Unit 3a

Question 1

Skeletal muscle characteristics

Answer 1

Attached to bones via tendon, cells are multi-nucleate, very large, striated- visible banding, cells are surrounded and bundled by connective tissue wrappings

Question 2

Where is the endomysium

Answer 2

Around single muscle fiber

Question 3

Where is the perimysium

Answer 3

Around a fascicle (bundle) of fibers

Question 4

What is the epimysium

Answer 4

Covers the entire skeletal muscle

Question 5

What is the fascia

Answer 5

Surrounds epimysium, fascia blends into a connective tissue attachment

Question 6

What are fascicles

Answer 6

A bundle of muscle fibres, arranged parallel to each other in 5 different patterns

Question 7

Parallel muscles

Answer 7

Long fascicles that extend the length of the muscle greater range of motion but less power

Question 8

Pennate muscles

Answer 8

Large number of fascicles greater power but a smaller range of motion

Question 9

Smooth muscle characteristics

Answer 9

No striations, single nucleus, found mainly in the walls of hollow organs

Question 10

Cardiac muscle characteristics

Answer 10

Has striations, usually has a single nucleus, found only in the heart

Question 11

Function of muscles

Answer 11

Produce movement, maintain posture, stabilize joints, generate heat

Question 12

Three basic muscle types found in the body

Answer 12

Skeletal muscle, cardiac muscle, smooth muscle

Question 13

What is in muscle cell aka muscle fibre

Answer 13

Nucleus, sarcolemma, and myofibrils

Question 14

What is sarcolemma?

Answer 14

Specialized plasma membrane

Question 15

What is the sarcoplasmic reticulum

Answer 15

Specialized smooth endoplasmic reticulum. Stores and releases Ca2+ needed for muscle contraction

Question 16

What are myofibrils

Answer 16

Bundles of myofilaments, make up the bulk of cytoplasm. Aligned in distinct bands

Question 17

I band

Answer 17

Light band

Question 18

A band

Answer 18

Dark band, composed of thick filaments

Question 19

What is a sacromere

Answer 19

Contractile unit of a muscle fibre (cell), composed of 2 types of myofilaments

Question 20

What are thick or myosin filaments

Answer 20

Composed of the protein myosin and ATPase enzymes. Extend the length of the A band

Question 21

What are thin or actin filaments

Answer 21

Composed of the protein actin. Attached to the z disc in the I band

Question 22

What is actin myosin cross bridging

Answer 22

Myosin filaments contain myosin heads or cross bridges. Cross bridges link thick and thin filaments together during contraction

Question 23

What is the “bare zone”

Answer 23

What the muscle is relaxed, actin filaments do not extend into the H-zone, hence the name “bare zone”

Question 24

What is skeletal muscle irritability or excitability

Answer 24

Ability to receive and respond to a stimulus

Question 25

What is skeletal muscle contractility

Answer 25

Ability to shorten when an adequate stimulus is received

Question 26

What is a motor unit

Answer 26

One Neuron and all the muscle cells stimulated by that Neuron

Question 27

What is the axon terminal

Answer 27

End of the nerve fibre (axon)

Question 28

What is the neuromuscular junction

Answer 28

Axon terminal meets the sarcolemma of the muscle

Question 29

What is the synaptic cleft

Answer 29

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

Question 30

What is a neurotransmitter (NT)

Answer 30

A chemical released by nerve upon arrival of nerve impulse to axon terminal

Question 31

Increasing Na in the cell causes what?

Answer 31

An electrical current to flow along the sarcolemma which triggers an action potential and a muscle contraction

Question 32

The sliding filament theory of muscle contraction

Answer 32

the actin (thin) filaments of muscle fibres slide past the myosin (thick) filaments during muscle contraction, while the two groups of filaments remain at relatively constant length.

Question 33

Contraction of a skeletal muscle

Answer 33

Contraction is all or none, muscle force depends upon the number of fibers stimulated. More fibers = greater muscle tension