Healing & Repair

Question 1

Resolution

Answer 1

-initiating factor removed
-tissue undamaged (infection removed)/able to regenerate

Question 2

Repair

Answer 2

-initiating factor still present
-tissue damaged & unable to regenerate
-replacement of damaged tissue by fibrous tissue
-collagen produced by fibroblasts
-REGENERATION CANNOT TAKE PLACE

Question 3

When does cirrhosis arise?

Answer 3

By damaging liver repeatedly - architectural damage
Damage at the same time as regeneration

Question 4

Describe lobar pneumonia

Answer 4

-affects a lobe of the lung
-alveoli filled w neutrophil polymorphs (acute inflammation) rather than air
-pneumocytes that line the alveoli can regenerate so the lung can be regenerated - the pneumocytes divide & reline the alveoli

Question 5

Can lobar pneumonia resolve?

Answer 5

It can resolve

Question 6

What type of lung damage occurs in covid?

Answer 6

Fibrosis

Question 7

What are the 3 types of skin wounds?

Answer 7

-abrasions
-incised skin wounds
-tissue loss

Question 8

What are abrasions?

Answer 8

Most supericial skin wounds, eg. road rash

Question 9

How do abrasions heal?

Answer 9

-normal skin -> abrasion
-scab forms over surface
-epidermis grows out from adnexa - protected by scab
-thin confluent epidermis
-final epidermal regrowth

Question 10

What are incised skin wounds?

Answer 10

-little damage to tissues on either side of cut
-2 sides of cut brought together accurately -> healing can proceed quickly

Question 11

How do incised skin wounds heal?

Answer 11

-can be sutured
-incision
-exudation of fibrin
-weak fibrin join
-epidermal regrowth & collagen synthesis
-strong collagen join

Question 12

How does a tissue loss injury heal?

Answer 12

-tissue loss injury/reason wound margins are not apposed requires another mechanism for repair
-skin edges cannot be brought together bc the cut is too deep to suture
-cells have to grow in
-fibroblasts grow in - epithelial cells grow across
-loss of tissue - granulation tissue forms - organisation - early fibrous scar - scar contraction
-phagocytosis to remove any debris
-granulation tissue to fill in defects & repair specialised tissue lost
-epithelial regeneration to cover the surface
-healing but bigger scar
-whiteness = collagen

Question 13

Examples of repair

Answer 13

1) heart after myocardial infarction - myocardial fibrosis - collagenous scarring - won’t contract with the rest of the heart

2) brain after cerebral infarction - gliosis (fibrosis in the brain)

3) spinal cord after trauma

Question 14

What is gliosis?

Answer 14

-fibrosis in brain
-glial cells instead of fibroblasts
-less dense scarring

Question 15

What cells regenerate?

Answer 15

-hepatocytes
-pneuomocytes
-all blood cells
-gut epithelium
-skin epithelium
-osteocytes - help remodel bone fractures

Question 16

What cells do not regenerate?

Answer 16

-myocardial cells
-neurones

Question 17

What is organisation?

Answer 17

-process by which specialised tissues that have suffered damage undergo fibrous repair to form a scar
-necrotic cells are replaced with collagen
-repair by formation of mature fibrovascular connective tissue
-occurs by the production of granulation tissue & removal of dead tissue of phagocytosis

Question 18

What are the processes involved in organisation/fibrous repair?

Answer 18

-phagocytosis of necrotic tissue
-angiogenesis (growth of new BVs by proliferation of endothelial cells)
-proliferation of fibroblasts & myofibroblasts -> allow collagen synthesis & wound contraction
-granulation tissue becomes less vascular to form a mature scar
-scar shrinks due to contraction of fibrils within the myofibroblasts

Question 19

What is granulation tissue?

Answer 19

-GT is loops of capillaries supported by myofibroblasts
-actively contracts to reduce wound size
-GT fills in gap that is initially left by damage to tissue
-angiogenesis occurs within the granulation tissue & the new capillaries provide O2, nutrients, cells required to repair the damage

Question 20

What happens if a fracture is not kept stable?

Answer 20

-repeated damage
-resolution cannot occur
-repair occurs instead of resolution
-fibrous tissue forms around the ends of bones -> bone ends become stiffer -> movement is reduced

Question 21

What cells are found in granulation tissue?

Answer 21

Capillary endothelial cells
Fibroblasts
Myofibroblasts

Question 22

Role of capillary endothelial cells in granulation tissue

Answer 22

Proliferate to form new capillaries - ANGIOGENESIS

Question 23

Role of fibroblasts in granulation tissue

Answer 23

Secrete collagen & other components of the extracellular matrix

Question 24

Role of myofibroblasts in granulation tissue

Answer 24

Fibroblasts with muscle filaments & attachments to adjacent cells - allows WOUND CONTRACTION