bone/muscle/joints Flashcards
Example of sesamoid bone
Patella
What makes bone hard?
Salts in the AGS crystallise to form a matrix - making bone super hard
What is the diaphysis?
Shaft, or middle of the bone
What Is the junction called between the diaphysis and the epiphysis?
Metaphysis
What covers the epiphysis?
Articular cartilage
What is inside the medullary cavity?
Yellow Marrow/ fat
What is the middle of the long bone shaft called?
Medullary cavity
What is the outer most layer covering the bone?
Periosteum, dense irregular connective tissue
cells of bone
osteogenic, osteoblast, osteocyte, osteoclast
what do osteogenic cells become?
osteoblasts
where are osteogenic cells found?
on the edge of bone ie. periosteum, endosteum
function of osteoblasts
bone forming cells
making of collagen/AGS/proteins
what do osteoblasts become and how?
osteoctyes, when it becomes trapped in matrix they have deposited
what are osteocytes
main bone cell, maintain bone via spidery fingers
where are osteocytes located?
in Lacuna
what are osteoclasts?
cell which eats/digests bone, not derived from osteogenic cells,
structure of osteoclasts
large cell(10X bigger than other bone cells), multinucleated cell lots of cells come together to form this cell, has lots of lysosomes,
location of osteoclast
edge of bone in pits next to osteogenic and osteoblast cells,
only bone cell in the middle of the bone
osteocytes
what is the contents of the bone matrix?
inorganic(calcium/phosphate = forms crystal matrix) + organic
what triggers mineralisation/crystallisation in bone and what is it made of?
osteoblast, salts(calcium and phosphate)
so what actually happens in mineralisation/calcification of bone?
osteoblasts trigger the deposit of mineral crystals around collagen fibres causing the matrix to harden
where is compact bone found?
edge of diaphysis
what structures does compact bone consist of?
osteons or Haversion systems and
what are osteons?
bone matris laid down in rings around blood vessels
what does the Haversian canal contain?
blood vessels
why are there blood vessels in bone?
bring in nutrients and carry away waste
how are osteons aligned?
alone lines of stress
types of lamellae
interstitial and circumferential
what are interstitial lamellae
old osteon that have been partially removed
bone was remade or remodelled due to changes in stress
all thats left is a few plates of bone, that used to be a ring but are now just plates
what are the black spaces within the bone matrix?
lacuna
what are lacuna?
empty spaces in bone where osteocytes sit
what connects lacuna?
canaliculi
what cells sit on the edge of bone?
osteogenic, osteoclast, osteoblasts
why are lacuna necessary?
as osteocytes have delicate arms and would be crushed by hard bone matrix
what is the space called that the “arms/legs” of osteocytes sit in?
canaliculi “little tunnel”
what is the importance of the lacuna/canaliculi structures in bone…besides protection from bone matrix
help move nutrients and oxygen through bone as nutrients cannot flow through rock hard bone matrix to get to cells(from blood vessels in Haversian canal
how is movement of nutrients through bone possible?
network of lacuna and canaliculi passing between osteocytes
what connects osteocytes?
gap junctions…they “hold hands (‘:”
where is spongey bone located?
in the epiphysis
what makes it spongey?
little spaces with bone
what do the spaces in spongey bone contain?
red bone marrow, developing red/white blood cells
why aren’t all our bone compact?
too heavy!
structure of spongey bone
Does not have Haversian canals…need because blood vessel can simply run through empty space
just have lamellae and lacuna containing osteocytes
don’t form osteons
function of yellow bone marrow?
fat (energy storage)
advantage of having energy storage such as yellow marrow within the bone?
as developing red/white blood cells in the red marrow within the epiphysis requires a lot of energy
difference between cartilage and bone
rubbery(not calcified or mineralised), proteins make the rubbery function
bone requires movement but not damage ends,
why is the end of bones covered in articular cartilage
to avoid damage to bone, resist compression, absorb shock, smooth reduces friction thus reducing pain
what are the cells of cartilage called?
“CHONDRO” - cells of cartilage
chondroblast, chondrocyte,
location and function of chondroblasts
near edge of bone, secret cartilage matrix
function and location of chondrocytes
maintain cartilage, sit within lacuna as pressure on joints could crush the poor chondrocyte
why is cartilage avascular?
as joints constantly experience pressure and stresses making it hard not to burst delicate blood vessels
does cartilage have blood vessels?
no
where does protective articular cartilage of a joint get its nutrients from?
fluid in joints(in living person), synovial fluid also from the blood vessels in the bone! nutrients diffuse across into cartilage
types of cartilage
articular/hyline
fibro
what is articular/hyaline cartilage consist of?
collagen, elastin in equal amounts
what does fibrocartilage mainly consist of?
collagen (more fibres)
what is the advantage of equal amounts of collagen and elastin fibres in articular cartilage?
strength and rubbery function
to maintain shape and function
where is fibrocartilage found?
intervertebral vertebra, not much movement is needed and more support is needed (entire body weight)
where is elastic cartilage found?
nose/ears
describe the appearance of fibrocartilage:
rows of chondrocytes in lacunae plus extensive bundles of collagen
location and function of the epiglottis
very back of throat, stops food going down wind pipe
how many bones do we have as a baby vs an adult?
270 vs 206
what is ossification?
formation of bone
when does ossification begin?
in early embryonic life
what are the two ossification methods?
intermembranous and endochondral ossification
what is intermembranous ossification?
bone formation from connective tissue
what is endochondral ossification?
bone formation from hyaline/articular cartilage
what kind of bone forms from inter membranous ossification?
flat and irregular bone
examples of flat bone
skull, sternum, ribs
example of long bones
tibia, fibula, femur, humerus
how does long bone form?
endochondral ossification?
step 1 of intermembranous ossification:
1) lump of connective tissue in an embryo, somewhere the skull/any other flat/irregular bone will eventually form
what is mesenchym? and what are its cells called
connective tissue in an embryo, mesenchymal cells
step 2 of intermembranous ossification
osteoblasts forming bone, becomes trapped, thus becomes osteocytes, now a lump of bone
step 3 of intermembranous ossification
blood vessel pierces lump of bone, bring in osteoclasts which make and destroy bone eventually making medulla spaces
formation of trabeculae
step 4 of intermembranous ossification
develops into skull through bone remodelling
general steps in endochondral ossification:
connective tissue –> cartilage –> bone!
step 1 of endochondral ossification:
embryonic fibroblasts(mesenchymal cells) becomes chondroblasts which makes cartilage, a lump of cartilage then appears in that space in the shape of the bone it will make
what type of bone does endochondral ossification make?
long bone
step 2 of endochondral ossification:
growth of cartilage model in length(chondrocyte division within matrix) and width(formation of new cartilage at edge of bone);
step 3 of endochondral ossification:
the chondrocytes in the mid region of the cartilage model(bone shaped cartilage) get really fat due to ingesting lots of glycogen(sugars) and burst, releasing their contents into the cartilage matrix/GS/fluid changing the pH and triggers calcification(calcium forms salts), salts stick on collagen which make bone hence death of chondrocytes.
step 4 of endochondral ossification:
all cells die due to calcification of cartilage and stop of nutrient flow, shaft hollows out, blood vessels penetrate shaft bringing osteoclasts, osteoclasts eat away all the dead cartilage, resulting in a large empty space…eventually filling with yellow marrow
summarise what happens after one chondrocyte ingests too much glycogen
chondrocytes get big, they die, causing calcification, making matrix in there really hard, kills of other living cells as they cant get nutrients anymore, dead tissue in the middle is removed by the osteoclasts brought in by blood vessles end up with a big space
endochondral ossification…AFTER birth
development of secondary ossification centre, blood vessel entre cartilage in epiphysis at birth, bringing osteoclasts eat away cartilage and osteoblasts enter forming spongey bone
during the after birth stage of endochondral ossification is all cartilage eaten away by osteoclasts?
no, some articular cartilage remains at the top(nice and smooth) and small amount remains between epiphysis and metaphysis called epiphyseal plate
what is the function of the epiphyseal plate?
responsible for bone growth in length
types of bone growth:
Length and width
Interstitial and appositional
where does interstitial bone growth occur?
epiphyseal plate
how does epiphyseal plate increase length of bone
cartilage divides, new cartilage creates new bone, slowly long bone will increase in length
what age does interstitial bone growth occur?
until the age of 18-25 years “growths spurts”
are epiphyseal plates renewable?
no, they only last for a certain amount of time, once they are gone epiphysis is completely spongey bone on the inside and length of bone is final
looking at an x-ray of a long bone, how would you tell whether it came from an adult or a child?
presence of epiphyseal plate(comes up as a black line)
Super simple summarisation of how epiphyseal plate increases length of bone
cartilage cells get really fat, they burst, they die, replaced with bone
where does cartilage become bone after birth?
the epiphyseal plate
process of appositional bone growth
osteogenic cells sitting on the edge of bone make osteoblasts which lay bone down around blood vessels
how does nutrition affect bone growth?
we don’t make minerals, so need to be getting adequate amounts from our diet (eg. calcium and phosphate) and vitamins (vit C for collagen)
other we just can’t make bone!
what is responsible for the “growth spurt”?
sex hormones produced at puberty
how do increase of sex hormone production stimulate growth?
hormones bind to chondrocytes in epiphyseal plate, basically tells/triggers them to make more bone thus rapidly increasing length of bone
and bind to osteoblasts increasing width
why do adolescent girls grow taller and faster than boys?
as oestrogen initially has a stronger effect than testosterone on bone cells, HOWEVER the effect wears out over time
where as testosterone tends to effect bone cells for longer, thus males grow for a longer period of time
what does hypertrophy mean?
over active
Which hormone has the largest effect on growth?
human growth hormone
where is the human growth hormone found?
pituitary gland(hangs of the back of the brain)
if we just kept growing and growing what would we be endanger of?
heart failure, too difficult to support that much tissue/organs
so is bone shaped fixed after growth spurt?
no, as an adult your bones are constantly being remade(replenished) and remodelled.
how ofter is the distal femur replaced?
around every 4 months
Why are fractures more likely to occur in inactive people?
as when you’re inactive less bone will be created by the osteoblasts however osteoclasts will not slow in eating your bone weakening the bone, decrease in bone density can lead to osteoporosis
types of fractures:
stress(abnormal physical trauma eg. falling down stairs) AND pathological fracture(bone weakened by disease eg. cancer, osteoporosis
how are joints classified?
function and structer
what is a joint?
where two bones meet..but can permit movement
types of structural joints (SC)
fibrous
cartilaginous
synovial
(based on whats between the bones)
types of functional classification of joints (FC)
immovable
slightly movable
freely moveable
description of a fibrous joint:
no cavity, bones connected via collagen..limiting movability
example of fibrous joints:
skull joints
immovable
what type of joint is the tibia and fibula?
fibrous immovable
description of cartilaginous joint
no cavity, little or no movement
cartilage is found between bone
example of cartilaginous joint:
intervertebral discs, stacked on top of one another with cartilage between them
description of synovial joints:
cavity containing fluid(synovial) and cartilage
freely movable
what contains the synovial fluid?
synovial membrane…reinforced by dense connective tissue(capsule)
what is the joint capsule made of and what is its function?
dense connective tissue, ensure synovial membrane does not break
what connects bone to muscle
tendons
what connects bone to bone?
ligament(dense regular connective tissue)
what does the joint capsule become after time?
joint ligament
where does synovial fluid come from?
made in the synovial membrane
what is the function of synovial fluid?
allows freely moveable joints
provides nutrients to cartilage
name of the special ligament in knees
articular ligaments
whats different about articular ligaments?
they are inside the joint
kind of cross over to avoid knee joints clashing together
what is an articular disk and where is it found?
plate of fibro(tough) cartilage that sits inside the knee, just kinda of in the middle
function of articular disk
matches both edges allowing joint to fit together nicely, thus making it more stable
what exists in a joint where there is friction between bone and skin?
sack of fluid called “bursa”
how many types of synovial joints?
6
where are ball and socket joints found?
shoulder and hip
what is the main function of the ball and socket joint?
allows the most movement of any joint in the body
difference between shoulder and hip ball and socket joints
hip socket is deeper than shoulder socket
hip has to support more weight for longer periods of time
which ball and socket joint is more stable: hip or shoulder?
hip
what cells secrete the organic components of the bone matrix?
osteoblasts
muscle tissue has the ability to
extensibility, elasticity, contractibility, excitability, responds to stimuli
what is the movement of your arm towards your ear called?
abduction
the movement of your arm towards your hip called?
adduction
how does the bone grow during appositional bone growth?
width
endochondral ossification begins with the formation of an
cartilage model, in the shape of the bone it will create(long bone)
where is fat stored within bone?
medullary cavity
where do secondary ossification centres occur?
in the epiphysis
the delicate connective tissue that surrounds the skeleton muscle fibres and ties adjacent muscle fibres together is the:
endomysium
the dense layer of connective tissue that surrounds the entire skeletal muscle is the:
epimysium
the interconnecting tiny arches of bone tissue found in spongy bone are called:
trabeculae
the lining of the medullary cavity is called the:
endosteum
what does the medullary cavity of bone contain?
marrow
what is the most abundant cell type in bone?
osteoctyes
the narrow passageways that contain cytoplasmic extensions of osteocytes are called:
canaliculi
what is the sarcolemma?
the plasma membrane of muscle cells
what allows action potenital to penetrate skeletal muscle cells?
transverse (T) tubules
what is the movement of palm side facing up called?
supination
what is the movement of palm side facing down called?
pronation
how are trabeculae organised in spongy bone?
along lines of stress
how is bone matrix dissolved
through action of osteoclasts
what is used as a means of naming muscles?
location, action, shape, attachment
functions of the skeletal system
protection of internal organs
body support
blood cell production
calcium homeostasis
function of sarcoplasmic reticulum
storage and release site for calcium ions
what allows action potential to travel quickly from one cardiac muscle cell to another?
gap junctions and intercalated discs
what is the motor protein that facilitates contraction in muscle cells?
myosin
function of osteogenic cell?
stem cell that develops into osteoblasts
function of osteoblast
bone making cell, secretes organic components of bone matrix eg. protein and collagen
function of osteocyte?
maintain bone matrix and allow nutrients and oxygen to pass through bone
function of osteoclast?
resorption of bone
How does x-rays of bones work?
patients are exposed to short x-ray bursts, calcium within bones absorbs x-rays making bones appear white in x-ray images
where can hyline/articular cartilage be found?
end of bones
in ribs and trachea
epiphyseal plate
where can fibro-cartilage be found?
intervertebral discs articular discs (menisci)...in knee
example of where elastic fibres can be found?
external ear
epiglottis
nose
what do are all connective tissues made of?
cells, fibres and extracellular matrix
what is the prefix for muscle cells
SARCO
can muscle cells divide?
no, however some satellite(stem) cells are present on the edge of muscles which can give rise to a few replacement cells
describe the contraction of muscles
an action potential(from nerve fibres) runs along muscle cells, penetrating through transverse (T) tubules triggering the sarcoplasmic reticulum to release masses of calcium into the cell which bind with action potential and causing actin to slide over myosin thus contracting the muscle
what are the striations that you see in skeletal muscle?
myosin
what is myofibral?
within muscle cell, two main components
myosin a thick protein
actin a thin filament
what is the benefit of the branching structure of cardiac muscle?
allow withstand of pulling forces in many directions
mainly the ability to rapidly spread signals to contract from cell to cell
1 - 2 - 4 - 8 ..
what is “special” about contraction of smooth muscle?
irregular arrangement of actin allows contraction of all directions, overall “shrinkage of cell”
what are the 2 types of smooth muscle cell?
visceral (single unit)
multiunit smooth muscle cell
what is the job of the prime mover in muscle contraction?
does most of the heavy lifting
what is the job of the relaxant muscle or “antagonist”?
to remain relaxed and allow extension to prevent damage
what is the job of the synergist muscle in contraction?
to stabilise joint, and ensure bone does not move incorrectly
what is the job of the fixator muscle in muscle contraction?
prevents movement of the bone that the prime mover is attached to.
