Module 3 (Skeletal Muscles)

Question 1

What is each skeletal muscle composed of

Answer 1

Skeletal muscle tissue, epithelial, connective and nervous tissue

Question 2

Functions of skeletal muscles

Answer 2

Contracts to move parts of the body
Maintain posture and stabilizes joints
Control excretion and swallowing
Produce heat
Support and protect internal organs

Question 3

What happens when skeletal muscles attach to 2 bones across a joint

Answer 3

When contracted, the muscle brings parts of those bones closer together

Question 4

Organization of skeletal muscle tissue

Answer 4

Consists of muscle tissue and CT
CT surrounds the muscle and attaches the ends of each muscle to bone

Question 5

What are the 3 layers of CT

Answer 5

Epimysium
Perimysium
Endomysium

Question 6

What is epimysium

Answer 6

Outermost layer of CT that surround the entire muscle and is continuous with the tissue that becomes the tendon

Question 7

What is perimysium

Answer 7

Middle layer of CT surrounding a bundle of muscle fibers within a muscle

Question 8

What is a bundle of muscle fibers called

Answer 8

Fascicle

Question 9

What is endomysium

Answer 9

Innermost layer of CT that surrounds the individual muscle cells within a muscle bundle

Question 10

Features of a muscle cell

Answer 10

Sarcolemma
Nuclei
Myofibril
Myofilaments
Sarcoplasmic reticulum
T-Tubules (transverse tubules)

Question 11

What is sarcolemma

Answer 11

Cell membrane surrounding a muscle cell

Question 12

How is sarcolemma different from endomysium

Answer 12

Beneath the sarcolemma are the nuclei, myofibrils, and sarcoplasm

Question 13

Nuclei of muscle cells

Answer 13

Multinucleated and located towards the outside of the myofiber

Question 14

What is myofibril

Answer 14

Structural units of the muscle cell and contain contractile myofilaments

Question 15

What are myofilaments

Answer 15

Contractile units of the muscle cell

Question 16

What is sarcoplasmic reticulum

Answer 16

Surrounds each myofibril and is where the muscle cell stores calcium
Needed for muscle function

Question 17

What are T-Tubules (Transverse tubules)

Answer 17

Extensions of the sarcolemma that surround the myofibrils and transmit nerve stimulation to the sarcoplasmic reticulum within the cell

Question 18

Organization of myofilaments

Answer 18

Organized into repeating structural units knows as sarcomeres

Question 19

What happens sarcomeres shorten

Answer 19

It causes contraction of the muscle

Question 20

What does each unit consist of

Answer 20

Actin and mysoin and one sarcomere spans from one z-line to the next

Question 21

What is actin and myosin

Answer 21

Thin (actin) and thick (myosin) filaments

Question 22

What is sarcomere banding

Answer 22

Refers to the distinct lines and bands that create the striated appearance
Due to the arrangement of actin and myosin

Question 23

What is the A-band

Answer 23

Made up of think and thin filaments
Appears darker when viewed histologically

Question 24

What is the Z-line

Answer 24

Composed of protein that makes a “zig-zag” line marking the beginning and end of each sarcomere

Question 25

Where can the Z-line be found

Answer 25

Lies in the middle of the I-band and is where the thin filaments attach

Question 26

What is the M-line

Answer 26

Composed of protein down the centre of the sarcomere "mid-line" and where thick filaments attach

Question 27

What is the I-band

Answer 27

Made up of thin filaments and appears lighter in colour

Question 28

How do muscles contract

Answer 28

Actin and myosin filaments slide over each other, which shortens the sarcomere This increases muscle tension

Question 29

Why do sarcomere appear to have light and dark bands

Answer 29

Because of the overlap of thick and thin filaments

Question 30

Why is the I-band light in colour

Answer 30

It is only area that consists thin filaments

Question 31

Why is the Z-line dark in colour

Answer 31

It contains an abundance of structural proteins

Question 32

Why is the A-band dark in colour

Answer 32

It consists of thick filaments and is even darker towards the sides because it overlaps with thin filaments

Question 33

How is the M-line similar to the Z-line

Answer 33

It also has an abundance of structural proteins that create a dark line

Question 34

Organization of skeletal muscles

Answer 34

The muscles of the body are generally organized as being superficial, intermediate, or deep