Chapter 4. Tissue Response to Injury: Inflammation, Swelling, and Edema
Inflammation
• The local response of the body to an __________________
• Purpose
–
–
Cardinal Signs of Inflammation
• Rubor:
• Calor:
• Edema:
• Dolor:
• Funca laesa:
* Each of these signs will occur to some degree when tissue is injured and the body responds
with the inflammatory process.*
Common Misconceptions of Inflammation
• Do you need to limit or eliminate inflammation?
• Answer:
– _________________ will not occur without inflammation.
• You cannot ____________________ inflammation.
• You can only _____________________ the signs of inflammation.
• Swelling, edema, and inflammation are synonymous – WRONG!
– _______________ and ________________ occur during inflammation.
– _______________ and ________________ are not the same.
– All edema causes swelling, but not all swelling is caused by edema.
Phases of Inflammation
• Inflammation consists of ____ sequential and overlapping events.








Ultrastructural changes
Chemical mediation
Hemodynamic changes
Leukocyte migration
Primary Injury
• Any occurrence that impairs tissue structure or function
• Most sports injuries are caused by
– Macrotrauma:
– Microtrauma:
• Other causes of injury include
–
Physical agents:
–
Metabolic processes:
–
Biological agents:
–
Chemical agents:
–
Endogenous chemicals: Normal secretions
• In abnormal locations (gout)
• In increased quantity in a normal location (stomach ulcers)
Ultrastructural Changes
• Cellular ________________ is disrupted and eventually breaks down.
• Contents spill out into the ____________________ spaces, thereby killing the damaged cell.
• Two causes
– Direct: ____________ injury
•
– Indirect: ______________ injury
•
• Enzymes (chemicals)
•
Occur as a direct result of ____________________ and indirectly as a result of
_______________________
Chemical Mediation
• Histamine, bradykinin, and other chemicals
• Modify and regulate the rest of the inflammatory response to:
–
–
Hemodynamic Changes
• Arteries dilate, increasing blood flow to the injured area.
– Blood vessels that were previously ___________________ open
– Therefore, blood flow through individual vessels ____________________
– And the rate of blood flow through individual vessels ____________________
•
Slowing of blood flow is necessary, so ________________ can move to the margins
• Leukocytes (WBCs)
– Marginate
– Tumble along the vessel wall
– Adhere to the vessel wall near an opening
– Pass though the vessel wall
Metabolic Changes
• ↓ __________________
• ↓ __________________
• Causes cell to switch to ___________________ metabolism
• Membrane functions slow down.
• Sodium pump maintains the concentration of intracellular sodium at a very low level.
• Passive diffusion of Na++ into cell
• ↑ ____________________ concentration in cell and organelles
• ↑ _____________ in cell
• Cells swell and burst
• ↑ Intracellular acidosis (lactic acid)
• Membrane attacked
• Lysosome digests cell
Permeability Changes
• Histamine and bradykinin increase the ______________________ of small blood vessels.
• The endothelial cells contract, pulling away from each other.
• Gaps are left, through which the ________________ can move out of the vessel and to the
injury site.
Leukocyte Migration
• _____________adhere to the endothelium (vessel wall) and/or to other white blood cells.
• ______________________ and _______________________ move out of the vessel by
squeezing through the endothelial gaps.
• Neutrophils first, then larger macrophages
Neutrophils
– Travel fast and arrive at the injury site first
– Provide the first line of defense
– When they die, they release chemical mediators that attract macrophages.
Macrophages
– Live for months
– Long-lasting second line of defense
– Release potent enzymes that may _____________________ connective tissue, thus
adding to the injury
– Release chemical mediators that may _____________________ inflammation
– Release factors that aid in healing
– Secrete proteins that are important in defense mechanisms
Phagocytosis
• Digestion of cellular debris and other foreign material into pieces small enough to be removed
from the injury site
• ______________ and ____________________________ work together
Chronic Inflammation
• Recurring inflammation
• _______________ inflammation occurring before the _______________ episode of
_______________ inflammation has finished
• Chronic inflammation
• Results from ______________________ but does not necessarily involve an
inflammatory reaction
• Structural disruption and microvascular damage may occur (causing pain and other
symptoms) before the classic inflammatory process is set into action.
• Accumulation of _________________ in the tissues
• Persists for several _____________, or ____________, and has vague and indefinite
termination
• Unable to eliminate the __________ of injury and restore normal ________________
• MOI =
Orthopedic Injury Model (Figures 4.10 – 4.12)
Contusion
– Three cells
– Nerve 1
– Blood vessel B
• Immediate ultrastructural change
– Local nerves and blood vessels may be disrupted or broken.
– This damage is called primary traumatic damage.
• Hemorrhage
– Extravascular ___________________ occurs from broken blood vessels.
– Few minutes only (usually)
– Clot forms, stopping hemorrhage.
– ____________ forms into strands, creating a network somewhat like a fishnet.
– This net captures circulating platelets.
– A plug forms to seal the damaged vessel.
•
•
•
•
Hematoma forms
• Comprised of ____________ and _________________________
• Places pressure on damaged and undamaged ____________ fibers
• Pain, from damaged nerve
– Muscle spasm and more pain
– Body attempts to protect itself by ______________ the area, thus
preventing aggravation of injury.
• Inhibition of muscular strength, range of motion, etc.
• Hematoma also triggers release of _____________________ mediators
Chemical Mediation
• The damaged cells release chemical mediators as a signal to the body that an injury has
taken place.
• Secondary enzymatic injury begins.
• _______________ release enzymes that digest cellular
_______________
• Additional cell ____________ occurs
• ______________ occurs.
• Chemical mediators released from dying cells cause
– Hemodynamic changes
– Permeability changes
– Leukocyte (white cell) migration
Hemodynamic changes
– Blood flow _____________ OR ______________
– Secondary ______________ injury begins.
The inflammatory response is not all positive.
• Example
– Slowed blood flow in the vessels on the periphery of an injury and decreased
blood flow from the damaged vasculature result in less oxygen to the cells.
• If prolonged, secondary __________________ injury occurs.
• The total amount of damaged tissue is ______________________, and more debris is
added to the hematoma.
Swelling, Edema, and Vessel Fluid Pressures
What Is Edema?
• Accumulation of ___________________ in the tissue
• What causes it?
– Unbalanced fluid dynamics
– Must understand normal fluid dynamics (review)
Fluid Filtration in Normal Tissue
Fluid in
•
•
•
Fluid out
Occurs constantly between capillary and tissue
Sum of multiple forces
In capillary and tissue
– Oncotic (osmotic) pulls
– Hydrostatic pushes
Hydrostatic Pressure
• Pressure exerted by a column of water
• The higher the column of water, the greater the pressure.
• Example: swimming
• The deeper you go, the higher the column of water above you and the greater the
pressure.
• The depth of the water, not the amount of water, is important.
• Hydrostatic pressure is exerted by the water portion of the blood.
• Hydrostatic pressure pushes water.
– Capillary hydrostatic pressure pushes fluid out of the capillary.
– Tissue hydrostatic pressure pushes fluid into the capillary.
capillary
CHP
tissue
THP
Oncotic Pressure
• Also called colloid osmotic pressure
• Results from the attraction of fluid by free protein
– Tissue oncotic pressure pulls fluid out of the capillary.
– Capillary oncotic fluid pulls fluid into the capillary.
capillary
COP
tissue
TOP
Fluid Filtration in Normal Tissues, Revisited
•Sum of all forces
What Causes Edema?
• Imbalance of fluid filtration caused by an injury
• Hematoma (tissue debris and hemorrhage) dumps large amounts of free protein into tissue
spaces.
• _________________ tissue oncotic pressure
• Fluid accumulates in _________________ thereby increasing
_____________________ and ______________________
What Is Swelling?
• Hemorrhaging and edema
– Can do nothing about hemorrhaging
– Can _____________________ edema
What Causes Swelling?
Fluid in
>
Fluid out
How Does Cold Decrease Swelling?
• As cold decreases secondary hypoxic injury, the amount of free protein in tissues decreases.
• This causes less tissue oncotic pressure (the major factor for edema).
• Cold can prevent edema from occurring only if applied soon after injury.
• Once edema develops, cold application cannot decrease that edema.
Time Course of Swelling
• Swelling immediately after injury is the result of direct hemorrhaging.
• Edema begins minutes to hours after injury and continues to develop over many hours.
– Accounts for the delayed nature of most swelling.
Secondary Injury and Edema
• Secondary injury results in increased _________________, and increased ________________
can contribute to increased secondary injury.
• Two mechanisms
– As ______________________ develops, the distance between blood vessel and tissue
cells __________________.
• More difficult for __________________ and other substances to diffuse from
the circulatory system to the tissue
– Edema can compress the blood vessel, thus decreasing circulation to the area.
Common Misconceptions Concerning Ice and Inflammation
• Many think the purpose of ice is to decrease inflammation.
• However, inflammation is necessary to prepare for healing.
• Healing cannot take place until much of the cellular debris is removed from the area.
– So decreasing inflammation is not helpful.
•
•
Misconception results from confusing inflammation with swelling.
• The more the swelling is contained, the quicker the injury can heal.
Another misconception concerning ice is that it should be used until the swelling is gone.
• Ice is effective for preventing swelling but not for removing swelling.
• Swelling reduction occurs as free protein is removed from the area.
Summary
• Inflammation is the body’s response to any injury.
– Protects the body against invasion by foreign bodies and prepares the injured tissue for
repair.
• After understanding inflammation, hemorrhaging, and edema, you will be qualified to educate
your athletes and coaching staff, who commonly apply ice to decrease inflammation after an
injury.
– You can explain that swelling is one of the signs of inflammation but is not the process
itself; they are separate but related processes.