Muscle Structure
The two kinds of protein filaments that produce the striations in muscles.
Actin and myosin
The idea that actin and myosin move over each other to shorten a muscle
Sliding filament theory
What does myosin do with ATP?
Breaks it down into ADP and P. It uses this energy for the next power stroke.
The motor neuron and the muscle fibers that it controls
Motor unit
When a muscle loses its ability to contract after prolonged use
What is muscle fatigue
Connective tissue that surrounds fascicles
Perimysium
What causes actin and myosin to detach?
ATP
What happens when ACh binds with receptors on the sarcolemma?
An influx of Na+ (depolarization). If the stimulus reaches threshold it can cause an AP.
Specialized portion of muscle fiber membrane at a neuromuscular junction
What is motor end plate
Myofibrils are divided into _______
Sarcomeres
The segment of a myofibril that extends from Z line to Z line
Sarcomere
Why is the sarcoplasmic reticulum important?
It releases calcium. Calcium binds to troponin, which uncovers the myosin-binding sites on actin.
Troponin and tropomyosin
Neurotransmitter that must be present to stimulate a muscle fiber.
Acetylcholine
Define a twitch.
A muscle fiber's response to a single AP from a motor neuron
These make up a muscle fiber
Myofibrils
The delay between when a muscle is stimulated and the time it responds
Latent period
Explain the power stroke in the cross bridge cycle?
Myosin heads pull thin filaments toward the M line (sarcomeres shorten)
Decomposes acetylcholine
Acetylcholinesterase
Differentiate between isotonic and isometric contractions.
Isotonic - muscle shortens and exceeds load Isometric - no shortening
The section of a muscle fiber that is made up only of actin
I band
How does an AP propagate from the sarcolemma to deep inside the cell
T-tubules
Connective tissue that wraps around muscle fibers?
Endomysium
Increasing the number of motor units being activated
Recruitment
Explain events that must occur for the muscle to relax