Inflammation + Tissue Repair

Question 1

What is inflammation?

Answer 1

A localised response to the circulation to injury, foreign body, hypersensitivity or infection.

Involving the movement of fluid + white blood cells into tissue spaces.

Question 2

What are the 2 forms of inflammation and their definitions?

Answer 2

Acute : rapid onset, short duration

Chronic : long lasting, different characteristics

Question 3

What are the 2 components of acute inflammation?

Answer 3

Vascular response

Cellular response

Question 4

What are the signs of acute inflammation?

Answer 4

Heat (increased blood flow)

Swelling (oedema)

Pain (inflamed tissue is stretched)

Redness (dilation of small blood vessels)

Question 5

What happens to blood flow in the vascular response?

Answer 5

Blood flow increases as a result of vasodilation of arterioles + precapillary sphincters (hyperaemia)

Question 6

What is tissue fluid formation dependent on in vascular response?

Is this decreased or increased in acute inflammation?

Answer 6

Tissue fluid formation is dependent on permeability of capillary endothelium.

Increased in acute inflammation.

Question 7

How is exudate created in the vascular response?

Answer 7

Increased fluid loss from capillaries along with movement of plasma proteins which normally are not permitted to leave capillaries.

This creates exudate.

Question 8

What is the cellular response in acute inflammation?

Answer 8

Neutrophils (type of WBC) leave the circulation and move to the site of inflammation where proteases destroy bacteria or cellular debris.

Question 9

What are the stages of the cellular response?

Answer 9

Margination

Pavementing + adhesion

Emigration

Chemotaxis

Phagocytosis

Question 10

What is margination in the cellular response?

Answer 10

Alteration of blood flow in capillaries. Neutrophils start to flow out at the periphery adjacent to endothelium.
Neutrophils stick to endothelium and line the vessel.

Question 11

What is pavementing + adhesion in the cellular response?

Answer 11

Leukocytes adhere to the linings of the capillaries.

Question 12

What is emigration in the cellular response?

Answer 12

Neutrophils leave the capillaries.

Question 13

What is chemotaxis in the cellular response?

Answer 13

Neutrophils are attracted to site of the injury.

Question 14

What is phagocytosis in the cellular response?

Answer 14

Neutrophils engulf and digest foreign material, bacteria etc.

Question 15

What are the outcomes of acute inflammation?

Answer 15

Resolution

Healing by fibrosis

Suppuration

Chronic inflammation

Question 16

What is resolution in acute inflammation?

Answer 16

Restoration of normal tissue structure and function with source of injury eliminated.

Question 17

What is healing by fibrosis in acute inflammation?

Answer 17

Normal tissue/function is not restored, scar tissue can be formed.

Question 18

What is suppuration in acute inflammation?

Answer 18

If inflamed issue is walled off, tissue can be destroyed by neutrophils and this forms pus.

Question 19

What is chronic inflammation as an outcome of acute inflammation?

Answer 19

Inflammation persists and is accompanied by scaring and fibrosis.

May occur with chronic infection, continued exposure to toxic substances or with autoimmune diseases.

Question 20

When does wound healing occur and what does it involve?

Answer 20

Occurs following acute inflammation.

Involved the removal of dead tissue and debris as well as replacing damaged tissue.

Can involve regeneration and repair.

Question 21

What is regeneration in wound healing?

Answer 21

Renewal of lost tissue with replacement by identical cells.

Involves proliferation of surviving cells and typically occurs when only epithelium is damaged.

Does not leave a scar.

Question 22

What is repair in wound healing?

Answer 22

Occurs if damage extends beyond epithelial layer and involves connective tissue response.

Tissue structure restored but not always functional.

Scarring may occur.

Produces vascular connective tissue (granulation tissue)

Question 23

What does the healing of a skin wound depend on?

What are the healing intentions?

Answer 23

The type of skin damage and the extent of tissue loss?

Small cut = heals by primary intention

Large cut, ragged edges = heals by secondary intention

Question 24

When does bleeding occur in injury and what is it followed by?

Answer 24

Bleeding occurs immediately following injury.

Followed by coagulation + formation of inflammatory exudate rich in fibrin.

Platelets aggregate and fibrin is deposited to form a blood clot.

Question 25

What is the function of a blood clot in wound healing and what is it’s process?

Answer 25

Provides protection to damaged area from infection and binds damaged surfaces.

Clot then dries and seals the wound, neutrophils + macrophages move into the area and phagocytise dead cells/bacteria.

Lysosomal enzymes + macrophages gradually digest the clot as tissue heals.

Question 26

What is the process of wound healing in a small cut?

Answer 26

If edges of wound are close together capillaries proliferate to provide a bridge across the gap.

Fibroblasts secrete collagen fibres.

Small vascular response + collagen production.

Epidermal cells detach from basement membrane.

• flatten to increase surface area.
• cover part of the wound.
• undergo cell division + edges of cells advance across wound.
• when wound is covered they return to their normal shape and re-attach to basement membrane.

Question 27

If a wound is deeper than the basement membrane of the epithelium what does it involve?

Answer 27

Regeneration of specialised cells

Production of connective tissue

Question 28

What is regeneration of specialised cells?

Answer 28

Epidermal cells detach from basement membrane.
-flatten to increase surface area + cover part of wound.

Cells divide and advance across wound.

Once wound is completely converted epithelial cells return to normal shape and rewatch to basement membrane.

Question 29

What is production of connective tissue?

Answer 29

Repairs dermis and subcut layer with granulation tissue.
Fibroblasts attracted by fibronectin realised by injured cells.
Fibroblasts produce fibronectin and proteoglycans that provide scaffolding for new connective tissue.
Fibroblasts produce new extra-cellular matrix + collagen fibres.
New capillaries form to increase blood supply.
Myofibroblasts (cross between fibroblast/muscle cell) attracted to area.
-these contract wound decreasing area needing repaired.

Question 30

What factors can affect wound healing and why?

Answer 30

Blood supply : vascular areas (face)heal faster than less vascular areas (foot). Poor blood supply e.g from peripheral vascular disease, impairs healing.

Infection: slow healing by increasing granulation tissue produced and increase scarring.

Lack of sensation: areas with impaired sensation heal more slowly. Neural changes can also affect blood supply.

Radiation: ionising radiation causes vascular damage, decrease cell division and granulation tissue formation.

Poor nutrition: vit C needed for collagen production. Adequate protein intake required for normal immune system function.

Chronic disease: diabetes, renal failure, cachexia, infection delay healing.

Question 31

What are the three main complications of wound healing?

Answer 31

Insufficient scar formation

Too much scar formation

Excessive contraction

Question 32

What is insufficient scar formation?

Answer 32

Scars not strong (damaged with coughing, laughing, vomiting)

Ruptured scar from surgery may cause hernia.

Ulceration due to poor blood supply.

Question 33

What is too much scar formation?

Answer 33

Excessive connective tissue matrix.

Densely vascularised.

Abundant collagen.

Blocks healing process + extends granulation period.

Forms hypertrophic or keloid scar.

Question 34

What is excessive contraction?

Answer 34

Excessive contraction may limit joint movement.

Causes deformity of wound e.g serious burns, soles of feet, palms of hands, may block lumen in GI tract.