Healing & Repair

Question 1

what is acute inflammation?

Answer 1

the complete restoration of tissues

Question 2

what kind of inflammation can healing arise from?

Answer 2

acute and chronic

Question 3

what is regeneration?

Answer 3

replacement with functional, differentiated cells

Question 4

what is repair?

Answer 4

production of a fibrous scar and changes is tissue structure/architecture

Question 5

what are labile cells?

Answer 5

normal state is active cell division, rapid regeneration

Question 6

what are stable cells?

Answer 6

variable rates of regeneration, rapid proliferation in response to injury

Question 7

what are permanent cells?

Answer 7

unable to divide, unable to regenerate

Question 8

what is the clotting phase? (haemostasis)

Answer 8

clot formation- mitosis of labile/stable cells

Question 9

what is the inflammation phase?

Answer 9

macrophages/neutrophils phagocytose and degrade infectious agent, stimulation of certain cells to start regenerating and or repairing tissue

Question 10

what is the proliferative phase?

Answer 10

formation of granulation tissue, fibroblasts key players, new CT, angiogenesis, GF essential.

Question 11

what is the first phase of granulation tissue?

Answer 11

mix of proliferating capillaries, fibroblasts, immune cells, new capillaries leaky- allowing cells & fluid into tissue

Question 12

what is the 2nd (fibrous) granulation tissue phase?

Answer 12

over time capillaries regress and immune cells return to blood, mature fibroblasts lay down collagen

Question 13

what is angiogenesis?

Answer 13

formation of new capillaries

from existing vasculature

Question 14

what are the 2 mechanisms of angiogenesis?

Answer 14

sprouting and intussusceptive

Question 15

what is angiogenesis driven by?

Answer 15

vascular endothelial growth factor

Question 16

what is the role of growth factors?

Answer 16

promote or inhibit cell growth and differentiation, bind to receptors on cell surfaces-balance important

Question 17

what are the functions of growth factors?

Answer 17

promote cell survival, locomotion, contractility, differentiation, angiogenesis

Question 18

what is fibrosis?

Answer 18

extensive deposition of collagen and formation of excess fibrous CT

Question 19

what is fibrosis driven by?

Answer 19

fibroblasts (controlled by macrophages) - caused by substantial or repeated damage

Question 20

what is the purpose of M2 macrophages in fibrosis?

Answer 20

essential- engulf/degrade, production of growth factors

Question 21

describe the maturation phase of healing?

Answer 21

disorganized granulation tissue remodelled by remaining cells, collagen fibres cross linked along tension lines, re-epithelization, regain of tensile strength, fibrous scar remains

Question 22

describe the inflammatory stage of fracture healing

Answer 22

hematoma formation at fracture w/i 24h, acute inflammatory response, bone cells deprived of O2, blood supply dies off

Question 23

describe the 1st repairing stage of fracture healing

Answer 23

capillaries form into hematoma, occurs w/i weeks fibroblasts produce collagen fibres, osteoblasts form spongy bone, granulation tissue forms then becomes fibrocartilage callus

Question 24

describe the 2nd repairing stage of fracture healing

Answer 24

chondrocytes and osteoblasts produce cartilage and bone, remaining granulation tissue is ossified, formation of hard bone callus at fracture site, w/i months

Question 25

describe the remodelling stage of fracture healing

Answer 25

osteoclasts and osteoblasts remodel the hard bone callus, cortical bone replaces woven bone, months- years, angiogenesis essential