The respiratory system

This system is responsible for the exchange of oxygen and carbon dioxide between the external environment and the internal environment of the body. It is closely linked with the cardiovascular system, as the exchange of gases takes place between the alveoli of the lungs and the blood in the pulmonary capillaries.

The system is composed of the:

^ nose and nasal passages

^ pharynx

^ larynx

^ trachea

^ bronchi and bronchioles

^ lungs, which are composed of alveoli.

Air passes through the larynx, which is sometimes known as the voice box. Sound is produced by passing air over the vocal chords in the larynx

The trachea is a large flexible but strong tube also known as the windpipe. Rings of cartilage maintain its shape

Lung

Venule

The alveoli are covered with very small capillaries, which allow oxygen and carbon dioxide to pass into and out of the blood stream

Arteriole

Alveoli

Artery '

Figure 2.16 The respiratory system.

Air passes through the larynx, which is sometimes known as the voice box. Sound is produced by passing air over the vocal chords in the larynx

The trachea is a large flexible but strong tube also known as the windpipe. Rings of cartilage maintain its shape

Lung

At the top of the throat is a flap of skin, the epiglottis, which prevents food or other particles entering the lungs

The trachea branches into two to enter the lungs as bronchi

The bronchus in each lung divides into bronchioles

Vein

Air is taken into the body through the mouth and nasal cavity. In the nostrils, the air is filtered by tiny hairs (cilia), warmed, and moistened by mucus

At the top of the throat is a flap of skin, the epiglottis, which prevents food or other particles entering the lungs

The trachea branches into two to enter the lungs as bronchi

The bronchus in each lung divides into bronchioles

Vein

Venule

Bronchioles sub-divide into small air sacs, alveoli. Most of the lung tissue is made up of millions of alveoli, which is where the exchange of oxygen into the blood and carbon dioxide out of the blood occurs

The alveoli are covered with very small capillaries, which allow oxygen and carbon dioxide to pass into and out of the blood stream

Alveoli

Arteriole

Artery '

Figure 2.16 The respiratory system.

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