Chapter 14
Inflammation, Tissue Repair,
and Fever
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Inflammation
• Inflammation is an automatic response to cell
injury that:
– Neutralizes harmful agents
– Removes dead tissue
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Inflammation
• Damaged cells
release
inflammatory
mediators
Corticosteroids
• These
compounds
stimulate
inflammation
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NSAIDs
damaged cells
release
inflammatory
mediators
local
responses
vascular cellular
stage
stage
systemic (wholebody) responses
white blood
cell response
acute-phase
response
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Acute Inflammation
• Vascular stage
– Prostaglandins and leukotrienes affect blood vessels
– Arterioles and venules dilate
º Increasing blood flow to injured area
º Redness and warmth result
– Capillaries become more permeable
º Allowing exudate to escape into the tissues
º Swelling and pain result
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Vascular Stage
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Question
What mechanism causes the redness (erythema)
associated with the inflammatory process?
a. Prostaglandins
b. Leukotrienes
c. Arachidonic acid
d. All of the above
e. a and b
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Answer
e. a and b
Rationale: Prostaglandins and leukotrienes cause
vasodilation, which brings more blood to the
injured/affected area. The symptoms caused by this
vasodilation are redness/erythema and warmth.
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Kinds of Exudate
• Serous
• Hemorrhagic
• Fibrinous
• Membranous
• Purulent
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Scenario
A woman has peritonitis.
• She has a distended abdomen, low blood
pressure, and fluid in her abdominal cavity
• After surgery, she is told to report any GI
distress as it may indicate fibrous adhesions
Question:
• What kinds of exudate are involved? What useful
purposes do they serve? What complications may
they cause?
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Cellular Stage
• White blood cells
enter the injured
tissue:
– Destroying
infective
organisms
– Removing
damaged cells
– Releasing more
inflammatory
mediators to
control further
inflammation and
healing
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White Blood Cells Involved in
Inflammation
• Granulocytes
– Neutrophils
– Eosinophils
– Basophils
– Mast cells
• Monocytes
– Monocytes  macrophages
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Leukocytes
• Leukocytes enter
the injured area
• Leukocytes express
adhesive proteins
Pavementing
• Attach to the blood
vessel lining
• Squeeze between
the cells
• Follow the
inflammatory
mediators to the
injured area
Emigration
Chemotaxis
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Leukocytes (cont.)
Leukocytes release many inflammatory mediators at the
injured area:
• Histamine and serotonin
• Platelet-activating factor
• Cytokines
– Colony-stimulating factors
– Interleukins
– Interferons
– Tumor necrosis factor
• Nitric oxide
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Question
Which leukocytes participate in the acute inflammatory
response?
a. Eosinophils
b. Monocytes
c. Neutrophils
d. All of the above
e. a and c
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Answer
d. All of the above
Rationale: Granulocytes and monocytes play a role in the
acute phase of the immune response. Eosinophils and
neutrophils are granulocytes, so all of the leukocytes
listed participate.
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Other Inflammatory Mediators
Other inflammatory mediators travel in the
plasma
• Kinins
• Coagulation and fibrinolysis proteins
• Complement system
• C-reactive protein
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damaged cells
release
inflammatory
mediators
local
responses
vascular cellular
stage
stage
systemic (wholebody) responses
white blood
cell response
acute-phase
response
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Acute-phase Response
• Leukocytes release interleukins and tumor necrosis factor
– Affect thermoregulatory center  fever
– Affect central nervous system  lethargy
– Skeletal muscle breakdown
• Liver makes fibrinogen and C-reactive protein
– Facilitate clotting
– Bind to pathogens
– Moderate inflammatory responses
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Fever
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Question
Tell whether the following statement is true or false.
Body temperature is controlled through negative feedback
loops.
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Answer
True
Rationale: When the body senses a change out of the
norm (as illustrated in the previous slides), it activates
mechanisms that oppose that change (vasodilation and
sweating with increased temperatures; vasocontriction
and shivering with decreased temperatures). This is
known as negative feedback. Positive feedback, on the
other hand, senses a change, but activates a mechanism
that exaggerates the change.
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Scenario
Mr. X says he has “chills and fever.”
• His daughter wants you to explain how he could
have both at the same time and from the same
disease
Question:
• Should she be keeping him warmer or helping
him cool off?
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White Blood Cell Response
• Inflammatory mediators cause WBC production
• WBC count rises
• Immature neutrophils (bands) released into blood
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Chronic Inflammation
• Macrophages accumulate in the damaged area and
keep releasing inflammatory mediators
• Nonspecific chronic inflammation
– Fibroblasts proliferate
– Scar tissue forms
• Granulomatous inflammation
– Macrophages mass together around foreign bodies
– Connective tissue surrounds and isolates the mass
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Scenario
• A man had tuberculosis long ago and when he first
had the disease, he had a fever, productive cough,
and bloody sputum
• Later, he had trouble breathing and the doctor said his
lungs were “consolidated” with fibrous proteins
• He recovered and his fever went down; he thought he
was cured
• Three years later, an x-ray showed nodules in his
lungs and he was told they contained the TB bacteria
Question:
• Identify inflammatory events in his case
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Tissue Repair
• Growth factors stimulate local cells to divide
• Tissue organization is controlled by the extracellular
matrix
• New cells are laid down on the extracellular matrix
– Tissue regeneration: injured tissue is replaced by the
same kind of cells
– Fibrous tissue repair: injured tissue is replaced by
connective tissue
º Granulation tissue  scar tissue
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Question
Tell whether the following statement is true or false.
If you get a paper cut, epithelial tissue will be replaced
with connective tissue.
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Answer
False
Rationale: The surface epithelial cells of the skin are most
likely to be damaged in this instance. Surface epithelial
tissue has the ability to regenerate, replacing the
damaged tissue with the same type (epithelial).
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Wound Healing
• Inflammatory phase
• Proliferative phase
• Remodeling phase
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