Anatomy: It contains the organs used for breathing: the nose, pharynx, larynx, trachea, bronchi, bronchioles, lungs (including pleurae), intercostal muscles and diaphragm.
Physiology: This system is responsible for breathing, taking in oxygen (inhaling) and getting rid of carbon dioxide (exhaling).
The respiratory system does two very important things:
Brings oxygen into our bodies, which we need for our cells to live and function properly
Helps us get rid of carbon dioxide, which is a waste product of cellular function
The nose, pharynx, larynx, trachea and bronchi all work like a system of pipes through which the air is funneled down into the lungs.
Inhalation / Exhalation
Air enters the lungs through a system of pipes called the bronchi. These two pipes start from the bottom of the trachea as the left and right bronchi. From here the bronchioles branch out many times throughout the lungs. At the end of the bronchioles are little thin-walled air sacs or bubbles, known as the alveoli.
Gas exchange takes place between the air and the blood in the alveoli. Covering each alveolus is a whole network of capillaries.
The lungs are covered by smooth membranes (pleurae). The pleurae have two layers:
A visceral layer- sticks to the outside surface of the lungs
A parietal layer- lines the inside of the chest wall (rib cage)
The pleurae are important because they help us breathe in and out smoothly, without any friction.
When we breathe in, the diaphragm contracts and flattens out, expanding the space in the chest and drawing air into the lungs.
When we breathe out, the diaphragm relaxes and draws upward, reducing the space in the chest cavity.
Other muscles, including the muscles between your ribs (called intercostal muscles), also help by moving your ribcage in and out.
The right lung is divided into three lobes (superior, middle, and inferior). This lung is larger.
The left lung is divided into two lobes (upper and lower). The cardiac notch, a space or notch for the heart, is on the left lung.