Anatomy and Physiology
Anatomy and Physiology - what the exam tests
This domain covers the structure (anatomy) and function (physiology) of the cell, tissues and major systems - skeletal, muscular, cardiovascular, respiratory, digestive, urinary, nervous, endocrine and reproductive - together with homeostasis.
Core rules
- Homeostasis is a stable internal environment maintained mainly by negative feedback (rising CO₂ → faster breathing); positive feedback is rare (labour contractions).
- Anatomical position: standing erect, palms forward, feet flat. Terms: anterior/posterior, proximal/distal, medial/lateral, supine/prone.
- Blood flow: right atrium → right ventricle → pulmonary artery → lungs → pulmonary veins → left atrium → left ventricle → aorta. The pulmonary artery is the only artery carrying deoxygenated blood.
- Respiratory: tidal volume about 500 mL; gas exchange occurs in the alveoli; vital capacity is the maximum air exhaled after maximum inspiration.
- Kidney: the nephron is the functional unit; glomerular filtration rate is about 125 mL/min.
Worked example
A resting adult has a heart rate of 75 beats/min and a stroke volume of 70 mL. Cardiac output = HR × SV = 75 × 70 = 5,250 mL/min, about 5.25 L/min. Reasoning: cardiac output is the volume each ventricle ejects per minute; if stroke volume falls in haemorrhage, the body raises heart rate to preserve output and blood pressure, which is why a rising pulse is an early warning sign.
Traps that cost marks
- Saying the pulmonary artery carries oxygenated blood.
- Confusing the lobes (right lung 3, left 2).
- Mixing afferent (towards) with efferent (away from) for vessels and neurons.
- Listing the small intestine out of order; it is duodenum → jejunum → ileum.