CSCS CSCS: Structure & Function of Body System 5 — Questions and Answers
Question 1: Which vertebral region has the greatest normal lordotic curve?
- Cervical and lumbar (Correct answer)
- Thoracic and sacral
- Lumbar only
- Cervical only
Correct answer: Cervical and lumbar
Both the cervical and lumbar regions exhibit a lordotic (anteriorly concave) curve, while the thoracic and sacral regions display kyphotic curves.
Question 2: An increase in stroke volume with no change in heart rate will result in:
- Decreased cardiac output
- No change in cardiac output
- Increased cardiac output (Correct answer)
- Decreased mean arterial pressure
Correct answer: Increased cardiac output
Cardiac output equals heart rate multiplied by stroke volume; if stroke volume increases while heart rate remains constant, cardiac output increases proportionally.
Question 3: Type IIa muscle fibers are often described as 'intermediate' because they:
- Contract more slowly than Type I fibers
- Have moderate oxidative and glycolytic capacity (Correct answer)
- Are only recruited during sub-maximal aerobic work
- Contain no mitochondria
Correct answer: Have moderate oxidative and glycolytic capacity
Type IIa fibers possess both aerobic (oxidative) and anaerobic (glycolytic) metabolic capacity, making them more fatigue-resistant than Type IIx but faster than Type I fibers.
Question 4: Which hormone secreted by the posterior pituitary increases water reabsorption in the kidney collecting duct?
- Oxytocin
- Growth hormone
- Antidiuretic hormone (ADH) (Correct answer)
- Prolactin
Correct answer: Antidiuretic hormone (ADH)
ADH (vasopressin), released from the posterior pituitary, acts on aquaporin channels in the collecting duct to increase water reabsorption and concentrate urine.
Question 5: The VO2max of an athlete is 60 mL/kg/min. This value represents:
- Maximum lactate production rate
- Maximal oxygen uptake relative to body mass (Correct answer)
- Resting metabolic rate in milliliters
- Maximum cardiac output per kilogram
Correct answer: Maximal oxygen uptake relative to body mass
VO2max expressed in mL/kg/min represents the maximum volume of oxygen consumed per minute relative to body mass, and is the gold standard measure of cardiorespiratory fitness.
Question 6: Which of the following accurately describes the 'all-or-none' principle of muscle contraction?
- A muscle either contracts maximally or not at all
- An individual motor unit either fires completely or not at all (Correct answer)
- All motor units in a muscle fire simultaneously
- A muscle fiber either shortens fully or maintains isometric tension
Correct answer: An individual motor unit either fires completely or not at all
The all-or-none principle applies to individual motor units: when the threshold is reached, all fibers within that motor unit contract maximally; graded force is achieved by recruiting more motor units.
Question 7: During aerobic exercise at moderate intensity, which energy substrate provides the majority of ATP after the first 20–30 minutes?
- Phosphocreatine
- Muscle glycogen only
- Blood glucose only
- A mix of carbohydrate and fat (triglycerides) (Correct answer)
Correct answer: A mix of carbohydrate and fat (triglycerides)
At moderate aerobic intensities beyond ~20–30 minutes, both carbohydrate (glycogen and blood glucose) and fat (intramuscular triglycerides and FFA) contribute substantially to oxidative ATP production.
CSCS CSCS: Structure & Function of Body System 5
Which vertebral region has the greatest normal lordotic curve?