Immunity22
Immunity and Defense
Page 1: Introduction
Immunity and Defense Overview
Basic concepts of immune response
Page 2: Objectives
Understand major functions, organization, and histological components of the lymphatic system
Explain mechanisms of innate defenses
Discuss development and activation of cellular and humoral immunity
Page 3: Immune System & Body’s Defense
Immune System: Protects from infectious agents and harmful substances
Usually operates unnoticed
Involves cellular and molecular structures for immunity
Function depends on the type of infectious agent
Page 4: Diseases and Infectious Agents
Infectious agents damage or kill hosts
Pathogenic agents: cause harm
Five categories:
Bacteria
Viruses
Fungi
Protozoans
Multicellular parasites
Page 5: Types of Infectious Agents
Bacteria: Shapes include spherical (cocci), rod-like (bacilli), coiled (spirilla)
Harmless vs. virulent bacteria
Examples of virulent bacteria: Clostridium tetani (tetanus), streptococcal bacteria (strep throat)
Page 6: Viruses
Obligate intracellular parasites that need host cells to reproduce
Infect cells to create copies of their nucleic acids and capsids
Some common infections: cold, Ebola, chickenpox, COVID-19
Page 7: Fungi
Includes molds, yeasts, multicellular fungi producing spores
Cause diseases like ringworm and vaginal yeast infections
Page 8: Protozoans
Eukaryotic cells without a cell wall
Examples include malaria and trichomoniasis
Page 9: Prions
Fragments of infectious proteins that cause diseases in nervous tissue
Example: Variant Creutzfeldt-Jakob disease
Page 10: Immune Cells and Their Locations
Leukocytes: Formed in red bone marrow
Types: Granulocytes (neutrophils, eosinophils, basophils), Monocytes (migrate as macrophages), Lymphocytes (B-lymphocytes, T-lymphocytes, NK cells)
Page 11: Cytokines
Small proteins that regulate immune activity
Produced by both innate and adaptive immune cells
Functions include:
Signaling immune and non-immune cells
Controlling development of immune cells
Regulating inflammatory responses
Page 12: Cytokine Categories
Interleukin (IL): e.g., IL-1, IL-2
Tumor necrosis factor (TNF): e.g., TNF-α
Colony-stimulating factor (CSF): e.g., granulocyte CSF
Interferon (IFN): e.g., INF-α
Page 13: Immunity: Two Intrinsic Defense Systems
Innate (nonspecific) system:
First line: skin and mucosae
Second line: antimicrobial proteins, phagocytes,
Quick response, ready for attack
Adaptive (specific) defense:
Third line: mounts attack against specific foreign substances
Takes longer to react but works alongside the innate system
Page 14: Innate and Adaptive Defenses
Innate Immunity: Immediate and nonspecific response
Adaptive Immunity: Delayed response to specific antigens through B-cells and T-cells
Page 15: Mechanisms of Innate Immunity
Physical barriers, chemical barriers, and inflammation as first responses to pathogens
Page 16: Inflammation Response and Its Importance
Inflammation prevents spread of pathogens and promotes repair
Four cardinal signs: redness, heat, swelling, pain
Page 17: Clinical View: Pus and Abscesses
Pus comprises dead leukocytes and pathogens
Abscess formation when pus is walled off
Page 18: Fever
Elevated body temperature as a response to pathogens
Pyrogens reset the body's temperature set point
Page 19: Adaptive Immunity
Recognizes and responds to specific foreign substances
Two arms: Humoral (B cells) and cellular (T cells)
Page 20: Activation of B-Lymphocytes
B-antigen encounter in lymphoid organs leads to clonal selection and antibody production
Memory B-Lymphocytes facilitate quicker responses upon re-exposure to the antigen
Page 21: Mechanisms of B-cell Activation
B-cells require two activation signals: antigen binding and help from T-cells
Page 22: Immunoglobulins
Antibodies (Ig) — five classes: IgD, IgM, IgG, IgA, IgE
Antibodies function by neutralization, agglutination, and opsonization
Page 23: Cell-mediated Immunity
Uses T-cells to directly target and destroy infected or abnormal cells
T-cells undergo positive and negative selection in the thymus to ensure proper function
Page 24: Autoimmune Disorders
Occurrence when immune system misidentifies self-antigens as foreign
Examples: Multiple sclerosis, Type 1 diabetes, Rheumatoid arthritis
Page 25: Allergies and Hypersensitivity
Immune responses that damage tissue; acute and delayed types
Anaphylaxis and symptoms associated with it may require immediate treatment
Page 26: Summary of Immune Processes
Immune response involves cooperation between various cells and cytokines
Key components: T-cells and B-cells, memory cells, and antibodies