The respiratory system

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The respiratory system

1. Define respiration.

Respiration is the process of converting glucose to energy, which goes to every cell in the body.

2. Describe the organs of external respiration.

The nose is divided into the right and left cavities and is lined with tiny hairs and mucous membrane, which secretes a sticky fluid, called mucus, which helps prevent dust and bacteria from entering the lungs. The nose moistens, warms and filters the air and is an organ, which senses smell.

     The naso-pharynx is the upper part of the nasal cavity behind the nose, and is lined with mucous membrane. The naso-pharynx continues to filter, warm and moisten the incoming air.

     The pharynx is a large cavity behind the mouth and between the nasal cavity and larynx. The pharynx serves, as an air and food passage but cannot be used for both purposes at the same time, otherwise choking would result. The air is also warmed and moistened further as it passes through the pharynx.

     The larynx is a short passage connecting the pharynx to the trachea and contains vocal chords. The larynx has a rigid wall and is composed mainly of muscle and cartilage, which help prevent collapse and obstruction of the airway. The larynx provides a passageway for air between the pharynx and the trachea.

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     The trachea is made up of mainly cartilage which helps to keep the trachea permanently open. The trachea passes down into the thorax and connects the larynx with the bronchi, which passes to the lungs.

3. Describe the mechanisms of external respiration including the interchange of gases within the lungs.

The job of the lungs is to transfer oxygen to the blood and to remove waste carbon dioxide from it. To do this the lungs contain millions of alveoli where gas exchange takes place. The alveoli are an ideal exchange surface because they have an enormous ...

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