Chapter 14: Muscle Tissue and Organization

Question 1

What are the 4 properties of muscle?

Answer 1

1. Excitability: responds to external stimuli w/ electrical changes
2. Contractility: tension may lead to shortening
3. Elasticity: returns to resting length when tension ceases
4. Extensibility: stretched by other muscles

Question 2

List the 5 functions of muscle.

Answer 2

1. Body movement
2. Maintenance of posture
3. Protection and support
4. Sphincters control passage of materials
5. Temperature regulation

Question 3

In the skeletal muscle structure, what dense irregular connective tissues make up the skeletal muscle and fascicle?

Answer 3

Skeletal muscle= epimysium
Fascicle= perimysium

Question 4

The endomysium is (___) connective tissue and makes up what skeletal muscle structure?

Answer 4

Areolar connective tissue
- endomysium= muscle fiber (cell)

Question 5

Identify the highlighted structures.

Answer 5

• Tendons
• Epimysium
• Perimysium
• Endomysium

Question 6

What is the sarcolemma?

Answer 6

The plasma membrane

Question 7

What structure is being described:
- extensions of sarcolemma deep into the cell
- allow for conduction of electrical signals
- increases surface area

Answer 7

T-tubules

Question 8

The sarcoplasmic reticulum has blind ended sacs called the (____) that stores calcium ions.

Answer 8

Terminal Cisterna

Question 9

Why is calcium important?

Answer 9

It allows for muscle contraction

Question 10

Identify the highlighted structures.

Answer 10

orange: sarcolemma
pink: sarcoplasma
red/purple: myofibrils
yellow: myofilaments
dark blue: sarcoplasmic reticulum
blue: terminal cisterna
green: transverse tubules (T-tubules)
yellow: Triad

Question 11

Where is the sarcolemma, T-tubule, and terminal cisternae located on this image?

Answer 11

• Sarcolemma
• T-tubule
• terminal cisterna

Question 12

What makes up the triad.

Answer 12

1. Terminal cisterna
2. t-tubule
3. Terminal cisterna

Question 13

The myofibrils are enclosed in which specific structure?
A. sarcoplasmic reticulum
B. sarcolemma
C. myosin
D. actin

Answer 13

A. sarcoplasmic reticulum

Question 14

The thick myofilmaents are called:

Answer 14

myosin

Question 15

The thin myofilaments are called (____) and the two types are called:

Answer 15

actin
- f-actin
- g-actin

Question 16

Label tropomyosin and troponin. Describe what Ca2+ binds to during which process.

Answer 16

Green: tropomyosin
- the actin cross-bridge is blocked by tropomyosin
Blue: troponin
- Ca2+ binds to troponin and undergoes conformational change
- tropomyosin unblocks actin for muscle contraction

Question 17

The sarcomeres are the contractile unit of a myofibril and contain what special characteristic?

Answer 17

striations

Question 18

Label the M line, H zone, A band, and sarcomere. Give a description of each.

Answer 18

Sarcomere: contractile unit
M line: protein structure; attachment for thick filaments
H zone: only thick filaments
A band: thick filaments and parts of the thin filaments

Question 19

Label the I bands, Titin, and Z discs. Give a description of each.

Answer 19

I bands: only thin filaments
Titin: very elastic protein; muscle stretched beyond resting
Z disc: protein structure; anchors thin filaments

Question 20

When the sarcomere shortens, what action is this called?

Answer 20

Contraction

Question 21

What 3 things make up the motor unit?

Answer 21

1. motor neuron
2. Muscle fibers
3. Neuromuscular junction

Question 22

Label this structure and describe its two types.

Answer 22

Motor unit
1. small motor units
- less power, precise control
- controlling two or three muscle fibers (eye/hand)
2. large motor unit
- more power, less precise
- controlling 2000 muscle fibers (thigh)

Question 23

What is the precise location the neuron innervates the muscle fiber?

Answer 23

Neuromuscular junction (NMJ)

Question 24

Label the following:
- neuromuscular junction
- synaptic cleft
- synaptic knob
- motor end plate

Answer 24

Labeled

Question 25

Which specific region is between the neuron and muscle? A. motor end plate B. synaptic knob C. synaptic cleft

Answer 25

C. synaptic cleft

Question 26

This structure has voltage-gated Ca2+ ion channels, synaptic vesicles that release acetylcholine, and is the extended tip of the motor neuron. Name this structure.

Answer 26

Synaptic knob

Question 27

What kind of receptor and pump is located on the motor end plate?

Answer 27

- ACh receptors - Na+/K+ pump

Question 28

What are the 3 steps of skeletal muscle contraction according to this image.

Answer 28

1. Neuromuscular junction: excitation of a skeletal muscle fiber 2. Sarcolemma, T-tubules, and sarcoplasmic reticulum: excitation-contraction coupling 3. Sarcomere: crossbridge cycling

Question 29

List three steps that occur at the neuromuscular junction.

Answer 29

1a. Nerve signal triggers influx of Ca2+ at synaptic knob - Ca2+ binds to proteins in synaptic vescicles 1b. Ca2+ binding causes synaptic vesicles to merge with synaptic knob membrane - ACh is released from the vesicles 1c. ACh diffuses across synaptic cleft and binds to receptors on motor end plate

Question 30

List three steps that occur at the sarcolemma, t-tubules, and sarcoplasmic reticulum.

Answer 30

2a. Binding of ACh to receptors on motor endplate triggers chemically-gated ion channels to open - Na+ influx, K+ efflux - membrane potential changes as Na+ enters = EEP (end plate potential) 2b. EEP initiates an action potential along t-tubules - Na+ channels open= depolarization - K+ channels open = repolarization 2c. Ca2+ release from channels in terminal cisternae due to action potential - Ca2+ diffuses out of the terminal cisternae into sarcoplasmic reticulum

Question 31

What are the types of muscle contraction?

Answer 31

1. Isometric contraction 2. Isotonic contraction

Question 32

Which isotonic contraction shortens as it contracts? Which one lengthens?

Answer 32

Concentric: shortens as contracts Eccentric: lengthens as it contracts

Question 33

List the three types of muscle fibers (twitches) and their oxygen state.

Answer 33

1. Slow (Type I, oxidative) 2. Intermediate (Type IIa, fast oxidative) 3. Fast (Type IIb, fast anaerobic)

Question 34

List 5 characteristics of slow twitch muscle fibers.

Answer 34

1. slow, less powerful contractions 2. smallest diameter 3. aerobic 4. abundant myoglobin - oxygen reserve - red color 5. very fatigue resistant (marathon runners: thighs)

Question 35

List 5 characteristics of fast twitch muscle fibers.

Answer 35

1. fast, powerful contractions 2. largest diameter 3. anaerobic 4. no myoglobin - white color 5. fatigue easily (sprinters, hand/eye muscles)

Question 36

Recall the 11 steps of muscle contraction starting with the electrical impulse and ending with ATP binding to myosin.

Answer 36

Steps 1-11.