Week 2 Flashcards
What kind of tissue is bone?
connective
Why is the bone structure ‘hard’?
calcified extracellular matrix (ECM)
Name some reasons that bones change throughtout your life.
age
intense pressure/movement
rebuilding from trauma
what are the bones 2 extracellular components?
organic - made of proteins
inorganic - made of minerals
what is the organic portion of the bone made of and what portion of the bone does it make up?
33% of bone in organic.
made of collagen (protein fibres)
and ground substance (proteoglycans)
what is the reason we have organic components in our bones?
organic means more flexible
resists tension
more bendy - less likely to snap.
woud be too bendy on its own
what is the organic portion of the bone made up of and what portion of the bones makes it up?
67% of the bone is inorganic
made of hydroxyapatite + ca minerals (salts)
what is the reason that we have inorganic compontents in our bones?
hard + resistent to compression
would be too brittle on its own (snap instead of bend)
what are the 4 types of bone cells and what are their function?
what % of the bone do they make up?
2% of the bones are cells
- ostgegenic (create osteoblasts)
- osteoblasts - MAKE create/build bone
- osteocytes - MAINTAIN tell other what to do, responsible for correct amount of destruction/formation.
- osteoclasts - DESTROY remove bone matrix
compact bone is arranged into a structural unit called a:
osteon
cancellous bone is made of a ___ structure.
trabecular
what are foramina?
holes in bones. they can let blood vessels in in order to supply blood and therefore nutrients to the bone tissue.
explain how blood supply enters into compact bone.
blood supple enters in through foramina and travels up the central canal of the osteons where the nurtients are carried through the canaliculi to the lacunae and therefore the entire osteon.
explain why blood supply enters into compact bone.
blood supply means that nurtients are reach all parts of the osteon and therefore it was heal/repair/function better/faster.
name the four parts of an osteon:
- central canal
- lamellae
- lacunae
- canaliculi
what is the central canal and what is its function?
blood vessels and nerves that travel up the centre of the osteon in order to supply nutrients to the osteon and therefore keep the bone healthy.
what is the lamellae and what is it made of?
layers around the central canal that form the shape of the osteon made of inorganic ECM (collagen, flexible)
what is the lacunae and what is its function?
‘lakes’ or voids between lamellae that house osteocytes
what is the canaliculi and what is its function?
channels through the ECM from the central canal to the lucanae that supply nurtients to the osteocytes.
What does ecm stand for?
extracellular matrix
long bones have an extra layer or ____ outside of the ___
circumferential lamellae , osteon
what are interstitial lamellae?
old osteons that are squished and will eventually be remodelled.
what is cancellous bone mostly made up of? (2)
trabeculae (little arms of weblike bone tissue, struts of lamellae)
marow that fills the gaps between the trabeculae
Where the osteocytes housed in cancellous bone?
in lacunae in between lamellae on the surface.
how does cancellous bone get nutrients?
because cancellous bone is made of trabeculae that are too thin for blood vessels, nutrients enter in straight through canaliculi.
how are trabeculae structured?
they are organised so that they can best resist force/ direct the force downn the stronger compact shaft/diaphysis of the bone.
how much of the skeleton is completely remdoelled each year?
10%
What is appositional growth?
it is the process of growth in which osteoblasts form ECM on the outer part of the bone, while osteoclasts destroy the internal tissue, allowing the bone to grow without becoming too heavy.
Where are osteoblast usually found in the bone?
on the outer surface just under the periosteum.
how are osteoclasts formed?
when the osteoblasts create more bone tissue, they leave some osteoblast behind which then mature into osteoclasts to destroy the inner layers.
Why is the destruction of the inner bone good?
As the osteaclasts destroy the bone it unlocked access to the minerals and calcium that were in that tissue. It also means that the bones can adapt to be certain shape/strength to deal with certain pressures.
what are the bodys requirements to continue bone homeostasis in a healthy way?
- sufficient calcium intake
- balanced diet
- regular exercise
what is osteoporosis and osteopenia and what is the difference between the 2?
Both: loss of bone density due to more destruction that creation of EMC.
osteoporosis: loss of bone density to the point that it becomes a clinical problem
ostepenia: normal loss of bone density that comes with age.
what are some of the impacts of osteoporosis?
- trabeculae become thinner
- affects cancellous most more which results in weak epiphysis
- prone to fractures and arthritis eg. compression fracture in the vertebrae (back pain)
which gender is more prone to osteoporosis and why?
women, as they experience a drop in estrogen when they go through menopause whereas mens estrogen levels remain constant. estrogen levels are linked with strength in bone therefore when they go through the drop then they are more prone to osteoporosis.
When and how are bones formed initially?
around 6 weeks after fertilisation bones begin to form as cartilage models
what is the transformation of catilage into bone called?
endochondral ossification (becoming bone in latin)
explain the 4 steps of ossification:
- calcification starts
- blood vessels and osteoblasts attach externally
- blood vessels and osteoblasts penetrate to the middle of the bone
- the Primary ossification centre is developed in the diaphysis.
what is calcification?
Calcification is the accumulation of calcium salts in a body tissue. It normally occurs in the formation of bone, but calcium can be deposited abnormally in soft tissue, causing it to harden.
what/where/when are the primary and secondary ossification centres?
both: are centres in which the ossficiation (bone to cartilage) occurs.
primary: in the diaphysis in stage 4 of endochondral ossification.
secondary: in the epiphysis much later, as the epiphysis remains as cartilage to start.
what/when/why is the epiphyseal plate?
to start of when the epiphesis and the diaphysis are seperated, they are bound only by the epiphyseal plate which is a growth plate made of cartilage. this allows the shaft to gorw and stay steady at the same time.
when does the epiphysis and the diaphysis join?
usualy at the start of puberty when the bones are finsihed the critical growth period.
what are the two types of ways that the bone grows to become larger?
- length: through growth/epiphyseal plates
2. width: appositional growth
are joints inorganic or organic
ORGANIC - no inorganic components
what are the functions of joints?
- hold bones together
- the point that bones meet (articulation)
- allows movement (not always)
name the 2 types of cartilage:
Hyaline (articular)
Fibrocartilage (resistent, tension and stability)
How does cartilage recieve nutrients?
blood vessels do not penetrate cartilage, so nutrients have to slowly diffsue into the tissue. this means they are slower to heal.
what is the general composition of cartilage?
collagen fibres in ground substance
few cells called chondrocytes in Lacunae
what can aid the diffusion of nutrients into cartilage?
compression/joint loading - using the joint + applying pressure to cartilage makes nutrients soak into tissue faster.
name a few reasons why exercise is good for your bones/joints:
- joint loading/compression of joints aids diffusion of the nutrients
- a requirement of bone homeostasis and a healthy balance of creation/destruction of bones
- bone tissue is able to adapt to tailor to the way you move.
what makes up hyaline cartilage?
collagen fibres (barely visible) high water content - is more flexible to compression/squish.
what is the function of hyaline cartilage?
- coats bones at joints (protects each other from erosion)
- resists excessive compression
- provides a smooth/frictionless surface to aid movement
- moulds to surfaces of bones where they articulate
what happens to hyaline cartilage in old age?
hyaline cartilage is prone to degridation, and as it wears down there is no longer protection between bones where they articulate. this can cause ebrasion and wearing down of the bone (linked with arthritis).
what is firbocartilage made of?
collagen fibres in bundles which orientate themselves to be thicker/stronger in parts of the bone which experience extra stress/weight bearing.
what is the function of fibrocartilage?
- resist compression and tension
- deepen the articluar srufaces
- act as a buffer/shock absorber as it distrobutes the force to a wider area.
what do ligaments and tendons do? (general)
ligaments: attach bone to bone
tendons: attach muscle to bone
resist/allow tension
what are ligaments and tendons made out of?
DFCT - dense fibrous connective tissue
dense bundles of fibres such as collagen, elastins, as well as fibroblast cells.
how do ligaments/tendons recieve nutrients?
they have blood vessels but very few, so are slow healers
Name 3 facts about ligaments (what/why):
- restrict movement
- connect bones
- mostly collagen, minimal elastin (not as stretchy)
name the 2 main ligaments in the ankle and what they do:
medial ligament restricts excessive eversion
lateral ligament restricts excessive inversion
Name 3 facts about tendons (what/why):
- muscles to bones
- facilitates movement - allos muscles to move bones
- more elastin than ligaments (more stretchy)
what is bony congruence/what does it effect?
it is the amount that bones are touching each other.
it effects the amount of soft tissue support eg. less congruence = more soft tissue supoort needed.
what is the difference between tissues and strucures?
tissues are a group of cells organised very well together into a structure that performs a function.
A structure is just something made up of tissue for a specific function/purpose.
what are the 3 classes of joints?
- Fibrous
- Cartilaginous
- Synovial
fibrous joints:
- what are they made of?
- what strucure are they?
- what is their function?
- what is an eg?
- least mobile in body*
1. DFCT tissue
2. ligament
3. limit movement, provide stability
4. cranial sutra
what does DFCT stand for?
dense fibrous connective tissue
cartilaginous joints:
- what are they made of?
- what are they connected to?
- what is their function?
- what is an eg?]
- some movement but not a lot*
1. fibrocartilage tissue
2. connected entirely by cartilage
3. various (weightbearing)
4. intervertebral disc, pubic symphysis
which is the most freemoving type of joint?
synovial
what determines the range of motion in the synovial joint?
- the shape of the bone ends
- the shape of the surrounding body parts etc bicep getting in the way of full full flexion of the forearm
- the type + function of joint and surrounding ligaments
what are epiphesis covered in?
articular cartilage
what does articular cartilage do?
trap water, aids in smooth movement
what is subcondral bone?
the bone on the end of the epiphesis which the bones articulate/there is a joint. it isextremely smooth so that vthe bones can move smoothly without causing damage.
what is the synovial membrane and what is it made of?
it is made of seceretory epipylial tissue that the lubricates the movement and so makes the joints movement smoother.
name the 3 levels of axial movement:
uniaxial - 1 axis
biaxial - 2 axes
multiaxial - many axis
what does ROM stand for?
range of movement
explain stability vs mobility:
in synovial joints there is a costant trade-off between stability and mobility. when there is more mobility there is stability and more risk of overextension/injury, however when there is more stability and less mobility there is less movement allowed.
name the 7 types of synovial joints:
- plane (slide n glide)
- hinge
- pivot
- condylar
- ellipsoid
- saddle
- ball and socket
name 2 characteristics and 1 example of the plane joint:
- multiaxial (s,c,t)
- just a little movement
rg. clavicle
name 1 characteristics and 1 example of the Hinge joint:
uniaxial (flexion/extension)
eg. elbow
how does a pivot joint move and what is an example?
unaxial (roatation)
eg. forearm to radio-ulna joint
name the key characteristic of the Condylar joint, how it moves, and example of it:
biaxial (flexion/extension, roation sometimes)
- when it is extended it locks, preventing rotation. when flexed a little roation can occur on the transverse plane (this is because of menisci).
eg. knee
how does the ellipsoid joint move and what is an example?
biaxial (f/e + add/abd = circ)
eg. wrist joint
how does the saddle joint move and what is an example?
biaxial (f/e + add/abd = circ)
plus somewhat rotation/opposition
eg. thumb joint, thumb can touch every finger
how does the ball and socket joint move and what is an example?
multiaxial (f/e + add/abd = circ, rotation)
eg. shoulder and hip.
