Potter's Pathology (Ch. 35) Flashcards Preview

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Flashcards in Potter's Pathology (Ch. 35) Deck (7)
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1

What are satellite cells?

What is their function?

Quiescent myoblasts beneath the basal lamina.

They're responsible for myofiber regeneration s/p trauma/disease.

2

What are myotubes?

 

Fusion of myoblasts, having multiple centrally placed nuclei.

Maturation leads to peripheral migration of nuclei (myofibers).

3

What are the different myofiber types?

Type IIc
Undifferentiated myofibers
16-20 wks

Type I
Slow-twitch fibers
16-20 wks

Type IIb
Fast-twitch fibers
25 wks

Type IIa
Fast-twitch
35 wks

4

What is the usual composition of myofiber types by birth?

40% Type I
>55% is abnl
Type I predominence

60% Type II
>80% abnl

< 10% Type IIc

5

Which ATPase stains Type IIc myofibers?

ATPase, pH 4.3
Intermediate staining

6

Describe the size comparision between Type I vs. Type II fibers as the fetus grows

Wohlfart A and B

Type I starts off smaller than type II

Type I myofibers grow, become = in size by 3 mo

Surpases Type II by puberty

Persistent of small or hypotrophic Type I fibers ==> non-progressive hypotonia, 

7