SKELETAL MUSCLE HISTOLOGY

What muscle cell is this?

cardiac muscle cell

What muscle cell is this?

smooth muscle cell

Myofirbril

tubes of contractile proteins arranged in thick and thin filaments

what causes striations in muscle cells?

alignment of sarcomeres between myofibrils

Hypertrophy

increased muscle strength due to addition of myofibrils

bright blue

muscle fibers

pink arrow

myofibrils

1

myofibril

2

T-tubules

3

sarcoplasmic reticulum

5

sarcolemma (muscle plasma membrane)

1

sarcomere

2

A-band

3

I-band

4

thick filament (myosin)

5

Z-disc

6

thin filament (actin)

what happens in muscle contraction?

binding of myosin heads on the thick filament to the thin filament

purple arrow

myofibrils (my)

pink

I-band

green

A-band

blue

Z-disc

what’s this?

skeletal muscle fibers in the tongue

what’s this?

muscle fibers cut in cross-section

what happens when muscles contract?

muscle fibers shrink

T-tubles

condicts muscle AP into interior of skeletal muscle fiber

Sarcoplasmic reticulum

stores & releases Ca2+

red 

striation 

blue

neuromuscular junction

neuromuscular junction

synapse between somatic motor neuron and skeletal muscle fibers

what NT does NMJ release?

Ach (nicotinic)

is it true that each skeletal muscle fiber received input from a single somatic motor neuron?

yes