What are the main parts and functions of the respiratory system?

The nostrils: Nostrils are involved in air intake, i.e. they bring air into the nose, where air is warmed and humidified. The tiny hairs called cilia filters out dust and other particles present in the air and protects the nasal passage and other regions of the respiratory tract.

Trachea: The trachea is also known as windpipe. The trachea filters the air we inhale and branches into the bronchi.

Bronchi: The bronchi are the two air tubes that branch off of from the trachea and carry atmospheric air directly into the lungs.

Lungs: The main organ of the respiratory system is lungs. Lungs are the site in body where oxygen is taken into and carbon dioxide is expelled out. The red blood cells present in the blood picks up the oxygen in the lungs and carry and distribute the oxygen to all body cells that need it. The red blood cells donate the oxygen to the cells and picks up the carbon dioxide produced by the cells.

Alveolus: Alveolus is the tiny sac like structure present in the lungs which the gaseous exchange takes place.

Diaphragm: Breathing begins with a dome-shaped muscle located at the bottom of the lungs which is known as diaphragm. When we breathe in the diaphragm contracts and flatten out and pull downward. Due to this movement the space in the lungs increases and pulls air into the lungs. When we breathe out, the diaphragm expands and reduces the amount of space for the lungs and forces air out.

the three components of a nucleotide are the nitrogenous base, the phosphate group and the five-carbon sugar.