THE RESPIRATORY SYSTEM
Parts of the Respiratory System The Nose or Nasal Cavity The Pharynx The Trachea The Lungs
Gas Exchange The Mechanism of Breathing Breathing Disorders Animation Links
The human respiratory system consists of the lungs and tubes associated with the lungs. It is located in the thorax or chest. The thorax issurrounded by the ribs. The diaphragm forms the base of the thorax.
Contractions of the diaphragm and the intercostals muscle change the size of the thorax and, thus, cause air to move in and out of the lungs.
The main job of the respiratory system is to get oxygen into the body and get waste gases out of the body. It is the function of the respiratory system to transport gases toand from the circulatory system.
Parts of the Respiratory System
THE HUMAN RESPIRATORY SYSTEM CONSISTS OF THE NOSE, NASAL CAVITY, PHARYNX, LARYNX, TRACHEA, SMALLER CONDUCTING PASSAGEWAYS (BRONCHI AND BRONCHIOLES), AND LUNGS.
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The Nose or Nasal Cavity
As air passes through the nasal cavities it is warmed and humidified, so that air that reaches the lungs is warmedand moist. The Nasal airways are lined with cilia and kept moist by mucous secretions. The combination of cilia and mucous helps to filter out solid particles from the air an Warm and moisten the air, which prevents damage to the delicate tissues that form the Respiratory System. The moisture in the nose helps to heat and humidify the air, increasing the amount of water vapour the air entering thelungs contains. This helps to keep the air entering the nose from drying out the lungs and other parts of our respiratory system. When air enters the respiratory system through the mouth, much less filtering is done. It is generally better to take in air through the nose.
To review: he nose does the following:
1. Filters the air by the hairs and mucous in the nose2. Moistens the air
3. Warms the air
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The pharynx is also called the throat. As we saw in the digestive system, the epiglottis closes off the trachea when we swallow. Below the epiglottis is the larynx or voice box. This contains 2 vocal cords, which vibrate when air passes by them. With our tongue and lips we convert these vibrations intospeech. The area atthe top of the trachea, which contains the larynx, is called the glottis.
The trachea or windpipe is made of muscle and elastic fibres with rings of cartilage. The cartilage prevents the tubes of the trachea from collapsing. The trachea is divided or branched into bronchi and then into smaller bronchioles. The bronchioles branch off into alveoli. Thealveoli will be discussed later.
These tubes are lined with mucous-secreting cells and tiny hairs called cilia. The mucous traps bacteria, dust and viruses. The cilia beat and create an upward current. This moves the mucous up and into the oesophagus. Here it goes to the stomach. When we clear our throats we force the mucous away from our vocal cords. This is often called coughing. Itis used to get rid of irritants and excess mucous from our respiratory system.
Click here to view an animation of coughing
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The lungs are spongy structure where the exchange of gases takes place. Each lung is surrounded by a pair of pleural membranes. Between the membranes is pleural fluid, which reduces friction while breathing. The bronchi are divided intoabout a million bronchioles. The ends of the bronchioles are hollow air sacs called alveoli. There are over 700 million alveoli in the lungs. This greatly increases the surface area through which gas exchange occurs. Surrounding the alveoli are capillaries. The lungs give up their oxygen to the capillaries through the alveoli. Likewise, carbon dioxide is taken from the capillaries...
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