immune responses

Immune System Overview

Layers of Defense

• First Layer of Defense: The body’s initial protective measures against pathogens. Components include:

  • Skin: A protective barrier preventing pathogen entry.

  • Cilia: Hair-like structures that trap and move pathogens out of the respiratory tract.

  • Stomach Acid: Acidic environment kills pathogens ingested with food.

  • Mucus: Traps pathogens in the respiratory and digestive systems.

  • Saliva: Contains enzymes that break down pathogens.

Second and Third Layers of Defense

• White Blood Cells: Play critical roles in immune response.

  • Types of white blood cells include:

    • Phagocytes: Example types include Monocytes, Macrophages, and Neutrophils.

      • Function: Engulf and digest pathogens through a process known as phagocytosis.

        • Phagocytosis Defined: "Phago" means to eat, and "cytosis" means movement within; it refers to the process where immune cells absorb pathogens.

    • B Cells: Produce antibodies against specific antigens.

      • Function: Create antibodies that recognize and bind to particular antigens.

    • T Cells: Analyze and respond to pathogens.

      • Types of T Cells:

        • Killer T Cells: Destroy infected or cancerous cells.

        • Helper T Cells: Assist other immune cells, including activating B cells to produce antibodies.

        • Suppressor T Cells: Regulate the immune response to prevent damage to healthy cells.

Vaccines

• Definition: Vaccines prepare the immune system to fight pathogens without causing the disease.

  • They may use:

    • Live but attenuated (weakened) viruses.

    • Inactivated (dead) viruses.

    • Specific antigen fragments from pathogens.

• Mechanism: Vaccines stimulate the immune system to produce antibodies and prepare for future encounters with the pathogen.

• Post-Vaccination Effects: Mild symptoms can occur as the body responds, producing antibodies and experiencing an inflammatory response.

Antigens and Antibodies

• Antigens: Foreign substances (like pathogens) that induce an immune response.

  • Various shapes correspond to different pathogens (e.g., square or triangle antigens).

• Antibodies: Proteins produced by B cells that bind specifically to antigens.

  • Each antibody has a unique shape that matches its corresponding antigen.

  • Function: Slow down pathogens and alert phagocytes for destruction.

Antibiotics vs. Vaccines

• Antibiotics: Used for bacterial infections; they kill bacteria but may also harm beneficial bacteria.

  • Risk of antibiotic resistance if overused.

• Vaccines: Prep the immune system for future infections, initiating a specific immune response without causing the disease.

Blood Types

• Self Antigens and Immunity: Blood antigens are recognized by the immune system.

  • Types of Blood:

    • O Negative: Universal donor (no antigens)

    • AB Positive: Universal recipient (contains all antigens)

• Erythroblastosis Fetalis: A condition in Rh-negative mothers carrying Rh-positive babies.

  • Risk: Mother's immune system may attack the baby's blood cells if antigens mix, leading to serious complications.

  • Preventative medications are available.

HIV/AIDs Overview

• HIV: The virus that leads to AIDS, attacking T cells and weakening the immune system.

  • Transmission: Through unprotected sex and blood contact.

  • Notable Impact: Causes vulnerability to various infections due to its targeting of crucial immune cells.