Chapter 1 pt. 2 Flashcards
Does a muscle contraction require energy?
Yes
How is energy created for a muscle contraction?
ATPase, located on the myosin head, splits the ATP to yield ADP, inorganic phosphate (Pi), and energy
What does the energy in a muscle contraction do?
It powers the tilting of the myosin head
How is energy required for muscle relaxation?
Calcium is returned to the sarcoplasmic reticulum by an active calcium pumping system that requires ATP
What happens after calcium is pumped back into the SR for muscle relaxation?
Troponin and tropomyosin return to the resting conformation by covering the active sites
What are type 1 muscle fibers?
Slow twitch fibers
What are type b/x muscle fibers?
Fast twitch fibers
How long does it take type 1 fibers to reach peak tension when stimulated?
110 ms
How long does it take type b/x fibers to reach peak tension when stimulated?
50 ms
What muscle fibers make up 50% of muscles
Type 1
What muscle fibers make up 25% of muscles?
Type 2a and 2x
What muscle fibers make up 1-3% of muscles?
Type 2c
How are muscle fiber types analyzed?
Muscle biopsy
What is the function of muscle biopsy?
allows us to study muscle fibers and gauge the effects of acute exercises and chronic training on fiber composition
What muscle fiber has a slow form of myosin ATPase?
Type 1
What muscle fiber has a fast form of myosin ATPase?
Type 2
What is gel electrophoresis?
A method for identifying fiber types by chemically separating the different types of myosin molecules
Which muscle fiber has a more developed sarcoplasmic reticulum?
Type 2
What determines whether a muscle fiber is type 1 or type 2?
The a-motor neuron
How many muscle fibers does an a-motor neuron innervate in type 1 motor units?
less than or equal to a cluster of 300 muscle fibers
How many muscle fibers does an a-motor neuron innervate in type 2 motor units?
more than or equal to 300 muscle fibers
All muscle fibers reach peak at?
20% peak force
What muscle has a very high percentage of type 1 fibers in everyone?
The soleus muscle (behind the gastrocnemius in the calf)
What type of muscle fiber has a high level of aerobic endurance?
Type 1
Type 1 fibers are efficient at producing ATP from the oxidation of?
Carbohydrates and fats
Aerobic means?
presence of oxygen
What type of muscle fiber performs better anaerobically?
Type 2
Anaerobic means?
Without oxygen
What type of muscle fiber fatigues the easiest and has limited endurance?
Type 2a
Which type 2 fiber is used in shorter, higher-intensity endurance events like mile run or 400m swim?
Type 2a
Which type 2 fiber is used in highly explosive events like the 100m dash or 50m sprint swim?
Type 2b
What determines our individual muscle fibers?
The a-motor neuron
How are muscle fibers differentiated?
Based on their neuron
Endurance and resistance training reduce the percentage of what type of muscle fiber?
Type 2b
Endurance and resistance training increases a fraction of what type of muscle fiber?
Type 2a
As we grow older we tend to lose what type of muscle fibers?
Type 2
What is the order recruitment of motor units?
Type 1, type 2a, type 2b
What is the principle of orderly recruitment?
The ranking of motor units in a given muscle
What type of muscle fiber has less force production?
Type 1
What type of muscle fiber has more force production?
Type 2
What is a static muscle contraction?
A muscle generates force without movement because the joint angle does not change
Concentric means?
Shortening
Eccentric means?
Lengthening
What are considered dynamic contractions?
Concentric and eccentric contractions
What is happening during a concentric contraction?
Thin filaments are pulled toward the center of the sarcomere
What is happening during an eccentric contractions?
Force is exerted when extending the elbow
What is rate coding?
The frequency of stimulation of the motor unit
What are the 3 types of rate coding
Twitch, summation, tetanus
What are the 4 things that generate force?
Motor unit recruitment, rate coding, length-tension relationship, and speed-force relationship
