SM_224a: Muscle Physiology and Mechanics Flashcards Preview

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Flashcards in SM_224a: Muscle Physiology and Mechanics Deck (21)
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1

Describe the three basic principles of muscle physiology/mechanics

  • Total muscle force at any moment is proportional to the total number of attached crossbridges (only attached crossbridges can generate force)
  • Muscle uses a diverse set of energy substrates for energy needed to power crossbridge interactions and produce force
  • CNS controls muscle force via activation of motor units, not whole muscles or individual muscle fibers

2

Total muscle force at any moment is proportional to the ______

Total muscle force at any moment is proportional to the number of attached crossbridges

3

Muscle uses ____ energy substrates to power crossbridge interactions and produce force

Muscle uses many energy substrates to power crossbridge interactions and produce force

4

CNS controls muscle force via activation of _____

CNS controls muscle force via activation of motor units

 

(not whole muscles or individual muscle fibers)

5

Describe the three main points about muscle physiology/mechanics

  • Muscle has mechanical characteristics (spring-like and viscous-like) that allow it to be a good motor for movement
  • Muscle energy utilization varies with intensity and duration of movement and exercise
  • Motor units within a single muscle form a heterogeneous population, with systematic differences in force output, contraction speed, and fatigue resistance

6

______ and _____ mechanical characteristics of muscle allow it to be a good motor for movement

Spring-like and viscous-like mechanical characteristics of muscle allow it to be a good motor for movement

7

Muscle energy utilization varies with _____ and _____ of movement and exercise

Muscle energy utilization varies with intensity and duration of movement and exercise

8

Motor units within a single muscle form a _____ population, with systematic differences in _____, _____, and _____

Motor units within a single muscle form a heterogeneous population, with systematic differences in force output, contraction speed, and fatigue resistance

9

Ca binds to the ______ complex

Ca binds to the troponin/tropomyosin complex

10

Movement of the _____ causes actin and myosin to slide past each other

Movement of the myosin head causes actin and myosin to slide past each other

11

Myosin is an ____ase

Myosin is an ATPase 

 

(hydrolyzes ATP)

12

____ is the most important regulator of number of attached crossbridges

Ca level is the most important regulator of number of attached crossbridges

13

Describe how the nervous system controls muscle

Nervous system controls muscle at single fiber level

  1. Motor command causes AP in motor neuron
  2. AP travels down the motor neuron to NMJ
  3. NMJ releases ACh
  4. ACh binds to receptor on muscle fiber
  5. AP in muscle fiber travels downt T tubule to sarcomplasmic reticulum
  6. Ca release from sarcoplasmic reticulum
  7. Muscle contracts

14

Mechanical events are _____ than electrical events

Mechanical events are slower than electrical events

 

(muscle fiber AP duration longer than motor neuron AP duration)

15

There is a ____ force the muscle fiber can generate

There is a maximum force the muscle fiber can generate

16

Most important regulator of number of attached crossbridges is _____

Most important regulator of number of attached crossbridges is Ca levels

 

(length of muscle and how fast the muscle moves also regulate number of attached crossbridges)

17

Muscle-tendon unit behaves like a _____

Muscle-tendon unit behaves like a spring

 

(triceps serae is most efficient for locomotion due to tendons, tendons are important for locomotion)

18

Describe energy utilization by muscle fibers

Energy utilization by muscle fibers

  1. ATP used up in a few seconds
  2. Creatine kinase used up within 10 seconds
  3. Anaerobic glycolysis
  4. Aerobic glycolysis: mitochondria generate a lot of energy
  5. Aerobic fat: fat has high energy density

19

Motor unit consists of _____ and _____

Motor unit consists of motor neuron and the muscle fibers it controls

20

Fast motor units fatigue ____

Fast motor units fatigue quickly

21

Slow motor units are used for _____

Slow motor units are used for large scale motions like posture

 

 

(b/c they do not fatigue, always active)

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