Anatomy and Physiology

Muscle Actions

  • When a muscle performs an action, other muscles assist in various ways.

Prime Mover/Agonist

  • The muscle that primarily performs a specific action.
  • Example: During plantarflexion, the gastrocnemius is the strongest muscle involved, making it the prime mover/agonist.

Synergist

  • A muscle that assists the prime mover/agonist in performing the action.
  • Synergists are not as strong as prime movers.
  • Example: During plantarflexion, the soleus contracts to provide additional strength, thus assisting the gastrocnemius. Therefore, the soleus is the synergist.

Antagonist

  • A muscle that performs the opposite action of the prime mover/agonist.
  • Every muscle has an antagonist.
  • Example: When the gastrocnemius contracts to perform plantarflexion, the tibialis anterior contracts to perform dorsiflexion, returning the foot to the starting position. The tibialis anterior is the antagonist to the gastrocnemius.

Fixator

  • A muscle that stabilizes an area or joint while an action is performed.
  • Stabilization prevents injury and allows optimal movement.
  • Example: The supraspinatus stabilizes the head of the humerus in the glenoid fossa during movements of the glenohumeral joint.

Analogy

  • Agonist (Prime Mover) : Batman (main character)
  • Synergist: Robin (helper)
  • Antagonist: The Joker (opposite of Batman)

Aerobic and Anaerobic Metabolism

Aerobic Metabolism

  • The process in which cells use oxygen to produce energy for proper function.
  • Oxygen is introduced into cells and enters the mitochondria.
  • The mitochondria uses oxygen and glucose to create adenosine triphosphate (ATP).
  • ATP is a molecule that transports important nutrients, such as protein, inside the cell.
  • ATP stores energy for future cell use and facilitates nerve impulse transmission and muscle contractions.

Anaerobic Metabolism

  • The process in which ATP is produced without oxygen.
  • Occurs when the lungs cannot supply cells with enough oxygen during high-intensity exercise (e.g., running).
  • The mitochondria produce ATP using only glucose.
  • Lactic acid is produced as a waste product.

Formulas

  • Aerobic Respiration: Glucose + O2 \rightarrow CO2 + H_2O + ATP
  • Anaerobic Respiration: Glucose \rightarrow ATP + Lactic Acid