Host Defence Non Immune Mechanisms Flashcards
What are the functions of the lungs?
Gas exchange - O2 and CO2
Control pH of the blood
Also have non respiratory functions such as speech, synthesis of hormones and neuropeptides
What is intrinsic, innate and adaptive immunity?
Intrinsic defences are always there they are physical and chemical barriers.
Innate defence is induced by infection - cytokines, macrophages NK cells.
Adaptive immunity is tailored to a pathogen - T and B cells — these are the only specific ones.
How is the epithelium involved in host defence in the lungs?
Respiratory epithelium serves to moisten and protect the airways. Also functions to act as a barrier to pathogens preventing infection and tissue injury by the mucociliary escalator.
They also secrete molecules - which act as chemical barriers:
Antiproeinases is an example.
What is the job of the non pathogenic bacterial flora of the lungs?
It is a non specific defence mechanism - competes with pathogens forming a hostile environment.
What is airway mucus?
It is a viscoelastic gel containing water, CHOs, proteins and lipids.
It is the secretory product of the goblet cells of the airway found on the surface of the epithelium and the submucosal glands.
What is the function of mucus?
Mucus protects the epithelium from foreign material (traps bacteria in its mucus mesh) and prevents fluid loss.
How is mucus removed from the lower respiratory tract?
Via the mucocilliary escalator:
The cilia beat in directional waves to move the mucus up the airways.
It is moved up to the pharynx where it is swallowed and hence removing the threat of a lung infection.
What is a cough?
It is an expulsive reflex that protects the lungs and respiratory passages from foreign bodies.
It can be voluntary or a reflex
Afferent by the vagus nerve and an efferent signal travels down the phrenic, and spinal motor nerves to expiratory musculature to produce the cough.
Causes of a cough?
Irritants - smoke, dust
Diseased conditions - COPD
Infections - influenza
What is a sneeze?
An involuntary expulsion of air containing irritants from the nose.
What happens after the airway epithelium are damaged from viruses that target the airway epithelial cells.
Following injury the airway epithelium will usually have a complete repair.
This is because the epithelium exhibit a level of functional plasticity.
One cell type can from another and so on until all damaged cells are regained in that area.
When damaged epithelium cells are repaired what can go wrong?
When the process goes wrong often it can result in pulmonary disease. Abnormal epithelial responses to injury underpin many obstructive lung diseases.
Often result in the formation of a mucus plug.
Non immune host defence =?
The nonspecific innate immune response provides a first line of defense that can often prevent infections from gaining a solid foothold in the body. These defenses are described as nonspecific because they do not target any specific pathogen; rather, they defend against a wide range of potential pathogens.
