What are the defense mechanisms of the respiratory tract ? Describe each one briefly
They strain out particles larger than 10 µm in diameter .
Most of the remaining particles of this impact on or near the tonsils and adenoids which are large collections of immunologically active lymphoid tissue in the back of the pharynx.
- Reflex bronchial constriction –
Particles 2 – 10 µm in diameter generally fail on the walls of the bronchi as the air flow slows in the smaller air passage and there they irritate bronchial constriction and coughing
Bronchial secretions by the respiratory mucosa contain immunoglobins ( IgA) and other substance that helps to resist infections and maintain the integrity of the mucosa , in addition , the epithelium of the paranasal sinuses appears to produce NO, which is bactriostatic and helps prevent infections
- Cilia of the respiratory epithelium
Cilia gets rid of particles ( 2 – 10 µm) which fail on the walls of the bronchi by beating rhythmically to move the particles with the mucus up the respiratory tract
- Pulmonary alveolar macrophages –
They play a major role in the pulmonary defense mechanisms . They are actively phagocytic and ingest inhaled bacteria and small particles ( less than 2 µm). They also process inhaled antigens for immunologic attack and they secrete chemokines that attract granulocyte to the lungs as well as substance that stimulate granulocyte and monocyte formation in the bone marrow.
Labels: CVS Revision, Physiology SEQ, Revision, RS, RS SEQs