What is the immune system?
Cells, tissues, and molecules that mediate resistance to infections
The immune system is crucial for protecting the body against pathogens.
Define immunology.
The study of structure and function of the immune system
Immunology encompasses various aspects of the immune response.
What is immunity?
Resistance of a host to pathogens and their toxic effects
Immunity can be innate or acquired.
What is an immune response?
Collective and coordinated response to the introduction of foreign substances mediated by the immune system
This response involves various cells and molecules.
List the roles of the immune system.
- Defense against microbes
- Defense against tumor cell growth
- Homeostasis
- Destruction of abnormal or dead cells
Homeostasis refers to maintaining stable internal conditions.
Name the organs of the immune system.
- Tonsils and adenoids
- Thymus
- Lymph nodes
- Spleen
- Payer’s patches
- Appendix
- Lymphatic vessels
- Bone marrow
Each organ plays a specific role in immune function.
What are the main types of immune cells?
- Lymphocytes
- T-lymphocytes
- B-lymphocytes, plasma cells
- Natural killer lymphocytes
- Monocytes
- Macrophages
- Granulocytes
- Neutrophils
- Eosinophils
- Basophils
These cells are essential for immune responses.
Identify the molecules involved in the immune system.
- Antibodies
- Complement
- Cytokines
- Interleukins
- Interferons
These molecules facilitate communication and action within the immune system.
Define an antigen.
A substance that reacts with antibody molecules and antigen receptors on lymphocytes
Antigens are typically foreign substances.
What is an immunogen?
An antigen that is recognized by the body as non-self and stimulates an adaptive immune response
Immunogens are crucial for initiating immune responses.
List the three characteristics that make an antigen immunogenic.
- High molecular weight
- Chemical complexity
- Foreignness (recognized as non-self)
These characteristics enhance the likelihood of an immune response.
What is the chemical nature of antigens?
Chemically, antigens are large molecular weight proteins and polysaccharides, including conjugated proteins like glycoproteins and lipoproteins
The structure of antigens influences their immunogenicity.
Define epitopes.
The actual portions or fragments of an antigen that react with receptors on B-lymphocytes and T-lymphocytes
Epitopes are the specific sites recognized by the immune system.
What is a hapten?
A small molecule that by itself is not immunogenic but acts as an antigen when it binds to a larger protein molecule
Haptens can elicit an immune response when attached to carrier proteins.
What are the two types of immunity?
- Innate (non-adaptive)
- Acquired (adaptive)
Each type has distinct mechanisms and responses to pathogens.
Describe innate immunity.
First line of immune response that relies on mechanisms existing before infection, characterized by rapid, non-specific responses without memory
Innate immunity acts quickly to prevent infection.
What mechanisms are involved in innate immunity?
- Mechanical barriers/surface secretion (skin, acidic pH in stomach, cilia)
- Humoral mechanisms (lysozymes, basic proteins, complement, interferons)
- Cellular defense mechanisms (natural killer cells, neutrophils, macrophages, mast cells, basophils, eosinophils)
These mechanisms work together to provide immediate defense.
Describe adaptive immunity.
Second line of defense based upon resistance acquired throughout life, relies on genetic events, responds slowly, is specific, and has memory
Adaptive immunity develops over time and improves with exposure.
What are the two types of adaptive immunity?
- Active immunity
- Passive immunity
Active immunity is developed through exposure or vaccination, while passive immunity is acquired from another source.
What is the role of T-lymphocytes in the adaptive immune response?
Eliminate intracellular microbes that survive within phagocytes or other infected cells
T-lymphocytes are critical for targeting and destroying infected cells.
What is the function of B-lymphocytes in the humoral immune response?
Recognize specific antigens, proliferate, and differentiate into antibody-secreting plasma cells
B-lymphocytes are key players in producing antibodies.
Define immunoglobulins.
Antibodies that belong to the gamma-globulin fraction of serum proteins, typically Y-shaped or T-shaped polypeptides
Immunoglobulins play a vital role in immune defense.
What are the five kinds of antibodies?
- IgG
- IgM
- IgA
- IgD
- IgE
Each type of antibody has distinct functions and characteristics.
What is the role of IgG?
Accounts for 70-75% of total immunoglobulin, secreted in high quantities during secondary exposures, crosses the placenta, and neutralizes microbes and toxins
IgG is crucial for long-term immunity.
