Human Anatomy & Physiology: The Respiratory System 2

The pharynx is a funnel-shaped structure that connects the nasal cavity and mouth to the larynx and the esophagus inferiorly. It serves as a passageway for both air and food.

The nostrils, also known as external nares, are the openings in the nose that allow air to enter the respiratory tract. They are responsible for the initial filtration, warming, and humidification of the inhaled air before it reaches the lungs.

The nasal conchae are the delicate, scroll-shaped bone plates that form the lateral walls of the nasal cavity. They help to increase the surface area of the nasal cavity, which aids in the filtration, humidification, and warming of the inhaled air. The nasal conchae also play a role in directing the airflow within the nasal cavity, ensuring that the air is properly distributed and reaches all parts of the nasal passages.

The nasal cavity is the space behind the nose, while the nasal septum divides it into right and left chambers.

The nose is covered with skin, which provides protection and sensation. It is supported by bone, specifically the nasal bones, which give structure and shape to the nose. Muscle is also present in the nose, allowing for movement and control of facial expressions. Finally, cartilage plays a crucial role in supporting and shaping the nose, particularly in the nasal septum and the external framework of the nose.

The inferior and middle nasal conchae are covered by respiratory mucosa, which is a specialized type of epithelium. This respiratory mucosa varies depending on its location within the nasal conchae. In addition to the epithelium, there is a supporting layer of connective tissue present.

The nasal hairs, also known as cilia, provide the first line of defense in the respiratory tract. They help to prevent the entrance of relatively large particles by trapping them in the nasal cavity. The large size of the nasal hairs allows them to effectively filter out these particles and prevent them from entering further into the respiratory system.

The cilia within the nasal mucous membrane help to move the mucus with the trapped particles toward the pharynx. As the mucus reaches the back of the throat, it is swallowed. The gastric juices of the stomach will destroy most microbes and thus help prevent respiratory infections.

The pharynx is a muscular tube that connects the nasal and oral cavities to the larynx and esophagus. It is approximately 5 inches long.

The pharynx serves as a common pathway for both the respiratory and digestive systems. It plays a crucial role in facilitating the movement of air from the nasal cavity to the lungs during respiration and also helps in the passage of food and liquids from the mouth to the esophagus during digestion. Additionally, the pharynx is involved in producing sounds of speech, making it essential for communication.

The upper respiratory tract consists of the nose, nasal cavity, sinuses, and pharynx. These structures are responsible for the initial filtration, warming, and humidification of the inhaled air. The nose acts as the main entrance for air and is lined with tiny hairs and mucus-producing cells that help trap and remove foreign particles. The nasal cavity is a hollow space behind the nose that further filters and moistens the air. The sinuses are air-filled cavities located in the bones of the face, which help to lighten the skull and produce mucus. The pharynx is a muscular tube connecting the nasal cavity and mouth to the larynx and esophagus, serving as a passage for both air and food.

The superior conchae, which are structures in the nasal cavity, are covered by specialized tissue called olfactory epithelium. This tissue contains receptors that are responsible for the sense of smell. These receptors detect odor molecules in the air and send signals to the brain, allowing us to perceive different smells.

The nasal mucous membrane is made up of a type of epithelium called pseudostratified ciliated columnar epithelium. This type of epithelium appears stratified, but all cells are in contact with the basement membrane. It is characterized by the presence of cilia, which help in moving mucus and trapped particles out of the nasal cavity. Goblet cells, which are specialized cells that secrete mucus, are also found in abundance in the nasal mucous membrane. These cells play a crucial role in trapping and removing foreign particles, as well as moisturizing and protecting the nasal passages.

The nasal mucous membrane has three main functions. Firstly, it warms the incoming air, ensuring that it reaches the lungs at a suitable temperature. Secondly, it moistens the air, preventing the respiratory system from becoming too dry. Lastly, the mucous membrane uses mucus to entrap dust and other small particles, preventing them from entering the lungs and causing potential harm.

The spaces in the bones of the skull that open into the nasal cavity are called sinuses, specifically paranasal sinuses. These sinuses are lined with a mucous membrane that is continuous with the lining of the nasal cavity. This mucous membrane helps to warm and humidify the air that passes through the sinuses and into the nasal cavity.

The paranasal sinuses serve to lighten the weight of the skull by providing air-filled spaces. Additionally, they modify sounds and speech sounds by acting as resonating chambers, which amplifies the sound produced.