| ACTIN |
One of the two main contractile proteins in a muscle fiber. |
| ADENOSINE TRIPHOSPHATASE (ATPase) |
The enzyme involved in the splitting of ATP and the release of energy. |
| ADENOSINE TRIPHOSPHATE (ATP) |
A chemical compound that breaks down to release the energy responsible for muscle contraction. |
| ATROPHY | A decrease in the overall size of an organic tissue. |
| BLOOD PRESSURE |
The pressure of the blood in the blood vessels; usually refering to arterial blood pressure divided into diastolic (the pressure when the heart is at rest between beats) and systolic
(the pressure when the heart is contracting). |
| CENTRAL NERVOUS SYSTEM |
The brain and spinal cord. |
| CONCENTRIC |
A contraction that involves the shortening of a muscle. |
| CONNECTIVE TISSUE |
The supporting and connecting structures of the body. |
| CROSS BRIDGE |
Projections of myosin (protein) that form links with actin filaments (protein) and pull them forward causing a contraction. |
| ECCENTRIC |
A contraction that involves the lengthening of a muscle. |
| FATIGUE |
A generalized or specific feeling of tiredness that may have a multitude of causes both mental and physical. |
| HYPERTROPHY |
An increase in the overall size of a tissue. |
| ISOMETRIC |
A contraction in which muscle tension increases, but the muscle does not shorten because it does not overcome the resistance. |
| ISOTONIC |
A contraction in which muscle tension increases, and the muscle shortens (sliding filament theory) as it overcomes the resistance. |
| MYOFIBRIL |
One of many fibrils consisting mainly of protein that filla muscle fiber. |
| MYOSIN |
One of the two main contractile proteins in a muscle fiber. |
| NEUROTRANSMITTER |
A chemical that spills across the synoptic gap between neurons, transmitting an electrical impulse. |
| PROTEIN |
Any one of a group of complex organic compounds containing nitrogen; formed from various combinations of amino acids. |
| RESISTANCE |
Any opposing force (mass, air pressure, ect.) which causes a muscle to tense or shorten in an effort to overcome it. |
| SKELETAL MUSCLE |
The most prevalent type of muscle in the body; usually anchored to bone to carry out voluntary movement. |
| SLIDING FILAMENT THEORY |
The leading theory of muscle contraction holding that protein filaments in muscle fibers slide past each other when a muscle contracts. |
| STAIRCASE EFFECT |
A condition in which a succession of individual muscle twitches produce greater and greater degrees of contraction. |
| TROPOMYOSIN |
A long thread like protein that circles actin filaments and covers binding sites receptive to myosin cross bridges. |
| TROPONIN |
A protein that works with calcium when muscle fiber is stimulated, helping to set the contractile mechanism into action. |
| TWITCH |
A simple muscle contraction lasting only a fraction of a second. |
IMPORTANT BIOFITNESS WORD DEFINITIONS