Healing and Repair

Question 1

what are the overlapping stages of wound healing

Answer 1

• haemostasis
• inflammation
• proliferation
• remodelling

Question 2

describe the haemostasis of healing and repair

Answer 2

• disrupted blood vessels lead to haemostasis through the use of platelets and clotting factors
• involves vasospasm and formation of a platelet plug
• coagulation
• fibrin mesh is then formed
• platelets produce TGF beta and PDGF fibronectin and PAF

Question 3

what are the different tissue regenerative capacity classifications

Answer 3

labile
stable
permanent

Question 4

describe labile cells

Answer 4

• skin, connectvie tissue, small and large intestine cells
• heal well as they have stem cells

Question 5

describe stable cells

Answer 5

liver
recover as there are mature differentiated cells that can divide or regenerate

Question 6

describe permanent cells

Answer 6

skeletal muscle, cartilage, neurons and cardiac tissue
weak capacity as they lack stem cells, cannot replace via hyperplasia
replaced by scar tissue or fibrosis
loss of function of the tissue

Question 7

what are the three intentions of wound healing

Answer 7

primary
secondary
tertiary

Question 8

describe primary intention of wound healing

Answer 8

this is when the wound edges come together, and the stem cells in the epidermis are brought together and can regenerate

Question 9

describe secondary intention for wound healing

Answer 9

wound edges are too far from each other. stem cells do not approximate, wound is healed from connective tissue

Question 10

describe tertiary intention for wound healing

Answer 10

wound is cleaned and left open due to a high likelihood of contamination
wounds are observed before being closed by primary or secondary intention

Question 11

describe blood clot formation

Answer 11

forms at site of trauma
starts where the affected vessels constrict and platelets can aggregate to the surface to form a plug
this plug is then reinforced by fibrin to form a clot

Question 12

describe inflammation in wound healing

Answer 12

cytokines and chemokines are produced from damaged cells to recruit neutrophils and macrophages to the area, vasodilate and increase permeability

Question 13

what forms a scab

Answer 13

blood clot and dead macrophages

Question 14

describe the epithelialisation phase of healing

Answer 14

this is when basal cells proliferate to replace lost or damaged cells
takes 48 hours
ends when the epidermis is rejuvinated
layer is weak and the dermal layer below has not regenerated yet

Question 15

describe the fibroplasia stage of healing

Answer 15

this is when the wound becomes stronger and more resistant to damage
fibroblasts produce collagen in fibroblasia to produce fibrils, which form bundles with high tensile strength and extracellular scaffolding to hold together the new epidermal cells
collagen also stimulates angiogenesis, so there is production of red granulation tissue

Question 16

describe the final stage of healing, maturation

Answer 16

wound gets even more physical support.
there is collagen cross linking, covalent bonds will form to enhance the tensile strength
collagen remodelling where fibroblasts will degrade the older subpar collagen
contraction where special fibroblasts called myofibroblasts produce contractile proteins to bring the edges of the wound together
repigmentation occurs to restore normal colour to the damaged skin via the proliferation of melanocytes

Question 17

what makes a wound chronic

Answer 17

wound cannot heal due to less immune cells travelling to the area like if there are narrowed capillaries
tissue cannot repair and undergo necrosis
decreased blood flow due to diabetes, prolonged compression or atherosclerosis

Question 18

how can an infection make a wound chronic

Answer 18

interferes with healing because pathogens can compete for oxygen, cause damage and inflammation

Question 19

how can oedema and swelling affect the healing of a wound

Answer 19

can affect the activity of fibroblasts