Breathing and Exchange of Gases

The human body needs a non-stop exchange of gases to continue doing the activities. Living cells take oxygen from the atmosphere and release carbon dioxide. This process is called the exchange of gases and is commonly known as respiration or breathing. The breathing and exchange of gases is a non-stop activity among living organisms. Today, in this article, we will be talking about the breathing and exchange of gases, Breathing Mechanisms & respiratory organs, the Human respiratory system and the breathing mechanism.

What happens in the process of breathing and exchange of gases?

In breathing and exchanging gases, simple molecules directly break with the help of oxygen. This process of molecules breaking down is called a catabolic reaction. Glucose, amino acids, fatty acids are simple molecules. The organisms can perform various activities when the simple molecules break down. During this process, carbon dioxide is released, and oxygen is uninterruptedly provided to the cells. This process of gaseous exchange takes place in breathing, where carbon dioxide (CO₂) is produced by the cells and oxygen (O₂) is taken from the atmosphere. This process is called breathing or respiration.

Breathing Mechanisms & Respiratory Organ:

The breathing mechanism differs for each species and depends mainly on organism levels and habitat. Lower invertebrates go through the process of simple diffusion wherein O₂ is exchanged with CO₂ over their body surface. Other animals like earthworms use moist cuticles to exchange the gases in the atmosphere. Insects transport and exchange gases within the body with the help of tracheal tubes. Aquatic animals exchange gases through gills, and it helps in bronchial respiration. All the terrestrial organisms – amphibians, reptiles, birds, mammals – use lungs for pulmonary respiration to exchange gases from the atmosphere. Amphibians, like frogs, can respire through their moist skin, which is termed cutaneous respiration.

Human Respiratory System

The human respiratory system consists of the following parts, which facilitate the breathing and exchange of gases:-

Nostrils: A pair of external nostrils are present above the upper lip. Nostrils run down to the nasal chamber through the nasal passage
Pharynx: This is the common passage of food and air. The nasal chamber opens into the pharynx
Trachea: The pharynx ends as it further opens through the larynx region into the trachea. The larynx region is a cartilaginous box that facilitates sound production. This straight tube extends to the mid-thoracic cavity and further divides into right and left primary bronchi
Epiglottis: A thin cartilaginous flap covers the glottis during the process of swallowing. This prevents the food from entering the larynx region
Bronchi: Repeated division is performed to develop the secondary and tertiary bronchi, which ends in terminal bronchioles
Incomplete cartilaginous rings: Incomplete cartilaginous rings support tracheae and primary, secondary and tertiary bronchi
Alveoli: Each bronchiole gives rise to many thin, irregular-walled structures called alveoli
Lungs: The network of bronchi, bronchioles, and alveoli looks like branches, and the branched network includes the lungs. Human beings have two lungs to facilitate the process of breathing. This helps in reducing friction between the lung surface

Breathing Mechanism:

The breathing mechanism involves two main practises – inspiration (or inhaling) and expiration (or exhaling). In the process of inspiration, the diaphragm and the external intercostal muscles contract. In the expiration process, the diaphragm and the external intercostal muscles relax. This results in inhalation and exhalation, where the body accepts oxygen from the atmosphere and sends out carbon dioxide produced by the cells. The diaphragm facilitates this process. The diaphragm is a large, dome-shaped muscle present under the lungs. It contracts continually and rhythmically.

Conclusion

All species require a continuous exchange of gases. Oxygen is inhaled from the atmosphere, and carbon dioxide produced by the cells is released. In the process of exchange of gases, oxygen molecules are taken into the bloodstream, and carbon dioxide molecules are expelled from the bloodstream into the atmosphere. By the process of diffusing, the exchange of gases gets completed from areas of high concentration to areas of low concentration in the lungs. The exchange of gases is called external respiration.