Immune System and Respiratory Function

T Cell Production and Immune Response

• Removal of Thymus:
    - Mr. Hartsell had his thymus removed.
    - Impact on T Cell Production:
      - T cell production would significantly decrease.
      - Thymus is crucial for T cell maturation and functionality.
      - Without the thymus, immature T cells cannot develop properly.
      - Results in a weakened adaptive immune response.
      - Increased susceptibility to infections.

Types of Immunity

• Innate Immunity:
    - First line of defense against pathogens.
    - Characteristics:
      - Fast.
      - Non-specific.
    - Components:
      - Physical barriers (skin, mucous membranes).
      - Inflammatory responses.

• Adaptive Immunity:
    - Functions slower than innate immunity but is highly specific.
    - Involves the action of:
      - T cells.
      - B cells.
    - Has memory capability, allowing faster responses to repeat exposures to the same pathogen.

Major Histocompatibility Complex (MHC) in T Cell Activation

• Role of MHC Molecules:
    - Major histocompatibility complex (MHC) molecules present antigens on cell surfaces.
    - T cells recognize antigens only when displayed on MHC molecules.
    - Activation Process:
      - This recognition activates T cells.
      - Activated T cells can identify and respond to infected or abnormal cells.

MHC and HLA in Organ Transplant and Rejection

• MHC and HLA:
    - MHC molecules are referred to as HLA (Human Leukocyte Antigen) in humans.
    - Function: Helps immune system distinguish between "self" and "non-self".
    - Organ Transplantation:
      - In organ transplants, a close match of donor’s HLA markers to recipient's is crucial.
      - If matching is poor, the immune system treats the tissue as foreign.
      - Leading to transplant rejection.

Active Immunity Through Vaccination

• Vaccination Scenario:
    - Clark received a vaccine; Nicole did not.
    - Type of Immunity:
      - Clark: Active immunity, as his body produced its own antibodies and memory cells in response to the vaccine.
      - Nicole: No immunity; resulted in infection.
    - Benefit for Clark:
      - Immune system was prepped to recognize and combat the measles virus swiftly.
      - Effectively prevented the illness.

Impact of Smoking on Respiratory Epithelium

• Effects of Smoking:
    - Smoking damages cilia and epithelial cells in the respiratory tract.
    - Consequences:
      - Reduced ability to clear mucus, debris, and pathogens from the airways.
      - Accumulation of mucus increases risk of infections and respiratory diseases.

Function of Surfactant in the Lungs

• Surfactant Function:
    - Reduces surface tension in alveoli, preventing collapse during exhalation.
    - Without Surfactant:
      - Alveoli collapse (condition known as atelectasis).
      - Difficulty in lung expansion.
      - Significantly impairs gas exchange and breathing.

Role of Bronchodilators in Respiratory Health

• Mechanism of Action:
    - Bronchodilators relax smooth muscle in the airways.
    - Result:
      - Widening of airways.
      - Decrease in airway resistance.
      - Enhanced air flow in and out of lungs, leading to improved breathing.

Digestive Function and Medications

• Bile Salts, CCK, and Secretin:
    - Bile Salts:
      - Function: Break down fats into smaller droplets (process known as emulsification) to facilitate digestion.
    - CCK (Cholecystokinin):
      - Stimulates gallbladder to release bile into the small intestine.
    - Secretin:
      - Stimulates liver and pancreas to release bicarbonate-rich fluids.
      - Helps neutralize stomach acid, creating optimal digestion environment.

• Proton-Pump Inhibitors (PPIs):
    - Mechanism of Action:
      - Block hydrogen ion (H⁺) pumps in stomach lining.
      - Result: Reduction in stomach acid production.
    - Clinical Implication:
      - Helps heal ulcers.
      - May slow protein digestion as stomach acid is needed to activate enzymes (e.g., pepsin).