Chapter 11: The Musculoskeletal System

Question 1

Answer 1

Question 2

Which zone or band in the sarcomere does NOT change its length during muscle contraction? Why?

Answer 2

The A-band does not change length during muscle contraction because it is the entire length of the myosin filament. The filaments do not change length, but rather slide over each over; thus, the A-band should remain a constant length during contraction.

Question 3

What are the events that intiate muscle contraction, in order? Start with neurotransmitter release and trace the pathway to the point where myosin binds with actin.

Answer 3

1. Release of acetylcholine from motor neuron
2. activation of acetycholine recepors in sarcolema
3. depolarization of sarcolema
4. spreading of signal using T-tubules
5. release of calcium from sarcoplasmic reticulum (SR)
6. binding od calcium to troponin
7. conformational shift in tropomyosin
8. exposure of myosin-binding sites
9. myosin binds to actin

Question 4

What roles does the binding of ATP to myosin head play in the cross-bridge cycle? What about the dissociation of ADP and inorganic phosphate from the myosin head?

• Binding of ATP
• Dissociation of ADP and inorganic phosphate

Answer 4

• Binding of ATP
  
  • ATP binding allows the myosin filament to disconnect from actin.
• Dissociation of ADP and inorganic phosphate
  
  • Causes th power stroke

Question 5

What is tetanus (the physiological phenomenon, not the disease)

Answer 5

Tetanus os the summation of multiple simple twitches that occur to quickly for the muscle to relax. This leads to a stronger and more prolonged contraction of the muscle.

Question 6

What are the three types of muscles?

Answer 6

1. Skeletal
2. Smooth
3. Cardiac

Question 7

____ is responsible for voluntary movement and is therefore innervated by the somatic nervous system?

Answer 7

Skeletal Muscle

Question 8

What are the types of fibers in skeletal muscles?

Answer 8

Slow-twitch fibers (Red fibers)

Fast-twitch fibers (White fibers)

Question 9

Slow twitch fibers

Answer 9

Have high myoglbin content and primarily derive their energy aerobically. Also contain many mitochondria to execute oxidative phosphorylation.

Muscles that contract slowly, but that can sustain activity (such as the muscles that support posture).

Question 10

Myoglobin

Answer 10

Ocygen carrier that uses iron in a heme group to bind oxygen, imparting a red color.

Question 11

Fast-twitch fibers

Answer 11

contain much less myoglobin. Thats why they appear white.

Muscles that contract rapidly, but fatigue quickly.

Question 12

____ muscle that is responsible for involuntary action?

Answer 12

Smooth

Question 13

What is special about smooth and cardiac muscles?

Answer 13

Myogenic Activity

They can contract without nervous system input.

Question 14

____ muscle has charectristics of both smooth and skeletal muscle?

Answer 14

Cardiac

Question 15

Cardiac muscle cells are conneted by ____, which contain many ____.

Answer 15

Intercalated discs

Gap Junctions

Question 16

____ is the basic contractile unit of skeletal muscle?

Answer 16

Sarcomere

Question 17

What are sarcomenres made up of?

Answer 17

Thick and Thin filaments.

Question 18

What are they made up of

Thick Filaments

Thin Filaments

Answer 18

Thick Filaments: bundles of myosin

Thin Filaments: bundles of actin with two proteins names Troponin and Tropomyosin.

Question 19

MNEMONINC

To remember which filament is asociated with troponin and tropomyosin.

Answer 19

Remeber that actin has a T in it.

Question 20

MENMONIC

To remeber which is the thin and thick filament.

Answer 20

Remeber Actin: Acthin

Question 21

The sarcomere Anatomy

• Z
• M
• I
• H
• A

Answer 21

• Z: Z is at the end of the sarcomere (Z is at the end of the alphabet)
• M: Middle of the Myosin filaments
• I: I is a thin letter (Thin filaments only)
• H: H is a thick letter (Thick filaments only)
• A: All of the thick filament, whether or not it is overlapping.

Question 22

_____ is a modified endoplasmic reticulum that contains a high concentration of Ca²⁺ ions.

Answer 22

Sarcoplasmic Reticulum

Question 23

A myofibril is _____. A muscle fiber (or myocyte, or muscle cell) contains ____. A muscle is made up of ____.

Answer 23

A myofibril is an arrangement of many sarcomeres in series. A muscle fiber (or myocyte, or muscle cell) contains many myofibrils within it, arranged in parallel. A muscle is made up of parallel muscle fibers.

Question 24

Sliding filament model and steps

Answer 24

1. ATP is hydrolyzed
2. Ca²⁺ binds to troponin; myosin binds to actin
3. Powerstroke occurs; the sarcomere contracts; ADP and P_i dissociate from myosin.
4. New ATP binds to m yosin, causing detachment of myosin from actin; hydrolysis of ATP to ADP and P_i causes reckoing of the myosin head.

Question 25

Troponin vs Tropomyosin

Answer 25

Tropoin: involved in the muscle contraction Tropomyosin: wraps around

Question 26

Rigor Mortis

Answer 26

After deatj, ATP production ceases. Myosin heads cannot detach from actin, making it impossible for muscles to relax and lengthen.

Question 27

Muscles cells exhibit what type of response?

Answer 27

All or nothing Either they respond completely to a stimulus or not at all.

Question 28

What type of energy reserve do we use to quickly generate ATP? Like for sprinting

Answer 28

Creatine Phosphate

Question 29

As exercising muscles run out of oxygen, they must use \_\_\_. What about Slow Twitch fibers? What about Fast Twitch fibers?

Answer 29

* Myoglibin reserves to keep aerobic metabolism going. * Have fewer mitochondria and must rely on glycolysis and dermentation to make ATP under most circumstances.

Question 30

What happens when muscle use eventually overwhelm the baility of the body to deliver oxygen? Last Resort

Answer 30

The even the Slow Twitch fibers (Red) must swtitch to anaerobic metabolism and produce lactic acid, at which point in the muscles begins to fatigue.

Question 31

What is the difference between compact bone and spongy bone? * Compact Bone * Spongy Bone

Answer 31

* Compact Bone * Dense and is used for its strength, it forms most of the outer layers of a bone. * Spongy Bone * Has many spaces between bony spicules called trabeculae ad it the site of marrow production. It is found in the inner core of the bone and also helps distribute forces or pressures on the bone.

Question 32

What are the three structural parts of a bone? Which part contributes most to linear grorth?

Answer 32

* Diaphysis * Metaphysis * Epiphysis * Growth plates are found in the epiphyses and contribute to linear growth.

Question 33

What chemical forms most of the inorganic component of the bone?

Answer 33

Most inorganic bone is composed of hydroxyapatite crystals.

Question 34

What are the functions of * Osteoblast: * Osteoclast: * Chindrocyte:

Answer 34

* Osteoblast: Build Bone * Osteoclast: Chew bone (break it down) * Chondrocytes: Form cartliage

Question 35

What liquid provides the lubricaton for movable joints? What tissue produces it?

Answer 35

* Synovial fluid * The Synovium