BIOL 1117 Lecture Notes - Cardiac Muscle, Joint Stability, Phosphagen
7 Feb 2014
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Document Summary
Isometric and isotonic contractions: isometric muscle contraction. This is contraction without a change in length. Contractions do not always lead to a shortening of a muscle; the muscle only develops internal tension. Two opposite but equal tension forces opposite each other. Each opposing muscle rebuilds up new tension in equal opposition to the other; thus, length of each muscle stays the same isometric contraction of postural muscles keeps the body erect against force of gravity. In each opposing muscle, cycling cross bridges rebind to same actin molecules with a new force generated repeatedly. Also, carrying an object in front of you is isometric for downward force of load is opposed by equal upward force of muscle tension: isotonic muscle contraction. Isometric and isotonic phases of contraction: at the beginning of contraction: isometric phase. Immediate energy needs: short, intense exercise oxygen need is briefly supplied by myoglobin for a limited amount of aerobic respiration at onset rapidly depleted.
