The Immune System, HIV/AIDS, and the Respiratory System: A Comprehensive Overview

Posted on Aug 25, 2024 in Biology

4 Phagocytic Leucocytes and Pathogen Ingestion

Phagocytes, found in the blood and body tissues, play a crucial role in the immune system. They identify and engulf pathogens through endocytosis. Lysosomes, enzymes within phagocytes, then break down these pathogens. Phagocytes can move through capillary pores, allowing them to ingest pathogens both in the bloodstream and within tissues.

5 Antigens vs. Antibodies

Antibodies are proteins that defend the body against pathogens. They bind to antigens, foreign substances found on the surface of pathogens, marking them for destruction. Each antibody typically binds to a specific antigen.

6 Antibody Production

Summary:

  1. Each lymphocyte produces a single type of antibody.
  2. These antibodies are located on the lymphocyte’s surface.
  3. Pathogens possess antigens on their surface.
  4. Antigens bind to corresponding antibodies.
  5. This binding activates the lymphocyte, leading to the production of clones.
  6. These clones generate more of the specific antibody.

7 HIV’s Impact on the Immune System

The Human Immunodeficiency Virus (HIV), the virus responsible for Acquired Immunodeficiency Syndrome (AIDS), targets and destroys a specific type of lymphocyte crucial for antibody production. Over time, this leads to a decline in active lymphocytes, resulting in reduced antibody production. Consequently, the body becomes highly susceptible to pathogens, making infections that would typically be easily managed in a healthy individual potentially life-threatening for those with HIV.

8 Cause, Transmission, and Social Implications of AIDS

Summary:

Cause:

  1. HIV is the causative agent of AIDS.
  2. HIV targets and destroys lymphocytes essential for antibody production.
  3. This leads to a gradual decrease in active lymphocytes.
  4. The body’s vulnerability to pathogens increases significantly.

Transmission:

  1. Sexual contact: Vaginal, anal, and oral sex (if cuts or tears are present).
  2. Sharing hypodermic needles among drug users.
  3. Mother-to-child transmission: Through the placenta, during childbirth, or through breast milk.
  4. Blood transfusions.
  5. Blood factors (e.g., Factor VIII used to treat hemophilia).

Social Implications:

  1. Grief and emotional distress for families and friends.
  2. Potential for economic hardship for affected families.
  3. Difficulties in finding partners, employment, and housing.
  4. Potential reduction in sexual activity within a population.

1 Ventilation, Gas Exchange, and Cell Respiration

Ventilation is the process of inhaling fresh air into the alveoli and exhaling stale air. This maintains the concentration gradients of oxygen and carbon dioxide, which is crucial for gas exchange.

Gas exchange occurs in the alveoli, where oxygen diffuses from the air into the capillaries and carbon dioxide diffuses from the capillaries into the air.

Cell respiration takes place in the mitochondria and cytoplasm of cells, using oxygen to produce energy (ATP) and releasing carbon dioxide as a byproduct.

2 The Importance of a Ventilation System

Summary:

  1. Maintains concentration gradients of oxygen and carbon dioxide in the alveoli.
  2. Provides oxygen for ATP production through cell respiration.
  3. Removes carbon dioxide, a waste product of cell respiration.
  4. Facilitates the diffusion of oxygen into the blood and carbon dioxide out of the blood.
  5. Ensures a high oxygen concentration and a low carbon dioxide concentration in the alveoli.
  6. Achieves this by removing carbon dioxide and supplying fresh oxygen.

3 Alveoli and Gas Exchange

Summary:

  1. Large numbers of alveoli provide a vast surface area for gas exchange.
  2. Thin walls (single layer of cells) in both alveoli and capillaries minimize diffusion distance, enabling rapid gas exchange.
  3. Dense capillary networks surrounding alveoli maintain low oxygen and high carbon dioxide concentrations, promoting diffusion.
  4. Fluid secretion within alveoli allows gases to dissolve and prevents alveolar collapse.

5 Mechanism of Lung Ventilation

Inhalation:

– External intercostal muscles contract, lifting the ribcage up and out.
– Diaphragm contracts, moving downwards and flattening.
– These actions increase thoracic volume, decreasing thoracic pressure.
– Pressure drops below atmospheric pressure, drawing air into the lungs.
– Air flows until lung pressure equals atmospheric pressure.

Exhalation:

– Internal intercostal muscles contract, pulling the ribcage down and in.
– Abdominal muscles contract, pushing the diaphragm upwards.
– These actions decrease thoracic volume, increasing thoracic pressure.
– Pressure rises above atmospheric pressure, forcing air out of the lungs.
– Air flows until lung pressure equals atmospheric pressure.