healing & repair

Question 1

what are the 4 stages of healing in soft tissues

Answer 1

clotting phase
inflammation phase
proliferative phase
maturation phase

Question 2

what type of repair occurs in hard tissues

Answer 2

fracture repair

Question 3

regeneration

Answer 3

replacement with functional, differentiated cells

Question 4

repair

Answer 4

production of a fibrous scar alongside changes in tissue structure/ architecture

Question 5

labile cells

Answer 5

continuously dividing and regenerating e.g oral keratinocytes of squamous epithelium of the skin

Question 6

stable cells

Answer 6

low levels of replication, rapid proliferation in response to injury, e.g oral fibroblasts

Question 7

permanent cells

Answer 7

unable to divide or regenerate e.g neurons

Question 8

what occurs during the clotting phase (haemostasis) of healing

Answer 8

clot formation via the coagulation system

mitosis of labile and stable cells

Question 9

what occurs during the inflammation stage of healing

Answer 9

innate immune response - macrophages, nuetrophils phagocytose and degrade infectious agents
stimulation of certain cells e.g keratinocytes to to start regeneration or repair

Question 10

granulation tissue

Answer 10

new connective tissue with microscopic blood vessels

Question 11

angiogenesis

Answer 11

formation of new blood vessels

Question 12

describe how granulation tissue is formed

Answer 12

1st phase - vascular granulation tissue - mix of proliferating capillaries, immune cells and fibroblasts. Capillaries are leaky so fluid and cells can enter the tissue
2nd phase - fibrous granulation tissue - capillaries regress and immune cells return to blood, fibroblasts lay down collagen

Question 13

describe the process of angiogenesis

Answer 13

new blood vessels are formed from existing vascalature either by sprouting or intussusceptive (splitting). process is driven by VEGF (vascular endothelial growth factor)

Question 14

what occurs during the proliferative stage of healing

Answer 14

granulation tissue forms, angiogenesis

Question 15

what is the role of macrophages during the proliferative stage of healing

Answer 15

M2 macrophages are essential in the healing and repair process. They engulf/ degrade pathogens and also produce growth factors e.g VEGF and TGFbeta

Question 16

what occurs during the maturation stage of healing

Answer 16

granulation tissue is rearranged and collagen fibres are linked

Question 17

primary intention

Answer 17

tissue regenerates itself, minimal damage

Question 18

second intention

Answer 18

large infected/ damaged area , larger amount of granulation tissue therefore more scar tissue present

Question 19

what are the 4 stages of fracture healing

Answer 19

inflammatory stage
repairing stage 1
repairing stage 2
remodelling stage

Question 20

what occurs during the inflammatory stage of fracture healing

Answer 20

heamatoma formation at fracture (blood clot within tissue)
immune response to clear debris and dying tissue
bone cells deprived of O2/ blood supply die off
occurs within days

Question 21

what occurs during the 1st repairing stage of fracture healing

Answer 21

occurs within weeks
granulation tissue forms and becomes fibrocartilage callus (soft callus)
osteoblasts produce spongy bone

Question 22

what occurs during the 2nd repairing stage of fracture healing

Answer 22

occurs within months
remaining granulation tissue is ossified (turned to bone)
formation of hard bone callus
chondrocytes and osteoblasts produce cartilage and bone

Question 23

what occurs during the remodelling stage of fracture healing

Answer 23

occurs over months/ years depending on severity
angiogenesis
osteoclasts and blasts remodel the hard callus (resorption and formation)