Inflammation Processes Quiz

Cardinal Signs of Inflammation

• Rubor: redness
• Tumor: swelling
• Calor: heat
• Dolor: pain
• Functio laesa: loss of function

Leukocyte Adherence to Endothelium

• Blood flow slows
• Wall shear stress decreases
• Leukocytes move to a more peripheral position
• Margination: neutrophils adhere to and align with vessels
• Rolling: cells bind and detach
• Adhesion: cells adhere via complimentary adhesion molecules

Chemotaxis

• Leukocytes cross the endothelium and basement membrane, entering extravascular tissue
• Cells follow a chemotactic gradient to reach the agent

Chemotaxis (Continued)

• Chemotaxis is the process of leukocytes leaving the circulatory system and moving toward tissue injury
• Bacterial products are chemotactic
• Endogenous chemotactic agents include cytokines
• The type of leukocytes that migrate depends on the stimulus and the inflammatory response's age
• Neutrophils dominate acute inflammation

Contrasting Inflammatory Responses

• Viral infections: lymphocytes are the initial responders
• Hypersensitivity reactions: lymphocytes and plasma cells are predominant
• Allergic reactions: eosinophils are the primary cell type

Bacterial vs. Viral Pneumonia

• Bacterial: Caused by streptococcus pneumonia; neutrophils and macrophages are the immune cells involved. Bacteria enter alveoli and multiply. Capillaries open allowing neutrophils to enter and fight the bacteria. Macrophages clean up debris.
• Viral: Caused by SARS-CoV-2 (COVID-19); lymphocytes are the principal immune cells. Viruses enter cells and replicate, leading to cell death. Lymphocytes recognize and destroy infected cells. Respiratory epithelial cells are replaced by type 2 pneumocytes.

Eosinophils

• Eosinophils are a type of white blood cell part of the innate immune response
• They defend against allergens, infections (like parasites), and autoimmune conditions

Acute Inflammation - Morphologic Patterns

• Serous inflammation
• Fibrinous inflammation
• Suppurative inflammation (purulent)
• Abscesses
• Ulcers

Serous Inflammation

• Characterized by cell-poor fluid accumulation in spaces
• Early stage of acute inflammation
• Examples include blisters from skin burns

Fibrinous Inflammation

• When vascular leaks are large, fibrinous exudate forms
• Examples include meningitis and pericarditis
• Fibrinous exudates are usually dissolved by macrophages
• Fibrosis occurs if exudates are not removed

Purulent Inflammation

• Characterized by pus (an exudate with neutrophils and necrotic debris)
• Purulent and suppurative inflammation are equivalent
• Bacteria are often the cause
• Acute appendicitis is an example

Abscesses

• Localized collections of purulent inflammatory tissue confined to a space
• Central portion exhibits necrosis
• Periphery contains preserved neutrophils and fibroblasts

Ulcers

• Local defects in organ or tissue surfaces
• Result from sloughing of necrotic, inflamed tissue
• Peptic ulcer disease is an example

Fate of Neutrophils

• Neutrophils undergo apoptosis (programmed cell death)
• They break down into smaller apoptotic bodies

Chronic Inflammation Morphologic Features

• Predominance of mononuclear cells (macrophages, lymphocytes, plasma cells)
• Lymphocytes (especially T cells) produce interferon gamma to activate macrophages
• Tissue destruction occurs
• Healing can involve fibrosis

Mast Cells

• Involved in allergic reactions, insect bites, and drug reactions