Synapse between a motor neuron and a muscle fiber.
What is the neuromuscular junction?
100
Plasma membrane of a muscle fiber.
What is the sarcolemma?
100
Motor neuron and all (4 to several hundred) muscle fibers it supplies.
What is a motor unit?
100
Neurotransmitter. Chemical transmitter substance released by some nerve endings. Exocytosed into synaptic cleft. Binds to chemically (ligand) gated ion channels.
What is acetylcholine (ACh)?
100
Middle area in the sarcomere where thick and thin filaments are found.
What is the A band?
200
The difference in electrical charge across the membrane: The inside of the cell is more negative compared to the outside of the cell. The Na+/K+ pump works to maintain or correct it.
What is the resting membrane potential (RMP)?
200
Ca2+ -storing tubular system similar to smooth endoplasmic reticulum.
What is the sarcoplasmic reticulum?
200
Contraction in which the muscle shortens.
What is concentric isotonic contraction?
200
Globular 3-polypeptide complex (one binds to actin, one binds to tropomyosin, one binds to Ca2+)
What is troponin?
200
Area in the sarcomere where only thin filaments are present but thick filaments are not.
What is the I band?
300
Loss of a state of polarity; loss or reduction of negative membrane potential
What is depolarization?
300
Contracting unit of a skeletal muscle fiber.
What is a sarcomere?
300
Contraction in which muscle tension is generated without shortening of the muscle.
What is isometric contraction.
300
Enzyme present at the neuromuscular junction synapses that degrades acetylcholine and terminates its action.
What is acetylcholinesterase (AChE)?
300
Separates the sarcomeres from each other.
What is the Z disc?
400
Depolarization (as a "local" event) - initial depolarization in sarcolemma.
What is end plate potential?
400
Cytoplasm of a muscle fiber.
What is the sarcoplasm?
400
Contraction in which a muscle lengthens.
What is eccentric isotonic contraction?
400
Rod shaped protein, spiral about actin core - helps stiffen and stabilize it. In relaxed muscle it blocks myosin binding sites.
What is tropomyosin?
400
Area of only thick filaments.
What is the H zone?
500
A large transient depolarization event, including polarity reversal, that is conducted along the membrane of a muscle cell or a nerve fiber.
What is an action potential?
500
Invaginations of the sarcolemma from the surface toward the center of the muscle fiber.
What are transverse tubules?
500
Varying strength of contraction for different demands.
What is a graded muscle response?
500
An enzyme that pumps sodium out of cells, while pumping potassium into cells. It has antiporter-like activity but is not actually an anti-porter since both molecules are moving against their concentration gradient.
What is a Na+/K+ pump?
500
Composed of supporting proteins holding thick filaments together at the H zone.