Exercise Physiology Chapter 1


Terms in this set (...)

A thin protein filament that acts with myosin filaments to produce muscle action
A rapid and substantial depolarization of the membrane of a neuron or muscle cell that is conducted through the cell
Action potential
An enzyme that splits the last phosphate group off ATP, releasing a large amount of energy and reducing the ATP to ADP and P
Adenosine Triphosphatase (ATPase)
A high energy phosphate compound from which the body derives its energy
Adenosine Triphosphate (ATP)
a motor neuron innervating extrafusal skeletal muscle fibers
α-motor neuron
Muscle Shortening
Concentric Contraction
Any muscle action that produces joint movement
Dynamic Contraction
Any muscle action in which the muscle lengthens
Eccentric Contraction
A sheath of connective tissue that covers each muscle fiber
The outer connective tissue that surrounds an entire muscle, holding it together
A small bundle of muscle fibers wrapped in a connective tissue sheath within a muscle
A type of muscle fiber with a low- oxidative capacity and a high glycolytic capacity; associated with speed or power activity
Fast Twitch (Type-II) fiber
The motor nerve and the group of muscle fibers it innervates
Motor Unit
An individual muscle cell
Muscle Fiber
The contractile element of skeletal muscle
one of the proteins that form filaments that produce muscle action
the protruding part of myosin filament. It includes the myosin head, which binds to an active site on an actin filament to produce a power stroke that causes the filaments to slide across each other
Myosin Cross Bridge
A giant protein that coextends with actin and appears to play a regulatory role in mediating actin and myosin interactions
The connective tissue sheath surrounding each muscle fascisulus
Plasma membrane, the selectively permeable lipid bilayer coated by proteins that composes the outer layer of a cell
The tilting of the myosin head, caused by a strong intermolecular attraction between the myosin cross-bridge and the myosin head, that causes the actin and myosin filaments to slide across each other
Power Stroke
The theory that motor units generally are activated on the basis of a fixed order of recruitment, in which the motor units within a given muscle appear to be ranked according to the size of the motor neuron
Principle of Orderly Recruitment
Refers to the frequency of impluses sent to a muscl. Increased force can be generated through increase in either the number of muscle fibers recruited or the rate at which the impluses are sent.
Rate Coding
A muscle fiber's cell membrane
The basic functional unit of a myrofibril
The gelatin-like cytoplasm in a muscle fiber
A longitudinal system of tubules that is associated with the myofibrils and that stores calcium for muscle action
Sarcoplasmic Reticulum (SR)
Immature cells that can develop into mature cell types, such as myoblasts
Satellite Cells
The speed of action associated with one muscle fiber
Single- fiber Contractile Velocity (Vo)
Principle asserting that the size of the motor neuron dictates the order of motor unit recruitment, with small-sized motor neurons being recruited first
Size Principle
A theory explaining muscle action: A myosin cross-bridge attaches to an actin filament, and then the power stroke drags the two filaments past one another
Sliding Filament Theory
A type of muscle fiber that has a high oxidative and a low glycolytic capacity, associated with endurance-type activities
Slow-Twitch (Type I) fiber
Action in which the muscle contracts without moving, generating force while its length remains static (unchanged).
Static (isometric) contraction
The summing of all individual changes in a neuron's membrane potential
Highest tension developed by a muscle in response to stimulation of increasing frequency
A protein that positions the myosin filament to maintain equal spacing between actin filaments
Extensions of the sarcolemma (plasma membrane) that pass laterally through the muscle fiber, allowing nutrients to be transported and nerve impulses to be transmitted rapidly to individual myofibrils
Transverse Tubules (T-tubules)
A tube-shaped protein that twists around actin strands, fitting into the groove between them
A complex protein attached at regular intervals to actin strands and tropomyosin
the smallest contractile response of a muslce fiber or a motor unit to a single electrical stimulus