Exam 4: Skeletal System Flashcards
5 functions of the skeletal system
support protection mineral storage blood cell production muscle attachment
why do men have a greater bone density?
- more muscle mass, put out more androgens to get more dense bone
- more obvious ridges so when muscle attaches to bone the bone can support and respond to it
losing bone density - teeth
if you lose teeth - there will be no stimulus on the alveolar process so you will lose bone density
- this is why they give you pegs with a fake tooth so you are still getting the stimulus and not losing bone density
4 components of the skeletal system
- bones
- cartilage
- tendons and ligaments
- bone marrow
ligament
bone to bone
tendon
muscle to bone
where can you find short bones
carpals and tarsals
where can you find flat bones
skull, sternum, pelvis
where can you find irregular bones
vertebrae
where can you find sutural bones
in certain flat bones
have multiple ossification sites - small ones get trapped
sesamoid bone
patella
takes pressure off of a joint to avoid rubbing against the bone
pushing it up gives more of a fulcrum action- adds strength
- most people have 5 in hand
- 2 big ones at metatarsal joint in big toe
how do you get turf toe
injury against sesamoid bones
- over extension of toe joint - stretch connective tissue at nobs and get swelling in there
flat bone
- sandwich of spongy bone between compact bone layers
compact bone
densely oriented - haversian canals going through it
spongy bone
more open, honey comb look
- trabeculae come together
- find bone marrow here
long bone
ex: femur
- only see pattern at ends
- very little spongy bone in the middle
- medullary cavity eventually filled with red bone marrow
- at age ten you start to fill with yellow bone marrow (fat)
- now you only find blood at the ends of bone
2 pathways of ossification
intramembraneous
endochondral
mesenchyme differentiates directly into bone; occurs in flat bone formation
- first form spongy bone and then remodel to get the traditional look
intramembraneous ossification
mesenchyme first puts down hyaline cartilage model which is later ossified; majority of bone formation
- ossifying network is aggressive (kill cartilage and replace it)
- how tall you will be is determined by how fast you can replace cartilage with bone
- long bone
endochondral ossification
mesenchymal cells associate into condensates in response to ______
bone morphogenic proteins (BMP)
when does intramembraneous ossification occur?
from 8th week of development to 2 years
intramembraneous ossification: cells differentiate into _____
osteoprogenitor cells
- give rise to cells that will make bone
intramembraneous ossification: what begins formation of bone matrix and what do these cells become?
activated transcription factors
become osteoblasts
osteoblasts near blood vessels secrete an increased amount of ____ and _____ forming the ossification site
type I collagen fibers and mucopolysaccharide
other osteoblasts align along the ossification site, secreting matrix until surrounded
osteocytes
action of ______ promotes mineralization of matrix by hydroxyapatite
alkaline phosphatase
does intramembraneous ossification have many sites of ossification?
yes
cells that get trapped in matrix exist in _____
lacunae
- you cannot take hard ecm to cel membrane of cell - would not be able to do diffusion
osteoblasts
form new bone
osteocytes
maintain existing form
osteoclasts
break down bone
ossification occurs in patterns of ___
spicules
spicules join in random loose ____
trabeculae
first bone you put down to heal a fracture
woven bone (type of spongy bone - less osteocytes than normal spongy bone) quick to put down - later will remodel to strengthen
lamellar bone - many layers
appositional growth
growth of bone by fusion of additional spicules
what does remodeling of bone result in?
cancellous and compact bone identical to that of the endochondral bone
the mesenchyme that covers the bone differentiates into fibroblasts and forms the ____
periosteum
forms in cavities of cancellous bone
marrow
derived from hemopoeitic progenitor cells and breakdown bone
osteoclasts
derived from osteoblasts line both the inner and outer surface of bone that is not being remodeled
- there incase an injury happens (reserve cells incase of a major fracture)
bone-lining cells
connective tissue membrane exists between the flat bone of skull forming____
fontanelles
fontanelles
soft spots
- cannot be born with true definite brain size
anterior fontanelle
- last to close
- frontal fontanelle
- closed completely by 2 yrs old
where is posterior fontanelle?
occipital
where is anterior lateral?
sphenoid
where is posterior lateral fontanelle?
mastoid
what can an infection do to fontanelles?
get bulging
when does the hyaline cartilage model begin?
as early as 5 weeks
endochondral ossification: mesenchymal cells are targeted by ___ and ____
BMP
fibroblast growth factors (FGF)
endochondral ossification: transcription factors activated resulting in differentiation of cells into _____
chondroblasts
endochondral ossification: what do chondroblasts secrete?
type II collagen and matrix
endochondral ossification: interstitial growth
the cartilage matrix binds large amounts of water increasing the size/area
- mitosis of chondroblasts also increases growth internally
endochondral ossification: appositional growth
connection to adjacent cartilage growth
endochondral ossification: mesenchyme around the hyaline cartilage becomes the _____
perichondrium
can you ossify matrix with type 2 collagen?
no - it is the wrong type of collagen so you need to replace it with bone, however you need cartilage first
what is the ground substance for cartilage?
chondroitin sulfate
hyaline cartilage
weakest out of all cartilages - least densely packed
endochondral ossification begins between _____ and continues to adult years _____
7-11 weeks
18-20 years
bone vs cartilage - which is vascular and avascular
bone - vascular
cartilage - avascular
where is the primary ossification site?
diaphysis - shaft of the bone
any site after a primary site is what?
secondary
diaphysis
goes out from the middle
epiphysis
secondary site starts here
goes to the middle
endochondral ossification: mesenchymal cells remaining in perichondrium respond to ____ and differentiate into ____
BMP signals
osteoblasts
osteoblasts set down a _____ around the _____
primary ossification site
bone collar
diaphysis
underlying chondrocytes enlarge; cartilage matrix reabsorbed; what cells produce alkaline phosphatase?
- what occurs?
hypertrophic cells
mineralization
hypertrophic cells die leaving a ____
cavity
what happens to the cavity formed by dying hypertrophic cells?
blood vessel infiltration of the cavity
calcified cartilage matrix is removed, _____ is set down, ______ is formed
osteoid matrix
medullary cavity
epiphyseal plate: structure
at the top: active cartilage - lacuna hyaline cartilage
middle: attack is being made on the cartilage
bone collar comes up sides - cells starting to hypertrophy - stressed
matrix disappearing
big open cavities in white- cartilage dies so bone can take over
bottom: bone marrow with tribeculae - cancellous bone
Application: Background On Signaling: why does the application of BMP in procedures like bone grafting and extraction socket healing may prove beneficial?
- it is going to cause growth
- adding growth factors and nutrients for it to heal quicker and more efficiently
- stimulating fibroblasts, epithelial, faster bone growth
- bone graft: better chance for it to take and be more stable
Application: Background On Signaling: why does the application of BMP in procedures like bone grafting and extraction socket healing may prove beneficial?
- it is going to cause growth
- adding growth factors and nutrients for it to heal quicker and more efficiently
- stimulating fibroblasts, epithelial, faster bone growth
- bone graft: better chance for it to take and be more stable
Application: Background On Signaling: why does the application of BMP in procedures like bone grafting and extraction socket healing may prove beneficial?
- it is going to cause growth
- adding growth factors and nutrients for it to heal quicker and more efficiently
- stimulating fibroblasts, epithelial, faster bone growth
- bone graft: better chance for it to take and be more stable
bone morphogenic proteins (BMP)
- belong to group of signaling molecules
signaling cells not differentiated into bone producing cells - important in embryogenesis, development, adult homeostasis
hydroxyapatite
extremely dense - no diffusion through it - need channels for blood supply to get in
osteon
unit of bone
- has central canal that can be haversian canal also - bone is highly vascular
concentric lamella
around haversian canal - do exchange through canaliculi and lacunae
circumfrential lamella
large layers that completely wrap bone on outside
interstitial lamella
remnants of remodeling bone
- change in osteon: some cells left outside concentric rings
perforating vessels - Volkmann’s canal
blood supply linked between 2 osteons
- if damage you can still get nutrients through another - cross flow
factors affecting bone growth (7)
- sex hormones
- growth hormones
- calcitonin
- parathyroid hormone
- calcitriol (vitamin D3)
- vitamin C
- vitamin A
sex hormones
stimulate bone formation (osteoblasts)
growth hormones
stimulate chondroblasts
calcitonin
inhibits osteoclasts
- increases excretion of calcium
parathyroid hormone
stimulates proliferation of osteoclasts
calcitriol (vitamin D3)
steroid hormone that increases absorption of calcium in intestinal tract
vitamin C
required for collagen synthesis
vitamin A
- in balance
- norm levels stimulate osteoblasts
- high levels stimulate osteoclasts
what 2 factors that effect growth work in oppostion to eachother?
calcitonin and parathyroid
decrease in mineral density
- precursor to osteoporosis
osteopenia
bone density decreases to point of point of a fracture risk
osteoporosis
measurement of bone mineral density (BMD) reported as T score
+1 to -1: normal based on 30yr old
- 1 to -2.5: osteopenia
- 2.5 and lower: osteoporosis
application: hormone irregularities
- what id prior to puberty vs after puberty starting to see growth plates closing?
- what would be diff in appearance?
before puberty: tall people bc hitting all cartilage - giantism
after puberty: growth plates closed already - acromegaly
