Physiology Quiz 3 (2/2) Flashcards
Motor unit
A single motor efferent nerve and the muscle cells it innervates
Efferent
Carry info away from CNS
Small motor units = _______ motor activity
Fine
Large motor units= ______ motor activity
Gross
What part of the body has the smallest motor units?
Muscles controlling the eye (4 muscle cells/1 motor efferent)
What part of the body has the largest motor units?
Some of he trunk musculature (1000 muscle cells/1 motor efferent)
Concentric muscle activity
Development of force by the muscle as it shortens
Example of concentric muscle activity
Bringing the weight up during a bicep curl
Eccentric muscle activity
Development of force by the muscle as it lengthens
Example of eccentric muscle activity
Lowering the weight during a bicep curl
What type of muscle activity uses more energy? (Concentric or eccentric)
Concentric
Which type of muscle activity is easier to learn motor control of? (Concentric or eccentric)
Concentric
DOMS
Delayed onset muscle soreness
When does DOMS peak?
48-72 hours after activity
What is DOMS caused by?
Repair of microtears in series elastic element (SEE) mostly caused by eccentric activity (less often with concentric). This microtearing causes inflammation, swelling, pain, and scarring
Elasticity
Shortens and returns to original configuration
Plasticity
Stretches, but it will reach a certain point where it will not return to original configuration
Plasticity range
Point a series elastic element stretches to where it will still return to original configuration; any further and it will not return to original configuration
Is plasticity good?
Yes, it can help with flexibility
Series elastic element
Structures that have the property of elasticity
- tendons
- connective tissue sheaths or muscle and myofibrils
- crossbridges
How is force transmitted in concentric activity?
It will absorb some force and transmit the rest (think about rubber band pulling water bottle water bottle)
How force is transmitted during eccentric activity
Develops force because it is undergoing a stretch force and thereby adds to the force developed eccentrically
Source of force in concentric activity
Crossbridges
Source of force in eccentric activity
Crossbridge activity SEE recoil (mostly this one)
Which type of muscle activity uses less energy (eccentric or concentric)
Eccentric
Unorganized scar
Random laying down of collagen fibrils as a scar forms
Decreases ROM
not desirable
Organized scar
Laying down of collagen fibrils in an organized and controlled manner
Less loss of ROM
Stretching helps develop this
Isometric contraction
As muscle develops force, distance between origin and insertion does not change (fibers still shorten)
Example of isometric contraction
Wall sit
Isotonic contraction
Muscle changing length but maintaining same force throughout movement
Isokinetic contraction
No change in velocity of movement
Likely to see change in length and force as contraction proceeds
Done on machine with a set degrees/sec
