Breathing is part of respiration. The food we consume has stored energy which is released during respiration, hence we respire to obtain energy from the food. This process is known as cellular respiration, where food is broken down in cells to release energy. It is universal in all living entities. When glucose is broken down with the use of oxygen it is called aerobic respiration and in the absence of oxygen, it is known as anaerobic respiration.
During respiration we inhale oxygen into our body and release carbon dioxide during exhalation. Inhalation and exhalation is a continuous process that occurs throughout our lives. Respiratory rate is the number of times a person breathes in a minute. Typically, an average adult human takes 12 to 20 breathes every minute.
Most of the living entities breathe through nostrils. The nostrils open up into the nasal cavity and eventually leads into the lungs. The lungs are enclosed within the ribcage, with the diaphragm positioned right below.
How Do Organisms Breathe Underwater?
Some entities live in water and are called aquatic animals. They have special features which enable them to breathe in water. Like all other animals, aquatic animals need oxygen to breathe. They obtain oxygen dissolved in the water. Lungs are good for terrestrial organisms, but for purely aquatic organisms, they are not very useful.
Fishes have gills which enables them to breathe. Gills are feathery organs projected out of the skin, richly supplied with blood vessels. Fish takes water through the mouth and forces carbon dioxide out of the gills. As water passes through gills, oxygen is diffused into the blood vessels which is then passed to the cells.
However, organisms like whales and dolphins swim to the water surface to breathe since they are mammals just like humans. They are warm-blooded animals and give birth to younger ones as opposed to laying eggs. Dolphins and whales have blowholes at the top of its head through which they breathe.
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