bacterial and viral infections of the larynx can cause the vocal cords to swell (get larger), which makes it difficult to speak. This condition is known as pharyngitis. Laryngitis can also be caused by tobacco smoke, alcohol, excessive talking, shouting , or singing.
Remember from the digestive system chapter that a flap of tissue called the epiglottis closes when you swallow food to prevent the food from entering the larynx. The epiglottis is in the open position when you breathe. Besides being part of the path of air, the larynx is also known as the voice box, the place where your voice comes from. Vocal cords are attached to the sides of the larynx. When air passes across the vocal cords, they vibrate and the voice is produced. The reason that people have differ voices is that their vocal cords differ in length and thickness . Because of the effects of the male hormone testosterone, men tend to have thicker and longer vocal cords than women.
After air passes through the larynx, it enters the trachea. A common word for trachea is "windpipe" the trachea is the fairly rigid tube that carries air from the larynx to the lungs. The trachea is fairly rigid because it is supported by rings of cartilage. (recall that cartilage is like bone, bus is more flexible). The many rings of cartilage surrounding the trachea keep it open for breathing and hold is shape
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