Ch. 9 Muscles and Muscle Tissue

Question 1

Skeletal and smooth muscles cells that are elongated are called…

Answer 1

Muscle fibers

Question 2

The type of muscle with the longest muscle cells and obvious striations that are activated voluntarily. It is responsible for overall body mobility

Answer 2

Skeletal muscle

Question 3

The muscle tissue that is found only in the heart, is striated and moves involuntarily. Makes up the bulk of the heart wall to pump blood

Answer 3

Cardiac muscle

Question 4

The muscle type that is found in the walls of hollow visceral organs and forces fluids and other substances through internal body channels. It is non striated and voluntary

Answer 4

Smooth muscle

Question 5

The ability of a cell to receive and respond to a stimulus by changing its membrane potential

Answer 5

Excitability or responsiveness

Question 6

The ability to shorten forcibly when adequately stimulated

Answer 6

Contractility

Question 7

The ability to extend or stretch

Answer 7

Extensibility

Question 8

The ability of a muscle cell to recoil and resume its resting length after stretching

Answer 8

Elasticity

Question 9

An overcoat of dense irregular connective tissue that surrounds the whole muscle

Answer 9

Epimysium

Question 10

Within each skeletal muscle, the muscle fibers are grouped into bundles called…

Answer 10

Fascicles

Question 11

A layer of dense irregular connective tissue that surrounds each fascicle

Answer 11

Perimysium

Question 12

A wispy sheath of connective tissue that surrounds each individual muscle fiber. It consists of fine areolar connective tissue

Answer 12

Endomysium

Question 13

The part where the muscle attaches on the movable bone

Answer 13

Insertion

Question 14

The part where the muscle attaches on the immovable or less movable bone

Answer 14

Origin

Question 15

The epimysium of the muscle is fused to the periosteum of a bone or perichondrium of a cartilage in this form of attachment

Answer 15

Direct (fleshy) attachments

Question 16

The muscle’s connective tissue wrappings extend beyond the muscle either as a ropelike tendon or as a sheetlike aponeurosis in this form of attachment

Answer 16

Indirect attachments

Question 17

The plasma membrane of a skeletal muscle fiber

Answer 17

Sarcolemma

Question 18

The cytoplasm of a muscle cell

Answer 18

Sarcoplasm

Question 19

Granules of stored glycogen that provide glucose during muscle cell activity for ATP production

Answer 19

Glycosomes

Question 20

A red pigment that stores oxygen

Answer 20

Myoglobin

Question 21

These account for about 80% of cellular volume and a single muscle fiber contains hundreds to thousands of these that run parallel to its length

Answer 21

Myofibrils

Question 22

A repeating series of dark and light bands that are evident along the length of each myofibril

Answer 22

Striations

Question 23

Dark and light bands that are nearly perfectly aligned in a intact muscle fiber, giving the cell its striated appearance

Answer 23

A bands (dark) and I bands (light)

Question 24

Each dark A band has a lighter region in its midsection called the…

Answer 24

H zone

Question 25

Each H zone is bisected vertically by a dark line called the... It is formed by molecules of the protein myomesin

Answer 25

M line

Question 26

Each light I band also has a midline interruption, a darker area called the...

Answer 26

Z disc

Question 27

The region of myofibril between two successive Z discs. It is the smallest contractile unit of a muscle fiber- the functional unit of skeletal muscle

Answer 27

Sarcomere

Question 28

The muscle equivalents of the actin or myosin-containing microfilaments. These structures are located within the sarcomere

Answer 28

Myofilaments

Question 29

Myosin makes up this type of filament and extends the entire length of the A band

Answer 29

Thick filaments

Question 30

This type of filament contains actin and extends across the I band and partway into the A band

Answer 30

Thin filaments

Question 31

This protein molecule consists of two heavy and four light polypeptide chains and has a rodlike tail attached by a flexible hinge to two globular heads.

Answer 31

Myosin

Question 32

The attachment of linking the thick and thin filaments together by the globular heads on the myosin molecule

Answer 32

Cross bridges

Question 33

Made up of kidney-shaped polypeptide subunits, which bear the active sites to which the myosin heads attach during contraction

Answer 33

Actin

Question 34

A rod-shaped protein, spirals about the actin core and helps to stiffen and stabilize it. In a relaxed muscle fiber, they block myosin-binding sites on actin so that myosin heads on the thick filaments cannot bind to the thin filaments

Answer 34

Tropomyosin

Question 35

A globular three-polypeptide complex that is a major protein in thin filaments

Answer 35

Troponin

Question 36

Composed of the giant protein titin and holds the thick filaments in place while also helping the muscle cell spring back int shape after stretching

Answer 36

Elastic filament

Question 37

An important structural protein that links the thin filaments to the integral proteins of the sarcolemma

Answer 37

Dystrophin

Question 38

An elaborate smooth endoplasmic reticulum that surrounds each myofibril

Answer 38

Sarcoplasmic reticulum (SR)

Question 39

Part of the SR that forms larger, perpendicular cross channels at the A band-I band junction

Answer 39

Terminal cisterns

Question 40

At each A band-I band junction, the sarcolemma of the muscle cell protrudes deep into the cell interior, forming an elongated tube called the...

Answer 40

T tubule

Question 41

Successive groupings of the three membranous structures (terminal cistern, T tubule, and terminal cistern)

Answer 41

Triads

Question 42

Activation of myosin's cross bridges ("shortening")

Answer 42

Contraction

Question 43

States that during contraction, the thin filaments slide past the thick ones so that the actin and myosin filaments overlap to a greater degree

Answer 43

Sliding filament model of contraction

Question 44

An electrical current generated by a nervous system stimulation

Answer 44

Action potential

Question 45

Nerve cells that activate skeletal muscle fibers. They reside in the brain or spinal cord

Answer 45

Somatic motor neurons

Question 46

Junction formed by several short, curling branches within a single muscle fiber by an axon

Answer 46

Neuromuscular junction or motor end plate

Question 47

The space that separates the axon terminal and the muscle fiber

Answer 47

Synaptic cleft

Question 48

Small membranous sacs containing the neurotransmitter ACh. They are located in the axon terminal

Answer 48

Synaptic vesicles

Question 49

The neurotransmitter that is released and binds to receptors on sarcolemma to ignite action potential

Answer 49

Acetylcholine or ACh

Question 50

The trough-like part of the muscle fiber's sarcolemma that helps form the neuromuscular junction. it is highly folded to provide a large surface area for the millions of ACh receptors located there

Answer 50

Junctional folds

Question 51

Located on the junctional folds of the sarcolemma

Answer 51

ACh receptors

Question 52

After ACh binds to the ACh receptors, its effects are quickly terminated by this enzyme that is located in the synaptic cleft... It breaks down ACh to its building blocks

Answer 52

Acetylcholinesterase

Question 53

A disease that involves a shortage of ACh receptors and results in drooping upper eyelids, difficulty swallowing and talking, and generalized muscle weakness

Answer 53

Myasthenia

Question 54

Depolarization (interior of the sarcolemma becomes less negative)

Answer 54

End plate potential

Question 55

During repolarization, a muscle fiber is in this period because the cell cannot be stimulated again until repolarization is complete

Answer 55

Refractory period

Question 56

The sequence of events by which transmission of an action potential along the sarcolemma causes myofilaments to slide

Answer 56

Excitation-contraction (E-C) coupling

Question 57

When actin and myosin become irreversibly cross-linked this occurs...

Answer 57

Rigor mortis

Question 58

The force exerted by a contracting muscle on an object

Answer 58

Muscle tension

Question 59

The opposing force exerted on the muscle by the weight of the object to be moved

Answer 59

The load

Question 60

When tension builds to the muscle's peak tension-producing capacity, but the muscle neither shortens nor lengthens

Answer 60

Isometric contraction

Question 61

When muscle length shortens and moves a load

Answer 61

Isotonic contraction

Question 62

The nerve-muscle functional unit that consists of one motor neuron and all the muscle fibers it innervates (supplies)

Answer 62

Motor unit

Question 63

A recording of contractile activity

Answer 63

Myogram

Question 64

A motor unit's response to a single action potential of its motor neuron

Answer 64

Muscle twitch

Question 65

The first few milliseconds following stimulation when excitation-contraction coupling is occuring

Answer 65

Latent period

Question 66

During this period, the cross bridges are active and the myogram tracing rises to a peak

Answer 66

Period of contraction

Question 67

During this period, contractile force is declining and the tracing returns to the baseline. It is initiated by reentry of Ca2+ into the SR

Answer 67

Period of relaxation

Question 68

Variations in strength, needed for proper control of skeletal movement

Answer 68

Graded muscle responses

Question 69

This occurs when the second contraction occurs before the muscle has completely relaxed. (Contractions are added together on top of one another)

Answer 69

Wave or temporal summation

Question 70

Sustained but quivering contraction when the degree of wave summation becomes greater and greater but hasn't reached maximal tension

Answer 70

Unfused or incomplete tetanus

Question 71

When muscle tension increases until it reaches maximal tension, the contractions fuse into a smooth, sustained contraction plateau called...

Answer 71

Fused or complete tetanus

Question 72

Controls the force of contraction more precisely

Answer 72

Recruitment (multiple motor unit summation)

Question 73

Stimuli that produce no observable contractions

Answer 73

Sub-threshold stimuli

Question 74

The stimulus at which the first observable contraction occurs

Answer 74

Threshold stimulus

Question 75

The strongest stimulus that increases contractile force. It represents the point at which all the muscle's motor units are recruited

Answer 75

Maximal stimulus

Question 76

1) The motor units with the smallest muscle fibers are activated first 2) As motor units with larger muscle fibers begin to be excited, contractile strength increases 3) The largest motor units, are controlled by the largest, least excitable neurons and are activated only when the most powerful contraction is necessary

Answer 76

Size principle of recruitment

Question 77

The phenomenon that relaxed muscles are almost always slightly contracted and helps stabilize joints and maintain posture

Answer 77

Muscle tone

Question 78

A type of isotonic contraction in which the muscle shortens and does work

Answer 78

Concentric contractions

Question 79

A type of isotonic contraction in which the muscle generates force as it lengthens

Answer 79

Eccentric contractions

Question 80

A unique, high-energy molecule stored in muscles that is tapped to regenerate ATP while the metabolic pathways adjust to the suddenly higher demand for ATP. It is involved in direct phosphorylation

Answer 80

Creatine phosphate

Question 81

The CP-ADP reaction in direct phosphorylation is catalyzed by this enzyme

Answer 81

Creatine kinase

Question 82

The initial phase of glucose breakdown that is used to form ATP in the anaerobic pathway

Answer 82

Glycolysis

Question 83

Overall process of pyruvic acid being converted to lactic acid

Answer 83

Anaerobic glycolysis

Question 84

A product of anaerobic glycolysis that diffused out of the muscles into the bloodstream and often leads to muscle soreness

Answer 84

Lactic acid

Question 85

Occurs in the mitochondria, requires oxygen, and involves a sequence of chemical reactions that break the bonds of fuel molecules and release energy to make ATP

Answer 85

Aerobic respiration

Question 86

The length of time a muscle can continue to contract using aerobic pathways

Answer 86

Aerobic endurance

Question 87

The point at which muscle metabolism converts to anaerobic glycolysis

Answer 87

Anaerobic threshold

Question 88

A state of physiological inability to contract even though the muscle still may be receiving stimuli

Answer 88

Muscle fatigue

Question 89

The extra amount of oxygen that the body must take in for these restorative process

Answer 89

Excess Post-exercise Oxygen Consumption (EPOC)

Question 90

The situation in which the muscle is slightly stretched and the thin and thick filaments overlap optimally, because this permits sliding along nearly the entire length of the thinfilaments

Answer 90

Ideal Length-tension relationship

Question 91

Cells that rely mostly on the oxygen-using aerobic pathways for ATP generation

Answer 91

Oxidative fibers

Question 92

Cells that rely more on anaerobic glycolysis and creatine phosphate

Answer 92

Glycolytic fibers

Question 93

Exercises such as swimming, jogging, fast walking, and biking are examples of...

Answer 93

Aerobic or endurance exercise

Question 94

Exercise such as weight lifting, or isometric exercises are examples of...

Answer 94

Resistance exercise