Skeletal Muscle Dynamics Flashcards
Twitch vs. tetanus
Twitch = single impulse Tetanus = maximum force resulting from increased frequency of stimulation
Internal and external elastic elements of muscle?
Internal = titin and nebulin External = tendons and connective tissue
Components of sarcomere (Z-disk, etc)
Z-disk = edges of sarcomere
M line = middle of sarcomere
A- band = length of thick filaments
Molecular mechanism of muscle contraction
ATP binds to myosin
ATP hydrolyzed and myosin moves down actin chain
ADP removed and cycle starts again
Control of muscle contraction
Tropomyosin in the way during relaxed state. Calcium must bind to troponin during contraction, troponin moves tropomyosin out of the way
What is the preload?
The force that sets the initial length of and establishes the degree of crossbridge overlap at the initiation of muscle contraction
What is the afterload?
The force that opposes the muscle’s shortening. The load the muscle is attempting to move
What is a motor unit?
A motor unit consists of a motor neuron and the collection of muscles it innervates
Components of muscle fiber type I
Small size
Slow
Red
Oxidative metabolism
Components of muscle fiber type IIa
Medium size
Intermediate speed
Red
Glycolytic/oxidative metabolism
Components of muscle fiber type II
Large size
Fast
White
Glycolytic metabolism
Fine motor control involves…?
Small muscle cells for control of delicate tasks
Load based control involves…?
Small fatigue resistant muscle fibers recruited first. As load increases, larger muscle fibers added
