ANA300Y1 Lecture Notes - Lecture 5: Myocyte, Skeletal Muscle, Muscle Tone
Document Summary
Motor unit = single motor neurons and all muscle fibres that it innervates. Fibres of muscles units are intermingled; no anatomical subdivisions; more uniform tension throughout. When not contracting, muscle still has some activated motor units; some tension generated but not enough to overcome resistance = resting tension. Rotating recruitment of different motor units, which maintains muscle tone. Muscle tone especially important in antigravity muscles (which are involved in balance and posture) 1000s of atp molecules consumed per cell. Aaerobic metabolism: requires o2 and organic molecules, produces atp and co2. Anaerobic: requires glycogen, produces atp, lactic acid. Some skeletal muscles use aerobic, some use anaerobic. Some skeletal muscle very vascularized = slow twitch fibres. Myoglobin is a storage depot for oxygen within skeletal muscles; slow twitch muscles need lots of myoglobin. Slow twitch fibres are red; fast twitch muscles are white ish. Fast twitch have lots of glycolytic enzymes in cytoplasm.
