Cellular Damage Inflammation/healing Flashcards
Define hyperplasia
Increase in the number of cells
Can only happen in organs that can regenerate cells
Physiological examples of hyperplasia
Compensation after partial hepatectomy
Pathological example of hyperplasia
Abnormal androgen response in BPH
Define hyper trophy
Increase in mass of each cell resulting in a larger organ overall
Physiological example of hypertrophy
Uterus in pregnancy
Pathological example of hyper trophy
Cardiac myocytes aortic stenosis
Define atrophy
A decrease in mass of cell
Physiological examples of atrophy
Uterus after birth
Pathological example of atrophy
Disuse, denervation,ischaemia, nutrition, aging, pressure
Define metaplasia
A reversible change where the cell type changes
Example of metaplasia
Barrotts oesophagus
Define necrosis
Cell death after an abnormal stress , it is always pathological
Regarding healing by first intention when do neutrophils appear
Within 24 hours
With regards to healing by first intention when is neovascularisation maximal
Day 5
What accounts for most wound strength
Collagen 1
With regards to healing by first intention when is collagen type 3 and type 1 deposited
Type 3 initially
Replaced by type 1 which is stronger
Describe platelets
Membrane bound smooth biconvex discs
Do not have a nucleus
Shed from megakaryocytes in bone marrow
Contain alpha and delta granules
Average life span 5-9 days
Products produced by macrophages that cause tissue injury and fibrosis
Arachidonic metabilites
Reactive oxygen species
Reactive nitrogen
Proteases
Cytokines
Coagulation factors
Factors released by macrophages which cause repair
Growth factor
Fibrogenic cytokines
Angiogrnic factors
Remodelling collagenesis
Which cells participate in phagocytosis
Monocytes
Macrophages
Neutrophils
Tissue dendritic cells
Mast cells
When does new collagen deposition occur
By day 3 of wound healing
With a clean surgical incision wound what is the wound strength by the end of the first week
10%
With clean surgical incision what happens to the destroyed dermal appendages
The do not recover
What is the first part of fracture healing
Haematoma
Occurs immediately after
Provides a firbin mesh for influx of inflammatory cells
What is the second part of fracture healing
Inflammation via degranulation of platelets and inflammatory cells
Activate osteoprogenitor cells in periosteum and medullary cavity
Osteoclastic and osteoblastic activity
What is the 3rd part of fracture healing
Procallus
No structural integrity for weight bearing
What happens in callus formation in fracture healing
Subperiosteal deposition of trabecular woven bone
Maximal girth at week 2-3
What are the 3 phases of fracture healing
Reactive
Reparative
Remodelling
What happens in the reactive phase of fracture healing
Haematoma forms immediately
Provides fibrin mesh
Sets up the framework for the formation of procallus
Fracture callus is most often made up of hyaline cartilage and woven bone
What happens in the reparative stage of fracture healing
Replacement of hyaline cartilage and woven bone with lamellar bone
Replacement of hyaline cartilage is known as endochindral ossification
Replacement of woven bone is known as bony substitution
What happens in the remodelling stage of fracture healing
Travecular bone replaces lamellar bone
The trabecular bone is resorbed by osteoclasts
Creates a shallow pit - howships lacuna
Osteoblasts deposit compact bone which is remodelled
What is healing by first intention - primary union
The wound is clean uninfected surgical incision approximated by surgical sutures
Incision involves limited number of epithelial cells and connective tissue cells as well as disruption of epithelial basement membrane continuity
What happens within 24 hours of clean virginal suture
Neutrophils appear at wound margins
Epidermis at its cut edges thickens because of mitotic activity
What happens between 24-48hrs of clean surgical suture wounds
Epithelial spurs develop fishing in the midline beneath the surface scab producing a thin epithelial layer
What happens at day 3 of clean surgical suture wounds
Granulation tissues invade the space, collagen appears
What happens at day 5 of clean surgical suture wounds
Neovascularization is maximal
Collagen fibres bridge the incision
Epidermis recovers
What happens at week 2 of clean surgical suture wounds
Accumulation of collagen and fibroblasts
Decrease in vascularity and inflammatory cells
What happens at one month of clean surgical suture wounds
The scar compromises a cellular connective tissue devoid of inflammatory infiltrate covered now by intact epidermis
What is healing by secondary intension
Extensive cell and tissue loss
Regeneration of parenchyma cells cannot reconstitute the original architecture
Abundant granulation tissue
What inflammatory reactions do mast cells participate in
Acute and chronic
Do mast cells release lysosomes
No
With regards to mast cells what does adenosine triphosphate do
Provides the emerge for mast cell degranulation
How do burns cause hypovolaemia
Increase in local interstitial osmotic pressure
Neurogenic and mediator induced increase in vascular permeability
Protein from blood is lost into interstitial tissue
Generalised oedema
How are neutrophils removed at the end of the inflammatory process
Apoptosis
System factor that impacts wound healing
Glucocorticoid excess
Diabetes mellitus
Blood flow - cvd pvd
Nutrition - protein vitamin c
