Chapter 35 Bio 191

Here is your cleaned

up vocabulary list with a dash (

immune system

An animal body's system of defenses against agents that cause disease.

innate immunity

A form of defense common to all animals that is active immediately upon exposure to pathogens and remains the same whether or not the pathogen has been encountered previously.

adaptive immunity

A vertebrate

lysozyme

An enzyme that destroys bacterial cell walls; in mammals, found in sweat, tears, and saliva.

phagocytosis

A type of endocytosis in which large particulate substances or small organisms are taken up by a cell. In mammals, mainly performed by macrophages, neutrophils, and dendritic cells.

neutrophil

The most abundant type of white blood cell. Neutrophils are phagocytic and destroy foreign invaders, typically surviving only a few days.

macrophage

A phagocytic cell present in many tissues that destroys microorganisms as part of innate immunity and functions as an antigen

natural killer cell

A type of white blood cell that kills tumor cells and virus

cytokine

A small protein secreted by various cell types, including macrophages and helper T cells, that regulates the functions of other cells.

interferon

A protein with antiviral or immune

inflammatory response

An innate immune defense triggered by physical injury or tissue infection. It promotes swelling, increases white blood cell infiltration, helps destroy pathogens, and aids tissue repair.

histamine

A substance released by mast cells that causes blood vessels to dilate and become more permeable during inflammatory and allergic responses.

lymphocyte

A type of white blood cell that mediates immune responses. The two main classes are B cells and T cells.

T cells

Lymphocytes that mature in the thymus. They include effector cells for the cell

B cells

Lymphocytes that complete their development in the bone marrow and become effector cells for the humoral immune response.

antigen

A substance that elicits an immune response by binding to receptors on B cells, antibodies, or T cells.

antigen receptor

A surface protein on B cells or T cells that binds to antigens and initiates adaptive immune responses. B cells have B cell receptors, while T cells have T cell receptors.

antibody

A protein secreted by plasma cells (differentiated B cells) that binds to a specific antigen; also called immunoglobulin. Antibodies have a Y

major histocompatibility complex (MHC) molecule

A host protein involved in antigen presentation. Foreign MHC molecules on transplanted tissue can trigger T cell responses that may cause transplant rejection.

antigen presentation

The process by which an MHC molecule binds to a protein antigen fragment and displays it on the cell surface so it can be recognized by a T cell.

memory cell

A long

clonal selection

The process by which an antigen binds to and activates lymphocytes with matching receptors. These cells proliferate and differentiate into effector cells and memory cells specific to that antigen.

primary immune response

The initial adaptive immune response to an antigen, which appears after a lag of approximately 10–17 days.

secondary immune response

The adaptive immune response following a second or subsequent exposure to an antigen. It is faster, stronger, and longer

humoral immune response

The branch of adaptive immunity involving B cell activation and antibody production, which defends against bacteria and viruses in body fluids.

cell

mediated immune response

helper T cell

A type of T cell that secretes cytokines when activated, promoting B cell responses (humoral immunity) and cytotoxic T cell responses (cell

antigen

presenting cell

cytotoxic T cell

A type of lymphocyte that kills infected cells, certain cancer cells, and transplanted cells.

immunization

The process of generating immunity artificially. Active immunization (vaccination) introduces an inactive or weakened pathogen to stimulate B and T cell responses and memory. Passive immunization administers antibodies for immediate but temporary protection.

monoclonal antibodies

Antibodies produced by a single clone of cultured cells, all specific to the same epitope.

allergen

An antigen that triggers an exaggerated immune response.

autoimmune disease

An immunological disease in which the immune system attacks the body's own cells or tissue

Define and describe innate and adaptive recognition

• Define and describe innate and adaptive recognition

• Innate = Immediate + Generalized + All animals.

• Adaptive = Antigen-specific + Memory + Vertebrates.

Describe how phagocytic immune cells protect against pathogens via phagocytosis

• Neutrophils: Most abundant white blood cells; quickly engulf and destroy pathogens.

• Macrophages: Engulf pathogens, destroy microorganisms, and can present antigens to activate adaptive immunity.

• Dendritic cells: Engulf pathogens and present antigens to activate T cells.

Describe barrier defenses

• Skin: Acts as a protective physical barrier that prevents pathogens from entering the body.

• Mucous membranes: Line respiratory, digestive, and reproductive tracts and trap pathogens in mucus.

• Cilia: Tiny hair-like structures that move mucus and trapped pathogens out of the respiratory tract.

Describe cellular innate defenses (35.1)

▪ TLRs

▪ Neutrophils

▪ Macrophages

▪ Natural killer cells

▪ Peptides and proteins

Cellular innate defenses - Internal, nonspecific immune defenses that recognize and destroy pathogens quickly without requiring prior exposure.

• Toll-like receptors (TLRs) - Receptors on immune cells that recognize common molecular patterns found in pathogens (PAMPs), triggering an immune response and inflammation.

• Neutrophils - Abundant white blood cells that are usually the first to arrive at an infection site; engulf and destroy pathogens through phagocytosis.

• Macrophages - Large phagocytic cells that engulf and digest pathogens, dead cells, and cellular debris; also release signaling molecules that promote inflammation and activate other immune cells.

• Natural killer (NK) cells - Immune cells that recognize and destroy virus-infected and cancerous cells by triggering apoptosis (programmed cell death).

• Peptides and proteins - Antimicrobial molecules that help defend against pathogens; include:

  • Defensins - Antimicrobial peptides that damage pathogen cell membranes.

  • Complement proteins - Bind to pathogens, promote inflammation, attract immune cells, and help destroy pathogens by forming membrane attack complexes.

  • Interferons - Proteins released by virus-infected cells that warn nearby cells and help inhibit viral replication.

Briefly describe the inflammatory response purpose and steps

Inflammatory response - A nonspecific innate immune defense that helps eliminate pathogens, prevent their spread, and begin tissue repair.

Steps:

1. Detection: Damaged cells and immune cells (especially mast cells) detect injury or infection and release histamine and other signaling molecules.

2. Vasodilation: Blood vessels widen, increasing blood flow to the affected area (causing redness and heat).

3. Increased permeability: Blood vessels become more permeable, allowing fluid and immune proteins to enter tissues (causing swelling).

4. White blood cell recruitment: Neutrophils and macrophages move toward the infection site through chemotaxis and destroy pathogens by phagocytosis.

5. Healing: Pathogens and dead cells are cleared, inflammation subsides, and tissue repair begins.

Define T Cells & B Cells and how they respond to pathogens (35.2)

▪ Antibodies

▪ MHC and antigen presentation

- T cells - Mature in the thymus and provide cell-mediated immunity.

• Helper T cells (CD4) - Activate B cells, cytotoxic T cells, and other immune cells through signaling molecules.

• Cytotoxic T cells (CD8) - Recognize and destroy virus-infected or cancerous cells.

• Memory T cells - Remain after infection and provide a faster response upon future exposure.

- B cells - Mature in the bone marrow and provide humoral (antibody-mediated) immunity. When activated, they differentiate into:

• Plasma cells - Produce and release antibodies that bind to specific antigens on pathogens.

• Memory B cells - Remain in the body and produce a faster, stronger response upon future exposure.

- Antibodies - Y-shaped proteins produced by plasma cells that bind to specific antigens, helping neutralize pathogens, mark them for destruction, and activate complement proteins.

- MHC (Major Histocompatibility Complex) - Proteins on cell surfaces that display antigen fragments so T cells can recognize them.

• MHC I - Found on nearly all nucleated cells; presents antigens from inside the cell to cytotoxic T cells (CD8), allowing them to identify infected cells.

• MHC II - Found on antigen-presenting cells (APCs), such as macrophages and dendritic cells; presents antigens from engulfed pathogens to helper T cells (CD4).

- Antigen presentation - The process in which cells display pathogen fragments (antigens) on MHC proteins for T cells to recognize and initiate an adaptive immune response.

Describe the 4 characteristics of adaptive immune system (35.2)

▪ Diversity

▪ Self-tolerance

▪ Proliferation

▪ Memory

Describe humoral and cell-mediate responses

▪ Understand the roles of B cells, antibodies, helper T cells, cytotoxic T cells