IS LESS 3

Innate Immunity

Consists of defenses against infection that are ready for immediate action when a host is attacked by a pathogen.

Innate Immunity Response to Repeated Exposure

Repeated exposures to groups of related microbes invoke virtually identical innate immune responses.

Innate Immunity Main Components

External Defense System and Internal Defense System.

External Defense System

Physical, chemical, and biological barriers that prevent most infectious agents from entering the body.

External Defense System Components

Microbiota, Skin, Sweat, Sebaceous Glands, Respiratory Tract, Urine, Vagina, Digestive Tract, Tears and Saliva.

Phagocytosis

Engulfment and destruction of foreign cells or particles by leukocytes, macrophages, and other cells.

Phagocytosis Importance

Together with inflammation, it brings immune cells to the injured area to promote healing.

Microbiota

Mixture of bacteria normally found at specific body sites that do not typically cause disease.

Microbiota Importance

Host microbiota and the immune system interact to maintain tissue homeostasis in healthy individuals.

Microbiota Functions

Regulates innate immune functions and homeostasis, adaptive immune functions in the intestines, and systemic innate and adaptive immune functions.

Skin

Acts as the body's physical barrier against microorganisms.

Skin Parts

Epidermis, Dermis, and Psoriasin.

Epidermis

Outer layer of the skin coated with keratin.

Keratin

Protein coating the epidermis that makes the skin impermeable to most infectious agents.

Epidermis Functions

Makes the skin impermeable to most infectious agents and is renewed every few days to maintain the barrier.

Dermis

Layer beneath the epidermis that contains protective structures and immune cells.

Dermis Contains

Blood vessels, hair follicles, sebaceous glands, sweat glands, macrophages, dendritic cells, and mast cells.

Macrophages in the Dermis

White blood cells found in the dermis that contribute to immune defense.

Dendritic Cells in the Dermis

White blood cells found in the dermis that contribute to immune defense.

Mast Cells in the Dermis

White blood cells found in the dermis that contribute to immune defense.

Psoriasin

Small antibacterial protein that is especially effective against Gram-negative organisms such as Escherichia coli.

Psoriasin Target Organism

Gram-negative bacteria, especially Escherichia coli.

Sweat

Contributes to external defense through the presence of lactic acid.

Lactic Acid in Sweat

Helps protect against microorganisms.

Sebaceous Glands

Help protect the skin by maintaining an acidic environment.

Skin pH Maintained by Sebaceous Glands

Approximately 5.6.

Acidic Skin pH Function

Prevents the growth of most microorganisms.

Respiratory Tract

Protects against infection through mucus, surfactants, ciliary movement, coughing, and sneezing.

Respiratory Tract Defense Mechanisms

Mucous secretions, surfactants, cilia, coughing, and sneezing.

Mucous Secretions

Block the adherence of bacteria to epithelial cells.

Surfactants

Produced by epithelial cells and bind microorganisms to help move pathogens out of the respiratory tract.

Cilia

Hair-like structures that remove about 90% of deposited material from the nasopharyngeal passages.

Cilia Function

Clear approximately 90% of deposited material from the nasopharyngeal passages.

Coughing

Helps expel pathogens from the respiratory tract.

Sneezing

Helps expel pathogens from the respiratory tract.

Urine

Protects the genitourinary tract by flushing microorganisms while its acidity helps remove potential pathogens.

Urine Defense Mechanism

Flushing action and acidic pH.

Vagina

Protected by lactic acid that maintains a pH of about 5 to prevent pathogen invasion.

Vaginal pH

Approximately 5.

Lactic Acid in the Vagina

Maintains the vaginal pH and helps prevent pathogen invasion.

Digestive Tract

Protects against microorganisms through gastric acid and beneficial bacteria.

Digestive Tract Defense Components

Hydrochloric acid (HCl), probiotics, and other beneficial bacteria.

Hydrochloric Acid (HCl)

Has a pH of approximately 1 and serves to halt microbial growth.

Hydrochloric Acid pH

Approximately 1.

Probiotics

Bacteria in the gut that provide health benefits to the host when acquired in adequate amounts.

Probiotics Function

Provide colonization resistance together with other beneficial bacteria.

Colonization Resistance

Protection provided by probiotics and other beneficial bacteria against pathogen colonization.

Tears and Saliva

Protect against infection through the enzyme lysozyme.

Lysozyme

Enzyme found in tears and saliva that attacks the cell walls of microorganisms, especially Gram-positive bacteria.

Lysozyme Location

Found in tears and saliva. Lysozyme Target

Internal Defense System Most Important Function

Phagocytosis.

Internal Defense System Major Soluble Component

Acute Phase Reactants (Acute Phase Proteins).

Pattern Recognition Receptors (PRRs)

Receptors encoded by the host's genomic DNA that determine which molecules are immunogenic and act as sensors for extracellular infection.

Pattern Recognition Receptors Functions

Determine which molecules are immunogenic, detect extracellular infection, detect viral components or viral intermediate products, induce production of pro-inflammatory cytokines, and distinguish self from non-self by recognizing PAMPs.

Pathogen-Associated Molecular Patterns (PAMPs)

Molecules associated with groups of pathogens that are recognized by cells of the innate immune system.

Pattern Recognition Receptors Recognize

Pathogen-Associated Molecular Patterns (PAMPs).

Examples of Pathogen-Associated Molecular Patterns

Peptidoglycan, Lipopolysaccharide (LPS), Zymosan, and Flagellin.

Peptidoglycan

Pathogen-associated molecular pattern found in Gram-positive bacteria.

Lipopolysaccharide (LPS)

Pathogen-associated molecular pattern found in Gram-negative bacteria.

Zymosan

Pathogen-associated molecular pattern found in yeast.

Flagellin

Pathogen-associated molecular pattern found in bacteria with flagella.

Toll-Like Receptors (TLRs)

Set of transmembrane receptors that recognize different pathogen-associated molecular patterns and activate an appropriate immune response.

Toll-Like Receptors Function

Identify the nature of pathogens and activate an appropriate effector response to eliminate them.

Discoverer of Toll-Like Receptors

Charles Janeway.

Highest Concentration of Toll-Like Receptors

Monocytes, macrophages, and dendritic cells.

Result of Toll-Like Receptor Activation

Production of cytokines and chemokines leading to rapid activation of the immune response.

Toll Protein

Protein involved in innate immunity originally discovered in the adult fruit fly Drosophila.

Toll Protein Highest Concentration

Monocytes, macrophages, and dendritic cells.

Cell Surface Toll-Like Receptors

TLR1, TLR2, TLR4, TLR5, and TLR6.

Endosomal Toll-Like Receptors

TLR3, TLR7, TLR8, and TLR9.

TLR2

Recognizes teichoic acid and peptidoglycan of Gram-positive bacteria.

TLR2 Recognizes

Teichoic acid and peptidoglycan of Gram-positive bacteria.

TLR4

Recognizes lipopolysaccharide (LPS) of Gram-negative bacteria.

TLR4 Recognizes

Lipopolysaccharide (LPS) of Gram-negative bacteria.

TLR5

Recognizes bacterial flagellin.

TLR5 Recognizes

Bacterial flagellin.

TLR10

Functions as an anti-inflammatory receptor.

NOD-Like Receptors (NLRs)

Intracellular receptors in which NOD stands for Nucleotide-binding Oligomerization Domain.

NOD

Nucleotide-binding Oligomerization Domain.

Mutation of NOD-Like Receptors

Associated with Crohn's disease.

Crohn's Disease

Painful inflammatory disease of the bowel caused by mutations in NOD-like receptors.

Systemic Lupus Erythematosus (SLE)

Associated with increased antibodies against self-nucleic acids that activate dendritic cells through TLR9.

Systemic Lupus Erythematosus Activates

Dendritic cells through TLR9.

Acute Phase Reactants (Acute Phase Proteins)

Normal serum constituents whose concentrations rapidly increase or decrease because of infection, injury, or tissue trauma.

Types of Acute Phase Reactants

Positive Acute Phase Reactants and Negative Acute Phase Reactants.

Positive Acute Phase Reactants

Serum proteins whose concentrations increase during infection, injury, or tissue trauma.

Examples of Positive Acute Phase Reactants

C-Reactive Protein (CRP), Serum Amyloid A (SAA), Complement Components, Alpha₁-Antitrypsin (AAT), Haptoglobin, Fibrinogen, and Ceruloplasmin.

Negative Acute Phase Reactants

Serum proteins whose concentrations decrease during infection, injury, or tissue trauma.

Examples of Negative Acute Phase Reactants

Albumin and Transferrin.

Main Biological Sign of Inflammation

Increase in the Erythrocyte Sedimentation Rate (ESR).

Positive Acute Phase Reactant Production Site

Hepatocytes (liver parenchymal cells).

Positive Acute Phase Reactant Production Time

Within 12–24 hours after increased cytokine levels.

Stimulus for Positive Acute Phase Reactant Production

Increased cytokine levels.

Inflammatory Cytokines

Interleukin-1 (IL-1), Interleukin-6 (IL-6), and Tumor Necrosis Factor-alpha (TNF-α).

Inflammatory Cytokine Production Site

Monocytes and macrophages.

Inflammatory Cytokine Function

Stimulate the production of Positive Acute Phase Reactants.

Interleukin-1 (IL-1)

Inflammatory cytokine produced by monocytes and macrophages that stimulates Positive Acute Phase Reactant production.

Interleukin-6 (IL-6)

Inflammatory cytokine produced by monocytes and macrophages that stimulates Positive Acute Phase Reactant production.

Tumor Necrosis Factor-alpha (TNF-α)

Inflammatory cytokine produced by monocytes and macrophages that stimulates Positive Acute Phase Reactant production.

C-Reactive Protein (CRP)

Positive Acute Phase Reactant that promotes phagocytosis by binding to receptors on monocytes, macrophages, and neutrophils. It is the most widely used indicator of acute inflammation.