Patho Unit 4 Flashcards
Understand: - Innate Immunity: Inflammation and Wound Healing (Ch 5) - Adaptive Immunity (Ch 6) - Infection and Defects in Mechanisms of Defense (Ch 7)
Innate (natural) Immunity
- Chemical and physical barriers
- Non-specific mechanisms
- Non-adaptive mechanisms
Adaptive (acquired) Immunity
Specific - Responds to a unique pathogen Adaptive - Variable response 2 Components - Cell-mediated and Antibody-mediated
First Line of Defense
Physical Barriers
- Skin, mucus membranes, vomiting, coughing, urination, defecation
Biochemical Barriers
- Mucus, perspiration, saliva, tears, cerumen, chemicals derived from normal flora, sebum
Second Line of Defense
Inflammation and Phagocytosis
Third Line of Defense
Adaptive, Specific immunity
- Cell mediated, Antibody mediated (humoral)
Inflammation
- Immediate, non-specific, and non-adaptive
- Universal response to injury
- Mediated by chemicals found in circulation
- Increases plasma and blood cells into tissues around the injury
- Defends against infections
- Promotes tissue repair and healing
Local Symptoms of Inflammation
microcirculation
- Vasodilation
- Increased capillary permeability
- White cell migration from the capillaries to the site of inflammation
- Inflammatory chemicals stimulate nociceptors
Local Symptoms of Inflammation
observable characteristics
- Heat
- Swelling
- Redness
- Pain
Vasodilation
Increased blood flow to decrease blood flow velocity
Exudation
Fluid and cells leak from blood vessels
- Serous, fibrinous, purulent, hemorrhagic
- Dilutes toxins
- Brings in plasma proteins
- Removes bacterial products and dead cells
Purpose and Benefits of Inflammation
- Destroy injurious agents
- Confine agents to limit their effects on the host
- Stimulate components of the adaptive immune system
- Promote regeneration and repair of tissue
Systemic Manifestations of Inflammation
- Fever
- Increased Pro-inflammitory and Anti-inflammitory plasma proteins by the liver
- Leukocytosis (Neutrophils)
Events of Acute Inflammation
Activation of:
- Complement System: direct or indirect destruction of cells (esp. bacteria)
- Coagulation System: isolates infections by trapping pathogens and prevents hemorrhage
- Kinin System: interacts with the coagulation system; pro-inflammatory
Complement System
A group of plasma proteins that participate at all levels of inflammation
- Enhances inflammation by opsonization of bacteria and degranulation of Mast cells
3 Pathways
- Classical
- Alternative
- Lectin
Classical Pathway of Compliment System
Activated by antigen-antibody complexes
Alternative and Lectin Pathways of Compliment System
- Activated by biologic substances (bacteria, fungi, toxins)
- Non-antibody dependent
Coagulation System
- Stops bleeding
- Localizes microorganisms
- Provides a meshwork for healing
Kinin System
- Activated by the coagulation system (intrinsic pathway)
- Primary kinin: bradykinin
- Augments inflammation (pro-inflammatory): vascular permeability, vasodilation, smooth muscle contraction
Cytokines
Chemical signal from one cell that affects another
- Can be pro- or anti-inflammatory
Interleukins
Cytokines produced primarily by macrophages and lymphocytes in response to microorganisms and products of inflammation
- Encourages cell adhesion
- Chemotaxis
- Proliferation and maturation of WBCs
- Both pro- and anti-inflammatory
Interferons
Proteins produced to protect against viral infections and encourage the immune system
- Defense against viral infections
- Made by leukocytes to help other cells defend against viruses
Mast Cells
Large, granular cells in loose connective tissue, adjacent to blood vessels
- Early initial activators of the inflammatory response
- Degranulation
- Synthesis of inflammatory mediators
Mast Cell Degranulation
Released from Granules:
- Histamine
- Mast cell protease = tryptase
- Proteoglycans (increase endothelial cell permeability)
Effects of Histamine
- Inflammation
- Contracts smooth muscle in bronchi, GI tract, and uterus
- Increases bronchial, intestinal, and salivary secretions
- Dilation of cerebral blood vessels (headache)
- Stimulates secretion of gastric juices
- Stimulates nerve endings to cause pain and itching
Leukotrienes
- Produce histamine like effect (slower, prolonged)
- Play an important role in asthma
- Inhibitors are used for more sever forms of asthma
Prostaglandins
- Encourage vascular permeability, chemotaxis, and pain
- Made by enzymes called Cyclo-oxygenases (COX)
- Non-steroidal anti-inflammatory drugs are COX inhibitors
Phagocytosis and Phagocyte Migration
- Rolling
- Margination
- Diapedesis
- Exudation
- Phagocytosis
Phagocyte Rolling
Cells slowed by interaction with endothelium
Margination
Increased stickiness by producing adhesion proteins on the cell
Diapedesis
Emigration of phagocytes through the retracted endothelial junctions and basement membrane
Neutrophils
- 70% of WBCs, live 5 days on average
- “Dive into pus and die”
- Phagocytose invaders, the drop chemical bombs on them to kill them
Macrophages
- Migrate into tissues
- Enter the site after 24 hours to help replace Neutrophils
- Survive longer than Neutrophils
- Professional Antigen-Presenting Cells (APCs)
Chronic Inflammation
Lasts longer than 2 weeks
- Occurs when the body fails to remove the cause of the inflammation (weak pathogens, large, resistant or persistent pathogens, or weak immune system)
Granuloma
Formed by Macrophages which join together like bricks in a wall to encircle the offender
Regeneration of Tissue
Results in the restoration of the structure, therefore function
- The goal of healing in inflammation
Repairing Tissue
The replacement of destroyed tissue with scar tissue
- Scar tissue restores strength, but not function
Wound Healing
- Clean up wound by phagocytizing particulate matter (debridement)
- Healing continues by:
- Filling in the wound
- Covering and sealing the wound
- Shrinking the wound
Simple Wounds
Regenerated and healed by primary intention
- Minimal tissue loss
- Examples: paper cut, incised wounds, sutured laceration
Open Wound
Requires more tissue replacement and healing occurs through secondary intention
- Examples: pressure sore, non-sutured laceration, burns
Regeneration and Repair Stages
- Inflammation
- Coagulation and infiltration of cells to facilitate healing
- Debridement and angiogenesis - Proliferation of New Tissue
- Fibroblast proliferation, collagen synthesis, and epithelialization - Remodeling and Maturation
- Cellular differentiation, scar tissue remodeling, capillaries removed from scar tissue
Dysfunctional Wound Healing
during inflammatory phase
- Hemorrhage
- Infection
- Chronic inflammation (excess granuloma formation)
Affected by:
- Diabetes, hypoxia, nutritional deficiency, reactivation of inflammatory responses, and anti-inflammatory medications
Dysfunctional Wound Healing
impaired collagen synthesis
From nutritional deficiency
- Lack of vitamin C (scurvy), iron, calcium, and copper
Dysfunctional Wound Healing
excessive collagen synthesis
Adhesions, hypertropic and keloid scars
Dysfunctional Wound Healing
wound disruption
Reopening (dehiscence) due to collagen disruption
- Wound healing by primary intention is now healing by secondary intention
Dysfunctional Wound Healing
excessive wound contraction
Vasoconstriction
Lymphocytes
- The most important cells of the adaptive immune response
- Originate in bone marrow and mature in either the bone marrow or in the lymph system
- Precursor cells differentiate into T cells (in the thymus) and B cells (in the bone marrow)
Antibody-Mediated (humoral) Immunity
B lymphocytes
- When stimulated develop into plasma cells
- The proteins released from plasma cells are antibodies
Cell-Mediated Immunity
T lymphocytes
- Recognize specific antigens
- Can directly attack abnormal cells
- Mediate adaptive immune responses
Immunogen
A molecule that will induce an immune response
Antigen
Molecule or fragment that binds with products of the immune system (antibodies, T cells, and B cells)
- IDs the cell as self or non-self
- IDs the type of cell
What makes an Antigen more immunogenic/antigenic?
- Large in size
- Organic
- Complex in structure
- Foreign (or at least recognized that way)
Natural Immunity
Not gained through modern medicine
- Active: body is exposed to disease and makes antibodies
- Passive: a baby receives antibodies from its mother through the placenta or breast milk
Artificial Immunity
Gained through artificial means
- Active: a person receives an injection of an attenuated of an attenuated (changed/weakened) pathogen that stimulates to body to form an antibody
- Passive: Injection of prepared antibody
Active Immunity
Long term immunity
- The body responds to a pathogen (antigen) to make antibodies
Passive Immunity
Short term immunity
- The body receives antibodies with no effort of its own
Immunoglobulins
Antibodies, distinguished by structure, location, and function
Classes: IgM, IgG, IgA, IgE, and IgD
IgM
- Very effective activator of the Complement System (1st responders)
- Pentamer
- 10% of total plasma antibody
IgG
- Actively transported across the placenta
- Monomer
- 75% of plasma antibody
- Longest half-life of the immunoglobulins (long-term immunity)
IgA
- Located in the plasma and body secretions
- Lacrimal glands, salivary glands, and lymphoid tissues in the breasts, bronchi, intestines, and GI tract
- Protects against pathogens that are inhaled, swallowed, or come in contact with external surfaces