Respiratory physiology

In physiology respiration is defined as the movement of oxygen from the outside environment to the cells within tissue |tissues, and the transport of carbon dioxide in the opposite direction. Respiration could also be defined as the release of energy from glucose and this is achieved through the breaking down of this glucose in the cells and oxygen from the atmosphere is absoloutely pivotal to this breaking down. Where oxygen is not present anaerobic respiration takes place. Glucose + Oxygen= Carbon dioxide + Water + Energy and if oxygen is not present Glucose= Carbon dioxide + Alcohol + Energy alcohol is not released by anaerobic respiration in humans, instead in its place Lactic acid is released.

The physiological definition of respiration differs from the biochemical definition, which refers to cellular respiration, a metabolic process by which an organism obtains energy (in the form of ATP) by oxidizing nutrients and releasing waste products. Although physiologic respiration is necessary to sustain cellular respiration and thus life in animals, the processes are distinct: cellular respiration takes place in individual cells of the organism, while physiologic respiration concerns the diffusion and transport of metabolites between the organism and the external environment.

In animals with lungs, physiological respiration involves respiratory cycles of inhaled and exhaled breaths. Inhalation (breathing in) is usually an active movement. The contraction of the diaphragm muscle cause a pressure variation, which is equal to the pressures caused by elastic, resistive and inertial components of the respiratory system. In contrast, exhalation (breathing out) is usually a passive process. Breathing in, brings air into the lungs where the process of gas exchange takes place between the air in the alveoli and the blood in the pulmonary capillaries

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