Objectives

    1. explain the physiology of normal airway clearance?

      • the normal airway clearance requires :

        1. a patent airway

          • structural support

        2. a functional mucocillary escalator

          • mucocillary mucosa line larynx to respiratory bronchioles

          • mucus orignates from goblet cells and move the mucus toward pharynx where it can be coughed or swallowed

        3. an effective cough

          • protective mechanism

        4. adequate humidification

      • Effective cough reflex to expel secretions and foreign particles

      • Adequate hydration to maintain mucus viscosity and facilitate movement

      • Proper lung mechanics, including adequate lung volumes and compliance.

      • Normal airway clearance is primarily achieved

      • through the coordinated actions of cilia, mucus production, and respiratory muscles, which work together to trap and expel inhaled particles and pathogens.

        This process involves several key steps:

        • Cilia: Tiny hair-like structures on the surface of airway epithelial cells beat in a coordinated manner to move mucus upwards toward the throat.

        • Mucus production: Goblet cells in the airway epithelium secrete mucus, which traps dust, allergens, and pathogens, preventing them from reaching the lungs.

        • Respiratory muscles: The diaphragm and intercostal muscles facilitate deep breathing, which helps to clear mucus from the airways through coughing or expectoration.

    2. Discuss conditions that would affect normal airway clearance physiology. Give an example of diease process that would affect each requirement of normal clearance?

      • Ciliary dysfunction: Conditions such as primary ciliary dyskinesia can impair the movement of cilia, leading to inadequate mucus clearance and increased risk of respiratory infections.

      • Excessive mucus production: Diseases like asthma can cause hypersecretion of mucus, which obstructs airways and hinders effective clearance.

      • Muscle weakness: Conditions such as muscular dystrophy may weaken the diaphragm and intercostal muscles, compromising the ability to generate sufficient force for effective coughing and mucus expulsion.

    3. Explain the four phases of a cough ?

      1. irritation : abnormal stimulus provokes sensory fibers in the airway to send a response to the brain

        • Inflammatory - swelling, bronchonconstriction

        • mechanical - mucus , dust, foreign body '

        • chemical - gas , chloride, smoke

        • thermal - cold air

      2. inspiration: cough center in brain generates signal via phrenic nerve to diaphragm for a 1 - 2 liter inhalation

      3. compression : epiglottis closes and a forceful contraction of the expiratory muscle against that closed glottis creates large pressure thorax

      4. expulsion: glottis opens, violent expulsion of flow is expelled, and velocity and dynamic compression displace mucus from lower to upper airway to be expelled