Chapter 10

Question 1

3 types of muscular tissues

Answer 1

1. Skeletal muscle
2. Cardiac muscle
3. Smooth muscle

Question 2

Skeletal appearance

Answer 2

multi-nucleated and striated

Question 3

Cardiac appearance

Answer 3

one nucleus, striated, and intercalated discs

Question 4

Smooth muscles tissue appearance

Answer 4

one nucleus and no striations

Question 5

Smooth muscle location

Answer 5

Various organs like hollow

Question 6

Functions of muscular tissue

Answer 6

◼ Producing body movements
◼ Stabilizing body positions
◼ Storing and mobilizing substances within the body
◼ Generating heat

Question 7

Properties of Muscular Tissue

Answer 7

◼ Electrical excitability
◼ Contractility
◼ Extensibility
◼ Elasticity

Question 8

Epimysium

Answer 8

outer layer; dense irregular connective tissue; Surrounds entire muscle organ

Question 9

Perimysium

Answer 9

middle layer; dense irregular connective tissue; Surrounds 10 - 100+ muscle fibers, creating bundles “fascicles”

Question 10

Endomysium

Answer 10

inner layer; areolar connective tissue; Surrounds each muscle cell/fibre; made of mostly fine reticular fibers

Question 11

Z discs

Answer 11

Narrow, plate-shaped regions of dense material that separate one sarcomere from the next.

Question 12

A band

Answer 12

Dark, middle part of sarcomere that extends entire length of thick filaments and includes those parts of thin filaments that overlap thick filaments.

Question 13

I band

Answer 13

Lighter, less dense area of sarcomere that contains remainder of thin filaments but no thick filaments. A Z disc passes through center of each I band.

Question 14

H zone

Answer 14

Narrow region in center of each A band that contains thick filaments but no thin filaments.

Question 15

M line

Answer 15

Region in center of H zone that contains proteins that hold thick filaments together at center of sarcomere.

Question 16

Thin filament

Answer 16

Actin

Question 17

Thick filament

Answer 17

Myosin

Question 18

Contractile muscle proteins

Answer 18

Myosin
Actin

Question 19

Regulatory

Answer 19

Troponin
Tropomyosin

Question 20

Structural muscle proteins

Answer 20

Titin
Nebulin
Alpha-actin
Myomesin
Dystrophin

Question 21

Myosin

Answer 21

Contractile protein that makes up thick filament; molecule consists of a tail and two myosin heads, which bind to myosin-binding sites on actin molecules of thin filament during muscle contraction

Question 22

Actin

Answer 22

Contractile protein that is the main component of thin filament; each actin molecule has a myosin-binding site where myosin head of thick filament binds during muscle contraction.

Question 23

Skeletal muscle

Answer 23

Organ made up of fascicles that contain muscle fibers (cells), blood vessels, and nerves; wrapped in epimysium.

Question 24

Fascicle

Answer 24

Bundle of muscle fibers wrapped in perimysium.

Question 25

Muscle fiber cell

Answer 25

Long cylindrical cell covered by endomysium and sarcolemma; contains sarcoplasm, myofibrils, many peripherally located nuclei, mitochondria, transverse tubules, sarcoplasmic reticulum, and terminal cisterns. The fiber has a striated appearance.

Question 26

Myofibril

Answer 26

Threadlike contractile elements within sarcoplasm of muscle fiber that extend entire length of fiber; composed of filaments.

Question 27

Filaments (myofilaments)

Answer 27

Contractile proteins within myofibrils that are of two types: thick filaments composed of myosin and thin filaments composed of actin, tropomyosin, and troponin; sliding of thin filaments past thick filaments produces muscle shortening.

Question 28

The Sliding Filament Mechanism

Answer 28

◼ Myosin pulls on actin, causing the thin filament to slide inward ◼ Consequently, Z discs move toward each other, and the sarcomere shortens

Question 29

The contraction cycle

Answer 29

1) myosin head hydrolyzes ATP and becomes energized and oriented 2) myosin head binds to actin, forming a cross-bridge 3) myosin head pivots, pulling the thin filament past the thick filament toward the centre of the sacromere (power stroke) 4) as myosin head binds ATP, the cross-bridge detaches from actin

Question 30

The force of a muscle contraction depends on the

Answer 30

length of the sarcomeres in a muscle prior to contraction

Question 31

Creatine phosphate provides

Answer 31

15 seconds of energy

Question 32

Anaerobic glycolysis provides

Answer 32

2 minutes of energy

Question 33

Cellular respiration provides

Answer 33

Several minutes to hours of energy

Question 34

Creatine phosphate

Answer 34

catalyzes the transfer of a phosphate group from CP to ADP to rapidly yield ATP

Question 35

Anaerobic Glycolysis

Answer 35

When CP stores are depleted, glucose is converted into pyruvic acid to generate ATP

Question 36

Cellular Respiration

Answer 36

Under aerobic conditions, pyruvic acid can enter the mitochondria and undergo a series of oxygen-requiring reactions to generate large amounts of ATP

Question 37

Muscle Fatigue

Answer 37

inability to maintain force of contraction after prolonged activity

Question 38

The onset of fatigue is due to

Answer 38

❑ Inadequate release of Ca2+ from SR ❑ Depletion of CP, oxygen, and nutrients ❑ Build up of lactic acid and ADP ❑ Insufficient release of ACh at NMJ

Question 39

Central fatigue occurs due to

Answer 39

changes in the central nervous system and generally results in cessation of exercise

Question 40

Why do you continue to breathe heavily for a period of time after stopping exercise?

Answer 40

To “pay back” your oxygen debt!

Question 41

extra oxygen goes toward

Answer 41

❑ Replenishing CP stores ❑ Converting lactate into pyruvate ❑ Reloading O2 onto myoglobin

Question 42

A motor unit consists of

Answer 42

a somatic motor neuron and the muscle fibers it innervates

Question 43

Activating only a few motor units will generally result in

Answer 43

a weak muscle contraction

Question 44

Activating many motor units will generally result in

Answer 44

a strong muscle contraction

Question 45

Motor unit recruitment is the process in which

Answer 45

the number of active motor units increases

Question 46

Weakest motor units are recruited

Answer 46

First

Question 47

Twitch contraction

Answer 47

brief contraction of all muscle fibers in a motor unit in response to a single action potential

Question 48

Wave summation occurs when a

Answer 48

second action potential triggers muscle contraction before the first contraction has finished ❑ Results in a stronger contraction

Question 49

Tone is established by

Answer 49

the alternating, involuntary activation of small groups of motor units in a muscle

Question 50

Isotonic

Answer 50

tension is constant while muscle length changes ❑ Concentric ❑ Eccentric

Question 51

Isometric

Answer 51

muscle contracts but does not change length

Question 52

Concentric contraction

Answer 52

Picking up a book

Question 53

Eccentric contraction

Answer 53

Lowering a book

Question 54

Between 30–50 years of age, about 10% of our muscle tissue is replaced by

Answer 54

fibrous connective tissue and adipose tissue

Question 55

Between 50–80 years of age another 40% of

Answer 55

our muscle tissue is replaced

Question 56

Consequences to aging is muscles is

Answer 56

❑ Muscle strength and flexibility decreases ❑ Reflexes slow ❑ Slow oxidative fiber numbers increase