Muscle metabolism Sarcoplasm contains creatine kinase and also myosin kinase. ADP degraded to AMP and ATP. AMP produced is degraded to IMP – inositol monophosphate by adenylic deaminase, which again converted to uric acid and excreted. Hydrolysis of ATP produces 7.3 kcal/mol. ATP + H2O → ADP + H3PO4 + 7.3 Kcal Metabolism of glucose […]
Thermal changes during muscle contraction Out of total energy liberated by the hydrolysis of ATP in a contracting muscle, only 40-45% can be converted into work energy and the rest is evolved as heat; i.e. the efficiency of muscle contraction is about 45%. It is recorded by using thermopile. Thermopile has plates of antimony and bismuth
Rigor mortis in muscles Process that causes the muscles in the body to stiffen resulting in rigidity due to a range of chemical changes in the muscle structure. Rigor mortis starts in the 2nd hour and is completed in 3 hrs after death. Rigor mortis disappears 24 – 36 hrs after death due to autolysis. Deficiency
Muscle fatigue Muscle Fatigue is the decrease in the working capacity of a muscle or tiredness of the muscle when it is continuously stimulated. It is characterized by diminished force of contraction, increased latent period and contraction period and prolonged relaxation period. The relaxation is incomplete i.e., the muscle is in a state of contracture‚
Factors influencing the strength of contraction in muscles Starling’s law The first factor is governed by the strength of stimulus. The second is mostly by the rate of effective stimuli. The last is by the initial length of the muscle fiber. In cardiac muscle, mechanical summation is impossible because of prolonged action potential (250msec.) almost completely overlaps
Factors influencing the strength of contraction in muscles Read More »
Summation of muscle contraction Summation is the added effect of individual muscle twitches to get strong and powerful muscle contraction. Summation occurs in two different ways By increasing the number of motor units to contract simultaneously. By increasing the rapidity of contraction of individual motor unit of a contracting muscle. Multi-motor unit summation (Spatial summation) The strength
Properties of muscle contractions When a muscle fiber is stimulated by minimal or maximal effective stimuli, the whole fiber contracts to the maximum or it will not contract at all. This law is applicable to single motor unit (motor nerve and all the muscle fibers it supplies). Whole cardiac muscle obeys this law because of
Stimulus for muscle and types Stimulus is an external agent, when applied to an excitable tissue provoke a visible response. Types of Stimuli(Based on strength) Sub threshold : sub minimal/ low intensity, unable to produce a response Threshold : minimum intensity, strong enough to initiate an action potential Sub maximal : higher strength than threshold Maximal : highest threshold strength
Sliding mechanism of contraction “Walk- along theory” of contraction (Sliding mechanism of contraction) In the relaxed state, actin filaments lie adjacent and parallel to the myosin filaments. In contracted state, the actin filaments extending from the z-discs are also pulled inward by head portion of the free ends of myosin filaments. Thus, muscle contraction occurs
Muscle contraction Muscle contraction is accomplished by a sliding together or telescoping of the interdigitating thick and thin filaments and as a result narrowing and eventual disappearance of the H zone and shortening of I band happen. Summary of events Before contraction ie in the absence of Ca2+ in the sarcoplasm, troponin T strongly binds with
