Respiritory Tract Defence Flashcards
List the structures of the respiritory tract
Nares & nasal cavity
Paranasal sinuses
Pharynx
Larynx
Trachea
Bronchi
Bronchioles
Alveoli
List the functional characteristics of the respiritory tract
Olfaction & taste (gustation)
Vocalisation
To warm, filter & humidify the air (complete by nasopharynx)
To conduct O2 & CO2 to and from the lungs
Defence of the lungs
What are the two defence systems which exclude or remove foreign objects from the respiritory tract?
Non Specific
-removal of physical particles
physical & anatomical
lubricants
reflexes
antimicrobial compounds
Specific
-recognition of particles by the immune system
passive immunity
lymph nodes
innate immune system
mucosal immunity
Explain the structures which prevent foreign bodies entering the lungs
Head postion (especially in grazing animals)
by positioning it downwards it encourages drainage of the respiritory tract
The sizing and position of the nares
Nasal cavity has narrow passages. It creates an airflow which encourages particle deposition
Explain how swallowing acts as a defence in the respiritory tract
Close proximity between oesophagus and trachea
Makes it easier to swallow foreign particles which will then be destroyed in the
stomach acid
Nasal Cavity
Ciliary motion moves foreign particles to the larynx
Larynx/Pharynx/Glottis
Glottis is covered by epiglottic cartilage meaning there is a prevention of food/liquids
to enter larynx & trachea
Explain how ‘Trapping’ works as a defence in the upper respiritory tract
Cilia
Line the nasal passages to the bronchioles
(Excluding pharynx as this is a squamous epithelium)
The symmetric & coordinated movement results in a wave of motions moving
foreign particle towards the pharynx
Mucus
Goblet Cells
Produce viscous secretion which forms gel over the sol
It is present in nasal, tracheal, bronchial epithelium (not terminal bronchioles)
Submucosal (subepithelial) glands
Present in bronchi (not bronchioles). The neck of the gland opens at the
epithelial surface & contain serous secretions
Clara cells
Found in alveoli (lower respiritory tract) & contain serous mucin
What is the Mucociliary escalator?
Mucociliary escalator
Term for apparatus of mucus & cilia
Responsible for the movement of mucus up & out of the Respiritory tract
Explain how antimicrobial compounds act as a defence for the respiritory tract
Defensins
These are short chain amino acids which are produced by macrophages,
neutrophils & epithelium
They are electrically attracted to bacteria, fungi & enveloped viruses and kill them by
embedding in the membrane & forming a pore
Lysozyme
These are antibacterial enzymes found in mucous. They work to break down
bacteria cell walls
Identify the major draining lymph nodes of the head and respiritory tract
Head
Parotid
Mandibular
Retropharyngeal
Thorax
Tracheobronchial
Outline the location and importance of the tracheobronchial lymph node
Found deep within the chest
Viewed radiographically
Used in meat hygiene inspections
Describe the cellular components of the defence system in the respiritory tract, including the lungs
List the cellular defences in the respiratory tract, including the lungs
Lymphoid tissue in the respiratory tract
-MALT & BALT
Alveolar leucocytes
Explain what MALT is
Mucosal associated lymphoid tissue
Aggregation of lymphocytes under ciliated epithelium
Explain what BALT is
Bronchial associated mucosal tissue
Aggregation of lymphocytes beneath non-ciliated beneath non-ciliated epithelium
Strategically located at bifurcations of bronchi turbulence & deposition of particles) to sample deposits
What are the alveolar leucocytes of a healthy lungs?
Macrophages
Lymphocytes
Occasional neutrophils
low levels of mucus
What are the alveolar leucocytes of diseased lungs?
Macrophages
Lymphocytes
Frequent neutrophils (neutrophilia)
Hemosiderophages
Excess mucus / secretions
Outline the diagnostic tools used for lungs
Bronchioalveolar wash (endoscope)
Tracheal wash (endoscope)
Describe the fate of inhaled particles within the respiritory tract
Trapped in mucus and transported via mucociliary escalator
swallow
Stimulation of receptors / reflexes: sneeze or cough / glottis closure
swallow
Stimulation of immune responses / antimicrobial agents in mucus / secretions
killed
What are the leucocytes you can find in the innate response to a respiritory infection?
Macrophages (phagocytosis)
Neutrophils (phagocytosis)
Basophils (degranulation)
Eosinophils (degranulation)
Mast cells (degranulation)
Originate from blood and interstitial fluid. They are carried from the lungs to the trachea
What are the molecules involved in the innate immune response during a respiritory infection
Lysozymes
Defensins
Surfactants
Cytokines
Complement
Inflammatory mediators
How is the adaptive immune response involved with protection of the respiritory system
These circulate in blood & interstitium
They can be recruited to the RT epithelium & lumen
Intraepithelial lymphocytes
associated with mucosal membrane which is adjacent to
site of particle deposition allowing for a rapid response
How is the mucosa involved in the adaptive immune response?
Contains Antibodies
All classes except IgM -not helpful due to large size in this area
Mucosal synthesis of IgA
Diffusion of IgG from serum
What is a bronchiolar spasm?
Sudden constriction of the smooth muscles in the walls of the bronchioles
What causes a bronchiolar spasm?
Irritation (particles, fumes)
Recent or current infection
(bacterial, viral, parasitic)
Allergy
Provide two examples of a allergic inflammation
-Equine asthma (recurrent airway obstruction, heaves, chronic obstructive pulmonary disease)
-Feline asthma
Both are inflammatory diseases
Both lead to bronchoconstriction /bronchospasm
Describe how inflammatory mediators interact with mechanisms of bronchiolar spasm
Allergens themselves are harmless
They activate T & B cells which leads to Type I hypersensitivity reactions:
IgE antibodies have been formed since B-cell first came in contact with antigen
IgE bind to mast cells/ basophils in mucous membranes
If allergen encountered again, mast cells/ basophils degranulate and release a large amount of
histamine & other inflammatory mediators
Inflammatory mediators lead to smooth muscle contraction around bronchioles, directly and via CNS
Bronchoconstriction
Outline the role of the CNS within bronchoconstriction
Inflammatory mediates stimulate neurones
Neurones send the signal to along the afferent parasympathetic pathway to the CNS via Vagus Nerve X
CNS relays this infomration back through the neurones through the efferent pathway
Neurones use neurotransmitter to transfer message to the host cells
smooth muscle then contracts causing bronchoconstriction
What is the treatment strategy and therapeutic mechanism to promote bronchodilation?
Agonist Drugs (clenbuterol, ventipulmin)
Stimulate specific receptors
What is the treatment strategy and therapeutic mechanism to prevent bronchodilation?
Antagonist drugs (ipratropium bromide)
Inhibit specific receptors
What is the treatment strategy and therapeutic mechanism to reduce allergic reaction?
Corticosteroids
Anti-inflammatory
What is the treatment strategy and therapeutic mechanism to stimulate mucociliary action?
Mucokinetic
Stimulate mucus & indirectly, ciliary motility
What is the treatment strategy and therapeutic mechanism to reduce allergic reaction?
Hyposensitisation (allergen immune therapy)
Modulate immune response
What is the treatment strategy and therapeutic mechanism to prevent infection?
Vaccination
Memory cells in adaptive immune response
