Human Respiratory System: Parts and Functions
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Respiratory System
The respiratory system includes the nose, throat, voice box, windpipe, and lungs.
At the top of the respiratory system, the nostrils bring air to the nose, where it is filtered, warmed, and moistened. Tiny hairs called cilia protect the nasal passageways and other parts of the respiratory tract, filtering out dust and other particles that enter the nose through the breathed air. Air can also be breathed in through the mouth. The two airways of the nose and mouth meet up at the pharynx, which is located at the back of the throat. The pharynx carries both food and air and is used for digestion and respiration. One path is for food: this is called the esophagus, which leads on to the stomach. The other side is for air: it is called the trachea.
A small flap of tissue called the epiglottis covers the air-only passage when we swallow, this stops food and liquid from going into the lungs. The larynx or voice box is located at the top of the trachea, the air-only pipe. This is where our vocal cords are. The trachea or windpipe, which is a 2cm to 3cm tube, then extends downwards from the bottom of the larynx for about 12cm. The walls of the windpipe are made strong by stiff rings of cartilage that keep it open. The trachea is also lined with tiny hairs. They sweep foreign particles and fluids out of the airways, keeping them from entering the lungs. The windpipe divides into two branches, and each one of these enters one of the two lungs of the body. Each branch resembles the limbs of a tree dividing into smaller, finer branches called bronchioles. The bronchioles end in tiny air sacs called alveoli, which look a bit like grapes. These structures enable fresh air to get to the air sacs, which are surrounded by tiny blood vessels or capillaries. The oxygen passes through these air sacs and travels through the capillary walls into the bloodstream. At the same time, carbon dioxide transfers from the bloodstream into the air sacs where it gets breathed out of the body.
Key Functions of the Respiratory System:
- Air Intake: Nostrils and mouth bring air into the body.
- Air Filtration: Cilia in the nasal passages filter out dust and particles.
- Gas Exchange: Oxygen enters the bloodstream, and carbon dioxide is expelled through the alveoli.
- Voice Production: The larynx houses the vocal cords, enabling speech.