Met 2: Lec. 7 Phys Of Lung Defense

Front 1

"What are the 3 main defence mechanisms of the upper conducting zone to protect the lower respiratory tract? Give example(s) of each mechanism (i.e. cough).

"

Back 1

"1. Physical (turbulent airflow, cough, cilia, epithelial cell shedding)
2. Chemical (mucus, NO, increased viscosity)
3. Cellular (phagocytosis by macrophages)"

Front 2

What can stimulate the cough reflex?

Back 2

"Afferent nerves stimulated by:
inhalation of particles, food, pathogens, inflammation, accumulated secretions, irritants


What is the physiologic mechanism for a cough?"

Front 3

Where is the respiratory epithelium found? What are its 4 protective functions?

Back 3

"The respiratory epithelium is found in the conduction zone.

1. Physical Barrier (from particles entering--tight junctions)
2. Anti-microbial function (antibodies, lysosomes secreted from glands, paracellularly & via exocytosis)
3. Pro-inflammatory function (maintains balance between pro-inflammation and inflammation)
4. Regulatory function (neuropeptide degrading enzyme, NO)"

Front 4

What are some functions of the nasal epithelium?

Back 4

"Filter, warm, humidify air
Entrap pollutants, dust, bacteria"

Front 5

What is the histological composition of the epithelium? (Stick to the main layers)

Back 5

"Ciliated cells
Goblet cells (secrete mucus)
Basal, serous cells
Basement membrane"

Front 6

Where is mucus produced? What happens to the mucus produced?

Back 6

"Goblet cells & submucosal glands.

It get swallowed or coughed out.

Identify the layers in the electron microscopy view of the trachea."

Front 7

How does movement of the cilia occur?

Back 7

The cilia are composed of microtubules surrounding an axon. The movement occurs from ATP hydrolysis, allowing the sliding of one of the tubules to cause motion in one direction (coordinated with other cilia).

Front 8

What is the main property of ASL that allows it to trap pathogens?

Back 8

"Ability to change its viscosity.

What are in the secretions from the mucus and serous cells that compose the ASL?"

Front 9

What are some mechanisms of humoral and cell mediated immunity found in the alveolar spaces?

Back 9

"Alveolar macrophages: for phagocytosis of bacteria & foreign material
Secretion of inflammatory molecules for immune response
Secrete bacteriacidal molecules (lysozomes, reactive oxygen species)
Immunoglobulins present within the lung mucosa (IgA & IgE)
Use arachiadonic products to stimulate vasoactive mechanisms & lymphocytes"

Front 10

Besides the reduction of surface tension, what other roles does surfactant play in the alveoli?

Back 10

"Activates macrophages
Down regulates the inflammatory response
Opsonization of micro-organisms, antigens"

Front 11

What factors impair lung defence mechanisms?

Back 11

"1. Microbial challenge (volume overload of virus & bacteria)
2. Organisms evade the defence mechanisms
3. Toxins & environmental exposures that have impaired the lung's defence mechanisms
4. Host factors:  systemic disease, genetic predisposition, developmental immaturity"

Front 12

True or false: abnormal surfactant has no effect on respiratory diseases, such as asthma, CF, acute respiratory disress syndrome

Back 12

False: Abnormal surfactant has been shown to be an aggrevating factor in these diseases (just not the main pathophysiology)

Front 13

"Is mucocilliary clearance faster or slower in the following situations:
Younger
Male
Sleeping
Strenuous exercise
Standing upright"

Back 13

"Younger - FASTER
Male - SLOWER
Sleeping - SLOWER
Strenuous exercise - FASTER
Standing upright - NO EFFECT"

Front 14

What are some ways an abnormal CFTR gene causes inflammation & infection?

Back 14

"Abnormal CFTR causes:
Infection: ASL is abnormal, which leads to impaired mucocillary clearance which impairs anti-microbial defences.
Inflammation, which is promoted by imbalance of cytokines, abnormal neutrophil functioning & abnormal epithelial regulation of inflammation."

Front 15

Explain how hypersecretions of mucus can lead to biofilms.

Back 15

Submucosal glands secrete too much ASL and cilia cannot remove it. This aggravates the epithelium, which creates a cycle of trying to stimulate cilia to remove the mucus, but they can't effectively respond. An oxygen gradient is created inside the mucus layer that favors bacterial colonization. Bacteria change their structure to be resistant to antibiotics, and progress to create biofilms.

Front 16

What happens if a bacterial infection is not erradicated soon enough?

Back 16

Leads to chronic bacterial infection, which brings on inflammation and decreased lung function. Too long and it leads to biofilms and irreversible lung damage.