Skeletal Muscle Physiology (Smith) Week 3 Flashcards Preview

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Flashcards in Skeletal Muscle Physiology (Smith) Week 3 Deck (17):

List the steps of skeletal muscle contraction (know the ORDER)


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List the Steps in the Cross Bridge Cycle

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What are the 3 main energy sources for Muscle Contraction

1. Creatine Phsophate (Anareobic, 1 atp, 15 sec)

2. Glycogenolysis (Anareobic respiration Lactic acid formation) (Glucose 2 ATP, 30 - 60 sec)

3. Cellular Respiration

- Energy: glucose, pyruvic acid, free fatty acids & amino acids - 38 ATP



Isotonic vs. Isometric Contractions

Isotonic: Tension generated by muscle is greater than the load (muscle shortens)

Isometric: The load exceeds the tension (muscle doesnt shorten) 


Explain the different types of muscle twitches and how they relate to Motor Unit Recruitment

Type I: Slow twitch (think marathons)

Type IIa: Fast twitch (think sprinting)

Type IIb: When load becomes even greater these are recruited to further supplement Type I & IIa


What is a Reflex  Arc?

A neural pathway that controls a reflex - Most of the time are INDEPENT of the brain and synapse in the spinal chord.


List the 6 steps of a reflex arch

1. sensory receptor

2. afferent neuron

3. integration center (CNS)

4. Interneuron

5. motor neuron

6. Effector (muscle) 


List and explain the 3 examples of Reflex Arcs

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What do the Muscle spindle and Golgi tendon organ do in respect to a reflex

Muscle spindle - measure muscle length (monosynaptic) 

Golgie tendon organ - Measure muscle tension (disynaptic)


What is "fractionation" 

All motor units in a muscle do not need to activate, however, the more units the larger the force generated by the muscle


The muscle twitch

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What is wave summation

AKA temporal summation

- Increasing the frequency of a stimulus held at a constant intensity


Unfused (incomplete) tetanus

Wave summating at a frewuency sufficient to produce periods of incomplete relaxation between contractions

AKA - Treppe or staircase effect


Define Tetanus

Prolonge contraction WITHOUT relaxation resulting from repeated stiulations so fast the muscle has no ooportunity to relax

- Tetanus is due to the binding sites on actin continually staying exposed



Define Fatigue 

The muscle loses tension despite continuing stimuli


What are the 2 subtypes of muscle fiber?

1. Extrafusal Fibers

- make up bulk of muscle 

- innervated by Alpha motor

- provide the FORCE

2. Intrafusal Fibers

- innervated by gamma motor 

-Form the muscle spindle


What are the 2 subtypes of INTRAfusal fibers

1. Nuclear bag fibers: Nuclei in bag like bundle, detect FAST changes in muscle length

2. Nuclear chain fibers: Nuclei in single row (chain), detect STATIC changes in length & tension