Chapter 12-muscles

Question 1

Extensor action

Answer 1

Increases the angle at a joint

Question 2

Flexor action

Answer 2

Decreases the angle at a joint

Question 3

Abductor action

Answer 3

Moves limb away from midline of body

Question 4

Adductor action

Answer 4

Moves limb toward midline of body

Question 5

Levator action

Answer 5

Moves insertion downward

Question 6

Rotator action

Answer 6

Rotates a bone along its axis

Question 7

Sphincter action

Answer 7

Constricts an opening

Question 8

The prime mover of any skeletal movement is the

Answer 8

Agonist muscle. In flexing for example, the flexor is the agonist muscle

Question 9

Flexors and extenders that act on the same joint to produce opposite actions are

Answer 9

Anatagonistic muscles

Question 10

Epimysium is the

Answer 10

Fibrous connective tissue proteins within the tendons extend around the muscle in an irregular arrangement forming a sheath (epimysium)

Question 11

Fascicles are

Answer 11

Inside the muscle epimysium divides muscle into columns called fasicles

Question 12

Connective tissue around fascia is

Answer 12

perimysium

Question 13

Plasma membrane of muscle is

Answer 13

sarcolemma

Question 14

What are antagonist muscles?

Answer 14

muscles (flexors and extensors) that act on the same joint to produce opposite actions

Question 15

What is a motor end plate?

Answer 15

Region on sarcolemma where the neuromuscular junction is the motor end plate

Question 16

Which are considered the dark bands and light bands?

Answer 16

A bands are dark, I bands are light.

Question 17

The motor neuron stimulates the muscle fiber to contract by _____________ at the neuromuscular junction

Answer 17

liberating acetylcholine

Question 18

Where is the cell body of a somatic neuron located?

Answer 18

the ventral horn of the gray matter of spinal cord.

Question 19

What is a motor unit?

Answer 19

Each somatic motor neuron together with all of the muscle fibers that it innervates.

Question 20

What are graded concentrations?

Answer 20

Where contraction strength is varied.

Question 21

What happens when a somatic motor neuron is activated?

Answer 21

All of the muscle fibers it innervates are stimulated to contract.

Question 22

When contractions of greater strength are required, larger and larger motor units are activated in a process known as

Answer 22

recruitment of motor units

Question 23

The light I band contains _____ filaments

Answer 23

thin

Question 24

The dark A band contains ______ filaments

Answer 24

thick

Question 25

Thick filaments are composed of the protein ______

Answer 25

myosin

Question 26

The thin filaments are composed of the protein ______

Answer 26

actin

Question 27

What is the central region of sarcomere?

Answer 27

H zone. Only contains thick filaments

Question 28

What is titin?

Answer 28

A type of elastic protein that runs through the thick filaments from the M lines to the Z disc

Question 29

Titin purpose

Answer 29

Contribute to elastic recoil of muscles that helps them to return to their resting length during muscle relaxation

Question 30

As sarcomeres shorten in length... the _ bands do not ______, but move ______ together

Answer 30

A, shorten, closer

Question 31

The I bands which represent the distance between A bands of successive sarcomeres _______ in length

Answer 31

decrease

Question 32

The thin filaments composing the I band _______

Answer 32

do not shorten

Question 33

During contraction, thick and thin filaments _______

Answer 33

remain the same length

Question 34

Shortening of the sarcomeres is produced not by shortening of the filaments but rather by _______ of thin filaments over and between the thick filaments

Answer 34

sliding

Question 35

The I bands (contain only thin filaments) and H bands (containing only thick filaments) get _______ during contraction

Answer 35

shorter

Question 36

Describe steps of sliding filament theory of contraction

Answer 36

1. A myofiber, along with all its myofibrils shorten by movement of the insertion toward the origin of the muscle. 2. Shortening of the myofibrils is caused by shortening of the sarcomeres- the distance between Z lines is reduced. 3. Shortening of the sarcomeres is done by sliding of the myofilaments-the length of each filament remains the same during contraction. 4. Sliding of the filaments id produced by asychronous power strokes of myosin cross bridges, which pull the thin filaments (Actin) over the thick filaments (myosin) 5. The A bands remain the same length during contraction, but are pulled toward the origin of the muscle. 6. Adjacent A bands are pulled closer together as I bands between them shorten. 7. The H bands shorten during contraction as the thin filaments on the sides of the sarcomeres are pulled toward the middle.

Question 37

Muscle contracts because _____ get shorter

Answer 37

myofibrils

Question 38

_____ filaments slide over and between _____ filaments towards the center

Answer 38

thin, thick

Question 39

Sliding of filaments is produced by the action of numerous

Answer 39

cross bridges that extend out from myosin toward the actin.

Question 40

Cross bridges are part of the _____ protein that extend from the axis of thick filaments to form "arms" that terminate in globular "heads"

Answer 40

myosin

Question 41

Each myosin head contains an _____ binding site which functions as ______

Answer 41

ATP binding site and ATPase

Question 42

Cross bridge power stroke steps

Answer 42

1. Resting fiber, cross bridge is not attached to acin. ADP. Inorganic phosphate are attached, 2. Cross bridge binds to actin 3. Pi is released from myosin head, causing conformational change in myosin. 4. Power stroke causes filaments to slide. ADP is released 5. A new ATP bings to myosin head, allowing it to release from actin. 6. ATP is hydrolyzed and phosphate binds to myosin, causing cross bridge to return to its orginal orientation.

Question 43

Twitch is a ____ ________

Answer 43

single contraction

Question 44

A single rapid contraction and relaxation of muscle fibers is a

Answer 44

twitch

Question 45

Skeletal muscles can produce

Answer 45

graded contractions, the strength of which depends on the number of fibers stimulated rather than on the strength of the contractions of individual muscle fibers.

Question 46

Imcomplete tetanus refers to

Answer 46

If muscle is stimulated by an increasing frequency of electrical shocks, its tension will increase to a maximum

Question 47

Complete tetanus refers to

Answer 47

Contraction that is smooth and sustained as it is during normal muscle contracction within body.

Question 48

Treppe (stair case effect) refers to

Answer 48

If cold muscle is repeatedly stimulated with maximum voltage to produce individual twitches, successive twitches get larger

Question 49

Treppe is caused by

Answer 49

accumulation of intracellular Ca++

Question 50

During isotonic contraction...

Answer 50

force remains constant throughout shortening process, length changes. (Lifting something off table)

Question 51

During isometric contraction...

Answer 51

exerted force does not cause load to move and length of fibers remains constant (Lifting table, holding the weight)