Skeletal Muscle And Nerve Tissue Histology

Question 1

What are the functions of skeletal muscle?

Answer 1

Voluntary movements, postural stability

Question 2

What is the function of cardiac muscle?

Answer 2

Contract the heart, pump blood throughout the body

Question 3

What is the function of smooth muscle?

Answer 3

Involuntary movements for respiration, digestion, blood vessel control

Question 4

What type of muscle is NOT striated?

Answer 4

Smooth muscle

Question 5

What type of muscle is used in voluntary movements?

Answer 5

Skeletal muscle

Cardiac and smooth are involuntary

Question 6

What muscle types are uninucleated?

Answer 6

Cardiac muscle, Smooth muscle

Question 7

What muscle type is multinucleated?

Answer 7

Skeletal muscle

Question 8

What muscle type is separated by intercalated discs?

Answer 8

Cardiac muscle

Question 9

What muscle type is weaker than the other two?

Answer 9

Smooth muscle

Question 10

What is a sarcomere?

Answer 10

Contractile unit of muscle made of actin and myosin myofilaments

Question 11

What is a fascicle composed of?

Answer 11

Group of myofibers

Question 12

What is the Fascicle surrounded by?

Answer 12

Perimysium (fascial covering)

Question 13

What is a muscle composed of?

Answer 13

Group of fascicles

Question 14

What are muscles surrounded by?

Answer 14

Epimysium (fascia)

Question 15

What do groups of sarcomeres make up?

Answer 15

Myofibril

Question 16

What makes up a muscle fiber?

Answer 16

Groups of myofibrils

Question 17

What is the composition of myosin?

Answer 17

Thick filament

• 2 heavy chains + globular heads
• 2 light chains

Held in place by titin proteins connected to Z-disk

Question 18

What is the composition of Actin?

Answer 18

Thin filaments

F-actin monomers bound together in double stranded chains

Question 19

What molecule is a “ruler” for determining the length of actin filaments?

Answer 19

Nebulin

Question 20

What covers the myosin binding sites on actin filaments?

Answer 20

Troponin on tropomyosin strands

Question 21

What are the components of a Sarcomere? What are their functions?

Answer 21

M-line: Myosin attachment (middle)

Z-disk: separates sarcomeres, actin and titin attachment (ends)

H-band: space on either side of the M-line where there’s no actin (middle region)

A-band: distance from one myosin head to the opposite myosin head (all- actin + myosin + H band)

I-band: space on either side of Z-disk, where there’s no myosin

Question 22

What allows myosin to bind to actin?

Answer 22

1. Ca is released from the SR.
2. Ca binds to troponin (which is blocking the myosin binding sites on the actin)
3. Troponin has a conformational change
4. Actin binding sites become accessible to myosin

Question 23

What makes the entire muscle shorten?

Answer 23

All myofibrils in a muscle contracting at the same time

Question 24

Do actin and myosin change in length?

Answer 24

NO. They only overlap each oher.

Question 25

Characteristics of Type I Skeletal Muscle Fiber types

Answer 25

- SLOW, less powerful contraction - (RED) Many mitochondria - Abundant myoglobin - Slow fatigability - Aerobic respiration

Question 26

Type IIA Skeletal Muscle Fiber Types

Answer 26

- FAST, Intermediate powerful contraction - (RED) Many mitochondria - Many myoglobin - Intermediate fatigability - Aerobic respiration

Question 27

Type IIB Skeletal Muscle characteristics

Answer 27

- Fast, powerful contraction - Few mitochondria - Few myoglobin - Rapid Fatigability - Anaerobic respiration

Question 28

What is the membrane around each muscle cell called?

Answer 28

Sarcolemma

Question 29

What is the function of T tubules?

Answer 29

(Transverse tubules) | - membrane system that conveys electrical impulses from sarcolemma into cell

Question 30

What does a Triad consist of?

Answer 30

T tubule + 2 Terminal cisternae

Question 31

What is the sarcoplasm? What is the sarcoplasmic reticulum?

Answer 31

1. Cytoplasm of muscle cell 2. Acts like smooth ER (Terminal cisternae is a flattened version on either side of transverse tubule)

Question 32

What is the neruomuscular junction? (NMJ)

Answer 32

- Skeletal muscle innervated by peripheral a-motor neurons from anterior horn of spinal chord 1 nerve/fiber, BUT >1 muscle fiber/nerve

Question 33

What is the action of the Neuromuscular Spindle Apparatus?

Answer 33

Reflexive response to prevent overstretching of a muscle

Question 34

What are the 5 components of the Neuromuscular Spindle Apparatus?

Answer 34

``` Extrafusal muscle fibers Intrafusal muscle fibers Type Ia sensory nerve fibers A-motor nerve fibers G-motor nerve fibers ```

Question 35

What is the arrangement of nerves?

Answer 35

Axon —> Fascicle —> Nerve

Question 36

What are multipolar neurons?

Answer 36

Multiple dendrites + 1 axon

Question 37

What are bipolar neurons?

Answer 37

Single dendrite + 1 axon

Question 38

What are pseudounipolar axons?

Answer 38

1 cell process + 1 single dendrite branch + 1 axon branch

Question 39

What cells myelinate axons in the PNS?

Answer 39

Schwann Cells

Question 40

What cells myelinate cells in the CNS?

Answer 40

Oligodendrocytes

Question 41

Extrafusal muscle fibers

Answer 41

Contract the muscle

Question 42

Intrafusal muscle fibers

Answer 42

Sense length and rate of change of the muscle

Question 43

Type Ia sensory nerve fibers

Answer 43

Afferent innervation of intrafusal fibers

Question 44

a-motor nerve fibers

Answer 44

Efferent innervation of extrafusal muscle fibers

Question 45

G-motor nerve fibers

Answer 45

Efferent innervation of intrafusal muscle fibers