Description: The nasal passages are one way for oxygen to enter the respiratory system
in addition to the mouth. Carbon dioxide can also be expelled out the
through the nasal cavity.
Description: The pharynx is the opening behind the oral cavity into the windpipe and
esophagus. It is the only other anatomical structure to handle both food
and air. The nasopharynx and oropharynx lead to the larynx.
Description: The larynx is made of tissue folds, called vocal cords, and cartilage. As
air passes through the larynx speech can be formed. A flap called the
epiglottis covers the larynx during the swallow reflex to prevent food from
entering.
Description: The trachea begins the lower respiratory tract. It is a tube held open by
incomplete rings of cartilage. The trachea partially collapses when the
esophagus swallows food. The tube is lined with goblet cells that produce
mucus to protect from foreign particles that are breathed in.
Description: Bronchi branch off the trachea into the
left and right lungs. They undergo further branching, as bronchioles, to
conduct air into the lungs for gas exchange.
Description: The lungs have small, thin walled air pouches called alveoli that allow for
efficient gas exchange with the blood. Alveoli are in alveolar sacs at the
ends of alveolar ducts containing blood vessels. Respiratory bronchioles
conduct air directly into the alveolar sacs.
