Muscular system

Question 1

Entire muscle

Answer 1

Wrapped in epimysium
Runs from origin to insertion

Question 2

Fascicles

Answer 2

Bundles of fibers
Wrapped in perimysium

Question 3

Muscle fibers

Answer 3

Individual muscle cells
Wrapped in endomysium

Question 4

myoblast

Answer 4

creates muscle cells

Question 5

Sarcolemma

Answer 5

Plasma membrane of muscle
T-tubules that extend deep into cell

Question 6

Sarcoplasm

Answer 6

typical organelles + contractile proteins

Question 7

Terminal cisternae

Answer 7

large chambers in the SR that store calcium ions and release them to cause muscle contraction

Question 8

Sarcomere

Answer 8

basic unit of contractile muscle, composed of protein filaments actin and myosin

Question 9

Myofilaments

Answer 9

Contractile proteins within myofibrils

Question 10

actin

Answer 10

myosin binding sites; thin filaments

Question 11

I band

Answer 11

Light regions of actin

Question 12

A band

Answer 12

Dark regions of myosin

Question 13

Z discs

Answer 13

Hold sarcomeres together

Question 14

Neuromuscular Junction

Answer 14

a synaptic connection between the terminal end of a motor nerve and a muscle. It is the site for the transmission of action potential from nerve to the muscle.

Question 15

resting membrane potential

Answer 15

-90mV
ECF positively charged, ICF negatively charged maintained by sodium-potassium pumps

Question 16

Neural Control of Skeletal Muscle

Answer 16

-Neuron fires
-Calcium channels on synaptic knob open
-Influx of calcium causes Ach to be released
-ACh diffuses across synaptic cleft
-ACh binds to receptors at motor end plate of sarcolemma

Question 17

Depolarization

Answer 17

Sodium rushes into the muscle cell
-Depolarization
-ICF becomes less negative (≤+30mV)

Question 18

Excitation-Contraction Coupling

Answer 18

Action potential reaches triad
calcium channel opens into SR
Calcium-release channels open, releasing it from the SR
Calcium floods sarcomeres

Question 19

Sarcomere Crossbridge Cycling

Answer 19

1. Crossbridge formation
2. Power stroke
3. Release
4. Reset
5. Cycling continues if calcium and ATP are available

Question 20

Repolarization

Answer 20

Sodium gates close
Potassium gates open (potassium rushes out of cell)
returns to -90mV

Question 21

Skeletal muscle contraction order

Answer 21

resting
motor neuron fires and releases ACh
ACh triggers motor end plate of sarcolemma
Depolarization
Excitation-contraction Coupling
Crossbridge cycling
Repolarization
Refractory period

Question 22

Skeletal Muscle Relaxation

Answer 22

1. Termination of nerve signal and ACh release; hydrolysis of residual ACh by acetylcholinesterase.
2. ACh receptors close; cessation of motor end plate potential.
3. No further action potential generated.
4. Closure of SR calcium channels and calcium release channels.
5. Return of calcium to SR via pumps.
6. Return of troponin and tropomyosin to original position, blocking actin’s binding sites.
7. Return of muscle to original length.

Question 23

Creatine phosphate

Answer 23

Phosphate group is transferred to ADP to form ATP
Anaerobic, occurs in cytosol

Question 24

Glycolysis

Answer 24

Glucose converted to 2 ATP molecules
Anaerobic, occurs in cytosol

Question 25

Aerobic cellular respiration

Answer 25

Requires oxygen
Occurs in mitochondria
Yields 32 ATP molecules
Glucose preferred fuel; triglycerides can also be used
Slower than glycolysis; yields far more ATP

Question 26

Creatine Phosphate System

Answer 26

Transfers high-energy phosphate from creatine phosphate to
adenosine diphosphate (ADP) to regenerate ATP

Question 27

Glycolysis

Answer 27

Breakdown of glucose by enzymes, releasing energy and pyruvic acid
Anaerobic
Fast; yields 2 ATP molecules/glucose molecule

Question 28

Aerobic Respiration

Answer 28

Slower; yields 32 ATP molecules/glucose molecule