Chapter 2 - Inflammation and Healing
Review of Body Defenses
Defense Mechanism: Mechanism used by the body to protect itself from any injurious agent
Nonspecific (first and second line of defense)
First line of defense · Nonspecific defense or general defense mechanism · Mechanical barrier: Like unbroken skin and mucous membranes · Ass
Specific (third line of defense)
Third line of defense · Process of stimulating the production of unique antibodies after exposure to specific harmful stimuli · Antibodies: Proteins
Inflammation
Is a protective mechanism in response to tissue injury
It is intended to localize and remove an injurious agent
Medical terminology referring to Inflammations usually ends with “itis”.
For example: pancreatitis, appendicitis, laryngitis, ileitis (ileum), blepharitis (eyelid)
1
,Causes of Inflammation
Direct physical damage like a cut or a sprain
Caustic chemicals like acid, drain cleaner
Ischemia or infarction
Allergic reactions
Extremes of heat or cold
Foreign bodies like splinters, glass
Infection
Insect bite
Small burn
Severity of inflammation depends on cause and duration of exposure
Function of Cellular Elements in the Inflammatory Response
Leukocytes (WBCs) Activity
Neutrophils Phagocytosis of microorganisms
Basophils Release of histamine leading to inflammation
Eosinophils Numbers are increased in allergic response
Lymphocytes (type of immune cells, T and B) Activity
T Cells Active in cell-mediated immune response
B Cells Produce antibodies
Monocytes Phagocytosis
Macrophages Active in phagocytosis
Types of Inflammation
Acute inflammation:
When tissue injury occurs · Damaged mast cells and platelets the body release chemical mediators like histamine, serotonin, prostaglandin and l
2
, Relatively short duration, lasting from a few minutes up to a few days.
Characterized by fluid and plasma protein exudation
Predominantly neutrophilic leukocyte accumulation.
Chronic inflammation
Chronic inflammation is characterized by the following · Prolonged duration (weeks to months to years) · There is less swelling and exudate but p
Relatively longer duration (days to years)
Influx of lymphocytes and macrophages with associated vascular proliferation and scarring
Pathophysiology of Inflammation
Steps of Inflammation
Injury to capillaries and tissue cells result in
Release of bradykinin (biochemical mediator) from injured cells
Biochemical mediator stimulates pain receptors
Pain stimulate mast cells (class of WBCs) and basophils (WBC) to release chemical mediators like histamine
Bradykinin and histamine cause vasodilation (capillary dilation), it increases blood flow and increases capillary permeability
Break in tissue cells allows bacteria to enter tissue, this results in the migration of neutrophils and monocytes to the site of injury
Phagocytosis, removal of debris in preparation for healing
3
Review of Body Defenses
Defense Mechanism: Mechanism used by the body to protect itself from any injurious agent
Nonspecific (first and second line of defense)
First line of defense · Nonspecific defense or general defense mechanism · Mechanical barrier: Like unbroken skin and mucous membranes · Ass
Specific (third line of defense)
Third line of defense · Process of stimulating the production of unique antibodies after exposure to specific harmful stimuli · Antibodies: Proteins
Inflammation
Is a protective mechanism in response to tissue injury
It is intended to localize and remove an injurious agent
Medical terminology referring to Inflammations usually ends with “itis”.
For example: pancreatitis, appendicitis, laryngitis, ileitis (ileum), blepharitis (eyelid)
1
,Causes of Inflammation
Direct physical damage like a cut or a sprain
Caustic chemicals like acid, drain cleaner
Ischemia or infarction
Allergic reactions
Extremes of heat or cold
Foreign bodies like splinters, glass
Infection
Insect bite
Small burn
Severity of inflammation depends on cause and duration of exposure
Function of Cellular Elements in the Inflammatory Response
Leukocytes (WBCs) Activity
Neutrophils Phagocytosis of microorganisms
Basophils Release of histamine leading to inflammation
Eosinophils Numbers are increased in allergic response
Lymphocytes (type of immune cells, T and B) Activity
T Cells Active in cell-mediated immune response
B Cells Produce antibodies
Monocytes Phagocytosis
Macrophages Active in phagocytosis
Types of Inflammation
Acute inflammation:
When tissue injury occurs · Damaged mast cells and platelets the body release chemical mediators like histamine, serotonin, prostaglandin and l
2
, Relatively short duration, lasting from a few minutes up to a few days.
Characterized by fluid and plasma protein exudation
Predominantly neutrophilic leukocyte accumulation.
Chronic inflammation
Chronic inflammation is characterized by the following · Prolonged duration (weeks to months to years) · There is less swelling and exudate but p
Relatively longer duration (days to years)
Influx of lymphocytes and macrophages with associated vascular proliferation and scarring
Pathophysiology of Inflammation
Steps of Inflammation
Injury to capillaries and tissue cells result in
Release of bradykinin (biochemical mediator) from injured cells
Biochemical mediator stimulates pain receptors
Pain stimulate mast cells (class of WBCs) and basophils (WBC) to release chemical mediators like histamine
Bradykinin and histamine cause vasodilation (capillary dilation), it increases blood flow and increases capillary permeability
Break in tissue cells allows bacteria to enter tissue, this results in the migration of neutrophils and monocytes to the site of injury
Phagocytosis, removal of debris in preparation for healing
3
