Human Physiology
Human Physiology covers digestion, breathing, circulation, excretion, locomotion, neural control and endocrine regulation.
Core rules
- Digestion: salivary amylase, pepsin in the stomach, pancreatic amylase, trypsin, lipase; absorption mainly in the small intestine; villi increase surface area.
- Breathing: tidal volume, inspiratory and expiratory reserve volumes, residual volume; oxygen transport by haemoglobin; the Bohr effect shifts the curve right with high CO₂ and low pH.
- Circulation: cardiac cycle, stroke volume, cardiac output = stroke volume × heart rate; SA node is the pacemaker; ECG waves P, QRS, T.
- Excretion: nephron, glomerular filtration, tubular reabsorption and secretion; ADH increases water reabsorption; the counter-current mechanism concentrates urine.
- Locomotion: sliding filament theory, actin and myosin, sarcomere.
- Neural and endocrine: resting potential, action potential, synapse; hormones and disorders such as diabetes.
Worked example
A person has tidal volume 500 mL, inspiratory reserve volume 2,500 mL, expiratory reserve volume 1,000 mL and residual volume 1,200 mL. Vital capacity = 500 + 2,500 + 1,000 = 4,000 mL. Total lung capacity = vital capacity + residual volume = 4,000 + 1,200 = 5,200 mL.
Traps
ADH acts on the distal tubule and collecting duct, not the glomerulus. Cardiac output is per minute, not per beat. The oxygen dissociation curve shifts right with high CO₂, high temperature and low pH. Insulin lowers blood glucose; glucagon raises it.