4. MR Flashcards

1
Q

What is hereditary spherocytosis?

A

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.

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2
Q

How are hereditary spherocytosis/eliptocytosis treated?

A

With normal blood transfusions.

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3
Q

What is hereditary eliptocytosis?

A

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.

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4
Q

What is myasthenia gravis?

A

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

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5
Q

What are the features of myasthenia gravis?

A

Muscle fatigue - drooping eyelids, extreme weakness.

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6
Q

What are the LDL receptor defect causes of familial hypercholesterolaemia?

A

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

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7
Q

What are the features of familial hypercholesterolaemia?

A

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

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8
Q

What is pheochromocytoma?

A

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

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9
Q

How can pheochromocytoma be detected?

A

Levels of vanillymandelic acid in urine.

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10
Q

What are the symptoms of pheochromocytoma?

A

Excessive sympathetic stimulation symptoms - sweating, tachycardia, etc.

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11
Q

How is pheochromocytoma treated?

A

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

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12
Q

What is retinitis pigmentosa?

A

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

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13
Q

What is nephrogenic diabetes insipidus?

A

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

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14
Q

What is familial male precocious puberty?

A

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

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15
Q

What are the signs of familial male precocious puberty?

A

Short stature as epiphyseal growth plates close early.

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16
Q

What is asthma?

A

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

17
Q

How do bronchi and bronchioles constrict?

A

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

18
Q

How is asthma managed?

A

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.

19
Q

What is hypertension defined as?

A

Systolic >140mmHg, or diastolic >90mmHg.

20
Q

What are the sequelae of hypertension?

A

Severe cardiovascular complications, like ischaemic heart disease.

21
Q

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

A

Short term - baroreceptor reflex. Long term - RAAS.

22
Q

How is hypertension treated?

A

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

23
Q

How do loop diuretic treat hypertension?

A

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

24
Q

How do ACE inhibitors treat hypertension?

A

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

25
Q

How do beta blockers treat hypertension?

A

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

26
Q

How do a1-adrenoceptor antagonists treat hypertension?

A

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

27
Q

What is thyrotoxicosis?

A

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.

28
Q

How is thyrotoxicosis treated?

A

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.