Ch. 14 p 213-219 Normal Immune Response only

Here’s a detailed yet digestible summary of Chapter 14: Immune Responses and Transplantation while maintaining all key information.

Conceptual Focus Areas

• Functional Ability – The immune system's ability to protect and function effectively.

• Immunity – How the body defends itself against disease.

• Infection – The role of immunity in preventing and combating infections.

• Inflammation – The immune response to harmful stimuli.

• Tissue Integrity – How immune function preserves and repairs body tissues.

The Normal Immune Response

Functions of the Immune System

1. Defense – Identifies and eliminates pathogens and foreign substances.

2. Homeostasis – Removes damaged or dead cells to maintain balance.

3. Surveillance – Detects and destroys abnormal or mutated cells.

Antigens

• Any substance that triggers an immune response.

• Most antigens are proteins, but carbohydrates, lipoproteins, and nucleic acids can also act as antigens.

• The body recognizes its own antigens and does not react to them (self-tolerance).

Types of Immunity

Innate Immunity (Natural Immunity)

• Present at birth and provides the first line of defense.

• Nonspecific – Can respond quickly to pathogens without prior exposure.

• Involves neutrophils and monocytes (types of white blood cells).

Acquired Immunity (Developed Immunity)

Divided into active and passive immunity:

• Active Immunity: Long-lasting because the body creates memory cells.

• Passive Immunity: Immediate but short-term protection (no memory cell production).

Lymphoid Organs & Their Role in Immunity

1. Primary (Central) Lymphoid Organs – Thymus and Bone Marrow

   • Bone marrow: Produces all blood cells, including immune cells (B and T lymphocytes).

   • Thymus: Matures T cells; shrinks with age, reducing immune function.

2. Peripheral Lymphoid Organs – Lymph Nodes, Spleen, Tonsils, Mucosal Tissues

   • Lymph Nodes: Filter pathogens and interact with B and T cells.

   • Spleen: Filters blood for foreign antigens.

   • Mucosal Lymphoid Tissue: Located in the gut, genitals, lungs, and skin; provides localized immune protection.

Cells Involved in the Immune Response

Mononuclear Phagocytes (Monocytes & Macrophages)

• Capture, process, and present antigens to T and B cells to initiate an immune response.

Lymphocytes (B & T Cells)

• B cells → Differentiate into plasma cells, which produce antibodies (humoral immunity).

• T cells → Responsible for cell-mediated immunity, targeting infected and abnormal cells.

Types of T Cells

• T Cytotoxic (CD8) Cells: Attack virus-infected and cancer cells.

• T Helper (CD4) Cells: Regulate immune response and activate other immune cells.

• Memory T Cells: Retain information for a quicker future response.

• Natural Killer (NK) Cells: Destroy infected and cancerous cells without prior sensitization.

Dendritic Cells

• Capture antigens and transport them to T cells, playing a role in immune activation.

Immunoglobulins (Antibodies) & Their Roles

Humoral vs. Cell-Mediated Immunity

• Primary Response (First Exposure): Takes 4-8 days to develop; IgM is produced first.

• Secondary Response (Repeat Exposure): Occurs 1-3 days; faster and stronger due to memory B cells, primarily producing IgG.

Cytokines: Chemical Messengers of the Immune System

Cytokines regulate immune responses and inflammation.

Key Cytokine Groups & Functions

Effects of Aging on the Immune System (Immunosenescence)

• Increased risk of infections and cancer due to declining immune function.

• Decreased production of antibodies and T cells.

• Thymus gland shrinks, leading to fewer new T cells.

• Weaker response to vaccinations.

Age-Related Immune Changes

⬆ Autoantibodies (increased risk of autoimmune diseases)
⬇ T cell and B cell function
⬇ Delayed hypersensitivity response
⬇ Response to vaccines

Key Takeaways

• The immune system has two main responses: humoral (antibody-mediated) and cell-mediated (T cell response).

• Innate immunity provides general protection, while acquired immunity is specific and long-lasting.

• Lymphoid organs (bone marrow, thymus, spleen, lymph nodes) play a crucial role in immune cell production and function.

• Cytokines are chemical messengers that regulate immune responses, inflammation, and cell growth.

• Aging weakens immune responses, making older adults more prone to infections and cancer.