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a contractile protein

Action Potential

an electrical event occurring when a stimulus of sufficient intensity is applied to a neuron or muscle cell, allowing sodium ions to move into the cell and reverse the polarity.

Aerobic respiration

respiration in which oxygen is consumed and glucose is broken down entirely; water, carbon dioxide, and large amounts of ATP are the final products.


(of a response) having a strength independent of the strength of the stimulus that caused it.

Anaerobic respiration

a form of respiration that does not require oxygen. (using electron acceptors other than oxygen)


muscles that act in opposition to an agonist or prime mover.


fibrous or membranous sheet connecting a muscle and the part it moves.


a reduction in size or wasting away of an organ or cell resulting from disease or lack of use.

Cardiac muscle

specialized muscle of the heart.

Creatine phosphate

high energy molecule C4H10O5N3P, found in muscle fibers but not other cell types. formed by the enzymatic interaction of an organic phosphate and creatine, the breakdown of which provides energy for muscle contraction.


the thin connective tissue surrounding each muscle cell.


the body's ability to continue using muscular strength and endure repeated contractions for an extended period of time, types of exercise, such as participating in an aerobics class, jogging or biking, result in stronger, more flexible muscles with greater resistance to fatigue


the sheath of fibrous connective tissue surrounding a muscle.


a bundle of nerve or muscle fibers bound together by connective tissue.


muscles acting to immobilize a joint or a bone; fixes the origin of a muscle so that muscle action can be exerted at the insertion.


soft; flabby; relaxed.


the movable attachment of a muscle as opposed to its origin.

Involuntary Muscle

smooth muscle, a muscle that contracts without conscious control and found in walls of internal organs such as stomach and intestine and bladder and blood vessels (excluding the heart)

Isometric contraction

contractions of the same length.

Motor Unit

a motor neuron and all the muscle cells it supplies.

Muscle Fiber

muscle cells.

Muscle tone

sustained partial contraction of a muscle in response to stretch receptor inputs; keeps the muscle healthy and ready to react.

Muscle twitch

a single rapid contraction of a muscle followed by relaxation.


one of the principal contractile proteins found in muscle.

Neuromuscular junction

: the region where a motor neuron comes into close contact with a skeletal muscle cell.


chemical released by neurons that may, upon binding to receptors of neurons or effector cells, stimulate or inhibit them.


attachment of a muscle that remains relatively fixed during muscular contraction.

Oxygen deficit

the volume of oxygen required after exercise to oxidize the lactic acid formed during exercise.


the connective tissue enveloping bundles of muscle fibers.

Prime mover

muscle whose contractions are primarily responsible for a particular movement; agonist.


the fine transparent tubular sheath that envelops the fibers of skeletal muscles.


the smallest contractile unit of muscle; extends from one Z disc to the next.

Skeletal muscle

muscle composed of cylindrical multinucleate cells with obvious striations

Smooth Muscle

muscle consisting of spindle-shaped, unstriped (nonstriated) muscle cells; involuntary muscle.

Synaptic cleft

the fluid-filled space at a synapse between neurons.


muscles cooperating with another muscle or muscle group to produce a desired movement.


a cord of dense fibrous tissue attaching a muscle to a bone.


the tense, contracted state of a muscle

voluntary muscle

muscle under control of the will; skeletal muscle


to move away from the midline of the body.


Movement of a body part toward the median plane


up and down movement that includes lifting the foot so that its superior surface approaches the shin (standing on your heels).


special movement of the foot achieved by turning the sole laterally.


occurs when a single chromosome undergoes breakage and rearrangement within itself


bending; the movement that decreases the angle between bones.

Plantar flexion

bending the foot or toes toward the plantar surface


the inward rotation of the forearm causing the radius to cross diagonally over the ulna


The act or process of turning around a center or an axis


the outward rotation of the forearm causing palms to face anteriorly.


circular movement of a body part.



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