Question

Name the tissue that lines the larynx and trachea, and describe its function. State the function of the cartilage of the larynx and trachea. (pp. 347-348)

Short answer

Answer: The larynx and trachea are lined by the pseudostratified columnar epithelium, which functions in secretion, mucus production, and protection. The cartilage in the larynx and trachea provides structural support and maintains the shape of the airway.

Step-by-step solution

Name the tissue lining the larynx and trachea.

The tissue that lines the larynx and trachea is called pseudostratified columnar epithelium. This is a type of tissue composed of tightly packed cells, giving it a layered appearance.

Describe the function of the pseudostratified columnar epithelium.

Some functions of the pseudostratified columnar epithelium are secretion and mucus production, as well as protection. The presence of mucus and cilia on the surface of the epithelium helps to trap and remove debris and pathogens, preventing them from reaching the lungs. Cilia move in coordinated, wave-like motions, pushing the mucus up to the throat, where it is swallowed or coughed out.

State the function of the cartilage in the larynx and trachea.

The function of the cartilage in the larynx and trachea is to provide structural support and maintain the shape of the airway. The larynx is made of different cartilages, which fits together to form a rigid framework. The cartilage also protects the vocal cords and allows for speech production. In the trachea, rings of C-shaped cartilage give it rigidity and prevent the airway from collapsing during breathing, ensuring that air can continuously flow in and out of the lungs.

Key concepts

Pseudostratified Columnar Epithelium

The lining of the larynx and trachea is known as pseudostratified columnar epithelium. This tissue consists of a single layer of cells that varies in height, giving it a deceptively multilayered appearance. Be it noted that despite this illusion, each cell makes contact with the basement membrane, emphasizing its truly singular layer.

The significance of this epithelial lining extends to both protection and physical function. The surface of the tissue is dotted with cilia, which are hair-like structures that engage in a synchronized waving movement, crucial for removing contaminants from the respiratory tract. In addition, goblet cells interspersed among the epithelial cells produce mucus, a sticky substance that traps dust, pathogens, and other particulates. Together, the mucus and cilia form an effective defense system, not only trapping but also propelling unwanted materials away from the lungs towards the throat, where they can be expelled.

Larynx and Trachea Function

The larynx, commonly called the voice box, and the trachea, also known as the windpipe, perform vital functions within the respiratory system. The primary role of the larynx is to safeguard the airway during swallowing and to facilitate phonation, the process of sound production. It houses the vocal cords, which vibrate to create sound, making it a critical structure for speech.

The trachea serves an equally essential function as the primary passageway for air to enter the lungs. It provides a clear and direct route for airflow due to its tubular structure. An intricate connection between the larynx and trachea ensures that air passes efficiently into the respiratory system while simultaneously preventing food and other materials from entering the lungs, thanks to the epiglottis, a flap-like structure that closes off the larynx during swallowing.

Airway Cartilage Structure

The robustness of the airway, specifically the larynx and trachea, derives from their unique cartilage structure. The cartilage of the larynx, composed of several pieces that include the thyroid, cricoid, and arytenoid cartilages, forms a protective casing around the vocal cords. These cartilages play a crucial role in voice modulation by adjusting the tension and position of the vocal cords.

In the trachea, the cartilage manifests as a series of stacked, C-shaped rings. These rings prevent the trachea from collapsing and ensure an unobstructed airway, which is particularly important during the act of inhalation and exhalation. The open part of the C faces the esophagus, allowing the trachea to expand slightly as food passes down. Moreover, the firm yet flexible nature of the cartilage allows the neck to move freely without compromising the airway.