Muscular System

Question 1

What are the seven major functions of muscles?

Answer 1

1. Movement of the body .
2. Posture
3. Respiration
4. Body heat
5. Communication
6. Constriction of organs and vessels
7. Contraction of heart

Question 2

Four major functional properties of Muscles?

Answer 2

1. Contractility
2. Excitability
3. Extensibility
4. Elasticity

Question 3

Contractility

Answer 3

Muscle shortens forcibly and opposing muscle lengthening is passive.

Question 4

Excitability

Answer 4

The capacity of a muscle to respond to a muscle stimulus.

Question 5

Extensibility

Answer 5

Muscle is able to extend beyond its normal resting state and still be able to contract.

Question 6

Elasticity

Answer 6

Muscle springs back to its original resting length after it has been stretched.

Question 7

Two main elements of muscle contractions?

Answer 7

1. Electrical component
2. Mechanical component

Question 8

Three muscle fibers that respond to and transmit electrical signals?

Answer 8

1. Sarcolemma
2. Transverse Tubules
3. Sarcoplasmic reticulum

Question 9

Sarcolemma is a?

Answer 9

Plasma membrane of muscle fibers

Question 10

Transverse Tubules are

Answer 10

Tube like inward folds of the sarcolemma

Question 11

Sarcoplasmic reticulum

Answer 11

Highly specialized smooth endoplasmic reticulum in skeletal muscle fibers that stores high levels of Ca2+

Question 12

Mitochondria and energy-storing glycogen granules constitute the cytoplasm, called the _____?

Answer 12

Sarcoplasm

Question 13

Bundles of protein filaments are called?

Answer 13

Myofibrils

Question 14

Muscle property of contractility is due to two main structures in muscle fibers called?

Answer 14

1. Myofibrils
2. Myofilaments (2 types)

Question 15

The protein filaments in the myofibrils interact to ____ the muscle fiber during contraction?

Answer 15

Shorten

Question 16

The ____ are threadlike structures that extend the entire length of the muscle fiber.

Answer 16

Myofibrils

Question 17

There are two types of myofilaments?

Answer 17

1. Actin myofilaments
2. Myosin myofilaments

Question 18

Actin myofilaments are Thin/Thick?

Answer 18

Thin filaments

Question 19

Myosin myofilaments are thin/thick

Answer 19

Thick filaments

Question 20

The ______ are the structural and functional units of the skeletal muscle.

Answer 20

Sacromeres

Question 21

The _____ in the sarcomere provides the mechanical aspect of muscle contraction.

Answer 21

Myofilaments

Question 22

The ____ is the smallest portion of the muscle that contracts.

Answer 22

Sarcomere

Question 23

What is the neuromuscular junction?

Answer 23

It is the site where the nerve fiber innervates the muscle fiber.

Question 24

When the membrane potential of a cell becomes more positive than its resting potential, the cell is

Answer 24

depolarized

Question 25

Which statement explains how the shortening of the sarcomere leads to contraction of the whole muscle?

Answer 25

Whole muscle is made up of subunits whose smallest functional unit is the sarcomere. When one shortens, the other units by default have shortened. When sarcomeres shorten, myofibrils which make up the muscle fiber also shorten because the myofibrils consist of sarcomeres joined end to end.

Question 26

Hyperpolarization occurs because voltage-gated Blank______ channels stay open longer than required to reach resting membrane potential.

Answer 26

potassium

Question 27

Describe myoglobin.

Answer 27

A molecule that stores oxygen in muscles

Question 28

A neuromuscular junction is also called a

Answer 28

synapse

Question 29

A shift in the membrane potential towards a less negative value is called a

Answer 29

depolarization

Question 30

During muscle contraction, the muscle shortens when

Answer 30

sarcomeres and muscle fascicles shorten

Question 31

What does the sliding filament theory of muscle contraction predict about myofilaments and sarcomere length?

Answer 31

During contraction, the thin myofilaments slide past the thick myofilaments. During contraction, the total length of the sarcomere decreases.

Question 32

Which factors contribute to the generation of the resting membrane potential? (select all that apply)

Answer 32

Diffusion of ions down their concentration gradients through the membrane The electrical attraction of cations and anions to each other Selective permeability of the membrane, allowing some ions to pass more easily than others

Question 33

Myoglobin would be most abundant in what type of muscle fiber?

Answer 33

Oxidative (slow) fibers

Question 34

Hypertrophy of muscles results from an increase in the

Answer 34

size of muscle fibers

Question 35

Acetylcholine diffuses across a synaptic cleft and binds to ligand-gated Blank______ channels.

Answer 35

sodium

Question 36

The portion of the sarcomere that binds Blank______ is troponin.

Answer 36

calcium

Question 37

Choose characteristics of the sodium-potassium ion pump.

Answer 37

Pumps sodium out of the cell against its concentration gradient Uses ATP

Question 38

Which of the following ionic movements causes the repolarization phase of the action potential?

Answer 38

The movement of a large number of potassium ions out of the cell.

Question 39

Acetylcholine released into the synaptic cleft is rapidly broken down to acetic acid and choline by

Answer 39

an enzyme acetylcholinesterase

Question 40

Describe what must occur before tropomyosin can move away from the myosin binding sites.

Answer 40

Calcium must bind to troponin

Question 41

Within a myofibril, calcium-binding sites are found on

Answer 41

troponin

Question 42

Acetylcholinesterase prevents Blank______ from accumulating within the synaptic cleft.

Answer 42

acetylcholine

Question 43

When an action potential reaches the axon terminal of a motor neuron, which substance diffuses into the axon terminal?

Answer 43

Calcium

Question 44

Choose characteristics of the sodium-potassium ion pump.

Answer 44

Pumps sodium out of the cell against its concentration gradient Uses ATP

Question 45

Which of the following ionic movements causes the repolarization phase of the action potential?

Answer 45

The movement of a large number of potassium ions out of the cell.

Question 46

Acetylcholine released into the synaptic cleft is rapidly broken down to acetic acid and choline by

Answer 46

acetylcholinesterase an enzyme

Question 47

When calcium enters an axon terminal,

Answer 47

acetylcholine is released from synaptic vesicles

Question 48

During relaxation, calcium levels in the sarcoplasm

Answer 48

fall

Question 49

When an action potential reaches the axon terminal of a motor neuron, which substance diffuses into the axon terminal?

Answer 49

Calcium

Question 50

When the muscle is no longer actively contracting, ATP is used to

Answer 50

break the bond between actin and myosin re-energize the myosin head move calcium back into the sarcoplasmic reticulum

Question 51

Which of the following molecules covers the active sites on the G-Actin molecule when the muscle fiber is relaxed?

Answer 51

Tropomyosin

Question 52

Slow twitch or Type I muscle fibers

Answer 52

have well developed blood supplies have high aerobic capacity but low anaerobic capacity have the highest resistance to muscle fatigue

Question 53

When a muscle fiber relaxes, ATP is used

Answer 53

to transport of Ca 2+ into the sarcoplasmic reticulum to maintain the normal concentrations of Na+ and K + across the sarcolemma to detach the myosin head from actin

Question 54

The molecule that inhibits the binding of myosin to actin by blocking the binding site is

Answer 54

tropomyosin

Question 55

Both fast-twitch and slow-twitch muscle fibers can increase in Blank______ as a result of exercise and training.

Answer 55

size capacity strength

Question 56

Fast twitch or Type II muscle fibers

Answer 56

have a fast form of myosin ATPase, which allows them to break down ATP more rapidly than other muscle fiber types respond rapidly to nervous stimulation

Question 57

Identify the effects of exercise on skeletal muscles. Exercise can

Answer 57

Increase the number of myofibrils Increase the number of mitochondria within a myofiber Increase the concentration of metabolic enzymes

Question 58

Describe what is meant by the threshold. It is

Answer 58

the minimum voltage that must be reached in order to cause the opening of the voltage gated ion channels of the axon hillock

Question 59

Which are effects of exercise on skeletal muscles?

Answer 59

Increase in the number of myofibrils Interconversion of type IIa and type IIb fibers Increase in the vascularity of muscle Increase in the number of mitochondria within a myofiber

Question 60

The depolarization phase is due to the opening a closing of Blank______ ion channels.

Answer 60

voltage-gated

Question 61

Each myosin molecule is composed of Blank______ heavy chains and Blank______ myosin heads.

Answer 61

2, 2

Question 62

Cardiac muscle cells are Blank______, which allows them to contract spontaneously and rhythmically.

Answer 62

autorhythmic

Question 63

Enlargement of muscles in children and adults that results from an increase in the size of each muscle fiber is called

Answer 63

hypertrophy

Question 64

The structure that is a modified form of smooth endoplasmic reticulum located in muscle cells is called__________ reticulum.

Answer 64

sarcoplasmic

Question 65

Which of the following are characteristics used in the naming of individual muscles?

Answer 65

Bone attachment sites Number of heads Function

Question 66

Which are characteristics used in the naming of muscles?

Answer 66

Origin and insertion Size and shape Region of the body