Unit 5

Question 1

What is the main function of muscle tissue?

Answer 1

Contraction — converting chemical energy into mechanical movement.

Question 2

What are muscle cells called?

Answer 2

Muscle fibers.

Question 3

What is the specialized plasma membrane of muscle cells called?

Answer 3

Sarcolemma.

Question 4

What is the name of the cytoplasm in muscle cells?

Answer 4

Sarcoplasm.

Question 5

What is the sarcoplasmic reticulum, and its function?

Answer 5

Specialized SER that stores calcium ions for muscle contraction.

Question 6

Is skeletal muscle voluntary or involuntary?

Answer 6

Voluntary.

Question 7

Describe the structure of skeletal muscle fibers.

Answer 7

Long, cylindrical, multinucleated (nuclei at periphery), striated.

Question 8

What are the three connective tissue layers in skeletal muscle?

Answer 8

Endomysium (fiber), perimysium (fascicle), epimysium (entire muscle).

Question 9

What is a motor unit?

Answer 9

One motor neuron + all the muscle fibers it innervates.

Question 10

What is a triad in skeletal muscle?

Answer 10

1 T tubule + 2 terminal cisternae of the sarcoplasmic reticulum.

Question 11

What is the basic contractile unit of skeletal muscle?

Answer 11

Sarcomere.

Question 12

What proteins are in thick and thin filaments?

Answer 12

Thick = myosin; Thin = actin (with troponin and tropomyosin).

Question 13

What happens during muscle contraction?

Answer 13

Actin slides over myosin → sarcomere shortens; A band stays the same.

Question 14

What are satellite cells?

Answer 14

Muscle stem cells that help repair and regenerate skeletal muscle.

Question 15

Is cardiac muscle voluntary or involuntary?

Answer 15

Involuntary.

Question 16

Describe the structure of cardiac muscle fibers.

Answer 16

Short, branched, 1 central nucleus, striated, connected by intercalated discs.

Question 17

What are intercalated discs, and their components?

Answer 17

Specialized junctions with desmosomes (adhesion) and gap junctions (electrical communication).

Question 18

What is a diad in cardiac muscle?

Answer 18

1 T tubule + 1 terminal cistern of the sarcoplasmic reticulum.

Question 19

Does cardiac muscle regenerate well?

Answer 19

No — very limited regeneration; damage often results in scar tissue.

Question 20

Is smooth muscle voluntary or involuntary?

Answer 20

Involuntary.

Question 21

Describe the structure of smooth muscle fibers.

Answer 21

Long, spindle-shaped (fusiform), 1 central nucleus, no striations, no sarcomeres.

Question 22

What type of filaments does smooth muscle have?

Answer 22

Thick (myosin) and thin (actin) anchored to dense bodies (like Z-discs).

Question 23

Does smooth muscle contain T tubules?

Answer 23

No.

Question 24

How does smooth muscle communicate for coordinated contraction?

Answer 24

Through gap junctions.

Question 25

Can smooth muscle regenerate?

Answer 25

Yes — by mitosis and hyperplasia.

Question 26

Which muscle types are striated?

Answer 26

Skeletal and cardiac.

Question 27

Which muscle types can regenerate?

Answer 27

Smooth (yes), Skeletal (limited via satellite cells), Cardiac (very limited).

Question 28

Which muscle types have T tubules?

Answer 28

Skeletal and cardiac.

Question 29

Which muscle types have sarcomeres?

Answer 29

Skeletal and cardiac (not smooth).

Question 30

Which muscle type is multinucleated?

Answer 30

Skeletal muscle.