Respiratory System Functions

Functions of the Respiratory System

• The respiratory system supplies oxygen to the body.
• It eliminates carbon dioxide.
• It oversees gas exchange between the blood and external environment.
• It provides passageways for air to reach the lungs.
• It purifies, humidifies, and warms incoming air.

Anatomy of the Respiratory System

• The respiratory system includes the nose, pharynx, larynx, trachea, bronchi, and lungs.
• The lungs contain alveoli.

Larynx

• The larynx, or voice box, routes air and food into the proper channels.
• It plays a role in speech.
• It is located inferior to the pharynx.
• It is formed by eight rigid hyaline cartilages and a spoon-shaped flap of elastic cartilage, the epiglottis.
• The thyroid cartilage is the largest of the hyaline cartilages.
• The epiglottis protects the superior opening of the larynx.
• The vocal folds vibrate with expelled air to allow us to speak.
• The glottis is the slitlike passageway between the vocal folds.

Trachea

• The trachea, or windpipe, is 10-12 cm long.
• It extends from the larynx to the level of the fifth thoracic vertebra.
• Its walls are reinforced with C-shaped rings of hyaline cartilage.
• The trachea is lined with ciliated mucosa that propels mucus.

Pharynx

• The pharynx is a muscular passageway, 13 cm long.
• It serves as a common pathway for air and food.
• The pharynx has three portions: nasopharynx, oropharynx, and laryngopharynx.
• The pharyngotympanic tubes drain the middle ear and open into the nasopharynx.
• The pharyngeal tonsil, or adenoid, is located in the nasopharynx.
• The palatine tonsils are in the oropharynx.
• The lingual tonsils are at the base of the tongue.

The Nose

• The nose is the only externally visible part of the respiratory system.
• Air enters the nose through the nostrils.
• The nasal cavity is divided by a midline nasal septum.
• The olfactory receptors for the sense of smell are located in the mucosa.
• The respiratory mucosa warms the air and traps incoming bacteria and foreign debris.
• The mucus produced by the mucosa's glands moistens the air and traps incoming bacteria and foreign debris.

Additional Structures

• Ciliated cells of the nasal mucosa create a gentle current that moves the sheet of contaminated mucus posteriorly.
• The conchae are mucosa-covered projections that increase the surface area of the mucosa exposed to the air.
• The palate separates the nasal cavity from the oral cavity.
• The paranasal sinuses are located in the frontal, sphenoid, ethmoid, and maxillary bones.
• The paranasal sinuses lighten the skull and act as a resonance chamber for speech.

Main Bronchi

• The right and left main bronchi are formed by the division of the trachea.
• Each main bronchus runs obliquely before it plunges into the medial depression of the lung on its own side.
• The right main bronchus is wider, shorter, and straighter than the left.

Lungs

• The lungs occupy the entire thoracic cavity, except for the mediastinum.
• The apex of each lung is just deep to the clavicle.
• The base of each lung rests on the diaphragm.
• Each lung is divided into lobes by fissures.
• The left lung has two lobes, and the right lung has three.
• The surface of each lung is covered with a visceral serosa called the pulmonary, or visceral pleura.

Respiratory Zone Structures

• The respiratory zone includes the respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli.
• The respiratory zone is the only site of gas exchange.

The Respiratory Membrane

• The walls of the alveoli are composed of a single, thin layer of squamous epithelial cells.
• Alveolar pores connect neighboring air sacs and provide alternative routes for air.
• The respiratory membrane, or air-blood barrier, includes the alveolar and capillary walls, their fused basement membranes, and occasional elastic fibers.
• Alveolar macrophages wander in and out of the alveoli, picking up bacteria, carbon particles, and other debris.
• Cuboidal cells produce surfactant, a lipid molecule that coats the gas-exposed alveolar surfaces and is important in lung function.

Learn about the essential functions of the respiratory system, including oxygen supply, elimination, gas exchange, and more. Understand how the respiratory system works to keep our body healthy.