In: Anatomy and Physiology
1. Describe differences between peripheral and central fatigue (6 marks = 3 differences for each)
2. Describe the difference between high frequency and low-frequency fatigue ?(6 marks = 3 differences for each)
3. Describe the role of inorganic phosphate in muscle fatigue
1.Difference between peripheral and central fatigue
Peripheral fatigue
Central fatigue
2.Differences between high frequency and low frequency fatigue
High frequency fatigue
Low frequency fatigue
3.Role of inorganic phosphate in muscle fatigue
Inorganic phosphate(Pi) which is a breakdown product of creatine phosphate has an important role in the development of muscle fatigue. When the muscle is being contracted for a long time, there will be ATP depletion. It causes the cell to do anaerobic respiration and it causes lactic acidosis which is one cause of muscle fatigue.Other than acidosis, anaerobic metabolism in the skeletal muscle also causes creatine phosphate to break down into creatine and inorganic phosphate.
It enters the sarcoplasmic reticulum of the muscle fibre and precipitates with Ca2+ ions inside the SR. This decreases the availability of free SR which should be released for muscle contraction. Also, when Pi increases, it will inhibit the ATP-driven Ca2+ uptake into sarcoplasmic reticulum.
Increased Pi also affect the force of actin-myosin crossbridges. Fewer cross-bridges will be in high-force states and force production decreases when Pi increases during muscle fatigue.