Anatomy of the Respiratory Tract

The upper respiratory tract warms, moistens, and filters the air we breathe.

Hair-like structures at the entrance of the nose that trap large dust particles. These hairs are called vibrissae.

Projections from the lateral wall of the nasal cavity that create turbulence in the airflow. This allows for more time for the air to be warmed, moistened, and filtered.

The lining of the nasal cavity. It's made of specialized cells that produce mucus to trap particles and cilia that sweep trapped particles to the pharynx to be swallowed.

Tiny, hair-like structures on the surface of the nasal mucosa that move trapped particles toward the pharynx.

Air-filled cavities within the skull that connect to the nasal cavity. They help lighten the skull and contribute to voice resonance.

The throat, a muscular tube shared by both the respiratory and digestive systems. It's divided into three parts: nasopharynx, oropharynx, and laryngopharynx.

A structure in the neck that protects the airway, prevents food from entering the lungs, and produces sound. It's made of cartilage, muscles, and vocal cords.

Tiny, flap-like structures in the larynx that vibrate to create sound when air passes through them.

The opening between the vocal cords, allowing air to pass through. It closes during swallowing to prevent food from entering the airway.

Cartilaginous structure that folds over the glottis during swallowing, preventing food or drink from entering the airway.

The uppermost cartilage in the larynx, connected to the tongue.

A large, shield-shaped cartilage that protects the larynx and forms the front of the neck.

Two pairs of small, pyramid-shaped cartilages in the larynx, crucial for controlling the tension and position of the vocal cords.

The trachea, a flexible tube, connects the larynx to the bronchi. It's about 4.5 cm long and 2.5 cm in diameter.

The trachea is located in front of the esophagus, which carries food to the stomach.

Rings of cartilage support the trachea, preventing it from collapsing. This helps maintain an open airway for breathing.

The lining of the trachea is covered in hair-like structures called cilia and mucus-producing cells (goblet cells). These work together to protect the lungs by trapping dust and other irritants.

The bronchial tree is a branching network of air tubes that connects the trachea to the tiny air sacs (alveoli) in the lungs.

Primary bronchi are the first branches of the bronchial tree. These large tubes supply air to each lung.

Secondary bronchi are the branches that deliver air to each lobe of the lung. The number of lobes per lung varies (3 right, 2 left).

As the bronchi branch into bronchioles, the amount of cartilage decreases, the amount of smooth muscle increases, and the epithelial lining gets thinner.

Tertiary bronchi, also known as segmental bronchi, are branches of the secondary bronchi that supply specific segments of the lungs. Each lung has 10 tertiary bronchi on the right side and 8 on the left. They are characterized by the presence of cartilage plates within their walls.

Bronchioles are smaller airways in the lungs lacking cartilage, unlike bronchi. They are lined with simple columnar epithelium with cilia and contain a layer of smooth muscle that allows them to constrict and dilate, controlling airflow.

Terminal bronchioles are the final segment of the conducting zone before the respiratory zone in the lungs. They are lined with simple columnar epithelium with cilia but lack goblet cells and mucous glands. These bronchioles are responsible for delivering air to respiratory bronchioles.

Respiratory bronchioles are the transition zone between the conducting airways and the gas exchange units (alveoli) in the lungs. They are lined with simple cuboidal epithelium, lack cilia, and contain Clara cells that produce surfactant. Alveoli directly extend from the lumen of these bronchioles allowing for gas exchange.

Clara cells are specialized cells found in the terminal and respiratory bronchioles of the lung. Their main function is to produce surfactant, which reduces surface tension in the alveoli and helps prevent their collapse during exhalation.

Tiny air sacs in the lungs where gas exchange occurs between the air and blood.

Alveoli are arranged in clusters called alveolar sacs, which are connected by elongated airways called alveolar ducts.

Alveoli are surrounded by a dense network of capillaries, providing a large surface area for efficient gas exchange.

Type I alveolar cells form the thin wall of alveoli, allowing for easy gas diffusion. Type II cells produce surfactant, which reduces surface tension and prevents alveoli from collapsing.

The respiratory membrane is formed by the thin layers of the alveolar wall, the basement membrane, and the capillary wall, allowing for rapid diffusion of gases.

The respiratory tract can be divided into conductive and respiratory portions. The conductive portion filters, warms, and moistens the air, while the respiratory portion is responsible for gas exchange.

The conductive portion includes the nasal cavity, pharynx, larynx, trachea, bronchi, and bronchioles, all involved in air transport and preparation.

The respiratory portion includes the respiratory bronchioles, alveolar ducts, and alveoli, where gas exchange actually takes place.