Adrenal Gland

Question 1

In order what are the layers of the adrenal gland?

Answer 1

1. Capsule
2. Cortex
3. Adrenal medulla

Question 2

What are the three layers of the adrenal cortex (in order)?

Answer 2

1. Zona glomerulosa
2. Zona fasciculata
3. Zona reticularis

Question 3

What does the zona glomerulosa produce?

Answer 3

Mineralcorticoids e.g aldosterone

Question 4

What does the zona fasciculata produce?

Answer 4

Glucocorticoids e.g cortisol

Question 5

What does the zona reticularis produce?

Answer 5

Androgens e.g DHEA

Question 6

What does the adrenal medulla produce?

Answer 6

Norepinephrine and epinephrine

Question 7

What are the functions of aldosterone?

Answer 7

1. Aldosterone increases uptake of sodium by the kidneys so less is lost in the urine. This leads to more water staying in the body.
   - –> increasing blood volume therefore increasing blood pressure.
2. Aldosterone promotes the loss of H+ in the urine, therefore helping to prevent acidosis.

Question 8

What controls aldosterone secretion?

Answer 8

The RAAS pathway

Question 9

Where is renin secreted from?

Answer 9

JGA in the kidneys

Question 10

Where is angiotensinogen produced?

Answer 10

The liver

Question 11

Explain the RAAS system.

Answer 11

1. Renin is produced by the kidneys in response to decreased blood pressure.
2. Renin travels to the liver where it converts angiotensinogen into angiotensin 1.
3. Angiotensin 1 travels in the blood to the lungs.
4. ACE is present in the lungs and converts angiotensin 1 into angiotensin 2.
5. Angiotensin 2 causes vasoconstriction and stimulates aldosterone production in the adrenal gland.

Question 12

Where does angiotensin II act?

Answer 12

The smooth muscle in the walls of arterioles.

Question 13

Where are glucocorticoids produced?

Answer 13

The zona fasciculata in the adrenal gland

Question 14

What are the effects of glucocorticoids?

Answer 14

1. Protein breakdown
2. Gluconeogenesis
3. Lipolysis
4. Resistance to stress
5. Increased blood pressure
6. Anti-inflammatory effects
7. Depression of immune responses

Question 15

What is the function of protein breakdown by cortisol?

Answer 15

Cortisol breaks down the proteins in muscle fibres increasing the number of amino acids in the blood, allowing new protein production.

Question 16

How does cortisol combat stress?

Answer 16

Increases blood glucose levels therefore there is more ATP available to combat stress.

Question 17

How does cortisol increase blood pressure?

Answer 17

Cortisol makes blood vessels more sensitive to hormones that cause vasoconstriction, thus increasing blood pressure.
—> Important in cases of severe blood loss.

Question 18

How do glucocorticoids have an anti-inflammatory effect?

Answer 18

Glucocorticoids inhibit white blood cells that participate in the inflammatory response.
However this also delays tissue repair slowing wound healing.
—> Useful in treating chronic inflammatory conditions such as rheumatoid arthritis.

Question 19

What is the importance of depressed immune response induced by glucocorticoids?

Answer 19

Glucocorticoids are prescribed after organ transplant to delay tissue rejection.

Question 20

Explain the control of cortisol secretion.

Answer 20

1. CRH produced by hypothalamus
2. Goes to AP through HPS
3. Corticotrophs in AP secrete ACTH
4. ACTH acts on the adrenal cortex stimulating cortisol production.

Question 21

Where are androgens such as DHEA secreted?

Answer 21

The zona reticularis in the adrenal cortex

Question 22

What is the main androgen secreted by the zona reticularis?

Answer 22

DHEA

Question 23

What does DHEA do in men?

Answer 23

Stimulates the production of testosterone

Question 24

What does DHEA do in women?

Answer 24

1. DHEA is converted into oestrogen
2. Increases libido
3. Growth of pubic hair

Note: after menopause the only source of oestrogen for women comes from DHEA.

Question 25

What controls DHEA secretion?

Answer 25

ACTH

Question 26

Where does epinephrine it's greatest effect?

Answer 26

The heart

Question 27

Where does noepinephrine have it's greatest effect?

Answer 27

Blood vessels

Question 28

What cells secrete epinephrine and norepinephrine?

Answer 28

Chromaffin cells in the adrenal medulla

Question 29

How is secretion of epinephrine and norepinephrine by chromaffin cells controlled?

Answer 29

Chromaffin cells are innervated by preganglionic cells of the ANS. This means the ANS has direct control over chromaffin cells and thus hormone release can occur very quickly.

Question 30

What are the main actions of norepinephrine and epinephrine?

Answer 30

1. Causes the fight or flight response, increasing heart rate and force of contraction. 2. Increased blood pressure 3. Increased blood flow the liver, heart, skeletal muscle and adipose tissue. 4. Dilates the airway to the lungs 5. Increased levels of glucose and fatty acids in the blood.

Question 31

What type of molecule is norepinephrine?

Answer 31

Neurotransmitter

Question 32

What type of molecule is epinephrine?

Answer 32

Hormone

Question 33

When is norepinephrine used?

Answer 33

To raise heart rate and modulate blood pressure

Question 34

When is epinephrine used?

Answer 34

Used as an effective antihistamine in the treatment of shock.

Question 35

What is Conn's syndrome?

Answer 35

High levels of aldosterone in the blood compared to renin.

Question 36

What is Conn's syndrome often caused by?

Answer 36

Lesion on the adrenal cortex

Question 37

How is Conn's syndrome diagnosed?

Answer 37

CT/MRI scan

Question 38

What are the symptoms of Conn's syndrome?

Answer 38

Hypertension Hyperatremia Hypokalaemia

Question 39

What is Cushing's syndrome?

Answer 39

The production of excess cortisol, often due to the excess production of ACTH.

Question 40

What often causes Cushing's syndrome?

Answer 40

A pituitary tumour

Question 41

What are the usual treatments for Cushing's?

Answer 41

Surgery, radiation, chemotherapy

Question 42

What are the clinical features of Cushing's?

Answer 42

``` Moon face (excessive fat around the face) Hypertension ```

Question 43

How do you diagnose Cushing's?

Answer 43

Urine test for cortisol levels at midnight.

Question 44

What is Addison's disease?

Answer 44

Deficiency of cortisol

Question 45

What can cause Addison's disease?

Answer 45

Autoimmune destruction of the adrenal gland. - --> Secondary cause can be a lack of ACTH production by the anterior pituitary - --> Use of steroids

Question 46

What are the clinical features of Addison's disease?

Answer 46

``` Anorexia Strange skin pigmentation Dizziness Hypotension Hypoglycaemia ```

Question 47

How is Addison's disease diagnosed?

Answer 47

``` Testing for: Hyponatremia Hyperkalaemia Low cortisol levels in the morning CT of adrenal gland MRI of pituitary ```

Question 48

What is the treatment for Addison's disease?

Answer 48

Hydrocorticosone

Question 49

What is the dexamethasone suppression test?

Answer 49

The overnight dexamethasone suppression test involves taking a dose of a corticosteroid medicine called dexamethasone to see how it affects the level of a hormone called cortisol in the blood. This test checks for Cushing's syndrome. In this condition, large amounts of cortisol are produced by the adrenal glands. Cortisol level should decrease after you receive dexamethasone. Low dose: Overnight -- 8 a.m. plasma cortisol lower than 1.8 micrograms per deciliter (mcg/dL) or 50 nanomoles per liter (nmol/L) Standard -- Urinary free cortisol on day 3 lower than 10 micrograms per day (mcg/day) or 280 nmol/L.

Question 50

What is the synacthen test?

Answer 50

A synacthen test tests for Addison's disease. It involves stimulating the adrenal glands and then checking to see if they respond.