Inflammation and Infection

Question 1

What is inflammation?

Answer 1

local vascular response to injury

it is normal, part of healing process, plays a role in body’s defense system

Question 2

What is acute inflammation.

Answer 2

initial response to injury, short in duration (hours to days)

Question 3

What are the two aims of acute inflammation?

Answer 3

1) localize injurious agent

2) remove injurious agent

Question 4

What is chronic inflammation?

Answer 4

inflammation that has a long duration (weeks to years), is a self-sustaining process and is problematic (no longer helpful)

Question 5

What two processes occur in inflammation? Do they occur sequentially?

Answer 5

1) vascular response
2) cellular response

no - they occur simultaneously

Question 6

What happens as part of the vascular response in inflammation?

Answer 6

• immediate, brief vasoconstriction (to stop bleeding, slow blood to allow time to clot)
• mast cells, leukocytes, platelets release mediator: histamine to increase capillary dilation and permeability and prostaglandin to increase capillary dilation and permeability and also to mediate pain
• mediators cause vasodilation, causing hyperemia, erythema, and warmth
• mediators cause capillary permeability to increase, causes exudate to form as fluid moves out from tissue
• exudate causes swelling and pain (can trigger immobilization)
• exudate also can dilute toxins

Question 7

What happens as part of the cellular response in inflammation?

Answer 7

• chemotaxis - cells in injured area use chemical mediators to attract cells to area, especially leukocytes
• margination - leukocytes stick/stop on the endothelium, process is aided by cell adhesion molecules (selectins, integrins, PCAM1- platelet cell adhesion molecule)
• diapedesis - cells move into tissue space, out of the vessel
• phagocytosis of cell debris and foreign particles

Question 8

What are the three components of exudate?

Answer 8

• cells
• protein
• fluid

Question 9

Explain what serous exudate is.

Answer 9

watery exudate with a high fluid content and low protein and cell content, usually indicative of minor injury

Question 10

Explain what purulent/suppurative exudate is.

Answer 10

• commonly referred to as pus
• contains dead WBCs (especially neutrophils), dead bacteria and necrotic cells, debris, protein
• cloudy, foul odour
• usually indicative of severe, acute inflammation, bacterial infection

Question 11

Explain what hemorrhagic/sanguineous exudate is.

Answer 11

• major component is erythrocytes

- usually indicates severe injury (since blood vessel severed)

Question 12

Explain what fibrinous exudate is.

Answer 12

• contains a lot of fibrinogen (gives rise to fibrin… means exudate is stringy, meshy)

Question 13

Explain what membranous exudate is.

Answer 13

• membrane forms from necrotic cells in a fibropurulent exudate

Question 14

List three reasons fever is beneficial.

Answer 14

1) enhances immune response
2) enhances phagocytosis
3) inhibits growth/replication of microbes

Question 15

What are the four main ways pathogens enter our bodies?

Answer 15

1) penetration
2) ingestion
3) inhalation
4) direct contact

Question 16

List and briefly explain the five stages through which an infection progresses as it runs its course.

Answer 16

1) incubation - no signs or symptoms but pathogen present
2) prodromal - general signs and symptoms
3) acute stage - signs and symptoms specific to disease, pathogen has maximum effect on body
4) convalescent stage - immune system has contained pathogen, begins to eliminate
5) resolution stage - no more pathogen, no signs or symptoms

Question 17

What are three laboratory techniques used to diagnose disease?

Answer 17

1) culture - incubate microbe, see if it grows, analyze colony or under microscope
2) serology - look at antibody titre
3) DNA and RNA sequencing - look for specific sequences of DNA or RNA specific to certain pathogens

Question 18

Explain the pathogenesis of fever.

Answer 18

• exogenous pyrogens (from microbes) induce the release of endogenous pyrogens ( from defense cells = mediators)
• mediators are: interleukin, interleukin 6 and tumour necrosis factor
• mediators cause production of prostaglandin E2
• PGE2 travels to hypothalamus, with help of cAMP (cyclic adenosine monophosphate), adjusts set point for temperature upwards

Question 19

What is CRP and why is it important?

Answer 19

C-reactive protein, it is produced by the liver and is involved in the complement cascade, it is a marker for inflammation (non-specific)

Question 20

How is inflammation treated?

Answer 20

• apply cold (vasoconstrict to reduce blood flow and consequently exudate)
• elevate (same mechanism as above… reduce blood flow)
• apply pressure (same as above)
• apply heat (enhance phagocytosis)
• NSAIDs - inhibit prostaglandin synthesis to reduce pain
• steroidal anti-inflammatory drugs - decrease prostaglandin and histamine = decreases mast cell and leukocyte activity, decreases permeability