Microanatomy Muscle Flashcards
What are the morphological features of skeletal muscle?
Peripheral nuclei
Multi nucleated
Cross striations that make up A bands and I bands
What are the morphological features of Smooth muscle?
Central nuclei
No striations
What are the morphological features of Cardiac muscle?
Central nuclei
Intercalated disks
Cross striations0
What is/are the mechanism(s) of Muscular dystrophy?
This group of diseases are all linked by an inherited mutation or defect in some protein that involves muscle
What are the morphological features of Muscular dystrophy?
Presents clinically as progressive muscle degeneration and necrosis
What occures in the acute phase of muscle degeneration & necrosis?
Muscle will swell & become edematous
What happens to muscle as it continues to degenerate & necrose?
Over time the muscle will shrink & become atrophic
What is an example of Muscular dystrophy?
Duchenne’s Type muscular dystrophy- dystrophin mutation
What is/are the mechanism(s) of Myotonia congenita?
Inherited defects in sodium & chloride ion channel function within the membrane of those muscles
What are the morphological features of Myptonia congenita?
Inability of skeletal muscle to relax
What is an example of Myotonia congenita?
Tennessee Fainting Goats
Why did we select for myotonia congenita in the Tennessee Fainting Goats?
Has myotonia & its hyper contractile & its skeletal muscle it’s going to have more muscular bulk
What is/are the mechanism(s) of Polysaccharide storage myopathy of horses?
Mutation in glycogen synthesis one GYS1 resulting in abnormal metabolism within the myocytes themselves
What are the morphological features of Polysaccharide storage myopathy of horses?
This is a storage disease that results from abnormal carbohydrate metabolism within the muscle cells
Explain the mechanism of muscle atrophy due to disuse and what fiber type it effects.
Occurs slowly & not as severe as cachexia or denervation
Often asymmetrical
Predominantly type 2 fibers
Give an example of muscle atrophy due to disuse?
Lameness/casted limb
Explain the mechanism of muscle atrophy due to Cachexia and what fiber type it effects.
Why this happens is due to the mobilization of protein from the muscle to supply energy
Symmetrical muscle atrophy
Predominantly type 2 fibers
Give an example of muscle atrophy due to cachexia?
systemic disease (neoplasia
starvation
malnutrition
Explain the mechanism of muscle atrophy due to Denervation and what fiber type it effects.
Normal myofiber size depends on trophic factors from its associated nerve
Following nerve damage, muscle atrophy occurs rapidly (weeks)
Loss of type 1 & 2 muscle fibers
Give an example of muscle atrophy due to denervation?
Roars syndrome: damage to the left recurrent laryngeal nerve
Explain the mechanism of muscle atrophy due to Endocrine disease and what fiber type it effects.
Presents as generalized weakness
Loss of type 2 fibers
Give an example of muscle atrophy due to endocrine disease?
Hypothyroidism
Hyperadrenocorticism
What is physiologic muscle hypertrophy? Give and example.
Increased myofiber size due to exercise conditioning
What is compensatory muscle hypertrophy?
The adjacent muscle fibers are going to undergo compensatory hypertrophy to try & make us for the ones that are atrophic
