Key Words
alveoli
“The alveoli resemble a bunch of grapes… They are made of one layer of squamous epithelial tissue and contain a rich network of blood capillaries. The capillaries allow oxygen and carbon dioxide to be exchanged between the blood and the lungs.”
epiglottis
“The epiglottis, a special leaflike piece of cartilage, closes the opening into the larynx during swallowing. This prevents food and liquids from entering the respiratory tract.”
larynx
“The larynx, or voice box, lies between the pharynx and trachea… The opening between the vocal cords is called the glottis.”
pharynx
“The pharynx, or throat, lies directly behind the nasal cavities… The pharynx is divided into three sections: nasopharynx, oropharynx, and laryngopharynx.”
trachea
“The trachea (windpipe) is a tube extending from the larynx to the center of the chest. It carries air between the pharynx and the bronchi… A series of C-shaped cartilages help keep the trachea open.”
bronchi
“The trachea divides into two bronchi near the center of the chest, a right bronchus and a left bronchus… Each bronchus enters a lung and carries air from the trachea to the lung.”
expiration
“When the diaphragm and intercostal muscles relax, the process of expiration (exhalation) occurs. Air is forced out of the lungs and air passages.”
lungs
“The right lung has three sections… The left lung has only two lobes… Each lung is enclosed in a membrane, or sac, called the pleura.”
pleura
“The lungs are enclosed in a membrane, or sac, called the pleura. The pleura consists of two layers of serous membrane… A pleural space… is filled with a thin layer of pleural fluid that lubricates the membranes.”
ventilation
“Ventilation is the process of breathing. It involves two phases: inspiration and expiration.”
bronchioles
“In the lungs, the bronchi continue to divide into smaller and smaller bronchi until, finally, they divide into the smallest branches, called bronchioles.”
external respiration
“External respiration is the exchange of oxygen and carbon dioxide between the lungs and bloodstream.”
nasal cavities
“A wall of cartilage, called the nasal septum, divides the nose into two hollow spaces, called nasal cavities. The nasal cavities are lined with a mucous membrane and have a rich blood supply.”
respiration
“The process of respiration is controlled by the respiratory center in the medulla oblongata of the brain… It causes an increased respiration rate when oxygen is low or carbon dioxide is high.”
cellular respiration
“Internal respiration is the exchange of carbon dioxide and oxygen between the tissue cells and the bloodstream… The cells then use the oxygen and nutrients to produce energy, water, and carbon dioxide.”
inspiration
“Inspiration (inhalation) is the process of breathing in air… The diaphragm and the intercostal muscles contract and enlarge the thoracic cavity to create a vacuum. Air rushes in through the airways to the alveoli.”
nasal septum
“A wall of cartilage, called the nasal septum, divides the nose into two hollow spaces.”
respiratory system
“The respiratory system consists of the lungs and air passages… This system is responsible for taking in oxygen… and removing carbon dioxide… The parts of the respiratory system are the nose, pharynx, larynx, trachea, bronchi, alveoli, and lungs.”
cilia
“Tiny, hairlike structures, called cilia, filter inhaled air to trap dust and other particles. The cilia then help move the mucous layer that lines the airways to push trapped particles toward the esophagus."
internal respiration
“Internal respiration is the exchange of carbon dioxide and oxygen between the tissue cells and the bloodstream.”
nose
“The nose consists of a bony framework and cartilage with skin covering this framework. It has two openings, called nostrils or nares, through which air enters.”
sinuses
“Sinuses are cavities in the skull that surround the nasal area… They are lined with a mucous membrane that warms and moistens air. The sinuses also provide resonance for the voice.”