Respiratory defenses Flashcards
What are the primary portals of entry for pathogens
Respiratory tract
GI tract
Name two secondary lymphoid tissues
Bronchial-associated lymphoid tissue (BALT)
Gut-associated lymphoid tissue (GALT)
How are pathogens transferred across mucosa
By M cells
What are mucus membranes
Layers of mucosal cells that line body cavities that open to the outside
What antimicrobial substance does mucus contain
Lysozymes, lactoferrin
Two characteristics of mucus
Contains antimicrobial substance
Mucosal cells are rapidly dividing
Physical and chemical barriers in respiratory tract
Nasal hair mucous secretions irregular chambers ciliated epithelium cough reflexes alveolar macrophages
Barriers in the nasopharynx
Squamous epithelium Nasal hairs Turbinates including mucosal lymphoid tissue Ciliated epithelium Mucous layer Innate factors Secretory IgA and some IgG
How do particles and bacteria come into contact with the mucosa lining the nasopharynx and larynx
An increase in air turbulence is caused due to the abrupt changes in direction of air flow that occur as the air moves through nasopharynx and larynx
Barriers in larynx
Cords
Epiglottis
Cough reflex
How are secretions above the sub-segmental level removed
By coughing
How are the secretions below the sub-segmental level removed
Moved upward by the mucociliary mechanism
then removed by coughing
Barriers in the trachea and bronchi
ciliated epithelium
Muscociliary escalator
cough reflex
Barriers in small airways and alveoli
Epithelial cells Alveolar macrophages Lymphocytes Innate factors IgG and IgA
What are some secretions in the respiratory tract
Lactoferrin Reactive oxygen species Interfons Inflammatory factors Antibodies
How many cilia is present in the ciliated cell in the trachea and bronchioles
200
What happens to the ciliary beat rate as you move down the tracheo-bronchia tree
ciliary beat rate slower
What impairs ciliary action
dehydration, smoking, inhalation of high oxygen concentrations, infections and ingestion of drugs
What is broncho-constriction
Defence mechanism where bronchi constrict in an effort to prevent entry of the irritants like dust and aerosols
where are lymphocytes found in the lung
In the submucosal collection BALT
What three immunoglobulins are found in greater concentration in the lung than in serum
IgA, IgG3 and IgG4
What two immunoglobulins contribute significanly to the defence against infection in lungs
IgG and IgA
What immune cell is not present in healthy lungs
How does it arrive to the lungs
Neutrophils
Recruited to the lung by a variety of stimuli
What immune cell is not present in healthy lungs
How does it arrive to the lungs
Neutrophils
Recruited to the lung by a variety of stimuli
why is mucus not present in alveoli
Mucus is too thick and would slow movement of oxygen and carbon dioxide
What defences are present in alveoli
Alveolar macrophages which ingest any deposited particle and digest them
When lung is exposed to serious threat, neutrophils are recruited to help
Where does proliferation occur in alveolar macrophages
Interstitium and alveolar space
What happens to the debris of phagocytosis in alveoli
Moved up to the level of the bronchioles so that they can be removed by cilia or removed from the lungs by lymphatic system
Where do particles between 5-10 microns deposite
In the trachea and main bronchi and can be removed by mucociliary transport
WhaT IS CHEMOTAXIS
Process by which phagocytes are attracted to microorganisms
What is the attachment stage of phagocytosis
the phagocyte adheres to the micorbial cell
Facilitated by opsonisation
What is the ingestion phase of phagocytosis
Pseudopods of phagocytes engulf the microorganism and enclose it in a phagosome to complete ingestion
What is the digestion phase of phagocytosis
Lysosomes fuse with the phagosome to form a digestive vacuole
the microbe is killed and digested
