Respiratory tract defense

Question 1

Describe some non-specific defence mechanisms of the respiratory system

Answer 1

1. Physical and anatomical measures e.g. position of the head
2. Lubricants e.g. mucus
3. Reflexes e.g. coughing, sneezing
4. Antimicrobials

Question 2

Describe some specific defence mechanisms of the head

Answer 2

1. Lymph nodes/tissue
2. Innate and adaptive immunity
3. Mucosal immunity- antibody and lymphocytes

Question 3

What could be a consequence of horses not being able to have their head down to graze

Answer 3

Shipping fever, accumulation of pathogens during transport, head being up for extended periods of time

Question 4

What can be a benefit of the air and food passages being clode together in the horses head regarding respiratory defence

Answer 4

Swallowing of foreign particles allows them to be destroyed by stomach acid

Question 5

How is the pharynx involved in draining lymphoid tissue

Answer 5

Draining from the tonsils

Question 6

What is the role of the arytenoid cartilages

Answer 6

Influence volume of air entering lower airways,

Question 7

When does the glottis demonstrate reflex closure?

Answer 7

After swallowing, stimulation of larynx, prevents large particles entering lower respiratory tract

Question 8

What lines the trachea

Answer 8

Lymphoid tissues, cillia, mucus and commensal organisms

Question 9

What is the role of the cilia

Answer 9

move in a coordinated fashion toward the pharynx

Question 10

What does the mucus consist of?

Answer 10

Mucoid gel layer, which touch the tips of the cilia.
The sol layer which covers the cilia.
Anti-bacterial lysozyme.

Question 11

What do the Mucus and cilia form?

Answer 11

mucociliary escalator

Question 12

Which cells produce mucus?

Answer 12

goblet cells

Question 13

What do submucosal glands do?

Answer 13

contain serous secretions

Question 14

What do myoepithelial cells do?

Answer 14

Aid the movement of secretions from the submucosal/subepithelial glands into the lumen

Question 15

What are defensins

Answer 15

antimicrobial peptides produced by macrophages, neutrophils & epithelium

Question 16

What are some non-specific defences of the lower respiratory tract

Answer 16

Branching airways, Bronchi surrounded by cartilagenous rings & smooth muscle

Question 17

How can the structure of the lower respiratory tract influence defence?

Answer 17

1. multiple branching of bronchioles causes turbulence & deposition of particles on mucociliary escalator
2. Irritant receptor and cough reflex
3. Lymphoid cells & tissues

Question 18

What defence systems are in place in the bronchiole

Answer 18

1. Ciliated cells
2. Smooth muscle surrounding the bronchioles
3. Lymphoid tissue beneath epithelium
4. No goblet cells are present in the bronchioles

Question 19

Describe some adaptions to defence by alveoli

Answer 19

1. Enterence is guarded by smooth muscle cells

2. There is a rapid migration of leucocytes from the blood into the alveoli

Question 20

What do Alveolar type II epithelial cells produce

Answer 20

Surfactant

Question 21

What are the caretaker functions of Alveolar type II cells?

Answer 21

1. If type I cells are damaged, type II cells proliferate and can act as progenitors for I or II
2. Synthesis, store and release surfactant into alveolar space where it prevents lung surface adhesion and optimises gas exchange

Question 22

Which lymphoid tissues are associated with the upper respiratory tract

Answer 22

Tonsils & lymphoid tissue in nasopharynx, Mucosal associated lymphoid tisse (MALT), Bronchus associated lymphoid tissue (BALT)

Question 23

What are the roles of the lymph nodes in upper respiratory tract defence

Answer 23

• 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

Question 24

What are the 3 main lymph nodes of the head (in horses), as well as another associated lymphoid tissue

Answer 24

Parotid, Mandibular, Retropharyngeal (tonsils)

Question 25

What are the 2 main lymph nodes of the neck (in horses)

Answer 25

Superficial cervical, Deep cervical

Question 26

What are the 4 main lymph nodes of the thorax (in horses)

Answer 26

Dorsal thoracic, Ventral thoracic, Mediastinal, Bronchial

Question 27

What are MALT and BALT?

Answer 27

Mucosal/Bronchus associated lymphoid tissue.
They are aggregations of lymphocytes beneath non-ciliated epithelium.
Strategically located at bifurcations of bronchi

Question 28

What might you see from a Bronchoalveolar lavage/Tracheal wash from a diseased lung/respiratory tract

Answer 28

Macrophages, lymphocytes, Frequent neutrophils, Hemosiderophages, excess mucus

Question 29

Which antibody classes are found the mucosa of the respiratory tract

Answer 29

All except Immunglobulin M

Question 30

What adaptive immune defences would you expect to find the the mucosa of the respiratory tract

Answer 30

Intraepithelial lymphocytes, Mucosal immunoglobulin, Serum immunoglobulin

Question 31

What factors may affect respiratory defences

Answer 31

1. particle size
2. Pattern of breathing
3. Artificial manipulaiton bypassing defences
4. Increased size of nares, particularly in horses

Question 32

Describe the development of bronchoconstriction

Answer 32

1. exposure to antigen/allergen
2. Inflammation
3. IgE present/synthesised
4. binds/crosslinks on mast cells & basophils
5. Results in degranulation
6. Granules contain inflammatory mediators and result in smooth muscle contraction, leading to bronchoconstriction

Question 33

What is strangles

Answer 33

A Highly contagious, bacterial infection (Streptococcus equi) that causes inflammation of the mucous membranes of the respiratory tract, resulting in abscesses and a nasal discharge.

Question 34

What role do agonist/antagonists drugs play in promoting bronchodilation

Answer 34

Stimulate/inhibit specific receptors to promote bonchodilation