Muscle Types, Structure and Contraction

Question 1

Striated muscle associated with voluntary movement

Contraction regulated by Somatic NS

Answer 1

Skeletal muscle

Question 2

Striated muscle in the heart

Contraction regulated by Autonomic NS

Answer 2

Cardiac muscle

Question 3

Muscle in blood vessels, visceral tissues

Contraction regulated by Autonomic NS

Answer 3

Smooth muscle

Question 4

Three layers of connective tissue surrounding the skeletal muscle:

Answer 4

1. ) Epimysium - layer of cells encasing entire muscle
2. ) Perimysium - layer of cells encasing bundle of muscle fibers (cells)
3. ) Endomysium - layer of cells encasing individual muscle fibers

Question 5

Cell membrane of individual muscle fibers (plasma membrane)

Answer 5

Sarcolemma

Question 6

Muscle fibers….(4)

Answer 6

• Sarcolemma
• Each cell has more than one nucleus
• Contain myofibrils made up of protein
• SR - surround myofibrils

Question 7

Repeating unit that forms the myofibrils (contractile unit)

Answer 7

Sarcomere

Question 8

Thick filaments

Answer 8

Myosin

Question 9

Thin filaments

Answer 9

Actin
Troponin
Tropomyosin

Question 10

I band, A band, H zone of Skeletal muscle contraction

Answer 10

I band = only thin filaments
A band = contains entire thick filament
H zone = only thick filaments

Question 11

During skeletal muscle contraction, what happens to each band/zone?

Answer 11

I band = gets smaller
A band = stays the same length (thick does not change)
H zone = gets smaller

Question 12

During skeletal muscle contraction, the sarcomere _____ due to a/an _____ of _______.

Answer 12

Shortens due to an overlap of thick and thin filaments

-NONE of the filaments themselves change length

Question 13

What do muscle contractions need? (3)

Answer 13

• ATP
• Nerve impulse (Acetylcholine)
• Calcium

Question 14

Attached to actin filaments and tropomysin and BINDS calcium

Answer 14

Troponin

Question 15

NO Calcium = blocks myosin binding site

Calcium = moves off the myosin binding site on the actin

Answer 15

Tropomysin

Question 16

Differences of smooth muscle from skeletal muscle (5)

Answer 16

1. Smaller
2. Spindle-shaped
3. Single nuclei, no t-tubules, poorly developed SR
4. more THIN filaments than skeletal, no troponin
5. Not organized into sarcomeres

Question 17

Smooth Muscle Myofibrils (3)

Answer 17

1. ) Thick filament through the sarcoplasm
2. ) Thin filament anchored to dense bodies and membrane
3. ) During contraction, thin filaments pulled together (from football-shaped –> globular)

Question 18

Smooth muscle contraction dependent on…

Answer 18

Ca2+ concentrations

-Processes more time-consuming than in skeletal muscle - slower contraction

Question 19

Single-unit Smooth muscle

Answer 19

“Joined” by gap junctions

Coordinated contraction

Question 20

Multi-unit Smooth muscle

Answer 20

Cells as individual units
More direct than neural control
ex: Eyes, arteries, hair erectors

Question 21

• Striated (has sarcomeres)
• Cells joined together with intercalated disks: gap junctions and desmosomes
• Regions with pacemaker activity
• Long contraction - relatively slow

Answer 21

Cardiac muscle

Question 22

Sliding Filament Theory

Answer 22

During muscle contraction, the thick and thin filaments slide over each other, increasing the degree of overlap, shortening each sarcomere

Question 23

The gap junctions of cardiac muscles allow for…

Answer 23

Beating of the heart

Question 24

The desmosomes of cardiac muscles allow for…

Answer 24

Muscle to generate a great deal of force

Question 25

Which of the following terms refers to the name of the plasma membrane of a muscle fiber?

Answer 25

Sarcolemma

Question 26

Which of the following terms refers to the name of the connective tissue layer that surrounds each muscle fiber?

Answer 26

Endomysium

Question 27

Which of the following proteins is not part of the thin filament in skeletal muscle?

Answer 27

Myosin

Question 28

What is the name of the repeating contractile unit that makes up the myofibril?

Answer 28

Sarcomere

Question 29

In the skeletal muscle, calcium binds to which of the following proteins?

Answer 29

Troponin

Question 30

During skeletal muscle contraction, ATP binds to which of the following proteins?

Answer 30

Myosin

Question 31

In which of the following types of muscle does calcium cause muscle contraction by increasing the phosphorylation of myosin?

Answer 31

Smooth muscle

Question 32

What is the name of the neurotransmitter involved in signaling skeletal muscle contraction?

Answer 32

Acetylcholine

Question 33

From what muscle fiber organelle is calcium released during muscle contraction?

Answer 33

Sarcoplasmic reticulum