Muscle Histology Flashcards
What is Duchenne muscle dystrophy
Muscle weakness due to absence of dystrophin protein, leading to damage beyond repair.
What is the difference between Duchenne and Becker muscle dystrophy
Duchenne = absence of dystrophin Becker= decrease in dystrophin however it is not absent, so is less severe than Duchenne
Explain the function of dystrophin protein
Forms a dystrophin glycoprotein complex that binds cytoskeleton of muscle fiber to the basal lamina.
Why is there muscle weakness in the absence of dystrophin?
No dystrophin glycoprotein complex, myofiber is not bound to basal lamina, leading to transient tears in the muscle during contraction. Excess Calcium influx occurs leading to distrubtions signaling.
How does the body compensate for the muscle tear
replaces the muscle with collagen and fat
What do the muscle fibers look like under a microscope
Some atrophied and some hypertrophied
Absence of endomysium
Describe the clinical picture of Duchenne muscle dystrophy.
Protruding belly due to weak abdominal muscles Walking on toes Big calf (collagen and fat) Weak glutes Shoulders pushed back abnormally
What type of fibers are predominant in endomysium?
Reticular fibers.
What type of collagen are reticular fibers?
Type III Collagen.
What is reticular connective tissue?
Connective tissue formed of predominantly reticular fibers.
Where can reticular fibers be found in the body
In the endomysium for mechanical support of muscles
Surrounding adipocytes
Surrounding arterioles
