Respiratory tract defense Flashcards
Describe some non-specific defence mechanisms of the respiratory system
- Physical and anatomical measures e.g. position of the head
- Lubricants e.g. mucus
- Reflexes e.g. coughing, sneezing
- Antimicrobials
Describe some specific defence mechanisms of the head
- Lymph nodes/tissue
- Innate and adaptive immunity
- Mucosal immunity- antibody and lymphocytes
What could be a consequence of horses not being able to have their head down to graze
Shipping fever, accumulation of pathogens during transport, head being up for extended periods of time
What can be a benefit of the air and food passages being clode together in the horses head regarding respiratory defence
Swallowing of foreign particles allows them to be destroyed by stomach acid
How is the pharynx involved in draining lymphoid tissue
Draining from the tonsils
What is the role of the arytenoid cartilages
Influence volume of air entering lower airways,
When does the glottis demonstrate reflex closure?
After swallowing, stimulation of larynx, prevents large particles entering lower respiratory tract
What lines the trachea
Lymphoid tissues, cillia, mucus and commensal organisms
What is the role of the cilia
move in a coordinated fashion toward the pharynx
What does the mucus consist of?
Mucoid gel layer, which touch the tips of the cilia.
The sol layer which covers the cilia.
Anti-bacterial lysozyme.
What do the Mucus and cilia form?
mucociliary escalator
Which cells produce mucus?
goblet cells
What do submucosal glands do?
contain serous secretions
What do myoepithelial cells do?
Aid the movement of secretions from the submucosal/subepithelial glands into the lumen
What are defensins
antimicrobial peptides produced by macrophages, neutrophils & epithelium
What are some non-specific defences of the lower respiratory tract
Branching airways, Bronchi surrounded by cartilagenous rings & smooth muscle
How can the structure of the lower respiratory tract influence defence?
- multiple branching of bronchioles causes turbulence & deposition of particles on mucociliary escalator
- Irritant receptor and cough reflex
- Lymphoid cells & tissues
What defence systems are in place in the bronchiole
- Ciliated cells
- Smooth muscle surrounding the bronchioles
- Lymphoid tissue beneath epithelium
- No goblet cells are present in the bronchioles
Describe some adaptions to defence by alveoli
- Enterence is guarded by smooth muscle cells
2. There is a rapid migration of leucocytes from the blood into the alveoli
What do Alveolar type II epithelial cells produce
Surfactant
What are the caretaker functions of Alveolar type II cells?
- If type I cells are damaged, type II cells proliferate and can act as progenitors for I or II
- Synthesis, store and release surfactant into alveolar space where it prevents lung surface adhesion and optimises gas exchange
Which lymphoid tissues are associated with the upper respiratory tract
Tonsils & lymphoid tissue in nasopharynx, Mucosal associated lymphoid tisse (MALT), Bronchus associated lymphoid tissue (BALT)
What are the roles of the lymph nodes in upper respiratory tract defence
- Detect foreign particles on mucosa
- initiate inflammation
- Antigen presenting cells process antigen for lecucocytes
- Drain to local lymph nodes/lymphoid tissues
- Leucocytes recruited to site of inflammation/antibody produce and foreign particle is eliminated
What are the 3 main lymph nodes of the head (in horses), as well as another associated lymphoid tissue
Parotid, Mandibular, Retropharyngeal (tonsils)
