Skeletal Muscle and Nerve Tissue Histology

Question 1

Thin actin microfilaments and thick myosin filaments organize into structures called

Answer 1

Myofibrils

Question 2

Skeletal muscle and cardiac muscle vs smooth muscle

Answer 2

Skeletal and cardiac muscle are striated, smooth muscle is not

Question 3

Groups of myofibrils make up a

Answer 3

Muscle fiber or myofiber

Question 4

Groups of muscle fibers/myofibers form a _____ which together, form a ____

Answer 4

Fascicle, which bundle together to form an entire muscle

Question 5

Myofibers are surrounded by

Answer 5

Endomysium

Question 6

Fascicles are surrounded by

Answer 6

Perimysium

Question 7

The entire muscle is surrounded by

Answer 7

Epimysium

Question 8

Skeletal muscle histological description

Answer 8

Multinucleated cylinders commonly referred to as myofibers. The nuclei are located in the periphery of the cell; the cytoplasm is primarily occupied by myofibrils

Question 9

What is the basic structural unit of a myofibril (not talking about actin or myosin) and what does it do

Answer 9

Sarcolemma, sleeves around each myofibril and stores calcium

Question 10

T-tubules

Answer 10

Invaginations of the sacrolemma

Question 11

Terminal cisternae

Answer 11

Dilated ends of SR that release calcium and trigger muscle contraction

Question 12

Sarcomere

Answer 12

Extends from one Z-line to the next Z-line

When a muscle cell contracts, every sarcomere shortens

Question 13

Z-line

Answer 13

Anchor site for actin (thin) filaments

Question 14

I-band

Answer 14

Only contains actin thin filaments

Question 15

M-line

Answer 15

Anchor line for thick myosin filaments

Question 16

H-zone

Answer 16

Contains only thick myosin filaments

Question 17

A-band

Answer 17

Overlap of thick and thin filaments plus the H-zone

Question 18

Effect on Z line during contraction

Answer 18

The thin filaments slide past the thick filaments, bringing the Z-lines closer together

Question 19

Do thin/thick filaments change length in contraction

Answer 19

No, only the degree of overlap between them changes

Question 20

Tropomyosin

Answer 20

Runs in groove formed by F-actin strands

Binds to troponin complex

Question 21

Troponin T

Answer 21

Binds the complex to tropomyosin

Question 22

Troponin I

Answer 22

Inhibits the binding of myosin to actin

Question 23

Troponin C

Answer 23

Binds calcium

Question 24

Type I muscle fiber- slow red

Answer 24

Slow oxidative
Contains slow ATPase, red due to high myoglobin
Contractions slower and less powerful
Contract for long periods of time without fatige

Question 25

Type IIa fibers

Answer 25

Oxidative glycolytic
Largest and most prevalent
Intermediate ATPase and provides power
Primarily aerobic, intermediate fatigue

Question 26

Type IIb fibers (fast white)

Answer 26

Fast ATPase produces fast contractions
Largely anaerobic
Rapid fatigue
Low myoglobin content

Question 27

Ganglia vs Nuclei

Answer 27

Neuron clusters in PNS are ganglia

Neuron clusters in CNS are nuclei

Question 28

Nissl substance

Answer 28

Abundant rough ER that take up the Nissl stain, reflects the need to make lots of neurotransmitters and protein to maintain this large cell

Question 29

Multipolar neuron

Answer 29

Many dendrites and one axon

Question 30

Bipolar neuron

Answer 30

One dendrite and one axon

Question 31

Unipolar neuron

Answer 31

One cell process from which branches a single axon and single dendrite

Question 32

Satellite cells

Answer 32

Surround the cell body of a neuron in the PNS

Question 33

Endoneurium

Answer 33

CT between axons

Question 34

Perineurium

Answer 34

CT surrounding clusters of axons forming fascicles

Question 35

Epineurium

Answer 35

CT surrounding several nerve fascicles

Question 36

Presynaptic knob

Answer 36

Axon terminal that contains synaptic vesicles loaded with neurotransmitters

Question 37

Skeletal vs smooth vs cardiac muscle innervation and axon contact

Answer 37

Every skeletal muscle cell receives an axon terminal but not all cardiac or smooth muscle cells are directly innervated

Question 38

3 Steps of innervation of skeletal muscle

Answer 38

1- Nerve impulse stimulates release of neurotransmitter into synaptic cleft
2- Neurotransmitter stimulates changes in sarcolemma that excite the muscle fiber. This stimulus is carried down the T-tubules to initiate fiber contraction
3. Enzymes in the synaptic cleft break down neurotransmitter and thus limit its action to a single muscle twitch

Question 39

Muscle spindle receptors

Answer 39

Monitor changes in length, rate of change and tension of muscle

Question 40

Intrafusal fibers

Answer 40

Nuclear bag fibers- wrapped at the center by type Ia nerve fibers; detect change in length and degree of tension
Nuclear chain fibers- wrapped at their ends by type II nerve fibers, detect static muscle length

Question 41

Extrafusal fibers

Answer 41

Muscle fibers outside the spindle, known as alpha motor fibers

Question 42

Golgi tendon organs

Answer 42

Encapsulated receptors found within myotendinous junctions that sense tension within the tendon