Microanatomy Muscle

Question 1

What are the morphological features of skeletal muscle?

Answer 1

Peripheral nuclei
Multi nucleated
Cross striations that make up A bands and I bands

Question 2

What are the morphological features of Smooth muscle?

Answer 2

Central nuclei
No striations

Question 3

What are the morphological features of Cardiac muscle?

Answer 3

Central nuclei
Intercalated disks
Cross striations0

Question 4

What is/are the mechanism(s) of Muscular dystrophy?

Answer 4

This group of diseases are all linked by an inherited mutation or defect in some protein that involves muscle

Question 5

What are the morphological features of Muscular dystrophy?

Answer 5

Presents clinically as progressive muscle degeneration and necrosis

Question 6

What occures in the acute phase of muscle degeneration & necrosis?

Answer 6

Muscle will swell & become edematous

Question 7

What happens to muscle as it continues to degenerate & necrose?

Answer 7

Over time the muscle will shrink & become atrophic

Question 8

What is an example of Muscular dystrophy?

Answer 8

Duchenne’s Type muscular dystrophy- dystrophin mutation

Question 9

What is/are the mechanism(s) of Myotonia congenita?

Answer 9

Inherited defects in sodium & chloride ion channel function within the membrane of those muscles

Question 10

What are the morphological features of Myptonia congenita?

Answer 10

Inability of skeletal muscle to relax

Question 11

What is an example of Myotonia congenita?

Answer 11

Tennessee Fainting Goats

Question 12

Why did we select for myotonia congenita in the Tennessee Fainting Goats?

Answer 12

Has myotonia & its hyper contractile & its skeletal muscle it’s going to have more muscular bulk

Question 13

What is/are the mechanism(s) of Polysaccharide storage myopathy of horses?

Answer 13

Mutation in glycogen synthesis one GYS1 resulting in abnormal metabolism within the myocytes themselves

Question 13

What are the morphological features of Polysaccharide storage myopathy of horses?

Answer 13

This is a storage disease that results from abnormal carbohydrate metabolism within the muscle cells

Question 14

Explain the mechanism of muscle atrophy due to disuse and what fiber type it effects.

Answer 14

Occurs slowly & not as severe as cachexia or denervation

Often asymmetrical

Predominantly type 2 fibers

Question 15

Give an example of muscle atrophy due to disuse?

Answer 15

Lameness/casted limb

Question 16

Explain the mechanism of muscle atrophy due to Cachexia and what fiber type it effects.

Answer 16

Why this happens is due to the mobilization of protein from the muscle to supply energy

Symmetrical muscle atrophy

Predominantly type 2 fibers

Question 17

Give an example of muscle atrophy due to cachexia?

Answer 17

systemic disease (neoplasia

starvation

malnutrition

Question 18

Explain the mechanism of muscle atrophy due to Denervation and what fiber type it effects.

Answer 18

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

Question 19

Give an example of muscle atrophy due to denervation?

Answer 19

Roars syndrome: damage to the left recurrent laryngeal nerve

Question 20

Explain the mechanism of muscle atrophy due to Endocrine disease and what fiber type it effects.

Answer 20

Presents as generalized weakness

Loss of type 2 fibers

Question 21

Give an example of muscle atrophy due to endocrine disease?

Answer 21

Hypothyroidism

Hyperadrenocorticism

Question 22

What is physiologic muscle hypertrophy? Give and example.

Answer 22

Increased myofiber size due to exercise conditioning

Question 23

What is compensatory muscle hypertrophy?

Answer 23

The adjacent muscle fibers are going to undergo compensatory hypertrophy to try & make us for the ones that are atrophic

Question 24

What is the cause of Hypertrophic Cardiomyopathy?

Answer 24

Primary heart muscle disease due to a genetic abnormality in myosin binding protins

Question 25

What morphological features are present with Hypertrophic Cardiomyopathy?

Answer 25

Cardiomegaly
Thick left ventricular wall and IV septum
Sequela- leading to thrombi formation