Bicarbonate buffer system

An acid-base buffer involving bicarbonate and carbonic acid, linked to dissolved carbon dioxide: CO₂ + H₂O ⇌ H₂CO₃ ⇌ H⁺ + HCO₃⁻. The reversible reactions buffer added acid or base and limit changes in pH.

In a simplified bicarbonate-buffer model with bicarbonate initially held constant, how does a fall in carbon dioxide affect pH?

A fall in carbon dioxide reduces carbonic acid and hydrogen ion concentration, raising pH before slower compensatory changes are considered.

Carbon dioxide rise Carbon dioxide fall

Fundamental effect · pH falls in a simplified model with bicarbonate initially fixed · pH rises in a simplified model with bicarbonate initially fixed

How do the kidneys support acid-base balance?

The kidneys conserve filtered bicarbonate and excrete acid, including hydrogen ions buffered in urine; net acid excretion can add new bicarbonate to blood.

Fluid enclosed inside cells by their plasma membranes; the intracellular fluid forms the fluid part of the cytoplasm.

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50 flashcards:19 classic question/answer,13 term definitions,6 concept explanations,7 clozes and5 comparisons. Introductory physiology practice contains50 flashcards and50 quizzes across body-fluid compartments and osmosis, neuronal membrane potentials, neuromuscular signaling and skeletal muscle contraction, basic cardiovascular mechanics, ventilation and gas diffusion, renal filtration and tubular transport, digestive motility and secretions, endocrine signaling, and bicarbonate-buffer relationships. Source evidence, concept links and25 learning objectives support targeted question-level feedback and review recommendations. This initial set covers normal foundational mechanisms and explicit simplified models, including basic cardiac arithmetic; it does not claim comprehensive clinical physiology, treatment guidance or medical-school curriculum alignment.