Ch. 11 Innate and Adaptive Immunity

What are the parts of the immune system?

The immune system has innate (general) and adaptive (specialized) components.

(Note: Innate immunity responds quickly and non-specifically, while adaptive immunity is slower but specific and retains memory of pathogens.)

What is immunity?

Immunity is the body’s ability to defend against specific pathogens or foreign substances.

(Note: Helps prevent disease development.)

What is the immune response?

The immune response is the activation of defense mechanisms; some act immediately (innate), others develop over time (adaptive).

(Note: Coordinated action maintains homeostasis and prevents infections.)

What are cytokines?

Cytokines are proteins produced by lymphocytes that influence immune cell activity and can contribute to autoimmune diseases and cancer.

(Note: They act as chemical messengers to coordinate the immune response, regulate inflammation, and direct cell interactions. They are like text messages between cells. Too many or the wrong messages can lead to "friendly fire" on the body's own tissues.)

What is the clinical relevance of cytokines in immune responses?

Cytokines mediate immune and inflammatory responses and can contribute to autoimmune diseases and cancer.

(Note: If immune cells are the soldiers, cytokines are their text messages and radio commands.)

What are chemokines?

Chemokines are a subset of cytokines that guide immune cells to infection or inflammation sites and can influence chronic disease progression.

(Note: Chemokines direct immune cells where to go. Analogy: Like GPS for immune cells, sometimes leading them to the wrong place.)

What are lymphokines?

Lymphokines are cytokines produced by lymphocytes that attract other immune cells, such as macrophages, to sites of infection. (Note: Facilitate communication between immune cells.)

What are monokines?

Monokines are cytokines produced by monocytes that attract neutrophils. (Note: Help recruit early-responder immune cells.)

What are interleukins?

Interleukins are cytokines produced by one leukocyte acting on other leukocytes.

(Note: Interleukins are like "text messages" that white blood cells send to each other to coordinate the immune system's attack and response.)

How do cytokines act?

Cytokines are released into blood or tissues and bind receptors on cells being called on to trigger responses. (Note: Cytokines are chemical messages that cells use to talk to each other and trigger actions like inflammation or immunity.)

What is innate immunity?

Innate immunity is the first line of defense, non-specific, and rapid against all microorganisms. (Note: Includes barriers, phagocytes, and proteins; limits infection spread until adaptive immunity activates.)

What are epithelial barriers?

Epithelial barriers are physical, chemical, and mechanical defenses like skin and mucous membranes. (Note: Block pathogen entry and secrete antimicrobial substances.)

How does skin defend the body?

Skin has dense cells, keratin (barrier), acidic environment, and antibacterial proteins. (Note: Provides physical protection and kills or inhibits pathogens.)

What is the function of cilia?

Cilia in the respiratory tract move trapped microbes to the throat. (Note: Physically remove pathogens to prevent lung infections.)

What are phagocytic cells?

Phagocytic cells, including neutrophils and macrophages, ingest and digest microbes.

(Note: Act as first cellular defense and present antigens to adaptive immune cells.)

What are neutrophils?

Neutrophils are the most abundant white blood cells, early responders, and process and present antigens.

(Note: Initiate adaptive immunity and destroy pathogens.)

What are macrophages?

Macrophages are long-lived tissue-resident phagocytes that clear bacteria, dead cells, and debris. (Note: Stimulate inflammation and present antigens for adaptive activation.)

What are dendritic cells (DCs)?

DCs are specialized antigen-presenting cells that capture antigens and present them to lymphocytes. (Note: Bridge innate and adaptive immunity.)

What are natural killer (NK) cells?

NK cells are lymphocytes that kill infected or tumor cells without prior exposure (without needing to have seen them before.) . (Note: Provide rapid innate cytotoxicity.)

How does pathogen recognition work in innate immunity?

Innate immunity uses pattern recognition to differentiate self vs non-self. (Note: Prevents the immune system from attacking the body’s own cells.)

What are PAMPs?

Pathogen-associated molecular patterns (PAMPs) are molecules on pathogens recognized by innate immune cells. (Note: Key signals for initiating phagocytosis and inflammation.)

What are PRRs?

Pattern recognition receptors (PRRs) are on innate immune cells and bind PAMPs. (Note: Trigger immune responses like phagocytosis and complement activation. Innate immune cells use their "scanner" (PRR) to detect the enemy's "ID badge" (PAMP).

What are Toll-like receptors (TLRs)?

TLRs are receptors in bone marrow cells that detect pathogens and regulate tissue homeostasis. (Note: Critical for immune sensing and repair processes.)

What are opsonins?

Opsonins are molecules that coat microbes, enhancing recognition by phagocytes. (Note: Facilitate ingestion and destruction of pathogens.)

Examples of opsonins

Examples of opsonins include antibodies (IgG) and complement proteins (C3b)

What is opsonization?

Opsonization is the process of coating microbes with opsonins to make them easier to ingest for phagocytosis. (Note: Increases efficiency of phagocytosis.)

What is adaptive immunity?

Adaptive immunity is specific and targets pathogens recognized as foreign, involving memory. (Note: It's your body's smart, targeted defense system that learns from every infection to protect you better in the future.)

What is the difference between humoral and cellular immunity?

Humoral immunity uses B cells to make antibodies that attack pathogens outside of cells, while cellular immunity uses T cells to directly destroy infected cells.

(Note: Humoral immunity uses B cells to handle threats that are "outside" of our own cells. Cellular immunity uses T cells handle threats that are "inside" our own cells.)

What is an antigen (immunogen)?

Antigens are molecules on pathogens that trigger antibody production by B cells . (Note: Initiates adaptive immune response.)

What are lymphocytes?

Lymphocytes are primary adaptive immune cells, including B and T cells.

(Note: Recognize specific antigens and mount targeted responses.)

What are B lymphocytes (B-cells)?

B lymphocytes provide humoral immunity , produce antibodies , and develop memory . (Note: Defend against extracellular pathogens.)

What are T lymphocytes (T-cells)?

T lymphocytes provide cell-mediated immunity , activate other immune cells, and reject grafts.

Note: Defend against intracellular pathogens.)

Where do T and B lymphocytes mature?

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

(Note: A B cell is like a cop who spots a wanted criminal (a free-floating antigen) on the street and arrests them. A T cell is like a cop who is only alerted when a citizen (one of your own cells) walks up and says, "I have a criminal hiding inside my house!" (This is called antigen presentation.)

What are regulatory cells?

Regulatory cells assist in controlling immune responses . (Note: Prevent excessive reactions that could harm the body.)

What are effector cells?

Effector cells carry out elimination of antigens.

(Note: Execute the immune system’s attack. Includes: Neutrophils, macrophages, NK cells, cytotoxic T cells (CD8+), effector helper T cells (TH1, TH2, TH17), and B-cells.)

What is the Major Histocompatibility Complex (MHC)?

MHC molecules allow lymphocytes to distinguish self from foreign antigens. (Note: Essential for T cell activation and antigen recognition.)

What are Antigen-presenting Cells (APCs)?

APCs engulf microbes and present antigens to lymphocytes. (Note: Bridge innate and adaptive immunity.)

What is humoral immunity?

Humoral immunity is B cell-mediated defense against extracellular microbes, forming antibodies and memory.

(Note: Key for antibody-mediated protection. Humoral immunity is the part of your immune system that uses proteins called antibodies, which float around in your blood and other body fluids like a security patrol.)

What is IgG?

IgG is the most abundant antibody , antiviral, antibacterial, and crosses the placenta . (Note: Provides fetal passive immunity. AND LONG TERM IMMUNITY)

What is the Primary humoral response?

Occurs on first exposure (never seen before) to antigen , producing antibodies slowly. (Note: Initial adaptive response.)

What is the Secondary humoral response?

The secondary response occurs on subsequent exposure to the same antigen, producing antibodies faster and stronger. (Note: Memory B cells allow rapid response. Your immune system remembers enemies it has fought before, so the second time it sees the same germ, it attacks much faster and stronger than the first time.)

What is cell-mediated immunity?

Cell-mediated immunity is T cell-driven defense against viral infections, grafts (organ transplants), and intracellular pathogens.

(Note: Does not rely on antibodies; protects against infected or altered self-cells. A T cell is like a cop who is only alerted when a citizen (one of your own cells) walks up and says, "I have a criminal hiding inside my house!" (This is called antigen presentation).)

What are cytotoxic T cells (CD8+)?

CD8+ T cells monitor and destroy compromised cells , including infected or cancerous cells.

(Note: Eliminate pathogens hiding inside host cells.T cell is like a cop who is only alerted when a citizen (one of your own cells) walks up and says, "I have a criminal hiding inside my house!")

What is the role of bone marrow in immunity?

Bone marrow is the site of B lymphocyte (B cell) maturation and hematopoiesis (making new blood cells). (Note: Produces stem cells for all blood and immune cells.)

What is the role of the thymus?

The thymus is the site of T lymphocyte (T cell) maturation, most active in neonatal and preadolescent stages. (Note: The thymus is like a "training school" for your infection-fighting T-cells, and it's most busy doing this training when you're a baby and a child.)

What is the role of lymph nodes?

Lymph nodes filter lymph, trap pathogens, and facilitate WBC transport and interaction . (Note: Serve as secondary lymphoid tissue for immune surveillance.)

What is the role of the spleen?

The spleen filters blood antigens and responds to systemic infections . (Note: Acts as a secondary lymphoid organ for circulating pathogens.)

What is MALT (mucosa-associated lymphoid tissue)?

Mucosa-associated lymphoid tissue (MALT) is lymphoid tissue in respiratory, gastrointestinal, and reproductive tracts . (Note: Provides local immune defense at mucosal surfaces.)

What is active immunity?

Active immunity occurs when the host mounts an immune response to an antigen, creating memory.

(Note: Provides long-term protection against future infections. When your body learns to fight a disease by itself, either by getting sick or through a vaccine, and then remembers how to beat it forever)

What is immunization?

Immunization is the induction of active immunity via a vaccine . (Note: Helps prevent disease by priming the adaptive immune system.)

What is maternal IgG transfer?

IgG antibodies are transferred via the placenta to provide fetal passive immunity. (Note: Protects the newborn before its own immune system is fully functional.)

What is immune tolerance?

Immune tolerance allows the immune system to react to foreign antigens but ignore self-antigens.

(Note: Prevents autoimmune diseases by marking them as "self" to prevent the immune system from attacking them.)

What is the role of helper T cells (CD4+) in adaptive immunity?

CD4+ T cells activate B cells, cytotoxic T cells, NK cells, and macrophages. (Note: Think of CD4+ T cells as the "generals" of your immune army. They don't fight directly, but they give the orders that tell your other soldier cells (like B cells and killer T cells) to activate and attack the enemy.)

What is the role of regulatory T cells (TREGS)?

TREGS suppress harmful self-reactive lymphocytes to prevent autoimmune reactions. (Note: Maintain immune homeostasis.)

What are immunoglobulins (Ig) and their main classes?

Immunoglobulins are antibodies: IgG, IgA, IgM, IgE, and IgD.

(Note: Each class has specific functions in immunity.)

What is IgA and its role?

IgA is found in secretions like saliva, tears, and breast milk. Prevents microbial attachment and provides mucosal immunity.

(Note: IgA is the antibody that acts like your body's "first line of defense" in your spit, tears, and even a mother's breast milk, protecting the wet, exposed surfaces of your body from germs.)

What is IgM and its role?

IgM is the first antibody produced during initial antigen exposure and can agglutinate pathogens. (Note: IgM is your body's "first responder" antibody. It's the first one made when a new germ shows up, and it works by clumping the invaders together to stop them from spreading.)

What is IgD and its role?

IgD is mostly on B cell membranes , functioning as a receptor. (Note: Think of IgD as a "radar dish" on the surface of B cells. Its main job is to act as an antenna, helping the B cell detect when a specific enemy (antigen) is nearby so it can activate and start fighting.)

What is IgE and its role?

IgE participates in allergic reactions, mast cell activation , and parasite defense. (Note: Links immunity to inflammation and parasite elimination.)

What are lymphoid organs and their types?

Lymphoid organs produce, mature, and store immune cells : primary (bone marrow, thymus) and secondary (lymph nodes, spleen). (Note: Sites for immune cell development and activation.)

Where is MALT located?

Mucosa-associated lymphoid tissue (MALT) is located in mucosal surfaces to provide local defense. (Note: Protects respiratory, GI, and reproductive tracts.)

What is passive immunity?

Passive immunity is temporary protection from another source , like maternal antibodies. (Note: Provides immediate but short-term defense.)

What is the role of maternal IgG transfer?

Maternal IgG role is to protect the fetus. (Note: Passive immunity before birth.)

What is the role of maternal antibodies in milk?

Maternal milk provides IgG, protecting the neonate until their immune system matures. (Note: Postnatal passive immunity.)

What is immune regulation?

Immune regulation ensures responses cease after antigen elimination, preventing tissue damage. (Note: Maintains balance in the immune system.)

How does aging affect immunity?

Older adults have reduced immune efficiency, slower responses, and higher infection risk. (Note: Immunosenescence reduces both innate and adaptive immunity.)

What are inflammatory cytokines?

Inflammatory cytokines mediate immune-tissue communication, recruit immune cells , and regulate inflammation. (Note: Essential for coordinating defense and repair.)

What is the complement system and its function?

The complement system consists of proteins in circulation that promote opsonization, inflammation, leukocyte migration, and pathogen lysis. (Note: Amplifies immune defense. “Complements/Boosts”)