Y2 Endocrinology Revision

Question 1

What are the subtypes of CD4+ cells?

Answer 1

Effector subsets: fight pathogens

• Th1: IFN-gamma
• Th2: IL-4 & IL-5
• Th17: IL-17

Regulatory subsets: regulate the effectors

• Tr1: IL-10
• Th3: TGF-beta
• CD25: IL-10 & TGF-beta

Question 2

What are Th1 cells responsible for?

Answer 2

• Fight intracellular pathogens, release IFN-gamma

Question 3

What are Th2 cells responsible for?

Answer 3

Fight extracellular pathogens, secrete IL-4&5

Question 4

What are Th17 cells responsible for?

Answer 4

Fighting extracellular bacteria and fungi, secrete IL-17

Question 5

What are microfold (M) cells?

Answer 5

• Specialised antigen uptake cells found in mucosa
• Take up antigens by phagocytosis
• M cells release antigens which are picked up by APCs which activate T-cells in GALT

Question 6

What is the dominant antibody class in the mucosal immune system?

Answer 6

IgA

• IgA is dimeric
• sits on the luminal surface where is neutralizes pathogens
• we produce 5g of IgA everyday
• binds to receptor via J chain and transports across the cell, it uses J chain to stop getting washed away
• coats membrane and stops pathogens binding
• IgA doesn’t produce inflammation or activate compliment

Question 7

What can take over if IgA is not present?

Answer 7

IgM – pentameric, also has a J chain

Question 8

What is NOD2?

Answer 8

• Protein encoded by the NOD2 gene on chromosome 16
• recognises bacterial molecules and stimulates an immune reaction
• expressed in Paneth cells, leads to expression of anti-microbial peptides
• mutation in NOD2 linked to Crohn’s

Question 9

What are aminosalicylates?

Answer 9

Drugs that dampen inflammation, mech. not well understood

• Mesalamine is the active ingredient

examples:

• Sulfasalazine
• Mesalazine

Question 10

What is methotrexate?

Answer 10

Immunosuppressor

• inhibits DNA synthesis and cellular replication

Question 11

What is infliximab?

Answer 11

MAB – binds to TNF-alpha and stops it working

Question 12

Discuss gastroenteritis

Answer 12

Infectious diarrheoa, inflammation of gut
- antibiotics not recommended

usually viral:

• norovirus
• rotavirus

bacteria:

• campylobacter
• E.coli
• salmonella

parasites:
- giardia lambila

Question 13

What is the role of the appendix

Answer 13

GALT – storage area of flora

people without an appendix often get recurrent bouts of c.diff because they don’t have their flora In storage

Question 14

What is absorbed in the duodenum?

Answer 14

Iron

Question 15

What do goblet cells secrete?

Answer 15

Mucins

Question 16

What is absorbed in the jejunum?

Answer 16

Sugars
Amino acids
Fatty acids

Question 17

What is absorbed in the ileum?

Answer 17

B12

Bile salts

Question 18

What are the 4 zones of the adrenal glands?

Answer 18

1. Glomerulosa: Mineralocorticoids
2. Fasciculata: Glucocorticoids
3. Reticulans: Androgens
4. Medulla: Catecholamines (80% adrenaline, 20% noradrenaline)

Question 19

What are steroid hormones derived from?

Answer 19

Cholesterol

Question 20

Discuss the HPA axis

Answer 20

1. Hypothalamus (corticotropin releasing H)
2. Pituitary (adrenocorticotropic H)
3. Adrenal glands (cortisol)

Question 21

Where is aldosterone released from?

Answer 21

Adrenal glands

Question 22

Discuss adrenal insufficiency

Answer 22

Primary: problem with gland not releasing cortisol

Secondary: problem with anterior pituitary not releasing ACTH

Tertiary: hypothalamus not releasing CRH

Question 23

Discuss Addison’s disease

Answer 23

• Primary adrenal insufficiency
• Usually autoimmune
• Diagnosed when cortisol <100mmol/L
• check cortisol, inject ACTH and check again

Question 24

What is fludrocortisone?

Answer 24

Synthetic adrenocortical steroid – mineralocorticoid and glucocorticoid properties

1) Increases ion and water transport
2) Raises extracellular fluid volume and blood pressure
3) Lowers potassium levels.

Question 25

What are the consequences of prolonged steroid use?

Answer 25

Adrenal atrophy, lack of ACTH production

Question 26

Discuss Cushing’s syndrome

Answer 26

- Prolonged exposure to elevated levels of glucocorticoids - most common cause is use of exogenous steroids e.g. for COPD \*test for urine cortisol – has to be 2x normal

Question 27

What is the difference between Cushing’s syndrome and disease?

Answer 27

Syndrome = symptoms associated with hypercortisolism Disease = ACTH producing adenoma in pituitary

Question 28

What is the dexamethasone suppression test?

Answer 28

Dexamethasone = synthetic cortisol Given to patient, should cause cortisol levels to drop below 50nmol/L \*If not – Cushing’s

Question 29

What is the function of mineralocorticoids?

Answer 29

Salt and water balance

Question 30

What is a glucocorticoid?

Answer 30

\*Cortisol is a glucocorticoid Corticosteroids involved in the metabolism of carbs, proteins, fats Have anti inflammatory properties e.g. hydrocortisone

Question 31

What is intrinsic clearance?

Answer 31

Theoretical max clearance of unbound drug by an eliminating organ

Question 32

What are the consequences of a lack of mineralocorticoids?

Answer 32

Fatal shock due to diminished cardiac output

Question 33

What converts corticosterone to aldosterone?

Answer 33

18-hydroxylase

Question 34

What are the actions of cortisol?

Answer 34

- Increases gluconeogenesis - Induces glucagon activity to increase blood sugar - increases protein catabolism

Question 35

What is congenital adrenal hyperplasia?

Answer 35

* Most commonly due to 21-Hydroxylase deficiency * Results in decreased cortisol and aldosterone * Excessive androgen production leading to masculinisation of female genitals Other cause = 11B-Hydroxylase deficiency which causes increased androgens and increased mineralocorticoids

Question 36

What is the role of angiotensin II in the production of mineralocorticoids?

Answer 36

Converts cholesterol to pregnenolone Converts corticosterone to aldosterone

Question 38

Which drugs have high glucocorticoid activity?

Answer 38

Dexamethasone Betamethasone

Question 39

Which drugs have moderate glucocortioid activity?

Answer 39

Hydrocortisone, Triamcinolone, Prednisolone

Question 40

What is fludrocortisone?

Answer 40

Synthetic adrenocortical steroid possessing very potent mineralocorticoid properties and high glucocorticoid activity