Question

What is respiration? Write a detailed note on the human respiratory system.

Answer 1

Respiration is a catabolic process which releases energy in the form of ATP. Respiration occurs all the time in all types of Living Organism. Respiration consumes oxygen and liberates carbon dioxide.

Complete answer:
Respiration is a multi step, enzyme mediated biochemical process in which organic compounds inside living cells release energy at various steps during the process.
The energy produced is stored in the form of ATP, which acts as energy currency in various cellular activities.
Human respiratory system-
The human respiratory system consists of the respiratory tract, a pair of lungs, and accessory organs that bring about breathing. The accessory organs are Thorax, Rib cage, diaphragm, and muscles.
The air we breathe enters through the external nostril opening. Through nasal passage, they enter the nasal chamber which opens into the nasopharynx.
Nasopharynx opens through the glottis of the larynx region into the trachea, which is a straight tube extending up to the mid-thoracic cavity which then divides and forms right and left primary bronchi. Bronchi undergo repeated division to form secondary, tertiary bronchioles ending up in terminal bronchioles.
At the end of the terminal branch, bronchioles vascularized bag-like structure is present which is known as alveoli. The branching network of bronchi and bronchioles and alveoli comprise the lungs.

We have two lungs. The parts starting with the external nostril up to the terminal bronchioles are considered the conducting part whereas the alveoli and their ducts form the respiratory or exchange part of the respiratory system. Exchange part is the site of actual diffusion of Oxygen and Carbon dioxide between blood and atmospheric air.

Note:
Respiration consists of four steps: breathing, external respiration, internal respiration, and cellular respiration.
Breathing is the bringing of oxygen rich fresh air to the respiratory surface and taking off carbon dioxide rich air to the outside. External respiration is the exchange of respiratory gases over the respiratory surface.Internal respiration is the exchange of gases at tissue level and their transport to and from the respiratory surface. Cellular respiration is the actual breakdown of substrate or respiratory substrate which occurs inside the living cells.