Muscular System 2

Question 1

total tension a fiber can produce depends on:

Answer 1

the rate at which nerve impulses arrive at the neuromuscular junction

Question 2

The more rapidly a muscle is stimulated, but ______ force it exerts

Answer 2

more

Question 3

Muscle fibers of a motor unit are dispersed:

Answer 3

throughout the entire muscle

Question 4

Muscles with precise movements have:

Answer 4

many small motor units

Question 5

The somatic motor neuron and all the skeletal muscle it stimulates:

Answer 5

Motor Unit

Question 6

A brief contraction of all the muscle fibers in a motor unit

Answer 6

Twitch Contraction

*A response to a single action potential in its motor neuron

Question 7

Shows how long a muscle contraction lasts:

Answer 7

Myogram

Question 8

A twitch lasts:

Answer 8

20-200 msec

Question 9

the “line” drawn by a myogram is a _____

Answer 9

tracing

Question 10

Stages of a twitch contraction:

Answer 10

• Latent Period
• Contraction Period
• Relaxation Period

Question 11

• 2 mseconds
• CA++ are released from the SR and filaments begin to exert tension
• There isn’t a contraction yet

Answer 11

Latent Period

Question 12

-10-100 mseconds

Answer 12

Contraction Period

Question 13

• 10-100 mseconds

- CA++ return to SR, which results in relaxation

Answer 13

Relaxation Period

Question 14

A second stimuli will cause a contraction:

Answer 14

wave summation

*Frequency of stimulation

Question 15

Stimulation of the skeletal muscle at a rate of 20-30x 1 sec

Answer 15

Unfused Tenanus

Question 16

• Stimulation rate of 80-100 stimuli/sec

- generate a sustained contraction where individual twitches cannot be discerned

Answer 16

Fused Tenanus

Question 17

Process by which the number of active motor units is increased
-only some motor units are active at a time to delay the period of muscle fatigue

Answer 17

Motor Unit Recruitment

Question 18

Why do only some motor units activate at a time?

Answer 18

To delay the period of muscle fatigue

Question 19

Some involuntary activated motor units that produced sustained contraction of the muscle fibers that generate muscle

Answer 19

Muscle Tone

Question 20

Contractions that are not long enough to generate actual movement

Answer 20

Muscle Tone

Question 21

A muscle shortens and pulls on another structure to produce movement

Answer 21

Concentric Isotonic Contractions

Question 22

The overall length of a muscle increases during a contraction

Answer 22

Eccentric Isotonic Contractions

Question 23

Tension is generated without shortening the muscles

Answer 23

Isometric Contractions

*Apply Pressure with hands on the table

Question 24

Muscle fibers differ in the content of _____

Answer 24

myoglobin

*Giving white and red muscle fibers

Question 25

Skeletal muscle fibers are classified into 3 main types:

Answer 25

1. Slow Oxidative 2. Fast Oxidative 3. Fast Glycolytic

Question 26

- Are the smallest in diameter - the least powerful of the muscle fibers - dark red because they contain large amounts of myoglobin - They have many mitochondria so they usually generate ATP through aerobic respiration - Have a low concentration velocity, but rarely fatigue

Answer 26

Slow Oxidative Fibers

Question 27

- Are Intermediate in diameter - Have large amounts of myoglobin - Generate lots of ATP through aerobic respiration and aerobic glycolysis - Are able to contract at a higher velocity

Answer 27

Fast Oxidative Fibers

Question 28

The ATPase in the myosin heads hydrolyzes ATP faster than the ATPase in slow oxidative fibers

Answer 28

Fast Oxidative Fibers

Question 29

- The largest in diameter - Have the most myofibrils (highest #) - Can generate the most powerful contractions - Have low myoglobin content and few mitochondria - Are white - Hydrolyze ATP rapidly to help cause fast and strong fiber contraction

Answer 29

Fast Glycolytic Fibers *Cannot contract for long (not as vascularized)

Question 30

- Principle tissue of the heart - Has actin and myosin, banding, and Z discs - The ends of these cells are attached to subsequent cells through intercalated discs - Require a constant supply of oxygen - Mitrochondria are larger

Answer 30

Cardiac Muscle Tissue

Question 31

- Usually activated involuntarily - Has thick and thin filaments but they are not arranged in orderly sarcomeres (thus no striations) - Lack T-Tubules and few SR - Has two types

Answer 31

Smooth Muscle Tissue

Question 32

Two types of smooth muscle tissue:

Answer 32

1. Visceral Smooth Muscle Tissue | 2. Multiunit Smooth Muscle Tissue

Question 33

Forms parts of walls of arteries and veins and hollow viscera

Answer 33

Visceral Smooth Muscle Tissue

Question 34

- Made of individual fibers | - found in the walls of large arteries, in airways to lungs, arrector pili, in iris, and the ciliary body

Answer 34

Multiunit Smooth Muscle Tissue

Question 35

What causes "Muscle Growth" after development?

Answer 35

Due to the increase in size of current muscle fibers

Question 36

Divide slowly and fuse to existing fibers of damaged fibers

Answer 36

Satellite Cells

Question 37

Replacement of muscle fibers by fibrous scar tissue

Answer 37

Fibrosis

Question 38

Additional cells can migrate from ____ to participate in muscle regeneration

Answer 38

red bone marrow

Question 39

all muscles are derived from the _____

Answer 39

mesoderm

Question 40

Somites are formed on the:

Answer 40

20th day of development

Question 41

Paired, blocklike masses of mesoderm, arranged segmentally alongside the neural tube of the embryo, forming the vertebral column and segmental masculature

Answer 41

somites

Question 42

What do somites form?

Answer 42

1. ) vertebral column | 2. ) segmental masculature

Question 43

Around ___, humans begin to loose skeletal muscle mass and it is replaced by fibrous connective tissue and adipose tissue

Answer 43

30

Question 44

Around age 30, what replaces skeletal muscle?

Answer 44

fibrous connective tissue and adipose tissue

Question 45

Around age 30, there is a decrease in:

Answer 45

Maximal strength

Question 46

Why are endurance and strength training programs so effective in older people?

Answer 46

They can slow or reverse age-associated decline in muscular performance

Question 47

Skeletal muscles work together or in opposition to:

Answer 47

create movement

Question 48

Muscles only:

Answer 48

pull

Question 49

What happens when muscles shorten?

Answer 49

The insertion usually moves toward the origin

Question 50

Whatever a muscle does, another muscle _____

Answer 50

counteracts

Question 51

Provides the major force for producing a specific movement:

Answer 51

prime movers

Question 52

oppose a movement

Answer 52

Antagonist

Question 53

- Add force to a movement | - Reduce undesired or unnessesary movements

Answer 53

Synergists

Question 54

Synergists that immobilize a bone or muscle origin

Answer 54

Fixator

Question 55

Bone or body region associated with the muscle

Answer 55

Location of a muscle *E.g., rectus femoris, temporalis

Question 56

Deltoid

Answer 56

Shape

Question 57

Maximus, minimus, longus

Answer 57

Relative Size

Question 58

Rectus, Transverse, Oblique

Answer 58

Direction of Fibers

Question 59

biceps and triceps

Answer 59

Number of origins

Question 60

The point of origin or insertion (e.g., sternocleidomastoid)

Answer 60

Location of Attachments

Question 61

Flexor/extensor

Answer 61

Action