The Muscular System: CHP 6

Question 1

List the 5 functions of the muscular system.

Answer 1

1. Body movement
2. Regulate organ volume
3. Heat Production
4. Stabilize body positions
5. Move substances in the body

Question 2

How much of the body mass do muscles make up?

Answer 2

40-50%

Question 3

What are the three types of muscle tissue?

Answer 3

Skeletal, cardiac, smooth

Question 4

Which types of muscle are striated?

Answer 4

Skeletal and cardiac

Question 5

What is skeletal muscle responsible for?

Answer 5

Body movements (voluntary/involuntary)

Question 6

What is cardiac muscle responsible for?

Answer 6

Generation of force to pump blood

Question 7

What is a unique ability of the cardiac muscle?

Answer 7

The ability to contract without oversight from the nervous system (autorhythmic)

Question 8

What is smooth muscle responsible for?

Answer 8

Moving substances in the body and regulating organ volume.

Question 9

Where is smooth muscle found?

Answer 9

Hollow body organ walls (stomach, uterus), attached to skin/hair follicles

Question 10

Describe the structure of smooth muscle.

Answer 10

Smaller cell size
Single nucleus
Spindle shaped
No T-tubules
Irregular filament arrangement

Question 11

Which muscle tissues are completely involuntary?

Answer 11

Cardiac and smooth

Question 12

How does cardiac muscle communicate?

Answer 12

Through gap junctions in intercalated discs

Question 13

What are intercalated discs?

Answer 13

The junction of two adjoining cardiac cells

Question 14

What do cardiac cells look like?

Answer 14

Branched

Question 15

What are pacemaker cells?

Answer 15

Heart muscle cells

Question 16

How many twitch contractions does cardiac muscle have per minute?

Answer 16

70-80 per min

Question 17

What are desmosomes?

Answer 17

Connections that mechanically bind cells like velcro

Question 18

What are hemidesmosomes?

Answer 18

Connections that mechanically bind cells to the basement membrane

Question 19

What is a sarcomere?

Answer 19

A building block of muscle fibers

Question 20

What is thin filament made of?

Answer 20

Actin protein

Question 21

What is thick filament made of?

Answer 21

Myosin protein

Question 22

What is a z disc?

Answer 22

The boundary of a sarcomere unit

Question 23

Explain the relationship between perimysium, endomysium, and epimysium.

Answer 23

All are a connective tissue. The epimysium surrounds the muscle, the perimysium surrounds a bundle of muscle fibers, the endomysium surrounds each muscle fiber.

Question 24

What are fascicles?

Answer 24

Bundles of muscle cells/fibers wrapped in connective tissue.

Question 25

True or False: Skeletal muscle is multinucleated.

Answer 25

True

Question 26

What is the plasma membrane of skeletal muscle tissue called?

Answer 26

Sarcolemma

Question 27

What does the sarcolemma form?

Answer 27

T-tubules (transverse)

Question 28

What is the endoplasmic reticulum of skeletal muscle called?

Answer 28

Sarcoplasmic reticulum

Question 29

What does the sarcoplasmic reticulum do?

Answer 29

Serves a calcium reservoir, located near the T-tubules

Question 30

What are myofilaments?

Answer 30

Threadlike proteins that allow muscle fibers to shorten

Question 31

Explain the function of a joint.

Answer 31

A joint is 2 bones, working together for movement. One bone is stationary and the other is moveable.

Question 32

What is the origin of the muscle?

Answer 32

The end of the muscle attached to the stationary bone

Question 33

What is the insertion of the muscle?

Answer 33

The end of the muscle attached to the moveable bone

Question 34

What is the belly of the muscle?

Answer 34

The part of the muscle between origin and insertion tendons (middle)

Question 35

How do muscles work?

Answer 35

In antagonistic pairs, opposing

Question 36

What does the agonist do?

Answer 36

Starts the desired action or movement

Question 37

What does the synergist do?

Answer 37

Reduces unnecessary movements to help agonist function efficiently

Question 38

What do the fixators do?

Answer 38

Stabilize the bones to allow the agonist to move other bones more efficiently

Question 39

What causes muscle fatigue?

Answer 39

Insufficient ATP Depleted creatine or glycogen Inadequate delivery of oxygen to muscle Lactic acid buildup

Question 40

Describe the first 3 steps of Excitation/Contraction Coupling.

Answer 40

1. Nerve impulses arrive @ axon terminal of motor neuron & trigger ACh release. 2. ACh diffuses synaptic cleft, binds to receptors, & triggers muscle action potential (AP). 3. Acetylcholinesterase destroys ACh so another muscle action potential does not arise unless ACh is released from motor neuron.

Question 41

Describe steps 4-6 of Excitation/Contraction Coupling.

Answer 41

4. Muscle AP traveling along transverse tubule opens Ca+ release channels in SR membrane, allowing calcium ions to flood sarcoplasm. 5. Ca2+ binds to troponin on the thin filaments, exposing binding sites for myosin. 6. Contraction: power strokes use ATP, myosin heads bind to actin, swivel, and release. Thin filaments are pulled toward the center or sarcomere.

Question 42

Describe steps 7-9 of Excitation/Contraction Coupling.

Answer 42

7. Ca2+ release channels close and Ca2+ active transport pumps use ATP to restore low levels of Ca2+ in sarcoplasm. 8. Troponin and tropomyosin slide back into position. 9. Muscle relaxes.

Question 43

The oxygen binding protein in skeletal muscle is...

Answer 43

Myoglobin