Skeletal Muscle And Nerve Tissue Histology

Question 1

What are the differences between skeletal, cardiac, and smooth muscle?

Answer 1

Skeletal muscle is striated, strong, quick, voluntary, fatiguable and multinucleated

Cardiac is striated, strong, quick, involuntary and can never fatigue, uninucleated, branched and separated by intercalated discs

Smooth muscle is not striated, weaker, slow and rhythmic, involuntary and uninucleated

Question 2

What is a sarcomere?

Answer 2

The contractile unit of muscle made up of actin and myosin myofilaments

Question 3

What is endomysium?

Answer 3

The fascia covering over myofibers

Question 4

What is a myofibril?

Answer 4

A chain of sarcomeres. It makes up muscle cells

Question 5

What is a fascicle?

Answer 5

A group of myofibers surrounded by perimysium

Question 6

A muscle is made up of a group of ____, and is surrounded by ____

Answer 6

Fascicles, epimysium

Question 7

What is myosin made up of?

Answer 7

2 heavy chains with a globular head (actin binding site with ATPase domain)

2 light chains

Held in place by Titian proteins connected to Z disk

Question 8

What is nebulin?

Answer 8

A ruler for determining the length of actin filaments

Question 9

What is the M-line?

Answer 9

Attachment site for myosin

Question 10

What is the Z-disk?

Answer 10

Separates sarcomeres; attachment site for actin and Titian

Question 11

What is the H band?

Answer 11

Space on either side of the M line where there is no actin

Question 12

What is the A band?

Answer 12

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

Question 13

What is the I band?

Answer 13

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

Question 14

What does troponin do?

Answer 14

Blocks the myosin binding sites on actin filaments

Question 15

What does calcium binding to troponin cause?

Answer 15

A conformational change that makes the actin binding site accessible to myosin heads

Question 16

Describe the sliding filament mechanism

Answer 16

Thin filaments slide past thick filaments (myosin heads crawl across actin filaments)

This brings Z-disks closer together

Question 17

What is the main difference between Type 1 and Type 2 skeletal muscle fiber types?

Answer 17

Type 1 is slow, less powerful contraction with many mitochondria, abundant myoglobin, slow fatiguability and aerobic respiration

Type 2a is fast/intermediate powerful contractions, many mito, myo, intermediate fatiguability and aerobic

Type 2b is fast powerful contractions, few mito, few myo, rapid fatiguability and anaerobic respiration.

Question 18

What is a sarcolemma?

Answer 18

Membrane around each muscle cell

Question 19

What is a sarcoplasm?

Answer 19

Cytoplasm of muscle cells

Question 20

What is the sarcoplasmic reticulum?

Answer 20

Tubular system acting like the smooth ER

Question 21

What is the terminal cisternae?

Answer 21

A flattened sac of SR on either side of a transverse T Tubule

Question 22

What is a transverse (T) Tubule?

Answer 22

Membrane system penetrating the muscle cell to convey electrical impulses from sarcolemme into cell

Question 23

What is a triad?

Answer 23

T-tubule and 2 terminal cisternae

Question 24

What do End Feet do?

Answer 24

Connect t-tubules with SR to allow Ca release

Question 25

What is the neuromuscular spindle apparatus?

Answer 25

A reflex response to help prevent over stretching of muscles

Question 26

What do extrafusal muscle fibers do?

Answer 26

Contract the muscle

Question 27

What do intrafusal muscle fibers do?

Answer 27

Sense length and rate of change of the extrafusal muscle fibers, which will cause the reflex response

Question 28

What are Type 1a sensory nerve fibers?

Answer 28

Afferent innervation of intrafusal fibers; these will sense the change in length and will send a signal to the spinal cord

Question 29

What are a-motor nerve fibers?

Answer 29

Efferent innervation of extrafusal muscle fibers; reflex reaction

Question 30

What are g-motor nerve fibers?

Answer 30

Efferent innervation of intrafusal muscle fibers; reflex reaction

Question 31

What is the Nissle substance?

Answer 31

An abundant rER within the cytoplasm of the soma

Question 32

What is a multipolar neuron?

Answer 32

A neuron with an axon with multiple dendrites and one axon

Question 33

What is a bipolar neuron?

Answer 33

A neuron with a single dendrite (multiple extension) and one axon

Question 34

What is a pseudounipolar neuron?

Answer 34

one cell process with a single dendrite branch and axon branch

Question 35

What does the myelin sheath do?

Answer 35

It allows for faster signal conduction velocity

Question 36

What is the neuromuscular junction? How many nerves per muscle fiber and how many muscle fibers per nerve?

Answer 36

Skeletal muscle innervated by peripheral alpha-motor neurons from the anterior horn of the spinal cord; 1 nerve per muscle fiber More than one muscle per nerve