TOB Clinical Conditions

Question 1

Ectopic pregnancy

Answer 1

Implantation of embryo in fallopian tube
Leads to rupture of tube
Miscarriage and haemorrhage

Question 2

Placenta praevia

Answer 2

Implantation of embryo into lower segment of uterine wall
Placenta blocks cervix
C-section required (can’t give birth naturally and at risk of haemorrhage)

Question 3

Marfan’s syndrome

Answer 3

Autosomal dominant
Misfolding of fibrillin leading to more elastic connective tissue
Very tall, arachnodactly (long digits), high arched palate
Death usually around 40 from aortic rupture -> catastrophic haemorrhage

Question 4

Ethlers-Danlos disease

Answer 4

Type 3 collagen deficiency leading to loss of structure (reticulin = scaffold)
Presents as stretchy skin, unstable joints, easy bruising

Question 5

Vitiligo

Answer 5

Autoimmune destruction of melanocytes
Leads to depigmentation
Psychosocial problems for dark skinned (not very noticeable on light skin)

Question 6

Alopecia areata/universalis

Answer 6

Autoimmune destruction of hair follicles
Can occur anywhere and everywhere
On head creates psychosocial problems (particularly for women)
Worsened by stress

Question 7

Psoriasis

Answer 7

Extreme overproduction of skin cells 
Too much corneum when it reaches that part of the cycle 
Manifests as scaling 
Cause unknown, genetic link present 
Treat with steroids

Question 8

Malignant melanoma

Answer 8

Aggressive skin cancer caused mainly by excessive UV radiation -> mutations in melanocytes
If it penetrates basement membrane it metastasises (brain/liver) = poor prognosis
Relatively rare in dark skinned people (melanin protects against UV - evolutionary as sunlight more concentrated near equator)

Question 9

Osteogenesis imperfecta

Answer 9

Autosomal dominant
Type 1 collagen deficiency/deformity (major component in ground substance in bone)
Most severe - no conversion of hyaline skeleton - incompatible with life
Most cases - repeated fractures -> bowed long bones, can be confused with NAI
Blue sclera - unknown cause, potentially due to thinning of cornea due to issues with collagen

Question 10

Rickets/osteomalacia

Answer 10

Vitamin D deficiency (not enough sunlight, dietary deficiency, decreased ability to convert it - liver/kidney pathology) -> less absorption of Ca2+ by small bowel -> less rigid bones
- Rickets - in children - bowed bones (epiphyseal growth plates not yet closed after puberty)
- Osteomalacia - in adults - bone/back ache, can be secondary to impaired hepatic/renal function
Both more common in dark skinned people as fair skinned people synthesise vit. D better (vit. D deficiency more lethal than UV radiation at European latitudes - evolution)

Question 11

Osteoporosis

Answer 11

Type 1 - menopausal, due to oestrogen no longer mediating clast function (2x more likely to fracture hip and 8x more likely to fracture vertebrae)
Type 2 - old age, due to loss of osteoblast function - no remodelling
Both due to clast > blast action

Question 12

Acromegaly/gigantism

Answer 12

Growth hormone stimulates increased bone deposition
Differing effects depending on whether the epiphyseal growth plates are closed
- Closed - increased intramembranous ossification -> larger flat bones (huge jaw)
- Open - increased intramembranous and endochondral ossification -> long bones get longer (longer femur -> taller)

Question 13

Cretinism

Answer 13

Neonatal hypothyroidism -> retardation and short stature

Corrected by giving thyroxine before 3 weeks

Question 14

Achondroplasia

Answer 14

Autosomal dominant
Deformed fibroblast growth factor receptor
Decreased endochondral ossification -> short limbs, enlarged forehead, normal trunk, 4ft high

Question 15

Myasthenia Gravis

Answer 15

Autoimmune destruction of end plate ACh receptors -> contraction ends suddenly when [ACh] drops
Droopy eyelids, fatigue, sudden collapse
Treatment - immunosuppression and AChesterase inhibitors (more ACh in synapse)

Question 16

Duchenne’s Muscular Dystrophy

Answer 16

X linked recessive
Absence of dystrophin -> muscle fibres tear on contraction -> Ca2+ induced necrosis
Fat and connective tissue replace muscle fibres
Gower’s sign (bracing thighs with arms, hunched to support weak legs)
Degenerative until chest muscles are destroyed, then death

Question 17

Becker’s Muscular Dystrophy

Answer 17

X linked recessive
Truncation of dystrophin -> muscle fibres tear on contraction -> Ca2+ induced necrosis
Fat and connective tissue replace muscle fibres
Slow progressive muscle weakness of the legs and pelvis

Question 18

Botulism

Answer 18

Botulinum toxin blocks ACh release -> no muscle contraction

Active ingredient in botox, stops facial muscle contration and therefore wrinkles

Question 19

Thyrotoxicosis

Answer 19

Increased BMR -> protein catabolism -> atrophy

Question 20

Hypoparathyroidism

Answer 20

Lack of PTH -> lack of Ca2+ absorption -> tetany (intermittent muscle spasms)

Question 21

Malignant hyperthermia

Answer 21

Autosomal dominant
Life threatening reaction to general anaesthesia
Release of Ca2+ from all sarcoplasmic reticulum -> huge spike in oxidative phosphorylation in skeletal muscle -> huge temp. spike -> control mechanisms overwhelmed -> death
Manage symptoms - paracetamol and other antipyrexials and give dantrolene (prevents Ca2+ release)

Question 22

Multiple Sclerosis

Answer 22

Autoimmune destruction of myelin sheath and Schwann cells -> decrease in conduction -> loss of function
Treatment - B interferon or steroids (mediate immune function)