Respiration is the biochemical process by which cells break down glucose to release energy, primarily in the form of ATP, using oxygen and producing carbon dioxide as a byproduct.

Aerobic respiration occurs in the presence of oxygen, producing more energy (ATP) and releasing carbon dioxide and water. Anaerobic respiration occurs without oxygen, yielding less energy and producing lactic acid (in animals) or ethanol and carbon dioxide (in yeast).

Alveoli are tiny air sacs in the lungs where gas exchange takes place. Oxygen from the air diffuses into the blood, while carbon dioxide in the blood diffuses out into the alveoli to be exhaled.

During inspiration, the diaphragm contracts and moves downward, increasing the volume of the thoracic cavity. This reduces pressure in the lungs, causing air to flow in through the airways to equalize pressure.

Tidal volume is the amount of air inhaled or exhaled in a single breath during normal breathing.

Vital capacity is the maximum amount of air that can be exhaled after a maximum inhalation, representing the total volume of air available for gas exchange.

The diaphragm is a muscle that plays a crucial role in breathing. Its contraction increases lung volume during inhalation, and its relaxation helps expel air during exhalation.

Respiratory rate refers to the number of breaths a person takes per minute. It is an important indicator of respiratory health.