Histology: Skeletal Muscle

Question 1

What in the embryo eventually becomes muscle cells?

Answer 1

Myoblasts (@ 4 wks)

Question 2

Characteristics of Skeletal muscle (3)

Answer 2

Striated, voluntary and non branching
Peripheral nuclei
Lots of cytoplasm

Question 3

Muscle is enclosed by what?

Answer 3

Epimysium

Epimysium > Perimysium > Endomysium

Question 4

Smaller muscle fibers are surrounded by what?

Answer 4

Perimysium

Epimysium > Perimysium > Endomysium

Question 5

Each muscle fiber is enclosed by what?

Answer 5

Endomysium

Epimysium > Perimysium > Endomysium

Question 6

Order of muscle fibers

Answer 6

Muscle > Fascicles > muscle fiber > myofibril

Question 7

Cross-striations are caused by what?

Answer 7

Stacks of myofibrils (contain sarcomeres)

Question 8

Sarcomeres do what?

Answer 8

Contraction

Question 9

Thick and thin filament

Answer 9

Myosin (shaped like golf club-provide driving force for movement. Myosin heads move along actin filaments)

(Thin=actin)

Question 10

Scaffolding proteins

Answer 10

Help support myofibrils. Help with contraction of myofilaments

Question 11

What do satellite cells do?

Answer 11

Repair and re-grow damaged muscle

Question 12

What is a neuromuscular junction?

Answer 12

Where neurons and skeletal muscle meet

Question 13

What is a motor unit?

Answer 13

A motor neuron and all the muscle cells it innervates

Question 14

Type 1 fibers

Answer 14

“Red” fibers
Slow twitch
Fatigue resistant

Marathon runner

Question 15

Type 2 fibers

Answer 15

“White” fibers
Fast twitch
Fatigue more easily

Sprinter

Question 16

What do neuromuscular spindles do?

Answer 16

Are sensors that help monitor the muscle’s position in space and the state of muscle contraction