Module 8A - Immune System Flashcards
What is the immune system?
• Complex network of cells, tissues, organs, and molecules that work together to defend the body against pathogens, including viruses, bacteria, fungi, and parasites
• Plays a crucial role in recognizing and neutralizing harmful substances from the environment and fighting against the body’s
own cells when they become cancerous
What is the immune system composed of?
• Leukocytes and Immune cells and proteins and other molecules
• Adaptable and Innate Immune system
• Lymphatic System
What are the key functions of the immune system?
Defense Against Pathogens
• Recognizing and eliminating pathogens
Surveillance Against Cancer
• Identifying and destroying cells that have become cancerous
Wound Healing and Tissue Repair
• Managing the process of inflammation and healing
Maintaining Homeostasis
• Removing dead cells and renewing tissues
What are the characteristics of the innate immunity?
- Non-Specific Response
• The innate immune system provides a general defense against pathogens, meaning it does not recognize specific pathogens but rather responds to several indicators of infection - Immediate Response
• It responds to pathogens within minutes to hours of exposure and is the body’s first line of
defense - No Memory
• Innate responses do not adapt to repeated infections; the response is the same each time a pathogen invades - Components
• Physical Barriers: Skin and mucous membranes • Chemical Barriers: Stomach acid, enzymes in tears and skin oils
• Cellular Defenses: Phagocytic
• Inflammatory Response: Release of cytokines that recruit immune cells to sites of infection
Advantages
• Provides immediate protection
• Protects against all pathogens
Disadvantages
• Lacks specificity
• No immunological memory
What are the characteristics of the adaptable immunity?
- Specific Response
• The adaptive immune system can recognize specific pathogens through antigens. Each
lymphocyte recognizes a unique antigen - Slower Response
• It takes days to become fully effective; it is activated after the innate immune response - Memory
• Once an antigen is recognized, the adaptive immune system creates memory cells that
allow it to respond more rapidly and effectively upon subsequent exposures - Components:
- Lymphocytes: T cells (cytotoxic and helper) and B cells
- Antibodies: Produced by B cells that specifically bind to antigens
- Effector Mechanisms: Cell-mediated immunity (T cells) and humoral immunity (antibodies)
Advantages
• High specificity for specific pathogens
• Immune memory leads to quicker responses upon repeated exposures
Disadvantages
• Takes time to mount an initial response
• Requires prior exposure to the pathogen
What are the key differences between innate and adaptable?
Speed and Timing
• Innate immune system acts immediately
• Adaptive system takes longer to respond but develops memory for a faster response on subsequent exposures
Specificity
• Innate immunity is non-specific
• Adaptive immunity is highly specific to a pathogen’s antigens
Memory
• Innate immunity lacks memory
• Adaptive immunity develops immunological memory, leading to an enhanced and faster response to repeated
exposures to the same pathogen’s antigens
Neutrophils
• Most abundant type of WBC in humans and are a critical component of the innate
immune system
• Primarily responsible for responding to infections, especially bacterial and fungal
Eosinophils
• Involved in combating parasitic infections and mediating allergic inflammatory
responses
Basophils
• Least common WBC
Monocytes
• Differentiate into Macrophages
• Numerous roles within the immune system
T-Lymphocytes (T-Cells)
• WBC responsible for mediating cellular immunity through the direct killing of infected host cells
• Created in the bone marrow and mature in the thymus
• Can differentiate into various subsets such as cytotoxic T cells, helper T cells, and regulatory T cells
B-Lymphocytes (B-Cells)
• Create humoral immunity by producing and secreting antibodies that target specific antigens
• Created and mature in the bone marrow and differentiate into plasma cells
• Plasma cells produce antibodies and memory B cells that provide long-term immunity to a specific antigen
Helper T Cells (CD4+ T Cells)
• Assist other cells in the immune system by releasing cytokines, which can amplify
the immune response
• Helper T cells are further categorized based on the cytokines they produce: T Helper 1 Cells (TH1), T Helper 2 Cells (TH2), T Helper 17 Cells (TH17)
Cytotoxic T Cells (CD8+ T Cells)
• Cells are responsible for directly killing infected cells, primarily those infected with viruses or transformed by cancer
• Recognize antigens presented by MHC class I molecules on the surface of infected cells
Memory T Cells
• After an initial response to a specific antigen, some T cells become memory cells
• Persist long-term in the body and enable a faster response upon re-exposure to the
same antigen
What do B-Lymphocytes differentiation into?
Plasma Cells
• Create and secrete large amounts of antibodies specific to the antigen they
are exposed to
• Antibodies play a key role in the immune response by neutralizing
pathogens or marking them for destruction by other immune cells
Memory B Cells
• Do not secrete antibodies but persist in the body for years or even decades
• Provide a rapid and robust response upon re-exposure to the same antigen
• Forms the basis of immunological memory.
Antigen
• Substance that the body recognizes as foreign, which can trigger an immune response aimed at attacking and eliminating it
• These substances can come from outside the body, like viruses or bacteria, or can be abnormal cells from within the body, such as cancer cells
• Can be proteins, polysaccharides, or other biochemical molecules derived from pathogens (such as viruses and bacteria) or from non-infectious sources (including pollen, food, and own body cells in cases of autoimmune
diseases)
• Basically, think of it as the SSN or SIN (for ya’ Canadians, eh)
What are the 5 Classifications of Antibodies / Immunoglobins?
IgG
• Most abundant (~80%)
• Humoral immunity
IgA
• Body secretions (saliva, tears, mucous membranes)
IgM
• First antibody produced with detection of foreign antigens
IgE
• Associated with allergies
IgD
• Found on the surface of B cells
What are Antigen-Presenting Cells (APCs)?
• Antigen-Presenting Cells (APCs) are specialized to capture microbial antigens and display these to lymphocytes
• Antigen-Presenting Cells (APCs)
• Dendritic Cells
• Macrophages
• B-Lymphocytes
• Display antigen complex with their Class II MHC molecule on their
surface
• Interact with T helper cells and B cells
What are the three classifications to immune system disorders?
• 1. Hypersensitivity
• 2. Autoimmune
• 3. Immunodeficiency
What is the pathogenesis to hypersensitivity? How are the reactions initiated? What are 4 types of immunodeficiency diseases?
It is an excessive or harmful reaction to an antigen that normally does not illicit an immunologic response
• Imbalance between effector mechanisms of immune response and control mechanisms that limit the response
Exogenous Antigens
• Microbes, chemicals, food, pollen, dust, drugs
• May range from itchy nose, runny eyes to extreme fatal situations- anaphylaxis
• Commonly referred to as allergies
Endogenous Antigens
• Our own cell antigens
• Lead to autoimmune diseases
Fo ur Types of Hypersensitivity Reactions
• Immediate (type I) hypersensitivity
• Commonly referred to as allergies
• Antibody-mediated (type II) hypersensitivity
• Immune complex-mediated (type III) hypersensitivity
• Cell-mediated (type IV) hypersensitivity
What is the pathogenesis to autoimmune?
• Disorders and diseases that are due to a failure of the body’s immune system for self-tolerance
• Immune system is unable to distinguish self-antigens from foreign antigens
• Immune system produces autoantibodies that attack the body’s own antigens
What is the pathogenesis to
immunodeficient immune disorders? What are 2 categories of immunodeficiency diseases?
• The immune system is deficient or not functioning at full capability
• Leaves the body vulnerable for the development of diseases and
disorders
• 1. Primary (congenital) immunodeficiencies
• 2. Secondary (acquired) immunodeficiencies
- Hypersensitivity reactions are when the body’s immune system
causes a deficient response to identified antigens.
• A) True
• B) False
B) False