Chapter 6 Muscular System

Question 1

Skeletal and smooth muscle cells are _________.

Answer 1

Elongated

Question 2

Contractions of muscles is due to the movement of ____________.

Answer 2

microfilaments

Question 3

Skeletal muscle characteristics

Answer 3

Attached by tendons to bones
Cells are multinucleate
Striated- have visible banding
Voluntary- subject to conscious control

Question 4

Sites of skeletal muscle attachments

Answer 4

Bones
Cartilages
Connective tissue coverings

Question 5

Smooth muscle characteristics

Answer 5

Lack striations 
Spindle-shaped cells
Single nucleus 
Involuntary- no conscious control
Found mainly in the walls of hollow organs

Question 6

Cardiac muscle characteristics

Answer 6

Striations
Usually have a single nucleus 
Branching cells
Joined to another muscle cell at an intercalated disc 
Involuntary
Found only in the heart

Question 7

Skeletal muscle functions

Answer 7

Produce movement
Maintain posture
Stabilize joints
Generate heat

Question 8

Microscopic anatomy of a skeletal muscle:

Sarcolemma

Answer 8

Specialized plasma membrane

Question 9

Microscopic anatomy of a skeletal muscle:

Myofibrils

Answer 9

Long organelles inside a muscle cell

Question 10

Microscopic anatomy of skeletal muscle: sarcoplasmic reticulum

Answer 10

Specialized smooth endoplasmic reticulum

Question 11

I band =

Answer 11

Light band

Contains only thin filaments

Question 12

A band=

Answer 12

Dark band

Contains the entire length of the thick filaments

Question 13

Microscopic anatomy of skeletal muscle:

Sacromere

Answer 13

Contractile unit of a muscle fiber

Question 14

Microscopic anatomy of skeletal muscle

Organization of the sacromere

Answer 14

Myofilaments

• thick filaments = myosin filaments
• thin filaments= actin filaments

Question 15

Microscopic anatomy of skeletal muscle

Thick filaments = myosin filaments

Answer 15

Composed of the protein myosin
Has ATPase enzymes
Myosin filaments have heads (extensions or cross bridges)
Myosin and actin overlap somewhat

Question 16

Microscopic anatomy of skeletal muscle

Thin filaments = actin filaments

Answer 16

Composed of the protein actin

Anchored to the Z disc

Question 17

Microscopic anatomy of skeletal muscle

At rest, there is a bare zone that lacks actin filaments called the _ ____.

Answer 17

H zone

Question 18

Microscopic anatomy of skeletal muscle

Sarcoplasmic reticulum

Answer 18

Stores and releases calcium

Surrounds the myofibril

Question 19

Skeletal muscles must be stimulated by a motor _________ (nerve cell) to contract.

Answer 19

Neuron

Question 20

Motor unit

Answer 20

One motor neuron and all the skeletal muscle cells stimulated by that neuron.

Question 21

Neuromuscular junction

Answer 21

Association site of axon terminal of the motor neuron and muscle

Question 22

Synaptic Cleft

Answer 22

Gap between nerve and muscle
Nerve and muscle do not make contact
Area between nerve and muscle is filled with interstitial fluid

Question 23

Neurotransmitter

Answer 23

Chemical released by nerve upon arrival of nerve impulse

Question 24

The neurotransmitter for skeletal muscle is

Answer 24

Acetylcholine (ACh)

Question 25

Acetylcholine attaches to the receptors on the ___________.

Answer 25

Sarcolemma

Question 26

Sarcolemma becomes permeable to ________.

Answer 26

Sodium

Question 27

The Sliding Filament Theory of Muscle Contraction

Answer 27

• activation by nerve causes myosin heads (cross bridges) to attach to binding sites on the thin filament.
• myosin heads then bind to the next site of the thin filament and pull them toward the center of the sacromere.
• this continued action causes a sliding of the myosin along the actin.
• the result is that the muscle is shortened (contracted)

Question 28

Isotonic contractions

Answer 28

Myofilaments are able to slide past each other during contractions.
The muscle shortens and movement occurs.

Question 29

Isometric contractions

Answer 29

Tension in the muscle increases.

The muscle is unable to shorten of produce movement.

Question 30

Exercise increases

Answer 30

Muscle size
Strength
Endurance

Question 31

5 Golden Rules of Skeletal Muscle Activity

Answer 31

1) with a few exceptions, all skeletal muscles cross at least 1 joint.
2) typically, the bulk of a skeletal muscle lies proximal to the joint crossed.
3) all skeletal muscles have at least two attachments: the origin & the insertion
4) skeletal muscles can only pull, never push.
5) during contraction, a skeletal muscle insertions moves toward the origin.

Question 32

Origin

Answer 32

Attachment to an immovable bone

Question 33

Insertion

Answer 33

Attachment to a movable bone

Question 34

Flex ion

Answer 34

Decreases the angle of the joint.
Brings two bones closer together.
Typical of hinge joints like the knee and elbow.

Question 35

Extension

Answer 35

Opposite of flexion.

Increases angle between 2 bones.

Question 36

Rotation

Answer 36

Movement of a bone around it’s longitudinal axis.
Common in the ball and socket joints.
Example when you move atlas around the dens of axis. (Shaking your head no)

Question 37

Abduction

Answer 37

Movement of a limb away from midline.

Question 38

Adduction

Answer 38

Opposite of abduction.

Movement of a limb toward mid line.

Question 39

Circumduction

Answer 39

Combination of flexion, extension, abduction, and adduction.
Common in ball and socket joint.

Question 40

Types of muscles:

Prime mover

Answer 40

Muscle with the major responsibility for a certain movement.

Question 41

Types of muscles:

Antagonist

Answer 41

Muscle that opposes or reverses a prime mover

Question 42

Types of muscles:

Synergist

Answer 42

Muscle that aids a prime mover in a movement and helps prevent rotation.

Question 43

Types of muscles:

Fixator

Answer 43

Stabilizes the origin of a prime mover

Question 44

3 types of basic muscles found in body

Answer 44

Skeletal muscle
Cardiac muscle
Smooth muscle