CLINICAL CONDITIONS Flashcards by Emily Stephens

What clinical conditions relate to connective tissue issues?

Scurvy
Marfan’s syndrome
Osteogenesis imperfecta

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What is scurvy due to?

Vitamin C deficiency - essential in collagen production to hydroxylation proline + lysine to procollagen

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Signs and symptoms of scurvy

Think pirates
- gum disease + tooth loss
- bruising
- hair loss
- bleeding from gums
- poor wound healing
- impaired bone development when young

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What cause Marfan’s Syndrome?

Mutation of fibrillin 1 gene&raquo_space; elastic tissue is abnormal
Autosomal dominant disorder

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Signs + symptoms of Marfan’s syndrome

Abnormally tall
Arachnodactyly - ‘spider fingers’
Arm span is greater than height
Frequent joint dislocation

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What are people with Marfan’s syndrome at risk of?

Aortic rupture

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What is osteogenesis imperfecta due to?

Mutation in col1A or col2A gene
Mutated collagen fibres that don’t cross link/not enough produced
Autosomal dominant

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Signs and symptoms of osteogenesis imperfecta

Weakened bone - ‘brittle bone disease’
Blue sclera
Spinal curvature
Hyper mobility
Poor teeth development
Shortened height + stature

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What is an eptopic pregnancy?

When implantation occurs at site other than uterine body often in fallopian tubes

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What is placenta praevia?

Implantation of zygote in lower uterine segment
Placenta blocks birth canal

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Why is a C section required in placenta paraevia?

Placenta blocks birth canal
Risk of haemorrhage due to fragile vessels

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What is sinus inversus?

Developmental disorder in which here is a complete mirror image of organs

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What causes sinus inversus?

Lack of left ward flow of signally molecules in trilamiar disc in gastrulation
Signals cannot initiate signalling cascades that correspond for development of left sidedness

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What clinical conditions are related to bone diseases?

Osteogenesis imperfecta
Rickets + osteomalacia
Osteoporosis
Achondroplasia

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What is rickets due to?

Vitamin D deficiency - produces calcitriol
Poor calcium mobilisation + ineffective mineralisation
Weakened bone development
In children

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Characteristic of rickets

Bowed legs

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What is osteomalacia?

Rickets in adults
Vitamin D deficiency

What is hydroxyapatite made of?

Calcium

What is osteoporosis?

A degernative bone disease in which the bone matrix is broken down+ bone demineralises&raquo_space; loss of structural density

Causes of osteoporosis

Mismatch of osteoblasts and osteoclast numbers
Results in greater rate of bone resorption than bone synthesis

Risk factors for osteoporosis

Menopause > age
Chronic kidney disease
Corticosteroids
Smoking
Inactivity

How is menopause a risk factor for osteoporosis?

Decreased oestrogen levels
Oestrogen is protective factor for osteoporosis

Outline primary type 1 osteoporosis

Post menopausal women
Due to increased osteoclast number
Loss of oestrogen after menopause

Outline primary type 2 osteoporosis

Occurs in ~70 year old men and women
Due to loss of osteoblast function
Loss of oestrogen and androgen

Outline secondary osteoporosis

Result of drug therapy - corticosteroids Steroids use increases osteoclast action + affects calcium excretion Bone remodelling affected

Modifiable risk factors of osteoporosis

Increase calcium intake Exercise Smoking cessation

What is achondroplasia? What type of inheritance is it?

Dwarfism Autosomal dominant mutation on the FGF3 receptor gene

Cause of achondroplasia What does this cause?

- Inherited mutation on the FGF3 receptor gene - FGF promotes collagen formation from cartilage >> affects endochondral ossification NOT intra-membranous - long bones affected, not flat bones - normal sized head + torso but smaller limbs due to inadequate long bone development

Characteristics of achondroplasia

Short stature Normal sized head and torso Long bones cannot lengthen properly

What clinical conditions relate to muscle dysfunction?

Duchene muscular dystrophy Rhabdomyolysis Myocardial infarction Botulism + organophosphate poisoning Malignant hypothermia

What is the cause of Duchene muscular dystrophy

Mutation of the dystrophin gene

What does the a mutation in dystrophin cause?

**Duchene muscular dystrophy** - Excess Ca2+ enters muscle cells - Ca2+ taken up by mitochondria - Water taken with it - Muscle cells burst > Rhabdomyolysis - High levels of creatine kinase + myoglobin

What is botulism toxin and what does it do?

Toxin produced by clostridium botulinum Blocks neurotransmitter release Causes non-contractile state of skeletal muscle

Uses of botulism toxin

- **clinically** - to treat muscle spasm + urgency UI - **cosmetically** - Botox - to treat wrinkles

What is organophosphate and what does it do?

A pesticide Inhibits the normal function of ACh esterase

Muscarinic symptoms of organophosphate poisoning

**SLUDGE** **S**alivation **L**acrimation **U**rination **D**efecation **G**I cramping **E**mesis

Nicotinic symptoms of organophosphate poisoning

**Days of the week MTWTF** **M**uscle cramps **T**achycardia **W**eakness **T**witching **F**asciculations - muscle twitch

What causes malignant hypothermia?

Mutation in RyR1 receptor

What type of inheritance is Marfan’s syndrome

Autosomal dominant

What type of inheritance is Duchene muscular dystrophy?

X linked recessive

What type of inheritance is achondroplasia?

Autosomal dominant

Outline collagen synthesis

1- preprocollagen undergoes vit C dependent hydroxylation of proline + lysine 2- precollagen formed - 3 PPC cross linked to form triple helix 3- C and N terminals of PC cleaved 4- tropocollagen formed 5- TP cross link formation 6- microfibrils, fibrils + collagen fibres made