The Animal World
Concept: Respiratory Organs in Animals
Breathing and Respiration:
Before we learn about the respiratory organs in animals, let us have a brief idea about breathing and respiration.
- The chemical process by which energy is released in the cells due to the breakdown of food is called respiration.
- The energy released during respiration is utilised to perform all bodily functions.
- The physical process of inhaling oxygen from the air and exhaling carbon dioxide in the environment is called breathing.
- The oxygen inhaled during breathing is responsible for the breakdown of food in the cells and subsequent release of energy, i.e., the oxygen we breathe in actually facilitates cellular respiration.
- The respiratory system in a living organism involves a set of organs working together to help the process of breathing.
- However, the set of organs is different for different animals based on the complexity of their body. Let us talk about them one by one.
- Amoeba are single-celled organisms belonging to the group Protozoa. They have a very simple body organisation.
- They do not have specific organs for the process of respiration.
- Exchange of gases in amoeba occurs by the process of diffusion across the cell membrane.
- The oxygen gas dissolved in the surrounding water diffuses through the cell membrane and is utilised by the cells to break down complex food materials and liberate energy.
- Other members of the Protozoa group who have similar respiratory systems are Hydra and Paramecium.
- In insects, the air is drawn in and out of the body through openings called spiracles. These openings are present on the body surface.
- Spiracles take the air to tube-like structures called the trachea located in the abdominal cavity.
- From the trachea, the air moves into smaller tubes called tracheoles that are present throughout the body.
- As a result, oxygen gets distributed to all the parts of the insect’s body.
- Fish and many other aquatic animals have special organs called gills.
- The gills allow fish to breathe underwater.
- Through these gills, oxygen dissolved in the water enters the body, and carbon dioxide is expelled from the body by the process of diffusion.
- Earthworms do not have specialised respiratory organs.
- They take in the atmospheric oxygen and expel carbon dioxide through their moist skin.
- Oxygen diffuses through the earthworm’s body surface and spreads across the body via a network of capillaries.
- Frogs are amphibians, i.e., they can survive both on land and in water. So, their bodies have evolved to breathe both in terrestrial and aquatic habitats.
- They use their moist skin for breathing in water and lungs to breathe on land.
- Frogs in the larval stage (tadpole) use gills for breathing.
Mammals and Birds:
- Mammals are terrestrial and use lungs for breathing.
- Birds also use their lungs for breathing.
- Exchange of oxygen and carbon dioxide in the lungs takes place in millions of tiny air sacs.
- These air sacs are called alveoli in mammals and atria in birds.
Respiratory System of the Human Body:
- Respiration occurs through the respiratory system which involves a group of organs that help oxygen reach the blood vessels and also facilitate the expulsion of carbon dioxide from the body.
- The organs of the respiratory system in man are—Nose, Nasal cavity, Mouth, Pharynx (throat), Larynx (voice box), Trachea (windpipe), Bronchi, Bronchioles, Lungs, and Alveoli.
The path followed by the oxygen gas as it enters the respiratory system is as follows:
The exchange of gases occurs in the alveoli, from where oxygen is transported to the blood and then carried to the whole body.
Diffusion: The movement of oxygen, nutrients, and other molecules across membranes (Note: Membranes are barriers that allow some things to pass and stop others).
Larval stage:A developmental stage in a living organism’s life cycle before it reaches the adult stage.
- Whales and dolphins breathe through gills.
- Animals do not have respiratory disorders.
Whales and dolphins are aquatic mammals and breathe through their lungs just like terrestrial mammals. They come to the surface of the water for the exchange of gases.
Animals are also affected by respiratory disorders like asthma and pneumonia. These disorders are quite common in cats and horses.