Physiology, system by system

Negative feedback, body fluid compartments, and the cell's working parts — the operating rules every organ-system lecture will quietly assume you know.

Resting potential, Nernst logic, and the action potential — the electrical grammar that neurons, muscle, and the heart all speak.

Synaptic transmission, EPSPs and IPSPs, summation, and the major neurotransmitter systems — how single-cell electricity becomes signaling, drugs, and disease.

Transduction, adaptation, the two somatosensory pathways, vision, hearing, and balance — how a stimulus becomes a signal, and where a lesion shows up.

The sarcomere, excitation-contraction coupling, the cross-bridge cycle, length-tension and force-velocity, and how smooth and cardiac muscle differ.

Hormone classes and receptors, the hypothalamic-pituitary axes, thyroid, adrenal, endocrine pancreas, and calcium balance — built on negative feedback.

Plasma and its proteins, red cell production and breakdown, iron and B12, anemia logic, platelets, the coagulation cascade and its brakes, and blood groups.

Cardiac action potentials, the EKG, the cardiac cycle, stroke volume and pressure-volume loops, hemodynamics, the microcirculation, and the reflexes and hormones that hold arterial pressure steady.

Lung volumes, the mechanics of breathing, gas exchange, oxygen and carbon dioxide transport, V/Q matching, and the chemoreceptor control of ventilation.

Filtration, clearance, segment-by-segment tubular transport, the concentrating mechanism, potassium, and acid-base interpretation — the kidney as the body's chemistry controller.

The gut wall and its own nervous system, motility from swallowing to defecation, the GI hormones, the four secretions, and how each nutrient, vitamin, and liter of water is absorbed.