BIOLOGY 173 Lecture Notes - Lecture 27: Lactic Acid, Muscle Tone, Myoglobin
Document Summary
Assigned topics in muscle physiology: what is treppe (the staircase effect) A muscle will contract more forcefully in response to the same stimulus after several contractions. Muscles are in a slightly contracted state. Occurs because some motor units are always active even when muscle s not contracting. These contractions are not enough tension to cause movement. Purpose: maintain posture, stabilize joints, keeps muscles firm and healthy: distinguish between isotonic and isometric contraction. Isotonic: muscle develops tension, overcomes resistance, and object is moved. Isometric: muscle develops tension but cannot overcome resistance (it is too great) and object is not moved: what are the causes of muscle fatigue. Causes: lack of oxygen, depletion of atp, accumulation of lactic acid. Ionic imbalances: distinguish between slow twitch and fast twitch fibers. Slow (red, type i) (dark meat: highly aerobic, contains myoglobin, an iron containing pigment that stores oxygen, abundant mitochondria, rich blood supply, fatigue resistant, high endurance, postural muscles.