“Respiration is process of producing energy with intake of oxygen and release of carbon dioxide in body.”

Depending on the availability of oxygen, respiration is classified as aerobic respiration and anaerobic respiration. In this blog, we will discuss in detail about respiration, it’s types, processes, and many more.

Aerobic and Anaerobic respiration

Aerobic respiration is the process of energy production in the presence of oxygen. Respiration in human beings is good example of aerobic respiration.
The process of producing energy from food in absence of oxygen then it is called as anaerobic respiration. For example yeast undergoes anaerobic respiration. Respiration occurs in two phases, external respiration and internal respiration.

External Respiration

External respiration is also known as breathing. It is the process of bringing oxygen rich air inside the body, absorption of oxygen and releasing out air having carbon dioxide. This process is carried out with the help of respiratory organs. Respiratory organs differ from animals to animal. Respiratory organ in fish is gills, in humans is lungs, whereas in some other animals it is skin.

How does respiration occurs in aquatic animals?

Aquatic animals are the ones which lives under water. These animals use oxygen dissolved in water. As oxygen dissolved in water in less as compared to air, to fulfill the demand of oxygen, aquatic animals breathe faster. Fish take water inside the body through mouth and release it over gills. Gills allows the dissolved oxygen in water to get diffused in blood. Animals like amphibians, turtles use skin for intake of oxygen in body. Blood capillaries below skin are places where oxygen is diffused in the blood.

Respiration in human beings

Respiration in humans occurs with help of respiratory tract and respiratory organ. Respiratory tract includes nostrils, pharynx, larynx and trachea. Respiratory tract starts with nostrils. The air passing through nostrils is filtered by fine hairs. While passing through respiratory tract, air also becomes moist and warm. Moreover, the mucus trap the dust particles in the air. Pharynx or throat passes the air from nose or mouth in the larynx.

Respiratory System in Humans

Larynx or voice box allows air pass to trachea. Trachea or windpipe is divided into two bronchi, one enters into right lung and other enters into left lung. Lungs are the respiratory organs in the thoracic cavity on the either side of the heart. Bronchi entering in right and left lungs divides into smaller and smaller bronchioles. These bronchioles end up in balloon like structure called alveoli. Exchange of gases occurs at surface of alveoli. Blood capillaries are surrounded at surface of alveoli. Through thin walls of capillaries, haemoglobin in blood absorbs oxygen and releases carbon dioxide in the alveoli by the process of diffusion. Thus oxygen is carried away with blood to all parts of body whereas, CO2 is released in air through the breathing tract.

Mechanism of breathing in human beings

Breathing occurs through inhalation and exhalation. During inhalation, muscular diaphragm contracts, the volume of thoracic cavity increases. Thus, pressure of air inside the lungs decreases. This allows the outside air to enter into lungs. During exhalation, diaphragm relaxes, the volume of thoracic cavity decreases, therefore, lungs gain their original size. Hence, the pressure inside the lungs becomes greater and air inside the lungs is pushed outside.

Respiration in plants

Plants have openings or pores normally underside of the leaf. These openings are called stomata. Exchange of gases takes place through stomata. With help of stomata, gases enter in the intracellular spaces of leaf from where it get diffused in the cell. Opening of stomatal pores is controlled by guard cells. During the day respiration and photosynthesis takes place simultaneously. Parts of plants such as roots, stem and leaf perform respiration and producing energy. Carbon dioxide released during respiration is reuse for photosynthesis hence, during day more oxygen is released. During night, in absence of sunlight, plants perform only respiration, therefore, plants take oxygen inside the body and release carbon dioxide outside the body.

Internal Respiration

Internal respiration is also known as cellular respiration. It is a biochemical process in which carbohydrates are oxidised within the cell to release energy. This process takes place in the mitochondria of cell, thus it is called as powerhouse of cell. Cellular respiration involves series of biochemical reactions. Glycolysis is process that takes place in all organisms.



In this process, six carbon molecule glucose is broken down in absence of air into three carbon molecule pyruvate in the cytoplasm of cell. As the process do not require oxygen it is anaerobic respiration. After glycolysis three carbon molecule pyruvate is again broken down in absence of oxygen forming ethanol carbon dioxide and releasing energy. In human muscle cell pyruvate molecule is broken down in presence of oxygen to carbon dioxide and water and energy. The energy released during cellular respiration is utilize to synthesise adenosine tri phosphate or ATP molecule. This ATP molecule acts as a fuel for other activities in cell.
It is interesting to know that, aerobic respiration releases more amount of energy as compared to anaerobic respiration.
Keywords: Respiration in plants, Respiration in humans, ATP, Adenosine tri phosphate, Glycolysis, Pyruvate, Photosynthesis, Aerobic respiration, Anaerobic respiration, Cellular respiration,

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