Ch. 11 - Muscle Physiology

Question 1

In a muscle cell, what is the network of channels extending throughout the sarcoplasm that stores Ca2+?

Answer 1

Sarcoplasmic Retiuclum

Question 2

What is the major structural unit of skeletal muscle?

Answer 2

Myofibril

Question 3

What do thick and thin filaments contain?

Answer 3

• Thick
  
  • Myosin
• Thin
  
  • Actin, troponin, tropomyosin

Question 4

How many T-tubules lie within a single sarcomere?

Answer 4

2

Question 5

What cells are responsible for skeletal muscle regeneration?

Answer 5

Satellite Cells

Question 6

Which parts of the sarcomere get shorter during contraction?

Answer 6

H and I bands

Question 7

What part of the sarcomere is the dark band and the light band?

Answer 7

dArk band = A band

LIght band = I band

Question 8

What are the 3 layers of connective tissue surrounding muscles?

Answer 8

1. Epimysium - surrounds entire muscle
2. Perimysium - surrounds muscle bundles
3. Endomysium - surrounds each muscle fiber

Question 9

What does each motor unit contain?

Answer 9

• Alpha-motor neuron
• Synaptic cleft
• Associated muscle fibers

Question 10

Where are the sources for ATP for muscle contraction?

Answer 10

• Glycogen stores –> Glycolysis
• TCA cycle –> oxidative phosphorylation
• Creatine Phosphate

Question 11

How do you remember the difference between type 1 and type 2 twitch speed?

Answer 11

• Type 1
  
  • 1 slow fat red ox
  • slow, lipid accumulation, red fibers, oxidative phosphorylation
• Type 2
  
  • 2 fast skinny white chickens
  • fast, low lipid accumulation, white fibers

Question 12

What are extrafusal and intrafusal fibers innervated by?

Answer 12

• Extrafusal - alpha-motor neurons
• Intrafusal - gamma-motor neurons

Question 13

What type of muscle fibers are the largest and fastest?

Answer 13

Type 1a fibers

Question 14

What type of fibers are non-adaptive?

Answer 14

Type 2 fibers - flower-spray endings

Question 15

Tell what reflex type and receptor for each of the following sensitivies:

• Change in length
• Change in tension
• Change in temperature

Answer 15

• ∆ in length - stretch, muscle spindle
• ∆ in tension - tendon, Golgi tendon organ
• ∆ in temp - nociceptor, flexor-withdrawal

Question 16

What does cardiac muscle behave as?

Answer 16

A functional synctium

Question 17

How are cardiac muscle fibers linked together?

Answer 17

By desmosomes

Question 18

What part of cardiac muscle coordinate the action of cardiac mucle cells?

Answer 18

Intercalated discs

Question 19

What is known as the pacemaker of the heart?

Answer 19

Sinuatrial (SA) node

Question 20

How is smooth muscle contraction stimulated?

Answer 20

• Autonomic nervous system (SNS, PNS)
• Hormones (epinephrine, oxytocin)

Question 21

What is the main process by which smooth muscle contracts

Answer 21

• Ca2+ enters cell and binds to calmodulin, which activated myosin light-chain kinase