Lecture 2 Flashcards
4x basic tissue types
Epithelial
Nerve
Muscle
Connective tissue
epithelial
covering tissues
nerves
Slow messages: hormones
Fast messages: conduction
muscle
contraction
Connective tissue
- mechanical support (mostly)
-bone
cartilage
tendons
ligaments
fascia
dermis
What 3x of the four tissue types are cellular tissues?
Epithelial
Nerves
Muscle
-little intervening space between the cells
Out of the four tissue types, which arent cellular tissues?
Connective tissue
Large amounts of Intracellular (Extracellular) materials
-lots of space b/w cells/cells far apart
-materials are produced by the cells and then laid down
What are the 4x types of cells?
Fibroblasts
Chondrocytes
Osteoblasts
Osteocytes
What are the 4x components of Intra/Extracellular materials?
- Fibres
- hydroxyapatite
- Matrix (PG)
- Glycoproteins
What is the difference between Proteoglycans and Glycoproteins?
Proteoglycans: more glycan
Glycoproteins: more proteins
-different ratio of protein:carbohydrate
What are 5x examples of proteoglycans
aggrecan versican biglycan decorin hyaluronan
Tendon
White = low vascular (few bV/capillaries)
= not a high level of maintenance
= materials stable/low turn over
collagen half life is year
-lasts a long time
-isnt replaced often and doesnt required alot of energy
What happens to collagen if tendon is stained with Masson Trichome under a light microscope?
Fibres = smallest element Collagen stain Red -fibres run length of tendon -strength of tendon resides in collagen fibres -paralled
What is the max magnification of a light microscope?
1000x
What is the magnification of an electron microscope?
5000x, 10000x, 50000x
What happens to collagen if tendon under a electron microscope?
fibrils = individual unit
cross banding pattern of the protein molecule arrangement within fibril
-regular arrangement
shows Collagen has a crystaline structure due to regular arrnagement of molecules= difficult to stretch/elongate collagen fibril
How much can you stretch a tendon?
2percent
- strength of mild steel
- will then take up all slack from collagen fibrils
- will not elongate
- need to be this way, as transmitting force from muscle to bone, allowing for movement of digits and limbs
- without non stretching tendons = No precise movements
How do you get precise movements?
By having an inflexible substance (tendons and their collagen) transmitting forces from muscle onto bone
-withstanding tension
What do tendons/collagen withstand?
tension
What is the difference between the arrangement of tendons and ligaments?
ligaments = less precise and dense
- very similar
- both carry tension
What are ligaments?
bone to bone
-both carry tension
What are tendons?
muscle to bone
-both carry tension
What 2x things do you do to take tension off a tendon?
Tenotomy
-cut a tendon in half
Neurectomy= Denervate
What happens after a Tenotomy + 10 days?
Red staining tissue –> green staining tissue
-same Maison Trichrome stain
-Tension taken off
-Round nuclei (no longer elongated.
-cells have shortened and can now divide
(if cells are lengthened then they cannot divide
-White space= PG
-tissue swells = as PG bind water
-CT require mechanical forces onto them otherwise they degenerate
What is the effect of pressure on tendon?
Tendon changes shape
- some red changes to green
- under pressure where it goes around the bone
- area of pressure = increased PG (blue stain
What do fibres under tension stain?
red
What do fibres under pressure and Maison Trichrome stain?
green
What do PG proteoglycans stain with Maison Trichrome?
Blue
What happens to a tendon under pressure?
Cells are now rounded (no longer elongated) Become chondrocytes (cartilage cells) in a piece of tendon i.e. fibrocartilage
What are the shapes of cells in tendon running rom an area with applied tension to applied pressure?
- Normal tenocytes
- fatter, more numerous
- rounder, more numerous
- grouped
- fibrocartilage
What are the functions of PGs proteoglycans ?
bind water
What is the PG proteoglycan content in Tendon?
LOW pg in tendon
0.15% dry weight
-dermatin sulphate chain (protein core + 1 chain of carb)
Mostly decorin
What is the PG proteoglycan content in cartilage?
HIGH pg in cartilage 2-4% -chondroitin sulphate chain (protein core + multiple chains of carbs) Mostly versican/aggrecan
What happens if you remove the pressure?
translocate tendon to be Infront of ankle
= no pressure
=within 10 days most of PG was lost
=Remodelled
(effect of translocation of the sesamoid on proteoglycan levels)
What happens if after removing pressure, you restore the pressure?
40 days infront of ankle, then 40days behind again
PG decreases and then increases again -but not as good as before
(3.5 and 4.7 months)
-The longer without pressure = harder to regain PG
“Easy to lose, hard to regain”
What is the meaning of the phrase “Easy to lose, hard to regain” re: CT connective tissue?
If you stop using CT
-very easy to lose structure
-if you start using them again, you can restore them, it is just very difficult to get back
-can remodel. but if too much of a change. is very hard to reverse that change (but can still happen)
(like your fitness-stop training, lose fitness quickly. to back to previous level, you need to train harder and longer to regain that fitness)
What are the 3x types of cartilage?
Hyaline cartilage
Fibrocartilage
Elastic cartilage
Where is hyaline cartilage mainly located in an adult?
mainly joints
costalcartilages -cartilage on end of ribs - another point of joints
cartilage = flexible = but become stiffer with age
What is PG proteoglycan content in articular cartilage?
High in articular cartilage = 10% dry weight
- especially in Load bearing regions (central) -Purple staining
- less PG peripherally - where arthritis begins
Where does arthritis begin?
Where your PG proteoglycan content is low
-peripheral (not where load is)
What makes cartilage so good under pressure?
Matrix contains aggrecan
-protein core + GAG carb side chains of CS sugar units
GAG carb chains stick out at right angles to protein core
-contain negative charges
-repel eachother (chains act as stiff bristles)
-more compress together = more resist that pushing
-bind water b/w chains (trapped internally in the molecule) = cannot compress water
(-ve charges + incompressibility to water) = PG aggrecan is ideally suited to withstanding pressure forces
-enormous load through joints all the time standing and walking
What would happen if you didn’t tether PG and you just put them into the matrix?
Would all go to sides
-PG only work becuase you hold them in position
How do you hold PG in position?
- Hylauronan (salt), the PG bind/attach to Hyaluronan (carb chain) + link protein that helps stabilise PG onto HA
- Hyaluronan isnt a strong substance. so need something else. - cartilage has Collagen fibrils. fine and lost of them. attach GAG -ve side chain to collagen electrostatically to +ve aa amino acids
- chains drape out onto collagen fibrils, everything gets locked into mix matrix
this matrix is ideally suited for withstanding pressure
How can you emasure PG content?
more PG = linear relationship = better at resisting pressure
Creep modulus
1. Probe into cartilage and indent.
2. Measure depth of depression for a given force
3. apply load for 2 second
4. cartilage “creeps” downwards = creep modulus
5.plot reciprocal vs dry weight of PG up to 10%
more PG = better joints= more resistance to pressure
What happens to Articular cartilage when compressive forces are removed?
Tendon = changes
Cartilage = nothing much changes if you remove pressure from joint IF YOU KEEP JOINT MOVING
-will maintain cartilage
How do you know that even if you remove pressure from cartilage (Not tendons) it wont change that much if you keep it moving?
- control sheep
- Rubber band on front leg = movement of wrist, no weight bearing (3 legged sheep) = swing
- Straight cast = weightbearing , no movement of joint (can walk on 4 legs)= straight
- Bent cast= off ground = no weight bearing, no movement = Bent group
-sampled artilcular surfaces of radiocarpal joint
-measured PG levels
Control had small loss but not that must (contrallateral limbs)
Bent: no movement, no weight bearing = 40% loss of PG in 4 weeks
Swing group= no loss=movement alone maintains PG Levels
- keep joint moving, dont have to put weight on it
- moving joint= a little residual pressure going across joint but is very small
What is the concept of passive therapy in physiotherapy?
Immobilised for long periods of time in hospital beds
= lose tension in tendons
=changes in CT structure
-just need someone to move you joints on a daily bases to maintain joints
Hypertrophic scars
whiter = lower BV
Healing process
Early=itchy with histamines
Scar tissue = laid down collagen
What are the Layers of normal skin?
Epidermis
Dermis - papillary + reticular layer(scar forming layer-basket weave of collagen)
Hypodermis(fatty latyer
Inversting fascia = second skin=layer of collagen
Where does scar tissue form?
3rd Reticular layer of skin
-basket weave of collagen
What are the components of a hypertrophic scar in the reticular layer?
tight collagenous bands curved above and below central area
central area= nodule= thick and hard to touch = properties of cartilage = high PG and round cells
collagenous bands = under tension
Tight bands, as pulled outwards, exert compressive force at right angles into central tissue
-this pressure = makes it think it should form cartilage = froms fibrocartilage
Where do scars form?
- where you have made a cut
2. where there is a distractive force while it is trying to heal (e.g. tension)
Why do scars form?
Becuase of Tensional forces
- Skin is Anisotrophic
- skin stretches more in one direction than another
What is a features of skin?
Skin is anisotrophic
meaning that skin stretches more in one direction than another
-can pick a fold of skin up in one direction for than another
-have more slack skin running AROUND your arm than you have running down your arm (can pull out that skin as more stretchy)
skin running down is ALREADY stretched, therefore cannot stretch it much more
How can the anisotrophic features of skin be formally presented in a graph?
Extension vs Load
-cut forearm skin - dumbell shaped so can clamp b/w jaws and pull
-Shape same (materials are consistent)
more stretch across LL (Langars lines)
What does LL stand for?
Langars Lines
What is the relationship between skin stretch and Langar’s lines?
With langar lines = cannot stretch much = skin running down arm is already stretched
How can the anisotrophic feature of skin be shown re wounds?
This difference in stretch with or across LL, is apparent in GAPING of wounds
-created by straight line incisions
-see if wound pulls over or stays closed (relatively)
Parallel to Langars line = lines of tension = wound doesnt open up as much
vs. Right angles to Langars line = wound opens up/gapes more
What is the theory behind Langars lines?
Weave of collagen and elastic fibres in dermis is NOT same/uniform in all directions
-some collagen fibres running at right angles, some stretched out
stretched out = alot of tension
right angles = more slack/less stretching already
No change in materials, is only arrangement of collagen fibrils that determine whether or not skin will stretch
How can you locate Langars Lines without an incision?
Puncture with round inked object
Ink circles become ellipses
-Ink outline=fusiform in shape because of natural tension within skin
-round prior to injury
-tension of skin has changed to ELIPSE shape
What happens if a body is stabbed?
Shape of wound will depend upon the epipoint of the knife relative to position to Langars lines
What are Langars Lines?
Lines of maximum tension
What is the significance of Langar’s Lines?
Incision made at right angles to the line of tension will result ina hypertrophic scar
Incision made parallel to the line of tension will result in minimum scaring (tiny line but not scaring)
What are features of Langar’s Lines over the shoulder blades vs waist?
Shoulders blades = vertical (can pick up verticle fold of skin)
Waist = horizontal
LL change /different angles inbetween
-also changes from one person to another - due to different body shape
How can you determine the individual pattern of Langers lines on a patient?
Flint circle ink pad + circle stamp.bottle top Fetal position and pull arm in Then straighten out -the circle becomes ellipsed -Long axis of ellipse = Langars line Mark long axis
Z-Plasty
scar on abdomen
Abdomen langar’s lines = horizontal (same as waist on back)
No scar seen Vertically
But even at 45 degrees (ends of Z shape) there is a Hypertrophic scar
What would happen if you had tumours across shoulder blade and had to remove them but wanted to avoid hypertrophic scars?
Langars Lines on shoulder blades = vertical
Map out pattern of LL for each tumour
Cut out with a margin around tumour -leave a few cm to allow for clearance
-Dart and shape
-cut along dart line to give alot of clearance
-you are removing alot of skin, but you wont have a scar
after cut has been made, skin pulls back even more
- but on sides of cut, skin is quite loose/slack
- can later bring back together and suture
After surgery, where there is no (hypertrophic) scar. What does a red dot indicate?
little bit of hypertrophic scar formation
- position relative to arm movement
- distractive forces coming in at right angles - when you stretching out upper arm
- could avoid by stapping down arm (avoids movement). But not practical
