BIOL 117 Module 18

What are the two main types of immunity in animals?

Innate Immunity and Acquired (Adaptive) Immunity.

What characterizes innate immunity?

Non-specific response; includes barriers and leukocytes.

What characterizes acquired immunity?

Specific response to antigens using lymphocytes like B-cells and T-cells.

What are the first-line defenses in innate immunity?

Physical barriers and secretions.

What happens when pathogens bypass barriers?

Leukocytes respond by ingesting or killing pathogens.

Which leukocytes are involved in innate immunity?

Mast cells, neutrophils, macrophages.

What do neutrophils do?

Phagocytize bacteria and fungi; release cytotoxins.

What do eosinophils do?

Target parasites; release cytotoxins and cytokines.

What do basophils do?

Target parasites; release cytotoxins and anticoagulant heparin.

What do macrophages do?

Engulf dead cells, present antigens to T cells.

What do dendritic cells do?

Present antigens to T cells.

What do natural killer cells do?

Kill infected or cancerous cells.

What do mast cells release during inflammation?

Heparin and histamine.

What is phagocytosis?

Engulfing of pathogens by leukocytes into a vacuole.

What is the role of lysosomes in phagocytosis?

They digest the engulfed pathogen.

What are MHC proteins?

Proteins that display pathogen fragments on the cell surface.

What are chemokines?

Molecules that signal other cells to the infection site.

What are histamines?

Molecules that dilate blood vessels during inflammation.

What is adaptive immunity?

Specific response using B and T cells to recognize antigens.

What are antigens?

Molecules on pathogens that provoke an immune response.

What are antibodies?

Proteins that bind to antigens to mark invaders for destruction.

What are B cells?

Lymphocytes that produce antibodies; humoral immunity.

What are helper T cells?

Activate B and T cells by detecting infection.

What are cytotoxic T cells?

Destroy infected cells; part of cell-mediated immunity.

Where do B and T cells mature?

B cells in bone marrow, T cells in the thymus.

What is clonal selection?

Process of activating and replicating lymphocytes specific to an antigen.

What is the function of MHC I proteins?

Present antigens from inside the cell; found on all nucleated cells.

What is the function of MHC II proteins?

Present processed antigens; found on immune cells.

What activates CD8+ T cells?

Interaction with MHC I; become cytotoxic T cells.

What activates CD4+ T cells?

Interaction with MHC II; become helper T cells.

How are memory cells formed?

After B or T cell activation, some differentiate into long-lived memory cells.

What causes allergies?

Hypersensitivity and IgE-triggered histamine release.

What are autoimmune diseases?

Conditions where the immune system attacks the body's own cells.

What are examples of autoimmune diseases?

Rheumatoid arthritis, Type 1 diabetes, MS, lupus.

What are immunodeficiency disorders?

Diseases where the immune system is weakened (e.g., HIV/AIDS).

What is a vaccine?

Preparation to stimulate immune response without causing disease.

What types of vaccines exist?

Prophylactic (preventive) and Therapeutic (treatment).

What are subunit vaccines?

Contain only parts of the pathogen that act as antigens.

What are toxoid vaccines?

Contain weakened toxins to prevent disease.

What are nucleic acid vaccines?

Contain DNA or RNA to produce antigens in the body.

How can vaccines be delivered?

Injection (subcutaneous, intramuscular, intradermal), oral, or intranasal.

What is the controversy around vaccines?

False claims linking vaccines to autism; disproven by science.

What is special about COVID-19 mRNA vaccines?

Use lipid nanoparticles to deliver mRNA coding for viral antigens.