Immunopathology - Week 5 - Healing & Regeneration

Question 1

Define healing.

Answer 1

Healing refers to the process by which the object (to be healed) is made whole, sound or well again.

Question 2

Define regeneration.

Answer 2

Regeneration is the replacement of damaged tissue with healthy tissue, with complete return to normal structure and function.

Question 3

Define repair.

Answer 3

Repair is when damaged tissue is replaced by scar tissue.

Question 4

Describe the Inflammatory phase in wound healing.

Answer 4

Occurs immediately and lasts 2 - 5 days.
Consists of:
- Homeostasis.
- Cellular and vascular phases of inflammation.
- Increased cell division and fibroblast migration.

Question 5

Describe the Proliferative phase in wound healing.

Answer 5

Occurs 5 days following injury and lasts 3 weeks.
Consists of:
- New blood vessel formation
- Proliferation of cells and fibroblasts -> forming granulation tissue.
- Overlying epithelial cells divide and migrate towards each other to cover granulation tissue.

Question 6

Describe the Maturation or Remodeling phase in wound healing.

Answer 6

Occurs 3 weeks after injury, and may last up to 2 years.
Consists of:
- Realigning and reorientation of the collagen along new lines of stress.
- Tensile strength continues to increase.
- Scar matures.
- Scar contracts causing disfigurement of skin and limitation of movement.

Question 7

What local factors influence wound healing and how do they do it?

Answer 7

1. Type, size and location of the wound
   - Smaller and clean wounds heal faster
2. Local wound infection
   - Delay wound healing by causing excessive granulation tissue.
3. Mechanical factors
   - Early movement can delay healing.
4. Foreign bodies
   - fragments of glass or steel can delay healing.
5. Ionizing radiation
   - Irradiated areas heal slower due to interference with blood supply.
6. Insufficient blood flow
   - Lack of blood means there is a lack of substances to help healing.
7. Type of tissue affected
   - Whether labile, stable or permanent cells are damaged.

Question 8

What systemic factors influence wound healing and how do they do it?

Answer 8

1. Circulatory status
   - Impaired circulation delays healing.
2. Nutritional status
   - Lack of nutrients impair healing.
3. Metabolic status
   - Poorly controlled diabetes can delay healing.
4. Hormones and Medications
5. Age
   - Older age causes collagen, thickening of vessels.
6. Haematological disorders
   - Lack of leukocytes can delay healing.
7. Immune status
8. Underlying disease states
   - People with chronic conditions heal slower.