Respiration in Animals

Respiration in Animals

Respiration is an important process which takes in plants as well as animals. In this article, we will discuss the Respiration in animals, and Respiration in animals definition along with the Types of respiration and the Process of respiration.

Respiration is the process of releasing energy from food that takes place inside the cells of the body. Respiration is essential for life because it provides energy for carrying out all the life processes which are necessary to keep the organisms alive. In this article, we will discuss respiration in animals and its types and processes.

What is Respiration in Animals?

The respiratory system is an oxidation mechanism in which food substances, including carbohydrates, lipids, and proteins are burned with tissue to produce carbon dioxide, water, and energy. Lungs are the principal organs of the respiratory system, and they are responsible for the exchange of gases that occur when we breathe.

Organs of Respiration in Animals

The following are the human respiratory organs: 

Nasal Cavity:

A pair of apertures above the mouth is known as a nostril in humans. Mucous glands are situated on the side of the Nasal passage and Nasal holes, by which the mucus is released. Nasal hairs and a semi-liquid substance present in the nose capture dust particles and microorganisms. 


It’s a muscular channel that connects the nasal cavity and larynx, as well as the mouth cavity and oesophagus. It facilitates breathing, food ingestion, and voice.


The Larynx is a component of the respiratory system that connects the pharynx and the trachea. Its major job is to make sound hence it’s also known as the voice box. It also aids coughing, swallowing, and respiratory track safety.


The trachea is a tube-like structure that is connected to the larynx and is 12 cm long. In the human body’s chest cavity, the trachea hangs like an inverted tree.


Lungs have a cylindrical rubber structure and are crimson in appearance. In the thoracic cavity, there are two lungs: the right lung and the left lung. The right lung remains, whilst the left lung is divided into two lobes. Each lung is bordered by a membrane called the pleural membrane, which is partially filled with fluid.

The four parts of the respiration process in animals are as follows:

External Respiration in Animals: This is the mechanism by which organisms exchange breathing gases with the environment.

It can be categorised into two sections which are:

Breathing: All animals have a pair of lungs that inhale and exhale air at a certain rate, which is referred to as breathing.

Inspiration: During this phase, atmospheric air enters the lungs, causing the lungs to expand as the capacity of the chest cavity increases.

Expiration: During this phase, the lungs’ absorbed atmospheric air is pumped out, the ribs return to their previous position due to contraction of the intercostal muscles, and the lungs’ absorbed air is pumped out.

Gas Exchange: Gas exchange occurs inside the lungs due to pressure differences and is accomplished through diffusion. The diffusion of oxygen and carbon dioxide is in opposite directions.

Internal respiration in Animals: Internal respiration is a gaseous exchange among blood and tissue fluid that occurs inside the body.

Transport of Gases: The transportation of gases is the process by which oxygen from the lungs reaches the cells and carbon dioxide from the cells reaches the lungs—the blood circulatory system assists in the transportation of gases.

Oxygen Transportation: oxygen is carried by haemoglobin. They combine to form an unstable molecule that reaches all of the body’s cells and decomposes to provide oxygen.

Carbon dioxide Transportation: Carbon dioxide is transported from the body’s cells to the lungs via haemoglobin.

Cellular Respiration: Cellular respiration is the process of oxidising glucose.

Types of Respiration in Animals

Anaerobic and aerobic respiration are the two forms of respiration. 

Anaerobic Respiration in Animals: It occurs without the presence of oxygen. Pyruvic acid is the last result of anaerobic respiration; throughout the process, the energy of ATP of four molecules is generated, of which two molecules’ energy is used to complete the process, and the remaining two molecules’ energy is used.

In animal tissue such as skeletal muscle cells, lactic acid is the end product. Excessive exercise creates lactic acid, which causes muscle soreness.

Aerobic Respiration in Animals: When food is oxidised in the presence of oxygen, it is referred to as aerobic respiration. Now at the completion of aerobic respiration, 30-32 ATP molecules per 1 molecule of glucose is released, with 55 to 60% of that energy being used and the remainder being lost as heat. The anaerobic respiration of yeast can also be used to ferment sugar. Humans gain energy through aerobic respiration. However, anaerobic respiration occurs in our muscles during strenuous physical activity when oxygen is used up faster in muscle cells than the human body can supply.

Modes of Respiration in Animals

  • In primitive unicellular creatures like Amoeba, respiration is accomplished through simple gas diffusion across the cell membrane. 
  • Animals that live in the soil, such as earthworms, use their epidermis to receive oxygen from the air and expel carbon dioxide. The earthworm uses its skin as its respiratory organ.
  • The respiratory organs of aquatic animals such as fish, prawns, etc., are gills. Gills absorb oxygen present in water and remove carbon dioxide from the body.
  • The respiratory organs of insects such as grasshoppers, cockroaches, houseflies, and mosquitos are tiny pores called spiracles on their bodies and air tubes called tracheae.
  • The lungs are the respiratory systems of land creatures such as humans, birds, lizards, dogs, and frogs. Frogs, on the other hand, breathe through both their lungs and their skin.


Respiration in animals is the process that involves taking in oxygen (of air) into cells, then using it for releasing energy, and then eliminating the waste products (carbon dioxide and water) from the body is respiration. Respiration in animals is divided into further external respiration, internal respiration, pulmonary ventilation, and cellular respiration.

Different animals use different modes and organs for respiration, but all of them have a good blood supply for transporting gases and work for the same cause.