Skeletal Muscle & Nerve Tissue Histology

Question 1

What is the function of muscles

Answer 1

Generate force with the use of ATP

Question 2

Describe the make up of a muscle cell

Answer 2

A muscle cell is a myofiber that is made up of myofibrils. These myofibrils are composed of chains of sarcomeres linked together. A sarcomere is a contractile uint made up of actin and myosin.

(Actin + Myosin) -> Sarcomere -> Myofibril (chains of sarcomeres) ->Myofiber

Question 3

What surrounds the muscle cell

Answer 3

Endomysium, a fascial covering

Question 4

Describe the make up of a muscle (not just the cell)

Answer 4

Myofiber -> Fascile (group of myofibers) -> Muscle (groups of Fasciles)

Question 5

What surrounds the Fascicle

Answer 5

Perimysium

Question 6

What surrounds the muscle itself

Answer 6

Epimysium

Question 7

What is myosin? Describe its make up

Answer 7

Known as the thick filament

Contains 2 heavy chains with globular heads with actin binding sites and ATPase Domains

Question 8

How is Myosin held in place?

Answer 8

With titin proteins connected to the Z-Disk

Question 9

Describe actin. What is it made of?

Answer 9

Known as the thin filament. Lies between myosin. Made up of F-Actin monomer that bind together to form double stranded chains

Question 10

What is the role of troponin in actin

Answer 10

Binds to tropomyosin which lays on the actin. Covers myosin binding sites when not in use

Question 11

What is the M-line

Answer 11

The attachment site for myosin within the sarcomere

Question 12

What is the Z-disk

Answer 12

Separates sarcomeres, attachment site for actin and titin

Question 13

What is the H band

Answer 13

Space on either side of M-Line where there is no actin

Question 14

What is the A band?

Answer 14

Distance from the end of one myosin head to the head of the opposite myosin (overlap of actin + myosin and H band)

Question 15

What is the I Band

Answer 15

Space on either side of the Z-disk where there is no myosin

Question 16

What is the role of calcium in skeletal muscle contraction?

Answer 16

When released into the muscle from the sarcoplasmic reticulum, it causes a conformational change in troponin to unbind from the myosin binding site and allow for the myosin head to attach to actin and cause a contraction

Question 17

What comes closer together with a contraction

Answer 17

The Z-Disks

Question 18

Do actin or myosin change in length?

Answer 18

No!

Question 19

How do all myofibrils in a muscle contract?

Answer 19

At the same time, shortening the entire muscle

Question 20

Define Type I skeletal muscle

Contraction type
Mitochondria
Myoglobin
Respiration

Example? Marathon runner

Answer 20

Slow, less powerful contraction

Many mitochondria

Abundant myoglobin

Aerobic respiration

Question 21

Define Type IIA Skeletal Muscle

Contraction type
Mitochondria
Myoglobin
Respiration

Answer 21

Fast/intermediate powerful contraction

Many mitochondria

Many myoglobin

Aerobic respiration (but less than Type I)

Question 22

Define Type IIB Skeletal Muscle

Contraction type
Mitochondria
Myoglobin
Respiration

Answer 22

Fast, powerful contraction

Few mitochondria

Few myoglobin

Aerobic respiration

Question 23

What is the sarcolemma

Answer 23

The membrane around each muscle cell

Question 24

What are transverse tubules

Answer 24

The membrane system penetrating the muscle cell that carries electrical impulses from the sarcolemma into the cell

Question 25

What it the purpose of end feet

Answer 25

To connect T Tubules with SR to allow for Ca release

Question 26

How is skeletal muscle innervated

Answer 26

Innervated by peripheral a-motor neurons from the anterior horn of the spinal cord

Question 27

How many nerves per muscle fiber

Answer 27

1

Question 28

How many muscle are innervated by one nerve

Answer 28

> 1

Question 29

What is released from the NMJ to activate depolarization of the muscle cell and the release of Ca

Answer 29

ACh

Question 30

What is the purpose of the neuromuscular spindle apparatus

Answer 30

A reflexive response to prevent over-stretching of a muscle

Question 31

What are A-motor neurons

Answer 31

Receive signal from Type 1a fibers and cause extrafusal muscle fibers to contract

Question 32

What do G-motor neurons do

Answer 32

Receive signal from type 1a fibers and cause intrafusal muscle fibers to contract

Question 33

Describe the make up of a nerve

Answer 33

Axon -> fascicle (group of axons) -> nerve (group of fascicles)

Question 34

What connective tissue surrounds the axon?

Answer 34

Endoneurium

Question 35

What connective tissue surrounds the fascicle

Answer 35

Perineurium

Question 36

What connective tissue surrounds the nerve

Answer 36

The epineurium

Question 37

On the axon, where is the endoneurium located

Answer 37

Superior to the myelan sheath

Question 38

Describe a multipolar neuron

Answer 38

Multiple dendrites and one axon

Usually found in efferent motor neurons

Question 39

What is a bipolar neuron

Answer 39

Single dendrite and one axon with the cell body in the middle

Found in CN 1,2,8

Question 40

Describe a pseudounipolar neuron

Answer 40

One cell process with a single dendrite branch and axon branch with the cell body off to the side

Found in afferent sensory neurons in the PNS

Question 41

What are the parts of the NMJ

Answer 41

Axon terminal
Synaptic cleft
Sarcoplasm of muscle fiber (receives ACh)