inotropic and chronotropic of the heart, increased renin, lipolysis
Beta 2 - Bronchial, vascular, uterine smooth muscle relaxation, glygogenolysis

Question 30

What are the symptoms of cathetholamine excess?

Answer 30

Dyspnea
Fatigue 
Headache
Hypertension 
Palpitation 
Congestive heart failure
Weight loss