Respiratory Tract Defence Flashcards
list the structures of the respiratory tract
- nares and nasal cavity
- paranasal sinuses
- pharynx
- larynx
- trachea
- bronchi
- bronchioles
- alveoli
what are the functional characterisitcs of the respiratory tract
- olfaction and taste
- vocalisation
- to warm, filter and humidify the air (nasopharynx)
- to conduct O2 & CO2 to and from the lungs
- defence of the lungs (prevent entry via swallowing, trapping, coughing, sneezing
what are the non-specific defences of the respiratory tract
- physical and anatomical (head position, cilia)
- lubricants (mucous)
- reflexes (coughing/sneezing)
- antimicrobial compounds (lysozyme)
what are the non-specific defences of the respiratory tract
- recognition of particles by immune system (passive immunity)
- lymph nodes/tissues (innate immune system)
- mucosal immunity (antibodies and lymphocytes
how does head position prevent entry of particles into the lungs
enourages drainage of respiratory tract (head below lungs while grazing)
how do the nares prevent entry of particles into the lungs
- size
- position
- distribution of hairs within
how do the nasal cavities prevent entry of particles into the lungs
- narrow passaages
- turbulence
- particle deposition
how does swallowing prevent particles from entering the lungs
the close proximity of air and food passaged in the head makes swallowing of foreign particles easy so they can be destroyed by the stomach acid
how does cilia and mucous work together to trap particles and prevent them from entering the lungs
cilia lining the nasal passages and bronchioles are symmetric and their coordinated movement results in waves of motion, moving particles toward the pharynx
- mucoid gel layer produced by goblet cells is touched by cilia
- aqueous sol layer covers the cilia
- contains antibacterial lysozyme
describe the antimicrobial compounds of the respiratory tract and how they work to kill pathogens entering the respiratory tract
defensins:
- short chains of amino acids
- produced by macrophages, neutrophils and epithelium
- electrically charged and attracted to the microbe where it embeds into the membrane and forms a pore
- kills bacteria, fungi and enveloped viruses
lysozyme
- in mucous
- anti-bacterial enzymes
- break down bacterial cell walls
list the mucous producing cells of the repiratory tract and they tpye of mucous they produce
goblet cells => produce viscous secretion which forms a gel layer over the sol (nasal, tracheal, bronchial epithelium)
submucosal glands => contain serous secretions stored at the neck of the gland which opens to the epithelial surface. present in bronchi
clara cells located in alveoli => produce a serous mucin (easily coughed up from lower lung)
which direction do cilia move as part of the mucociliary escalator
towards the pharynx
identify the major draining lymph nodes of the head and respiratory tract
head:
- parotid
- mandibular
- retropharyngeal
thorax:
- thracheobronchial (in deep chest
describe the lymphoid tissues in the respiratory tract
mucosal associated lymphoid tissues: aggregation of lymphocytes under ciliated epithelium
bronchus associated lymphoid tissues: aggregations of lymphocytes beneath non-ciliated epithelium, strategically located at the bifurcations of the bronchi to sample deposits and (potentially) start immune response
compare and contrast the leukocytes you would encounter in histology of the healthy vs diseased lung
healthy lung:
- macrophages
- lymphocytes
- occasional neutrophils
- low levels of mucous
diseased lung:
- macrophages
- lymphocytes
- frequent neutrophils (neutrophilia)
- hemosiderophages (alveolar macrophages that have ingested and digested RBCs)
- excess mucous/secretions
