Biochemistry, Physiology, and Pathology
Core concepts
Build the metabolic map: glycolysis, the Krebs cycle, oxidative phosphorylation, gluconeogenesis, glycogen metabolism, and the pentose phosphate pathway. Know the rate-limiting enzymes and their regulation, and how insulin and glucagon switch between storage and mobilization. Understand lipid metabolism (beta-oxidation, ketogenesis, cholesterol synthesis) and amino acid metabolism (transamination, urea cycle, nitrogen disposal).
Physiology and pathology
Know the major organ systems at a functional level: cardiovascular (cardiac output, blood pressure regulation, RAAS), respiratory (gas exchange, acid–base), renal (filtration, reabsorption, acid–base handling), endocrine (thyroid, adrenal, pancreatic), and hematologic (hemostasis, anemia types). Link pathology to laboratory findings: diabetes (hyperglycemia, HbA1c), renal failure (rising creatinine, electrolyte disturbance), liver disease (transaminases, bilirubin, albumin), and anemia (MCV-based classification).
Traps in questions
- Confusing the rate-limiting enzyme with the regulated enzyme in a pathway.
- Mixing up respiratory and metabolic acid–base disorders (check pH, pCO2, and bicarbonate together).
- Assuming all anemia is iron deficiency; use MCV to classify.
- Forgetting that the urea cycle disposes of nitrogen, while transamination only transfers it.
Worked example (rule of thumb)
For acid–base questions, first look at pH (acidemia vs alkalemia), then at pCO2 and HCO3−. If pH is low and pCO2 is high with normal bicarbonate, it is respiratory acidosis; if pH is low with low bicarbonate, it is metabolic acidosis. Then check whether compensation is appropriate.