Anatomy, Physiology and Exercise Effects on Body Systems
Anatomy, Physiology and Exercise Effects on Body Systems
This domain tests basic body structure and function, and how acute exercise and long-term training change the skeletal, muscular, circulatory, respiratory and nervous systems.
Core facts
- Skeleton: 206 bones in an adult - axial 80 (skull, vertebral column, ribs, sternum) and appendicular 126 (limbs and girdles).
- Muscle: about 600 skeletal muscles; three types - skeletal (striated, voluntary), smooth (involuntary, organs), cardiac (involuntary, heart).
- Contraction: isotonic (concentric/eccentric, movement), isometric (no movement), isokinetic (constant speed). Agonist produces movement, antagonist opposes it, synergist assists.
- Heart: four chambers; resting rate ≈ 72/min; stroke volume ≈ 70 mL; cardiac output ≈ 5 L/min; normal BP 120/80 mmHg.
- Lung volumes: tidal volume ≈ 500 mL; vital capacity ≈ 4.8 L in males; residual volume ≈ 1200 mL.
- Energy systems: ATP-PC (seconds), glycolytic/lactic acid (up to about 2–3 minutes), aerobic (long duration).
Exercise effects
- Acute: heart rate, stroke volume, cardiac output, ventilation and oxygen uptake rise; blood is redistributed to working muscle; sweating and body temperature rise.
- Chronic: lower resting heart rate, larger stroke volume and cardiac output, greater vital capacity, more capillaries and mitochondria, muscle hypertrophy, stronger bones and ligaments, faster recovery.
Worked example
Resting heart rate 60/min, stroke volume 80 mL. Cardiac output = 60 × 80 = 4800 mL ≈ 4.8 L/min. Reasoning: CO = HR × SV; in exercise both factors rise, so CO can reach about 20 L/min in a trained adult.
Traps
- Confusing vital capacity with total lung capacity.
- Saying training increases resting heart rate; it lowers it.
- Mixing residual volume (air left after full exhalation) with tidal volume.
- Describing hypertrophy as an increase in the number of muscle fibres.