- Besides acting as mechanical barriers, the skin epidermis and mucosae of the body have other attributes that contribute to their protective roles. Cite the common body locations and the importance of mucus lysozyme keratin acid pH and cilia.
Part B:
- After a week of scuba diving in the Bahamas, Mary Ann boards an airplane. During her flight home, she develops aching joints, nausea, and dyspnea, which resolve upon landing. During the flight, the cabin pressure was equivalent to an altitude of 8000 feet. Explain her problems.
The skin epidermis and mucosae serve as important protective barriers, contributing to the body’s defense mechanisms in the following ways:
- Mucus:
- Common Locations: Found in the respiratory, gastrointestinal, and urogenital tracts.
- Importance: Mucus traps microbes, dust, and foreign particles, preventing their entry into deeper tissues. It also contains antimicrobial substances like antibodies that help neutralize pathogens.
- Lysozyme:
- Common Locations: Present in saliva, tears, mucus, and other body secretions.
- Importance: Lysozyme is an enzyme that breaks down the cell walls of certain bacteria, providing an antimicrobial effect that helps protect tissues from bacterial invasion.
- Keratin:
- Common Locations: Found in the skin epidermis, hair, and nails.
- Importance: Keratin is a tough, fibrous protein that provides structural integrity to the outermost layer of the skin, creating a durable barrier that resists abrasion and provides protection from pathogens, chemicals, and physical trauma.
- Acid pH:
- Common Locations: Skin, stomach, and vagina.
- Importance: The acidic environment on the skin (pH ~5.5) and in the stomach (pH ~1-2) inhibits the growth of many harmful microbes. This acidic barrier serves as a protective factor by creating an environment that is hostile to pathogenic organisms.
- Cilia:
- Common Locations: Lining of the respiratory tract (trachea and bronchi).
- Importance: Cilia are tiny hair-like structures that move in coordinated waves to propel mucus, along with trapped particles and pathogens, out of the respiratory tract, keeping the airways clear and reducing the risk of infection.
Part B:
Mary Ann’s symptoms of aching joints, nausea, and dyspnea (difficulty breathing) during her flight home likely indicate decompression sickness (DCS), commonly known as “the bends.” This condition is caused by the formation of nitrogen bubbles in the bloodstream and tissues due to a rapid decrease in pressure. Here is why it may have occurred:
- Diving Effects: During her week of scuba diving, Mary Ann was likely breathing compressed air, which increases the amount of nitrogen dissolved in her tissues.
- Pressure Changes: While underwater, the increased pressure causes more nitrogen to dissolve in the blood and tissues. Upon resurfacing, this nitrogen normally off-gasses slowly and is exhaled from the body. However, during her flight, the cabin pressure was equivalent to an altitude of 8000 feet, reducing atmospheric pressure further than at sea level.
- Nitrogen Bubble Formation: The rapid change in pressure (due to flying) may have caused nitrogen to come out of solution too quickly, forming bubbles in her tissues and bloodstream, leading to symptoms such as joint pain, nausea, and dyspnea.
Mary Ann’s symptoms resolving upon landing suggest that the pressure changes during the flight were the main cause. Proper prevention for divers often involves waiting for a period of time (called a “no-fly” period) after diving to allow for complete off-gassing of nitrogen before flying.