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.