The following factors affect excitability and contractility and therefore alter in various ways, the nature of the simple muscle curve: Factor # 1. Strength and Duration of Stimuli: For stimulation to occur, two factors are necessary—a minimum strength and an adequate duration of the stimulus. Chronaxie, which includes both these factors is the measure of excitability of a tissue. Factor [...]
Following chemical changes take place during contraction in the anaerobic and aerobic phases in human body. 1. Glycolysis and Oxidative Breakdown: This process involves many separate enzymes and different intermediates. The end products are pyruvic or lactic acid. The first step in the liberation of energy for contraction is the breakdown of glycogen in the muscle fibre. The glycogen reacts [...]
The following changes are found to accompany any muscular contraction: 1. Mechanical Changes 2. Thermal Changes 3. Electrical Changes. 1. Mechanical Changes: During, contraction, the muscle fibre shortens in length, increases in thickness, but the total volume remains same (or slightly increases). The muscular contraction may be isometric when the length of the muscle fibres remains constant but the tension [...]