The respiratory tract is a complex system that keeps you breathing. It's split into upper and lower parts, each with unique structures. The upper tract filters and preps air, while the lower tract handles gas exchange in the lungs.
From nose to lungs, this system works together to keep you alive. It filters out nasty stuff, warms and humidifies air, and swaps oxygen for carbon dioxide. Understanding how it all connects is key to grasping respiratory health.
Respiratory Tract Anatomy
Upper and Lower Respiratory Tracts
Top images from around the web for Upper and Lower Respiratory Tracts
13.2 Structure and Function of the Respiratory System – Human Biology View original
Is this image relevant?
Organs and Structures of the Respiratory System | Anatomy and Physiology View original
Is this image relevant?
Mechanics of Breathing | Boundless Anatomy and Physiology View original
Is this image relevant?
13.2 Structure and Function of the Respiratory System – Human Biology View original
Is this image relevant?
Organs and Structures of the Respiratory System | Anatomy and Physiology View original
Is this image relevant?
1 of 3
Top images from around the web for Upper and Lower Respiratory Tracts
13.2 Structure and Function of the Respiratory System – Human Biology View original
Is this image relevant?
Organs and Structures of the Respiratory System | Anatomy and Physiology View original
Is this image relevant?
Mechanics of Breathing | Boundless Anatomy and Physiology View original
Is this image relevant?
13.2 Structure and Function of the Respiratory System – Human Biology View original
Is this image relevant?
Organs and Structures of the Respiratory System | Anatomy and Physiology View original
Is this image relevant?
1 of 3
The respiratory tract is divided into the upper and lower respiratory tracts, each containing specific structures that facilitate the movement and conditioning of air
The upper respiratory tract includes the nose, nasal cavity, paranasal sinuses, and pharynx (nasopharynx, oropharynx, and laryngopharynx) which filter, warm, and humidify incoming air
The lower respiratory tract consists of the larynx, trachea, bronchi, bronchioles, and lungs which are responsible for conducting air to the lungs and facilitating gas exchange
Key Structures of the Respiratory Tract
The larynx, also known as the voice box, connects the pharynx to the trachea and contains the vocal cords, which are responsible for sound production
The trachea, a flexible cartilaginous tube, extends from the larynx to the primary bronchi and is lined with pseudostratified ciliated columnar epithelium and contains C-shaped cartilage rings that prevent collapse
The lungs, the primary organs of the respiratory system, are divided into lobes (three on the right and two on the left) and are enclosed by the pleural membranes
The nose and nasal cavity contain hair and mucus that trap particles and pathogens, preventing them from entering the lungs
The extensive blood supply and large surface area of the nasal cavity help to warm and humidify the air to body temperature and near 100% humidity
Respiratory Tract Functions
Upper Respiratory Tract Functions
The upper respiratory tract functions to filter, warm, and humidify incoming air, preparing it for entry into the lower respiratory tract and lungs
The nose and nasal cavity trap particles and pathogens with hair and mucus, preventing them from entering the lungs
The extensive blood supply and large surface area of the nasal cavity warm and humidify the air to body temperature and near 100% humidity
Lower Respiratory Tract Functions
The lower respiratory tract is responsible for conducting air to the lungs, facilitating gas exchange, and expelling air during exhalation
The trachea, bronchi, and bronchioles act as a conduit for air to reach the alveoli, where gas exchange occurs
The alveoli, tiny sac-like structures in the lungs, are surrounded by capillaries, allowing for efficient diffusion of oxygen into the bloodstream and carbon dioxide out of the bloodstream
The upper and lower respiratory tracts work together to maintain proper ventilation, gas exchange, and homeostasis within the body
Respiratory Mucosa and Ciliated Epithelium
Structure and Function of Respiratory Mucosa
The respiratory mucosa lines the majority of the respiratory tract and consists of a layer of epithelial cells, a basement membrane, and a lamina propria which plays a crucial role in protecting the respiratory system from pathogens and debris
The respiratory epithelium is primarily pseudostratified ciliated columnar epithelium, which contains goblet cells that secrete mucus and ciliated cells with hair-like projections called cilia
Goblet cells produce mucus, a sticky substance that traps inhaled particles, pathogens, and debris, preventing them from reaching the lungs
Ciliated Epithelium and the Mucociliary Escalator
Cilia are tiny hair-like projections on the surface of the epithelial cells that constantly beat in a coordinated manner to move the mucus and trapped particles towards the pharynx, where it can be swallowed or expelled (mucociliary escalator)
The respiratory mucosa also contains antimicrobial substances, such as lysozyme and defensins, which help to neutralize pathogens and protect the respiratory system from infection
Damage to the respiratory mucosa or ciliated epithelium, such as from smoking or pollutants, can impair the mucociliary escalator and increase the risk of respiratory infections and diseases
Conducting vs Respiratory Zones
Conducting Zone
The conducting zone consists of the structures that facilitate the movement of air from the external environment to the lungs, including the nose, pharynx, larynx, trachea, bronchi, and bronchioles
The main function of the conducting zone is to filter, warm, and humidify the incoming air and to conduct it to the respiratory zone
The conducting zone does not participate in gas exchange, as its epithelium is too thick for efficient diffusion of gases
Respiratory Zone
The respiratory zone consists of the structures where gas exchange occurs, including the respiratory bronchioles, alveolar ducts, and alveoli
The main function of the respiratory zone is to facilitate the diffusion of oxygen from the air into the bloodstream and the diffusion of carbon dioxide from the bloodstream into the air
The respiratory zone has a thin epithelium and an extensive network of capillaries surrounding the alveoli, which allows for efficient gas exchange
The transition from the conducting zone to the respiratory zone occurs at the level of the terminal bronchioles, which are the smallest branches of the bronchial tree that do not contain alveoli