Chapter 8: Muscular System

Question 1

What are intercalated disks?

Answer 1

Intercalated discs are unique structural formations found between the myocardial cells of the heart.

Question 2

What is Fascia?

Answer 2

It’s the loose connective tissue outside the muscle organs that forms a flexible, sticky “packing material” between muscles, bones, and the skin.

Question 3

The muscle’s attachment to this more stationary bone is called its _____.

Answer 3

Origin.

Question 4

Its attachment to the more movable bone is called the muscle’s _____.

Answer 4

Insertion.

Question 5

The muscle fiber’s internal framework is organized into many long cylinders, each made up of two kinds of thread-like microfilaments called ____ and ___ myofilaments.

Answer 5

Thin and Thick

Question 6

The thick myofilaments are formed from a protein called ____.

Answer 6

Myosin

Question 7

The thin myofilaments are composed mainly of the protein ____.

Answer 7

Actin

Question 8

Explain the Sliding Filament Model.

Answer 8

According to this model, during contraction the thick and thin myofilaments in a muscle fiber first attach to one another by forming crossbridges that then act as levers to ratchet or pull the myofilaments past each other.

Question 9

The connecting bridges between the myofilaments form only if _____ is present.

Answer 9

calcium

Question 10

What is a tendon?

Answer 10

Tendons are dense, fibrous connective tissue that anchor muscles firmly to bones.

Question 11

What is the basic contractile unit of muscle?

Answer 11

Sarcomere

Question 12

The repeating units, or sarcomeres, are separated from each other by dark bands called _____.

Answer 12

Z Lines

Question 13

Of all the muscles contracting simultaneously, the one that is mainly responsible for producing a particular movement is called the _____ _____ for that movement.

Answer 13

prime mover

Question 14

What is it called when muscles help the prime mover produce a given movement?

Answer 14

Synergist muscle

Question 15

What is it called when a muscle opposes the action of a prime mover in a given movement?

Answer 15

Antagonist muscle

Question 16

We are able to maintain our body position because of a continuous, low-strength muscle contraction called muscle tone or ___ ____.

Answer 16

Tonic Contraction

Question 17

What is Oxygen Debt?

Answer 17

The amount of extra oxygen needed by muscle tissue to oxidise lactic acid following exercise.

Question 18

What are the three primary functions of the muscular system?

Answer 18

1) Movement 2) Posture 3) Heat Production

Question 19

How would you define the term posture?

Answer 19

Muscle tone, or tonic contraction, holds muscles in position. In other words, muscle tone maintains posture.

Question 20

How does muscle function affect body temperature?

Answer 20

The contraction of muscle fibers produces most of the heat required to maintain body temperature.

Question 21

Muscle fibers are stimulated by a nerve cell called a ____ ____.

Answer 21

Motor Neuron

Question 22

The point of contact between the nerve ending and the muscle fiber is called a ____ _____.

Answer 22

neuromuscular junction (NMJ)

Question 23

Define Motor Unit.

Answer 23

Combination of a motor neuron with the muscle fibers it controls

Question 24

What is a Twitch Contraction?

Answer 24

A twitch is a quick, jerky response to a stimulus. Twitch contractions can be seen in isolated muscles during research but play a minimal role in normal muscle activity.

Question 25

What is Tetanic Contraction?

Answer 25

It is more sustained and steady. It is produced by a series of stimuli bombarding the muscle in rapid succession.

Question 26

Explain the 2 types of isotonic contraction.

Answer 26

1) Concentric contraction, in which the muscle shortens. 2) Eccentric contraction, in which the muscle lengthens but still provides work.

Question 27

When the muscle contracts and no movement results, it is called an ____ ____.

Answer 27

isometric contraction

Question 28

What role does acetylcholine play in muscle contraction?

Answer 28

Acetylcholine (ACh) is a neurotransmitter released by the motor neuron that moves across the neuromuscular junction (NMJ) to trigger events within the muscle fiber and thus resulting in a muscle contraction.

Question 29

_____ is a movement that decreases the angle between two bones at their joint.

Answer 29

Flexion

Question 30

_____ movements are the opposite of flexion. They increase the angle between two bones at their joint.

Answer 30

Extension

Question 31

_____ means moving a part away from the midline of the body, such as moving your arm out to your side.

Answer 31

Abduction

Question 32

_____ refers to moving a part toward the midline,

Answer 32

Adduction

Question 33

___ ___ is another name for muscle cell.

Answer 33

Muscle Fiber

Question 34

The minimal level of stimulation required to cause a fiber to contract is called the ____ ____.

Answer 34

threshold stimulus

Question 35

_____ describes the hand position when the body is in anatomical position.

Answer 35

Supination