Healing And Repair Flashcards
What r the 3 process of wound healing?
* Haemostasis – as vessels are open • Inflammation – as there has been tissue injury • Regeneration (also called resolution) and repair – as structures have been injured or destroyed.
Define regeneration?
-regeneration can occur as long as____cells r intact.
growth of cells and tissues to replace lost structures.
-regeneration can occur as long as the STEM CELLS R NOT DESTROYED!.
***it requires a connective tissue scaffold.
What is the difference between an abrasion and an ulcer? ana ulcer/abrasion goes all the way below the _____layer of skin
Ulceration is a severe form of an abrasion, its more deeper, and is difficult to see in skin, and injury that goes below muscularis muscosa
they r cells with long proliferative activity and show asymmetric replication
name it, and explain what is meant by asymmetric replication
STEM CELLS
in aysmetric replication> one daughter cell remains a stem cell, while the other differentiated into a mature nondiving cell
Where abouts in the tissues are the stem cells? (3)
intestinal mucosa> bottom of crypts
liver> btw hepatocytes and bile ducts
epidermis> basal layer next to to the BM
regeneration can tay place bs feeha shar6, name it
1) tissue damage should not be very EXTENSIVE> cuz u loose ur connective tissue SCAFFOLD and u need that for regeneraton to take place!
What is fibrous repair (organisation) and when does it occur?
Healing with formation of fibrous connective tissue = scar
* when a PERMANENT tissue is damaged> fibrous connective tissue will form in that area making SCAR.
describe the processes of Fibrous repair and name the cells involved!
- Phagocytosis of necrotic tissue debris by inflammatory cells
- Proliferation of endothelial cells which results in small capillaries that grow into the area (angiogenesis)
- Proliferation of fibroblasts and myofibroblasts >synthesise collagen, cause wound contraction (the repair tissue at this stage is called GRAN-ULTION TISSUE)
The granulation tissue becomes less vascular and matures into a fibrous scar
The scar matures and shrinks due to contraction of fibrils within myofibroblasts.
describe this image, what type of tissue is this? what does it consist of? why is it so very red? what is its function?
GRAN-ULATION tissue
- granular appearence & texture
- very red> bc it contains many developing capillaries, these r very delicate> easy to bleed
Consists of:
- Developing capillaries
- Fibroblasts and myofibroblasts
• Chronic inflammatory cells
Function
-fills gap> capillaries supply oxygen and nutrients and cells>contracts and closes hole.
Which cells are involved in fibrous repair?
-inflammatory cells -endothelial cells -fibroblasts and myofibroblasts
What is collagen? function? which type is most commonly found?
- most abudant protein in animals, type 1 is most common
- Provides extracellular framework for all multicellular organisms,
(i. e., responsible for holding body together, including the skeleton)
Type ______ collagen makes up basement membranes
4
four=floor
lol.
What (4) diseases are the result of defective collagen synthesis? which ones r inherited? aquired?
Aquired
-scurvy
Inherited
- ehlers-danlos syndrome
- osteogeniss imperfcta
- Alborts syndrome
Name disease caused by VC deficiency! name symptoms
SCURVYY
vitamen C deficiency > procollagen can’t do hydroxylation in ER > reduced cross- linking and defective helix formation > ppl unable to heal wounds 3adl>tendacy to BLEED
- bleeding gums
- loss of tooth
ppl had black bones when they died> bc there was a lot of bleeding in ur bones!
How are regeneration and repair triggered and controlled?
Cells communicate with each other to produce a proliferative response
Cell to cell signalling can be via:
- Hormones
- Local mediators (e.g. GF)
- Direct cell-cell or cell-stroma contact
Controlled?
via integrins and cadherin, if theyre not their, cells will divide.
Amongst local mediators, ______r the most important in regeneration and repair.
Growth Factors
considered as “local hormones” they act over a short distance.
Polypeptides that act on cell surface receptors
They kick start the cell cycle.
-they r coded by proto-oncogenes
Apart from cell proliferation, what other effects can growth factors have?
• Inhibition of division
- Locomotion
- Contractility
- Differentiation
- Viability
- Activation
- Angiogenesis
Types of growth factors and what produces them
- EGF
- VGEF
- PDGF
- TNF
Produced by cells such as platelets, macrophages, endothelial cells.
what is contact inhibition? how r malignant cells different in contact inhibition? what r the adhesion molecules found on cells?
most cells in the body dont like to be on their own, they’ll keep proliferating until they TOUCH other cells then they stop!>>this is called CONTACT INHIBTION
-they do they same but they just DONT FUCKING STOP.
- Cadherins bind cells to each other
- Integrins bind cells to the ECM
why do surgeons use sutures that dont have much of a surface area on them?
so bacteria wont grow there. since bacteria r attracted to foreign stuff.
What is healing by primary intention? when do we see it?
What is healing by secondary intention? whe do we see it?
NEAT inscisional,closed, non-infected wound> typical surgical wound
Excisional wound WITH tissue loss!, infected> ulcers, infarct, abcess
theres more to it alaa bs maly khlg aktb.
when performing a split skin graft, how does the donor site heal without making a scar?
when u do a split skin graft, u take off a peice of skin and then u put it in this machine) like speghetti machine, it’ll pierce holes in that skin peice (looks like net) >> then they put that on the area of burn>> it grows back quickly without making a SCAR bc u r splitting it a very SUPERFICIAL level, and we left the structures behind (hair, glands whatevs)
How does bone heal?
A fracture results in a:
haematoma>>>fills gap, surrounds the bone injury.
A fibrin mesh and then granulation tissue>>Platelets and inflammatory cells release cytokines>> activate osteoprogenitor cells to osteoclastic and osteoblastic activity.
Soft callus (also called procallus or fibrocartilagenous callus) >> consists of fibrous tissue and cartilage within which woven bone begins to form.
Hard callus (or bony callus) >>laid down by osteoblasts. The bone formed initially is woven bone. It is weaker as it is less organised than lamellar bone but it can form quickly.
Formation of lamellar bone which is more organised and stronger than woven bone.
Remodelling of the bone occurs in response to mechanical stresses placed on it. Bone not physically stressed is resorbed and the outline of the bone is re-established.
What things can influence wound healing? (local and systmeic factors)
LOCAL
- Type, size, location of wound
- Mechanical stress
- Blood supply (face has good blood supply, limbs dont)
- Local infection
- Foreign bodies (during surgery)
- Denervation
SYSTEMIC
- Age
- Anaemia, hypoxia and hypovolaemia>less o2 delivey to healing tissue
- Obesity>increase tension on wound
- Diabetes
- Genetic disorders
- Drugs
- Vitamin deficiency-vc deficiency inhibits collagen
- Malnutrition > lack of aa needed for protein synthesis
What are the complications of fibrous repair? (3)
1) insufficient fibrosis > formation of adhesions>ruining organ function
2) excessive fibrosis > keloid scar
3) excessive contraction > obstruction of tubes,
4) disruption of normal architecture of tissue > ex: cirhossis of liver
a complication of fibrous repair is causing a LOSS OF FUNCTION of that tissue. give an example.
healed MYocardial infarcation with scar tissue!>> NON CONTRACTING area of myocardium
Where for example do u see primary healing?
In surgical wounds.
Oesophageal stricture
Q
healing and repair in:
- Cardiac muscle
- Liver
- Peripheral nerve
- Cartilage
- Central nervous system
• Cardiac muscle> limited
• Liver> its the real boss ass shit> regenerates like a star #lifegoals
• Peripheral nerve>When a nerve is severed the axons degenerate. The proximal stumps of the degenerated axons sprout and elongate. They use Schwann cells vacated by the distal degenerated axons to guide them back to the tissue that the nerve innervates
• Cartilage>got no blood supply, lymphatic drainage, innervation> heals like a pussy
• CNS> Neural tissue is a permanent (non-proliferative tissue) > is replaced by proliferation of CNS supportive elements (glial cells).
name tissues of the body r divided into 3 groups depending on their proliferative activity and examples:
Labile tissues: continuously dividing, proliferate in life replacing destroyed cells (ex:secretory glands of body, lining of GI and urinary, bone marrow cells.
Stable tissues (quiescent): cells that multiply ONLY when needed. They spend most of the time in the quiescent G0 phase of the cell cycle.
ex: kideny, liver, bone, pancreas (horse in stables. itha ba3’ainahum, 6ala3nahum)
permanent tissues (non dividing) : can’t undergo mitosis & only a few or no stem cells r present. heal with a SCAR.
Ex: neurons, cardiac muscle, skeletal muscle
function of fibroblasts and myofibroblast in wound healing?
F-secrete collagen. MY- have the ability to contract and close the wound tight. (develop contractile proteins)
REVIEW COLLAGEN ALAAA
OK OK
Which collagen tyle is responsible for basment membrane formation?
Type 4
During woumd healing, when is the weakest point?
Around 10 days
What does resolution mean
Everything goes back as if nothing ever haopend (no scar formed)
Is the skin (dermis & epidermis) labile or stable?
Stable
If dermis is damaged with cutt>> u get STABLE
if epidermis is damaged with cutt>> LABILE
Ok
For RESOLUTION u need>> labile and stable tissue
Ok
What does granulation tissue comtain?
Fibroblast and myofibroblasts and shwaya collagen. Its only purpose is to make scar tissue.
Scar shrinks down, itll contract and cause a >> CONTRACTURE in ur muscle, this is more obvious with SECONDARY INTENTION
Thats why u have to do physiotherapy and keep move that arm , so it wont stiffen and shrink
How r embryonic stem cells different from adult stem cells?
what is meant by totipotent and unipotent?
embryonic stem cells= can give rise to ANY tissues of the human body>#TOTIPOTENT
adult stem cells= can give rise to one type of adult stem cell>#UNIPOTENT
some adult stem cells are described as multipotent bc they can produce several types of differentiated cell.
Name an example
haematopoietic stem cells
ok
it what cases does fibrous repair occur? regeneration?
why is this scar white? and why do scars stretch as they get older?
cuz sometimes u dont get regeneration of MELANOCYTES.
bc fibroblast and myofibroblasts cant lay down elastin!
why does this dude have no hair on the area of his scar?
bc Sweat glands and hair follicules can’t regenerate!
process of collagen synthesis, how long does it take to be made?
- location
- cells involved
- enzymatic modification
- different name involved as it passes by.
ur glorious notes lallsy ;D
1-2 HOURS
when u heat it, it shrink is size!
guess who?
duuuh collagen!
COLLA-GEN
colla> latin for glue
Gen>(genesis) forming
collagen is GLUE forming!
not rocket science btw
in scurvy> old scars break down & open up as fresh wounds, why?
Because collagen turnover in scars remains high long after the healing process appears clinically complete.
Normal collagen is replaced by defective collagen and consequently old scars open up.
Name different types of collagen and explain where each one is seen?
what r 3 types of cell signaling?
PEA
paracrine
endocrine
autocrine
what kind of Drugs can interfere with healing and repair? in a negative and good way
Steroids> inhibit collagen synthesis
antibiotics> treat bacterial infection, reduce inflammation> spead up healing
Which cells help guide the sprouting axons to the muscle?
shwann cells.
describe this image?
Which people are especially at risk for developing this complication?
Keloid scar
overgrowth of fibrous tissue due to overproduction of collagen 3. that exceeds the borders of the scars.
-African Caribbean
What is most common, main complication of wound healing?
Infection
If its infected> pus will form > more painful red and swollen
What is ‘proud flesh’? if necessary how is it treated?
It is the opposite of a keloid. A keloid has over-healed. Proud flesh has under-healed.
Why can humans and guinea pigs get scurvy but not dogs or cats?
Scurvy does not occur in most animals because they can synthesize their own vitamin C. However, humans and other higher primates, lack an enzyme necessary for vitamin C synthesis and must obtain vitamin C through their diet!
What is a pressure sore and why do they occur?
Which patients are most at risk?
How can they be prevented and treated?
occur when someone is admitted to hospital
Prevention is the best approach:
- Changing the patient’s position as much as possible.
- Pillows, regular turning, fleece under the heels, special mattresses and beds.
Treat the patient’s general condition.
Pain relief.
Dressings - particularly gel and foam-based dressings.
Antibiotics - may be needed if there are any signs of infection.
Surgery - sometimes needed to remove damaged or dead skin (debridement). Plastic surgery may be used to close a pressure ulcer that is not healing and skin grafts may be needed.
Describe the extracellular steps of collagen synthesis
