Lecture #13: Muscles

Question 1

Hydrostatic

Answer 1

Fluid-filled space (ex: earthworm)

Question 2

Endoskeleton

Answer 2

Bones, living (grows w/ body)

Question 3

Osteoblasts

Answer 3

bone building cells (B)

Question 4

osteoclasts

Answer 4

bone destroying

Question 5

Exoskeleton

Answer 5

Insect, crab (skeleton is outside body, helps prevent water loss + provides protection
- needs to shed (non-living)

Question 6

Flexim

Answer 6

move toward body

Question 7

Extension

Answer 7

move away from body

Question 8

Abduction

Answer 8

to move away from midline

Question 9

Aduction

Answer 9

to move toward midline (D)

Question 10

Tendon

Answer 10

connects muscle to bone

Question 11

Ligament

Answer 11

connect bone to bone

Question 12

Cartilage

Answer 12

end of long bone
- disks for cushion at joints

Question 13

How to change intensity (force) of contractions?

Answer 13

1. change the number of twitches/sec for individual fiber
   - if second twitch occurs before first twitch relaxes, you increase the force
2. change the number of fibers that twitch
   - doesn’t change the intensity of a single twitch
   - single twitch is all or none

Question 14

Tetanus

Answer 14

constant contractions
- greater max force

Question 15

Smooth muscle

Answer 15

involuntary, no striations (stripes)
- slow, low intensity contractions (wave)

Question 16

Cardiac muscle

Answer 16

involuntary, striated, light fatigue

Question 17

Skeletal muscle

Answer 17

voluntary, striated

Question 18

Oxidative fibers

Answer 18

fatigue slowly, less forceful, lots of mitochondria and myoglobin (reddish tint)

Question 19

Glycolytic

Answer 19

fast response, forceful contractions, fatigue more quickly
- less mitochondria and myoglobin (paler appearance)

Question 20

Postural muscles of back

Answer 20

Almost all oxidative fibers

Question 21

Biceps

Answer 21

mix of oxidative and glycolytic fibers
- fatigue very fast (glycolytic fibers)

Question 22

Breakdown of muscle?

Answer 22

Whole muscle
|
Bundles of muscle fiber
|
Individual muscle fiber (individual multinucleated cell (very long))
|
Myobril - bundle of myofilaments
|
Myofilaments - actin (thin) + myosin (thick)

Question 23

Motor endplate

Answer 23

motor neuron connected to muscle cells

Question 24

How are myosin and actin in relaxed state?

Answer 24

myosin and actin are long

Question 25

How are myosin and actin in contracted state?

Answer 25

Myosin and actic remain the same length but have more overlap, appearing shorter
- sacromere is shorter

Question 26

Muscle contraction

Answer 26

sources of energy - ATP, creatine phosphate, glucose, glycogen (1st - muscle, 2nd - liver), (fat)

Question 27

steps to muscle contraction?

Answer 27

1. Action potential travels down a motor neuron
2. Neurotransmitter (acetycholine) crosses the synaptic gap from the motor neuron toward the muscle cell
3. the muscle cell depolarizes, creating an action potential within the muscle cell
4. the action potential within the muscle cell causes Ca++ (calcium) to be released from the saracoplasmic reticulum
5. Ca++ binds to the actin-troponin-tropomyosin complex, allowing myosin to form cross-bridges to actin
6. Using energy from the conversion of ATP to ADP, myosin binds to actin in a high energy configuration
7. Myosin relaxes to its low-energy configuration, sliding the actin filament past it, shortening the sarcomere
8. Myosin reattaches to actin further along the actin filament, and the process starts over (steps 6 and 7)
9. When nervous stimulation stops, muscle contraction stops, and calcium is pumped back into saracoplasmic reticululm

Question 28

How much ATP does 1 molecule of glucose with oxygen provide (aerobic)?

Answer 28

34 ATP

Question 29

How much ATP does 1 molecule of glucose WITHOUT oxygen provide (anaerobic)?

Answer 29

2 ATP (less than aerobic)

Question 30

How to sustain contractions?

Answer 30

Need oxygen to generate ATP from glucose, myoglobin, and mitochondria

Question 31

Athletic training

Answer 31

Aerobic (stamina)
- make fibers more oxidative-like
- more mitochondria
- more myoglobin
- greater blood supply to muscle

Question 32

Strength

Answer 32

• thicker muscle fiber (requieres protein for more actin and myosin)
• (little increase in # of muscle fibers)
• more dense bones