Respiratory System

Question 1

What is the first line of defense in the respiratory system?

Answer 1

The vibrissae are small hairs that line the nasal cavity. They help trap particulate matter and potentially infectious material.

Question 2

What enzyme is located in the nasal cavity and assists in the defense against pathogens?

Answer 2

Lysozymes are enzymes located in the nasal cavity (also found in tears and saliva) that attack the peptidoglycan wall of gram-positive bacteria.

Question 3

What is the mucociliary escalator mechanism?

Answer 3

The mucociliary escalator mechanism is the internal airways that are lined with mucus which traps particulate matter and large invaders. The underlying cilia then propel the mucus up the respiratory tract to the oral cavity, where it can be expelled (coughing) or swallowed.

Question 4

What cells and antibody type are located inside the lungs to defend agaisnt pathogens and foreign invaders?

Answer 4

The lungs contain macrophages, mast cells, and IgA antibodies to help combat agaisnt foreign particulate and pathogens.

• The macrophages engulf and digest pathogens, and then signal to the rest of the immune system that there is an invader.
• IgA antibodies are contained in the mucousal surfaces and help protect against pathogens that contact the mucous membranes.
• Mast cells also populate the lungs and these cells have pre-formed antibodies on their surfaces. When the right substance attaches to the antibody, the mast cell release inflammatory chemicals into the surrounding area to promote an immune response.
  
  • Unfortunately, these antibodies are often reactive to substance such as pollen and molds, so mast cells also provide the inflammatory chemicals that mediate allergic reactions.

Question 5

What is the bicarbonate buffer system and how is it related to respiratory rate?

Answer 5

The bicarbonate buffer system is:

CO₂ + H₂O <–> H₂CO₃ <–> H⁺ + HCO₃^-

• During acidosis, the respiratory rate increases to expel CO₂ which increases the blood pH.
• During alkosis, the respiratory rate decreases to retain CO₂ which decreases the blood pH.

H⁺ is a strong acid whereas HCO₃^- is a weak acid. That is why increasing both of them does not yield a constant pH.

Question 6

How is the intrapleural space related to inhalation and exhalation?

Answer 6

During inhalation, the intrapleural pressure is necessarily lower than the atmospheric pressure because the expansion of the chest cavity causes expansion of the intrapleural space, decreasing its pressure.

During Exhalation, the intrapleural pressure is necessarily greater than the atmospheric pressure because the compression of the chest cavity causes compression of the intrapleural space, increasing its pressure.

• Boyle’s Law explains this relationship
  
  • Pressure is inversely related to volume