Introduction to Immunology and Immunity

Study Notes

Immunology and Immunity

Immunology is the study of the immune system, including its functions in health and disease, and various immunological disorders.
Immunity serves as a defense mechanism against foreign agents entering the body.

Types of Immunity

Two main types of immunity exist: innate (nonspecific) and adaptive (specific), each containing cellular and humoral components.

Innate (Nonspecific) Immunity

Acts as the first line of defense against pathogens and is present from birth.
Responds to all foreign substances in a uniform manner without memory.

Adaptive (Specific) Immunity

Functions as the second line of defense and has a memory component for previously encountered pathogens.
Composed of specialized cells that specifically target and eliminate pathogens.

Differences between Nonspecific and Specific Immunity

Nonspecific immunity operates independently of antigens and provides an immediate response without memory.
Specific immunity requires antigen recognition, features a lag time for response, and establishes immunologic memory.

Origin of Immune Cells

Immune cells originate in the bone marrow and can be classified into myeloid (neutrophils, basophiles, eosinophils, macrophages, dendritic cells) and lymphoid (B and T lymphocytes, natural killer cells) lineages.

Development of Immune Cells

Primary lymphoid tissues, such as the bone marrow and thymus, serve as factories for immune cell development.

Sites of Immune Response

Secondary lymphoid tissues, including the spleen, tonsils, lymph nodes, adenoids, skin, and liver, are where immune responses are conducted.

Influencing Factors on the Immune System

Key factors affecting the immune system include heart health, age, heredity, and nutrition.

Components of Nonspecific Immunity

Nonspecific immunity encompasses anatomical, humoral, and cellular barriers, along with the process of phagocytosis.

Anatomical Barriers to Infection

Mechanical barriers include skin and bodily movements that prevent infections.
Chemical barriers involve substances like fatty acids, lysozyme, and defensins that inhibit pathogen growth.
Biological factors comprise normal flora that prevent pathogenic bacteria colonization.

Humoral Barriers to Infection

Humoral factors like lactoferrin and transferrin bind iron to limit bacterial growth, while interferons limit viral replication, and lysozyme breaks down bacterial cell walls.

Cellular Barriers to Infection

Neutrophils and macrophages are key phagocytic cells that eliminate pathogens.
Natural killer cells target infected body cells and potential cancer cells, while eosinophils combat parasitic infections.

Functions of Macrophages

Macrophages play multiple roles, including disposal of microbes, antigen presentation, regulation of immune response, and contributions to both innate and adaptive immunity.

Phagocytosis

Phagocytosis is a specialized process where immune cells engulf and digest invading pathogens.

Description

Explore the fundamental concepts of immunology and the different types of immunity. This quiz covers definitions and important aspects of the immune system and its functions in health and disease. Test your knowledge on key terms related to immunity and immunological disorders.