The Respiratory System

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The respiratory system
The respiratory system is responsible for providing oxygen and removing carbon dioxide, heat and water vapours. All living creatures require oxygen and give off carbon dioxide. Oxygen is required for every cell in your body to function. Structure of the respiratory system:

Normally air is taken in through your nose however sometimes it is taken in through your mouth and passes through a series of airways to reach the lungs. This series of airways is known as the respiratory tract and can be divided into two parts. The upper respiratory tract includes the nose, nasal cavity, mouth, pharynx and larynx; and the lower respiratory tract includes the trachea, bronchi and lungs. Nasal cavity: Your nose is divided into the external nose and the internal nasal cavity. When you breathe in the air enters through the nostrils into the cavity. The hair in your nostrils filters the air to get rid of the stuff that’s not needed like dust before it passes into the two passages of the nasal cavity. The air is then warmed and moistened in the passages before it passes into the nasopharynx. A sticky mucous layer traps small objects that the hair in the nostrils didn’t filter out and is sent to the pharynx to be swallowed by the tiny hairs called cilia. Epiglottis: This is a small flap at the back of your tongue, the epiglottis closes the top of the trachea when you swallow to make sure food and drink go down to your stomach and not into your lungs. Pharynx: This connects the nasal cavity and mouth to the larynx and oesophagus. This is known as the throat, the pharynx is a small tube from the base of the skull to the sixth cervical vertebra. The muscular pharynx wall is made up of skeletal muscle throughout its length. This is a passageway for food as well as air; therefore special adaptations are required to prevent chocking from happening. Larynx: This known as the voice box. The larynx has rigid walls of muscle and cartilage, it contains the vocal cords. It also connects the pharynx to the trachea. It goes from the third to the sixth vertebra. Trachea: This known as the windpipe and represents the start of the lower respiratory tract. It contains rings of cartilage to prevent it from collapsing and is very flexible. It travels down the neck in front of the oesophagus and branches into the right and left bronchi. Bronchus: The right and left bronchi are formed by the division of the trachea. They transport air into the lungs. The right bronchus is shorter and wider than the left. By the time the air reaches the bronchi it is warm, moistened and clear. Once inside the lungs, each bronchus subdivides into lobar bronchi: three on the right and two on the left. The lobar bronchi branch into segmental bronchi, which divide again into smaller and smaller bronchi. Overall, there are approximately 23 orders of branching bronchial airways in the lungs. Bronchioles: Bronchioles are small airways that extend from the bronchi. They are the first airway branches of the respiratory system that don’t contain cartilage. Bronchioles end in clusters of thin-walled air sacs, known as alveoli. Lungs: The right and left lung occupy most of the thoracic cavity and go down to the diaphragm. They hang suspended in the right and left pleural cavities straddling in the heart. The left lung is smaller than the right because the heart is behind the left lung. Lobes: Each lung is divided into lobes; the left lung has two and the right lung has three. Pleural membrane and cavity: The lungs are surrounded by membranes known as pleura. These contain a cavity with fluid that lubricates the pleural surfaces as the lungs contract and expand. This prevents friction when the lungs contract and expand and also keeps the lungs airtight. Thoracic cavity: This is the chamber of the chest that is protected by the thoracic wall; it is separated from the abdominal cavity by the diaphragm. Visceral pleura: This is the innermost of the two pleural membranes;...
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