Respiration is a term used in both biology and biochemistry.

• Respiration by individual organisms is the use of dioxygen or the production of carbon dioxide or heat by the organism. Respiration in plants is offset by photosynthesis that uses carbon dioxide and produces dioxygen during daylight hours. The three quantifiers (carbon dioxide, dioxygen, and heat) all reflect metabolic activity, but are not all proportional to each other, as is revealed by the method of indirect calorimetry. This makes the term rather sloppy.
• Cellular respiration is the process in which the chemical bonds of energy-rich molecules such as glucose are converted into energy usable for life processes, represented in chemical nomenclature as "C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + Energy released/ATP"
• The respiratory system of humans and other mammals comprises the lungs and other organs involved in breathing.
• Mechanical ventilation is a method to assist or replace spontaneous breathing.

Ademhaling