Pathology of Inflammation and Repair

Question 1

What is the definition of inflammation?

Answer 1

Systemic and local reaction of tissues and microcirculation to a pathogenic insult that allows inflammatory cells, plasma proteins, and fluid to exit blood vessels and enter the interstitial space

Divided into acute and chronic inflammation

Question 3

What is acute inflammation?

Answer 3

Inflammation that arises in response to infections (to eliminate pathogen) or tissue necrosis (to clear necrotic debris)

Presence of edema and neutrophil in tissues

Question 4

What are the cardinal signs of acute inflammation?

Answer 4

• Redness (rubor) and warmth (calor): due to vasodilation which increases blood flow, occurs via relaxation of arteriolar smooth muscle. Key mediators are histamine, prostaglandins, and bradykinin
• Swelling (tumor): due to leakage of fluid from postcapillary venules into the interstitial space (exudate). Key mediators: histamine
• Pain (dolor): releasing of prostaglandins, neuropeptides, and cytokines; bradykinin and PGE2 sensitize sensory nerve endings
• Loss of function (functio laesa): leukocytes that are recruited and activated by the offending agent and by endogenous mediators release toxic metabolites and proteases extracellularly
• Fever: pyrogens cause macrophages to release IL-1, IL-6, and TNF, which increase cyclooxygenase activity in perivascular cells of the hypothalamus

Question 5

What causes edema?

Answer 5

Increased blood to the injured area and increased vascular permeability leading to the accumulation of extravascular fluid rich in plasma proteins

Question 6

What are the outcomes of acute inflammation?

Answer 6

• Resolution and healing: anti-inflammatory cytokines (IL-10, TGF beta)
• Continued acute inflammation: persistent pus formation, IL-8 from macrophages recruits additional neutrophils
• Abscess formation: acute inflammation surrounded by fibrosis, macrophages mediate fibrosis via fibrogenic growth factors and cytokines
• Chronic inflammation: macrophages present antigens to activate CD4+ T cells, which secrete cytokines that promote inflammation

Question 7

What are the most prominent inflammatory cells in foci of acute inflammation during the first 24 hours?

Answer 7

Neutrophils

Question 8

What is neutrophilia?

Answer 8

Increased neutrophils in the peripheral blood

Question 9

What is chronic inflammation?

Answer 9

The outcome of acute inflammation when the inciting injury is persistent or recurrent or when the inflammatory reaction is insufficient to completely degrade the agent. The is a delayed, but more specific, response.

Question 10

What cells are involved in chronic inflammation?

Answer 10

Lymphocytes and plasma cells in tissue

Question 11

What are the most prominent inflammatory cells in many viral infections?

Answer 11

Lymphocytes

Question 12

What are the predominant inflammatory cells in allergic reactions and parasitic infestations?

Answer 12

Eosinophils

Question 13

Which inflammatory cells are sources of histamine?

Answer 13

Mast cells and basophils

Question 15

What are some important causes of basophilia?

Answer 15

Chronic myelogenous leukemia and other myeloproliferative diseases

Question 16

What can cause neutrophilic leukocytosis?

Answer 16

• Acute bacterial infections, especially those caused by pyogenic organisms
• Sterile inflammation caused by, for example, tissue necrosis (MI, burns)

Question 17

What can cause eosinophilic leukocytosis?

Answer 17

• Allergic disorders such as asthma, hay fever, parasitic infections
• Drug reactions
• Certain malignancies (Hodgkin and some non-Hodgkin lymphomes)
• Autoimmune disorders (pemphigus, dermatitis herpetiformis) and some vasculitides
• Atheroembolic disease (transient)

Question 18

What can cause monocytosis?

Answer 18

• Chronic infection (tuberculosis, bacterial endocarditis, rickettsiosis, malaria)
• Autoimmune disorders (SLE)
• Inflammatory bowel diseases (ulcerative colitis)

Question 19

What can cause lymphocytosis?

Answer 19

• Accompanies monocytosis in many disorders associated with chronic immunologic stimulation (tuberculosis, brucellosis)
• Viral infections

Question 20

What is exudation?

Answer 20

The escape of fluid, proteins, and blood cells from the vascular system into the interstitial tissue or body cavities

Question 21

What is exudate?

Answer 21

Extravascular fluid that has a high protein concentration and contains cellular debris

Question 22

What does the presence of exudate imply?

Answer 22

The existence of an inflammatory process that has increased the permeability of small blood vessels

Question 23

What is transudate?

Answer 23

Fluid with low protein content (most of which is albumin), little or no cellular material, and low specific gravity

Question 24

What is edema?

Answer 24

Excess of fluid in the interstitial tissue or serous cavities; can be either an exudate or a transudate

Question 25

What is pus rich in?

Pus is a purulent, inflammatory exudate

Answer 25

Leukocytes (mostly neutrophils), the debris of dead cells, and in many cases, microbes