What is respiration? Define external and internal respiration

Respiration is defined as the breakdown of complex compounds in simpler compounds in presence of O₂.

Body consumes O₂ and release CO₂ in this process.

Respiration is mainly of two types:

External respiration-

It takes in alveoli of the lungs.

It is the process in which O₂ is breathed in and CO₂ is breathed out.

It is also termed as ventilation.

Internal respiration-

It is also called cellular respiration.

In this, breakdown of substance occurs in presence of O₂ ; it releases energy and CO_2.

If respiration occurs in absence of O₂ is termed as anaerobic respiration.

Hence, respiration is the process in which complex substances are broken down to simpler substances in the presence of O₂