Biological Systems for Nutrition Practice

Think in linked compartments and controls

Anatomy names the structures and connections; physiology explains movement, control, and response; microbiology explains host interactions with microorganisms; biochemistry explains reactions and molecular regulation. Nutrition depends on all four. The gastrointestinal tract must digest and absorb, blood and lymph must transport, cells must metabolize, lungs must exchange gases, kidneys must regulate the internal fluid, and nervous and endocrine signals must coordinate intake and use. Homeostasis is dynamic rather than constant. Sensors detect change, integrators compare it with a regulated range, and effectors respond through nerves, hormones, muscles, glands, and behavior. A laboratory abnormality can arise from intake, absorption, distribution, metabolism, storage, excretion, inflammation, medication, or measurement, so trace the pathway before assigning a nutrition cause.