The Human Respiratory System

As mentioned in the post named Respiration, humans cannot rely on simple diffusion for gas exchange. Instead, we have to rely on a specialized respiratory system to do so.

In this post, I will be describing how the human respiratory system works.   

Nose

The nose (nasal cavity) is where the air comes into our body. The nostrils contain tiny hair that clean the air, and the epithelium lining have capillaries that warm the blood. Also, the turbinate bones are lined with a thin membrane that secrets mucus, which moistens the air.

(turbinate bones: thin bones in the nose that increase surface area, and warm and moisten the air)

Larynx

• The larynx house the vocal cords

Trachea 

• have mucous cells and cilia.
• mucous cells trap foreign particles, and cilia brush them away
• maintains its rigidity because of the cartilage rings

Bronchi

• like the trachea, they are also reinforced with cartilage
• lead to bronchiole, and then alveoli

Alveoli

• Spherical hollow cavities (grape-like structures) that are lined up with capillaries
• where gas exchange occurs

Lung surfactant: a complex substance that reduces the surface tension throughout the lung

Lungs

• The right lung has three lobes, while the left lung has only two lobes (to accommodate for the heart) 
• protected by a flexible membrane called pleura, which allows the lung to expand and contract

Types of respiration:

• Breathing: the act of drawing air into and then out of the lungs
• External respiration: gas exchange between the air and the blood
• Internal respiration: gas exchange between the blood and other cells
• Cellular respiration: the process in which cells convert oxygen and glucose into useful energy, creating carbon dioxide in the process.