Collagen and Collagen Abnormalities Flashcards
What is collagen composed of?
Triple helices of various polypeptide alpha chains - rope like appearance
What is the most common type of collagen and where is it found?
Type 1
Bones, tendons,ligaments, skin, sclera, cornea, blood vessels, hollow organs
What type of collagen is secreted by epithelial cells?
Type IV: makes up Basement membranes
What disease are the result of defective collagen synthesis? Name an acquired one and an inherited one
Acquired: scurvy
Inherited: Ehlers-Danlos syndrome
Osteogenesis imperfecta
Alport syndrome
What is scurvy?
Vitamin C deficiency
How does scurvy result in collagen defects?
Inadequate vitamin C dependent hydroxylation of procollagen alpha chains = reduced cross linking and defective helix formation
Therefore collagen lacks strength and is vulnerable to enzymatic degradation
Particular effects collagens supporting blood vessels
What effect does scurvy have on wound healing?
Unable to heal wounds and there is a tendency to bleed
What are some symptoms of scurvy?
Inability to heal wounds Tooth loss (teeth arent held in) Old scars break down and open up (collagen turnover in scars remains high long after healing process appears complete)
What is Ehlers- Danlos syndrome?
Inherited disorder in which there is a defective conversion of procollagen to tropocollagen
Meaning collagen fibres lack adequate tensile strength
What are the symptoms Ehlers-Danlos syndrome?
Poor wound healing
Skin is hyper extensible (but will recoiled due to elastic fibres), thin, fragile and susceptible to injury
Hypermobile joints - more like to dislocate joints
In some more severe forms what can Ehlers-Danlos syndrome lead to?
Rupture of colon, large arteries or cornea
Retinal detachment
What osteogenesis imperfecta?
Brittle bone disease (or lobstein’s disease)
When one has too little bone tissue and therefore extremely fragile skeleton
What are the symptoms of osteogenesis imperfecta?
Susceptible to breaking bones
Blue sclerae- too little collagen within them and they are translucent
Hearing impairment
Dental abnormalities
What is Alport syndrome?
X-linked disease (affects more males)
Abnormal type IV collagen
What does Alport syndrome cause?
Dysfunction in glomerular basement membrane, cochlea of ear and lens of eye
Presents with haematuria in children/adolescents progressing to renal failure
Neural deafness
Eye disorders
