4. MR

Question 1

What is hereditary spherocytosis?

Answer 1

Autosomal dominant condition where spectrin in RBC is depleted by 50% so erythrocytes become rounded and are more prone to lyses, resulting in haemolytic anaemia.

Question 2

How are hereditary spherocytosis/eliptocytosis treated?

Answer 2

With normal blood transfusions.

Question 3

What is hereditary eliptocytosis?

Answer 3

Autosomal dominant condition where spectrin in RBC is depleted by 50% so erythrocytes become rugby ball shaped and are more prone to lyses, resulting in haemolytic anaemia.

Question 4

What is myasthenia gravis?

Answer 4

Autoimmune destruction of end plate ACh receptors, which leads to less depolarisation of muscle fibres and difficulty contracting muscles.

Question 5

What are the features of myasthenia gravis?

Answer 5

Muscle fatigue - drooping eyelids, extreme weakness.

Question 6

What are the LDL receptor defect causes of familial hypercholesterolaemia?

Answer 6

Receptor deficiency, non-functional receptors, receptor binding normal but no interaction with coated pits so can’t form proper coated vesicle.

Question 7

What are the features of familial hypercholesterolaemia?

Answer 7

Excess circulating cholesterol, deposited as tendon xanthomas, xanthelasmas, or corneal arcus. Also causes atherosclerosis and associated risks with that.

Question 8

What is pheochromocytoma?

Answer 8

Noradrenaline secreting tumour of the chromaffin cells of the adrenal medulla.

Question 9

How can pheochromocytoma be detected?

Answer 9

Levels of vanillymandelic acid in urine.

Question 10

What are the symptoms of pheochromocytoma?

Answer 10

Excessive sympathetic stimulation symptoms - sweating, tachycardia, etc.

Question 11

How is pheochromocytoma treated?

Answer 11

With alpha-methyl tyrosine, blocks biogenic amine synthesis by inhibiting tyrosine hydroxylase, reducing levels of noradrenaline produced.

Question 12

What is retinitis pigmentosa?

Answer 12

Loss of function in rhodopsin GPCR leading to progressive degeneration of vision due to damage of rod cells.

Question 13

What is nephrogenic diabetes insipidus?

Answer 13

Loss of function to V2 ADH receptor so kidneys don’t retain water and lots of urine is passed, leading to dehydration and death.

Question 14

What is familial male precocious puberty?

Answer 14

Gain of function in LH receptor so andorgens are produced in larger quantities more quickly and puberty can start from age 2.

Question 15

What are the signs of familial male precocious puberty?

Answer 15

Short stature as epiphyseal growth plates close early.

Question 16

What is asthma?

Answer 16

Bronchoconstriction resulting in shortness of breath, wheezing. From release of inflammatory mediators in response to an irritant or allergen.

Question 17

How do bronchi and bronchioles constrict?

Answer 17

Parasympathetic innervation driven by M3 receptors -> Gaq-> phospholipase C -> Ca2+ release.

Question 18

How is asthma managed?

Answer 18

B2 agonists like salbutamol or salmetrol, to active B2 receptors -> Gs->cAMP->PJA->MLCK stopped-> bronchodilation. Steroids/antihistamines dampen immune response long term. Methylxanthines preserve cAMP.

Question 19

What is hypertension defined as?

Answer 19

Systolic >140mmHg, or diastolic >90mmHg.

Question 20

What are the sequelae of hypertension?

Answer 20

Severe cardiovascular complications, like ischaemic heart disease.

Question 21

How is hypertension dealt with in the body short term and long term?

Answer 21

Short term - baroreceptor reflex. Long term - RAAS.

Question 22

How is hypertension treated?

Answer 22

Loop dieuretics, ACE inhibitors, beta blockers, a1 adrenoceptor antagonists.

Question 23

How do loop diuretic treat hypertension?

Answer 23

Target NKCC2 channels in nephron to block Na+ and H2O reabsorption so blood volume falls.

Question 24

How do ACE inhibitors treat hypertension?

Answer 24

Block angiotensin converting enzyme from making ATII from ATI so stops increase in TPR and stops Na+/H2O retention directly and via aldosterone.

Question 25

How do beta blockers treat hypertension?

Answer 25

B1 adrenoceptors in myocardium blocked so negative chronotropy through less cAMP -> HCN channels closing and negative inotropy from less Ca2+ channels open.

Question 26

How do a1-adrenoceptor antagonists treat hypertension?

Answer 26

a1-adrenoceptors in peripheral arterioles blocked so dilation or arterioles,

Question 27

What is thyrotoxicosis?

Answer 27

A result of hyperthyroidism, T4 upregulates the number of adrenoceptors present so there is increased heart rate through B1 receptors and increased sweating from sympathetic innervation.

Question 28

How is thyrotoxicosis treated?

Answer 28

Carbimazole blocks iodine uptake and thyroxine synthesis long term, short term symptoms are relieved by a non-specific beta adrenoceptor antagonist for symptoms relief, like propranolol.