Causes Of Cell Injury

Major causes

1. Oxygen Deprivation

- Hypoxia

- Ischemia

2. Physical Agents

3. Trauma

4. Temperature Extremes

5. Radiation

6. Electrical Injury

7. Chemical agents and drugs Infectious agents

8. Immunologic reactions

9. Genetic abnormalities

10. Nutritional imbalances

Cellular Response Depends on?

Type, Severity, & Injury Duration

Hypoxia

• Inadequate Oxygen Availability

Causes from Hypoxia

• Reduced Blood flow

• Respiratory failure

• Reduced oxygen-carrying capacity

• Severe blood loss

• Carbon monoxide poisoning

Ischemia

• Generally more damaging than hypoxia

• Decreases delivery of nutrients & removal of metabolic waste.

Inflammation

Protective response of vascularized tissues to infection, tissue injury, or other harmful stimuli.

Major Functions of Inflammation

• Eliminate the initial cause of injury

• Remove damaged and dead cells

• Initiate tissue repair

• Prevent the spread of infection and injury

• Inflammation is beneficial when appropriately controlled, but excessive or prolonged inflammation can cause tissue damage.

Causes of Inflammation

Infections

Tissue Necrosis

Foreign Bodies

Immune Reactions

Infections

• Bacteria

• Viruses

• Fungi

• Parasites

Tissue Necrosis

• Ischemia

• Trauma

• Toxins

Foreign Bodies

• Splinters

• Dirt

• Sutures

Immune Reactions

Autoimmune & Allergic Disorders

Major Components of Inflammation

• Vascular reaction

• Vasodilation

• Increased blood flow

• Increased vascular permeability

• Leakage of plasma proteins

• Formation of inflammatory edema

Acute Inflammation

• Rapid onset

• Short Durations (Hours/ Days)

• Main cells: Neutrophils

• Prominent Vascular Changes

• Mild / Limited Tissue Injury

• Minimal Fibrosis

• Prolonged/ slow onset

• Long Durations (Weeks / Years)

• Main cells: Macrophages & Lymphocytes

• Less Prominent Vascular Changes

• Significant Tissue Injury

• Common Fibrosis