Medical Science and Human Body Systems
Medical Science and Human Body Systems tests structure, function and normal values across systems, with clinical correlations such as cardiac output, respiratory volumes, hormone source and blood composition.
Normal values to memorise
- Blood pressure below 120/80 mmHg; cardiac output about 5 L/min; blood pH 7.35-7.45; haemoglobin 13-17 g/dL in men and 12-15 g/dL in women; RBC lifespan about 120 days; roughly one million nephrons per kidney.
Systems
- Alveolar gas exchange; surfactant comes from type II pneumocytes; tidal volume is about 500 mL and vital capacity about 4.8 L.
- Digestion: salivary amylase acts on starch, pepsin on protein, pancreatic trypsin and lipase on protein and fat; absorption occurs in small-intestinal villi.
- Endocrine: insulin from beta cells, glucagon from alpha cells, thyroxine from the thyroid, cortisol from the adrenal cortex, ADH from the posterior pituitary.
Worked example
Heart rate is 75 beats/min and stroke volume 70 mL. Cardiac output = 75 x 70 = 5,250 mL/min, about 5.25 L/min. If stroke volume falls and heart rate does not rise, cardiac output falls.
Traps
Arteries carry blood away from the heart, not always oxygenated blood. Systole is contraction, diastole relaxation. Insulin and glucagon come from different islet cells. Tidal volume is not vital capacity, and weight is not mass.