Anatomy, Physiology and Basic Human Body Systems
This domain tests the structure and function of the body - enough anatomy and physiology to recognise when a system is failing and to report it accurately.
Organisation of the body
Cells → tissues (epithelial, connective, muscular, nervous) → organs → systems. Homeostasis is the body's drive to keep temperature, pH, glucose and fluid balance stable.
Systems and the facts examiners use
- Skeletal: 206 bones in an adult; protects organs, stores calcium, and blood cells form in bone marrow.
- Muscular: skeletal (voluntary), smooth (involuntary) and cardiac muscle; movement, posture and heat.
- Circulatory: four-chambered heart; the right side pumps deoxygenated blood to the lungs, the left side pumps oxygenated blood to the body; arteries carry blood away from the heart.
- Respiratory: nose → pharynx → larynx → trachea → bronchi → bronchioles → alveoli, where gas exchange happens.
- Digestive: mouth → oesophagus → stomach → small intestine (duodenum, jejunum, ileum) → large intestine → rectum; most absorption is in the small intestine.
- Urinary: the nephron is the functional unit; the kidney filters blood and regulates water and electrolytes.
- Nervous and endocrine: electrical and hormonal control; pancreas (insulin) and thyroid (thyroxine) are common examples.
- Skin: the largest organ - barrier, temperature control, sensation.
Worked example
Trace oxygenated blood: pulmonary veins → left atrium → mitral valve → left ventricle → aorta → tissues. Return path: venae cavae → right atrium → tricuspid valve → right ventricle → pulmonary artery → lungs. Reasoning note: the pulmonary artery is the only artery carrying deoxygenated blood, and the pulmonary vein the only vein carrying oxygenated blood.
Traps that cost marks
- Calling the pulmonary artery oxygen-rich.
- Placing alveoli in the trachea instead of at the end of the bronchioles.
- Saying the stomach absorbs most nutrients - it mainly begins protein digestion.