#1: Injury, Inflammation, Healing

Injury → _ → Healing

Inflammation

What are the 7 mechanisms of cellular injury?

Ischemic, infectious, immune reaction, genetic, nutritional, physical, chemical

Ischemic injury

• Cause

• Mechanism

• Consequence

• Reduced blood flow to tissues

• Decreased ATP production, leads to cellular swelling/dysfunction

• Cell damage all the way to necrosis

Infectious injury

• Cause

• Types

• Mechanism

• Consequence

• Microorganisms cause cellular damage

• Viral, bacterial, fungal

• Direct or indirect cellular disruption due to microorganisms

• Cell damage, death

Viruses can be either directly or indirectly cytopathic. What does this mean?

Direct attacks RNA, indirect attacks DNA

Immune reactions

• Cause

• Mechanism

• Consequence

• Autoimmune disease, hypersensitivity reactions, immune system’s response to cell death

• Immune cells damage or release substance to damage cells

• Reversible up to cell death

Genetic Injury

• Cause

• Mechanism

• Consequence

• Inherited genetic disorders that disrupt cell function

• Genetic mutations, additions, deletions

• Mild dysfunction to cell death

Nutritional Injury

• Cause

• Mechanism

• Consequence

• Deficiency or excess of nutrients

• Imbalances can cause issues with cellular energy production, protein synthesis

• Mild cell dysfunction up to death

Physical Injury

• Cause

• Mechanism

• Consequence

• External physical forces

• Physical agents can cause direct damage to cell membranes/organelles

• Reversible up to cell death

Chemical Injury

• Cause

• Mechanism

• Consequence

• Exposure to toxic chemicals, drugs, pollutants

• Chemical agents can damage cell membranes, disrupt metabolism and DNA

• Reversible up to cell death

What are the common cellular pathways in cell damage?

ATP deletion, mitochondrial damage, calcium influx, increased ROS, membrane damage, ER stress, DNA damage

What are the two types of irreversible injury and describe them!

Necrosis: swelling, rupture, release of contents

Apoptosis: programmed cell death

What are the 5 adaptations to cellular damage?

1. Atrophy

2. Hypertrophy

3. Hyperplasia

4. Metaplasia (change in morphology)

5. Dysplasia (Hyp + Met)

What are the main clinical signs of inflammation?

• Two types?

Calor, rubor, tumor (swelling), dolor, impaired function

• Acute and chronic

What are the four processes in inflammation?

Vascular changes, immune reactions, chemical modulator release, phagocytosis

What are the vascular changes?

Transient vasoconstriction (clot) followed by vasodilation (capillary permeability, movement of healing agents)

Immune reactions involve - and -. The - peak at 24 hr, - at 2+ days

Leukocytes and macrophages. Neutrophils, macrophages

4 chemical mediators and what they do!

1. Histamine- vasodilation, bronchoconstriction

2. ACD

3. Cytokines- IL-1 and TNF

4. Nitric oxide- Vasodilation, reduce inflammatory process

Macrophages - -, fibroblasts - - -, stem cells