Muscle Physiology pt 3 Flashcards
Power movements are done with ____ attached to the muscle fibers
Precise movements are done with ____ attached to the muscle fibers
Large Motor Unit
Small Motor Unit
____: simplest contraction resulting from a muscle fibers response to a single action potential from a motor neuron.
Response of a muscle to a single threshold stimulus
Could be strong or weak depending on the number of motor units activated
_____ A graphic recording of mechanical contractile activity
____ Line recording contraction activity
Muscle Twitch
Myogram
Tracing
Three phases of Muscle Twitch:
- _____ events of the Excitation-contraction coupling, the time between stimulus and start of contraction. NO muscle tension
- _____ Cross bridge formation
Tension increases (10-100 ms) - ____ Initiated by Ca2+ reentry into SR, actin slides back into place
Tension declines to Zero
- Latent period
- Period of Contraction
- Period of relaxation
Muscle Contraction Timing:
Action potential / latent period
CONTRACTILE RESPONSE:
After excitation:
Muscle relaxation:
Action potential / latent period (1-2 msec)
CONTRACTILE RESPONSE:
After excitation: (15-50 msec)
Muscle relaxation ( Additional 15-50 msec)
____ (variations in the degree of muscle contraction)
Strength varies with needs or different demands
Required for proper control of skeletal movement
Responses are graded by:
____ & ____ of Neural Stimulation
Graded Muscle Responses
Frequency and Strength of Neural Stimulation
Graded Muscle Responses:
_____ results in single contractile response (muscle twitch)
Stimulated after completely relaxed
_____ results if TWO identical stimuli are received by a muscle in rapid succession
Stimulated NOT completely relaxed
____ (unfused) Frequency of stimulation only allows incomplete relaxation
____ (Fused) Frequency of stimulation allows no relaxation
(____ = ATP deficient)
Single stimulus
Wave (temporal) summation
Incomplete tetanus
Complete Tetanus
Muscle fatigue
Muscle fibers can respons to repeated stimuli before they are fully relaxed, this is called ____
Twitch Summation
_____ Caused by a muscle fiber at max stimulation with no relacation that causes MAXIMAL CONTRACTION
It will last until muscle becomes fatigued
Tetanus
____ (Multiple motor unit summation) Stimulus sent to more muscle fibers leading to more precise control or increased strength of contractions
Types of stimulus involved
_____ stimulus not strong enough so no contractions are seen
____ stimulus are strong enough to cause first observable force. The minimal strength needed tos tart a contraction
____ strongest stimulus that increases maximum contractile force
Recruitment
Subthreshold stimulus
Threshold stimulus
Maximal stimulus
Motor unit 1 recruits ___
Motor unit 2 recruits ____
Motor unit 3 recruits ____
Recruited small fibers
Recruited Medium Fibers
Recruited Large Fibers
The strenght of a muscle contraction is determined by the ___ and number of ___ rectuited to perform a task
HOWEVER ___ are ____
Size and number of motor units
Motor units are all-or-none
Factors affecting muscle tension: (3)
Motor unit recruitment
Size of the muscle
Muscle twitch summation
Smallest subset ot muscle fibers is called a:
It is one motor neuron and all the muscle fibers it innervates
Motor unit
Motor Unit Recruitment
_____: Some muscle fibers are always active to maintain muscles even with no movement is taking place
_____: Activation of more motor units to increase tension in the muscle as the load increases, more force is needed
Baseline muscle tone
Motor Unit Recruitment
_____
Number of muscle fibers per motor unit
Fibers produce more ___ in response to demands placed on them (ex. athletic training)
Fibers ____ when not used
Size of muscle
Myofilaments
Hypertrophy
