What are the three main parts of human respiratory system?

The three main parts of the human respiratory system are:

1. Upper respiratory tract: This includes the nose, pharynx (throat), and larynx (voice box). The nose, pharynx, and larynx act as passageways for air to travel in and out of the lungs. They also help to filter and warm the air, and protect the body from foreign particles and microorganisms.

2. Lower respiratory tract: This includes the trachea (windpipe), bronchi, and lungs. The trachea is a long tube that connects the larynx to the lungs. The bronchi are branches of the trachea that lead to the lungs. The lungs are two large, spongy organs that are located on either side of the heart. The lungs are responsible for exchanging oxygen and carbon dioxide during the process of respiration.

3. Respiratory muscles: These muscles include the diaphragm and the intercostal muscles. The diaphragm is a large muscle that separates the chest cavity from the abdominal cavity. The intercostal muscles are located between the ribs. These muscles work together to expand and contract the chest cavity, which draws air in and out of the lungs.