LO 3 Flashcards
Define injury
The result of an alteration in the environment that causes tissue damage or necrosis
Describe inflammation
Allows the body to eliminate injurious agents, contain injuries, and heal defects
List the body’s innate defenses
- Physical barrier - Intact skin or mucosa
- Mechanical defense - Respiratory system’s cilia and mucus
- Antibacterial activity - Enzymes in saliva
- Removal of foreign substances - Flushing action of tears, saliva, urine, and diarrhea
- Inflammation process - White blood cells
Describe inflammation
- Nonspecific response
- Extent and duration of injury - extent and duration of inflammatory response
- Local or systemic
- Acute, chronic, or combination
What are the 5 localized signs of inflammation?
- Redness
- Heat
- Swelling
- Pain
- Loss of normal tissue function
What are the 3 systemic signs of inflammation?
- Pyrexia (fever)
- Leukocytosis (high WBC)
- Lymphadenopathy - swelling of lymph nodes
List the sequence of microscopic events in order during inflammation
- Injury to tissue
- Constriction of microcirculation - Less blood loss (vasoconstriction)
- Hyperemia - Dilation of blood vessels
- Increase in permeability of fluid + cells emigrating creating exudate (fluid that leaks out of cells into nearby tissues)
- Increased blood viscosity (due to added cells/WBCs/clotting factors)
- Results in decreased blood flow
- Margination of WBCs (WBCs migrate to vessel walls) - Means chemotaxis (alert to immune system for increase action)
- WBCs enter tissue - emigration - exudate and edema (fluid retention)
- WBCs ingest foreign material - phagocytosis
Describe hyperemia
- Increased blood flow in capillary beds of injured tissue
- Will produce erythema (redness) and heat
Describe exudate
- Increased blood plasma and proteins in injured tissue - Helps dilute injurious agents but results in excess fluid in tissues: Edema
- Serous (watery) exudate - Mainly plasma fluids and proteins, a few WBCs
- Purulent exudate (suppuration) - Contains plasma fluids and proteins, tissue debris, and many WBCs
Describe emigration
The process by which WBCs escape from blood vessels through gaps in endothelial cells
Describe chemotaxis
Directed movement of WBCs toward the site of injury
Describe phagocytosis
- The process by which WBCs ingest and then digest foreign substances
- May include pathogenic organisms and tissue debris
Describe white blood cells in the inflammatory response
- Neutrophils: Polymorphonuclear leukocytes (PMNs)
- Monocytes circulating in blood - transform into macrophages when in tissue
- Lymphocytes and plasma cells - Seen in chronic inflammation and the immune response
- Eosinophils and mast cells - Seen in both inflammation and the immune response, related to histamine production
Describe neutrophils (Polymorphonuclear
Leukocytes/PMNs)
- Function - phagocytosis
- Multilobed nucleus and granular cytoplasm that contains lysosomal enzymes
- Constitute 60% to 70% of WBC population
- Derived from stem cells in bone marrow
Describe macrophages
- Function - Phagocytosis; play a role in immune system
- Single round nucleus and do not have granular cytoplasm
- Constitute 3% to 8% of WBC population
- Derived from stem cells in bone marrow
- Monocytes can transform into macrophages when necessary
Describe biochemical mediators
- Cause many of the events in the inflammatory response - Basic mediators can recruit other mediators and immune mechanisms- alarm system
- May be derived from - blood, endothelial cells, WBCs and platelets, pathogenic organisms as they injure the tissue
- Three interrelated systems - Kinin system; Clotting mechanism; Complement system
Describe the Kinin system
- Active in early phases of inflammation
- Activated by substances in plasma and injured tissue
- Causes increased - Dilation of blood vessels at the site of injury; Permeability of local blood vessels
- Induces pain
Describe Clotting mechanism system
- Clots blood and mediates inflammation
- Some of the clotting mechanism products that are activated during tissue injury cause local vascular dilation and permeability by activating kinin
Describe the complement system
- Involves the production of a sequential cascade of plasma proteins - They are present in blood in an inactive form; A trigger (usually an antibody-antigen complex) initiates the sequence of steps; These plasma proteins function in inflammation and immunity
- Some components cause WBCs known as mast cells to release histamine - Histamine causes an increase in vascular permeability and vasodilation-classic signs of allergies
- Other components cause cell death, form chemotactic factors for WBCs, and enhance phagocytosis
Describe prostaglandins (released by the body)
- Cause increased vascular dilation and permeability, tissue pain and redness, and changes in connective tissue (CT)
- Results in slow down of body for healing
Describe lysosomal enzymes (released by the body)
- Act as chemotactic factors-activate/attract other parts of immune response promoting healing
- May cause damage to connective tissue and to the clot
Describe endotoxins (released by pathogenic microorganisms)
- Produced by cell walls of gram-negative bacteria
- Serves as chemotactic factor; can activate complement, function as an antigen, and damage bone and tissue
Describe lysosomal enzymes (released by pathogenic microorganisms)
Have a similar chemical composition and action as those released by WBCs
Describe how fevers occur
- Controlled by the hypothalamus
- Pyrogens - Fever-producing substances produced by WBCs and pathogens (act on hypothalamus)
- The hypothalamus increases body temperature by way of prostaglandins
- Elevated body temperature an attempt to kill temperature sensitive bacteria/virus
Describe Leukocytosis
- Increased WBC count
- It is the body’s attempt to provide more cells for phagocytosis
- The type of WBC that is increasing in number can aid in differential diagnosis - Viral infection: Increase in lymphocytes; Bacterial infection: Increase in neutrophils; Allergic reaction: Increase in eosinophils
Describe Lymphadenopathy
- Enlarged and palpable superficial lymph nodes
- The enlarged nodes occur because of changes in lymphocytes, which are the primary cells of the immune response
- Hyperplasia: An increase in the number of cells
- Hypertrophy: Enlargement of individual cells
Describe chronic inflammation
- Caused by persistent injuries
- Repair cannot be completed until source of injury is removed
- Cells involved include - Macrophages, Lymphocytes, Plasma cells, Neutrophils, Monocytes, Fibroblasts
Describe Granulomatous Inflammation
- Formation of granuloma: Microscopic groupings of macrophages surrounded by lymphocytes and plasma cells
- These macrophages group together to form multinucleated giant cells
- Associated with foreign body reactions and some infections such as tuberculosis
Describe hyperplasia
- An increase in the number of cells, often in response to chronic irritation or abrasion
- May return to normal if the insult subsides, or may persist after removal of the irritant
Describe hypertrophy
- An increase in the size of cells
- May be seen in cardiac muscle as a response to hypertension
Describe atrophy
A decrease in size or function of a cell, tissue, organ, or entire body
Describe regeneration
The process by which injured tissue is replaced with tissue identical to that present before the injury
Describe repair
The restoration of damaged or diseased tissues
What microscopic events take place the day of injury?
- Blood flows into injured tissue to produce a clot
- The clot contains fibrin, clumped red blood cells (RBCs), and platelets