Muscle Contraction and Exam Preparation

Exam Review Schedule

  • A review session will occur on the Saturday after next (next Saturday).
  • This is to help students prepare, following the last review which assisted with the skeletal system.
  • The review will start at 10 AM.

Upcoming Lectures and Tests

  • This week: Complete the muscle lecture.
  • Tuesday's lab: Finish the muscles in lab.
  • In two weeks: Lecture test and muscle lab test scheduled.
  • Possible adjustment to lab test timing if students feel overwhelmed.

Types of Muscle Contractions

  1. Tonic Contraction

    • Definition: Partial contraction of a muscle without movement.
    • Purpose: Maintains muscle tone (e.g., twitching while sleeping).

  2. Isotonic Contraction

    • Definition: Smooth, continuous contraction with constant strength and speed.
    • Explanation: Unlike accelerating a car gradually, muscle contractions are all-or-nothing; frequency sent by the brain dictates contraction.

  3. Isometric Contraction

    • Definition: Maximum contraction without movement (e.g., pushing hands together hard).
    • Example: Forces are exerted in opposite directions causing no visible movement.

  4. Twitch

    • Definition: A single contraction and relaxation.
    • Explanation: Triggered by an impulse; contraction may not happen if the threshold is not reached.

  5. Treppe (Staircase Effect)

    • Explanation: Repeated contractions lead to an increase in contraction force.
    • Purpose: Warm-up exercises increase body temperature to prevent injury.

  6. Tetanus

    • Definition: Constant contraction due to uninterrupted impulse from the brain.
    • Note: Leads to fatigue due to buildup of lactic acid from continuous contraction.

  7. Convulsion (Abnormal)

    • Definition: Uncoordinated tetanic contractions of the entire muscle (e.g., epileptic seizures).

  8. Fibrillation (Abnormal)

    • Definition: Uncoordinated contractions of individual muscle fibers (e.g., heart conditions).

Muscle Contraction Reaction

  • ATP (Adenosine Triphosphate): Main energy source for muscle contraction.
    • Breakdown leads to ADP (Adenosine Diphosphate).
  • Creatine Phosphate: Quickly reforms ATP from ADP for continued muscle contractions.
  • Glycogen: Stored as energy in the liver and muscle, breaks down into glucose and lactic acid during activity.
  • Oxygen Debt: Created when muscle fatigue occurs due to lactic acid buildup; requires extra oxygen for recovery post-exercise.

Lactic Acid Buildup and Cramps

  • Lactic acid: Byproduct of glycogen breakdown during muscular activity, leads to cramps if not removed.
  • Cramps signify the death of muscle cells due to lactic acid accumulation and lack of oxygen.
  • Oxygen Debt: Results in a need for increased breathing to oxidize lactic acid into CO₂ and H₂O post-exercise.

Practical Implications in Exercise

  • Proper warm-up prevents muscle strain and injury.
  • Awareness of oxygen debt and lactic acid is crucial for competitive athletes to manage fatigue and performance.