bone and joint midterm 1

what are the functions of bone

body support and shape

movement

protection of vital organs

mineral storage

hematopoiesis

what minerals are stored in bones

calcium, phosphate, carbonate, magnesium, sodium, potassium

what is hematopoiesis

formation of blood cellular components

how much of the bone's mass do cells make up

5-8%

what is found in the extracellular matrix

organic matrix

inorganic matrix

what is organic matrix

35% of bone

osteoid

what is the main protein found in organic matrix making up 90-95%

type 1 collagen

what is inorganic matrix

65%

what makes up 70% of inorganic matrix

hydroxyapatite

what minerals are the most common in bone and make up hydroxyapatite

calcium and phosphorous

what are the characteristics of cortical/compact bone

aka lamellar bone

slow, orderly deposition of collagen fibers (dense, strong)

outer covering --> supports and protects bone

what are the characteristics of trabecular/cancellous/spongy bone

-lamellar and woven bone

-rapid and haphazard deposition of collagen fibers

-less structured and strong

-inner part of the bone

where is spongy bone found

medullary cavity

skull

vertebral bodies

what are the 2 layers of the periostium

outer fibrous layer

inner cambium layer

what is the active layer of the periostium

inner cambium layer

what happens in the inner cambium layer

osteoblastic/osteoclastic activity

growth repair nutrition

what are the characteristics of the endostium

lines inner margin of cortex and all trabeculae

osteoblastic/osteoclastic activity

growth and repair

what are the anatomical divisions of the bone

epiphysis

physis

metaphysis

diaphysis

what division of the bone is the end of the bone that supports articular cartilage

epiphysis

what division of bone is the secondary growth center

epiphysis

what is the composition of the epiphysis at maturity

cancellous bone with thin cortex

what are the pathologies of the epiphysis

dysplasias

ischemia

arthritis

neoplasms

does articular cartilage extend beyond the epiphysis

no

can you see cartilage on x ray

no but you can see the space it would occupy

aka for physis division

epiphyseal/growth plate

when would you consider someone skeletally immature

growing physis

growth plates are still open

where is the location of the physis

just beneath epiphysis

what is the composition of physis until skeletal maturity

cartilage

what are the zones of physis anatomy

reserve zone --> proliferative zone --> zone of maturation and hypertrophy --> calcification zone

what physis zone is closer to the epiphysis

reserve zone

immature cells

what are the pathologies of physis

abnormal growth

what is the constriction between physis and shaft

metaphysis

what is the area of remodeling where calcified cartilage becomes osseous tissue

metaphysis

what is the most metabolically active area of bone during growth

metaphysis

what is metaphysis commonly subject to

venous stasis and pooling

what are the pathologies of metaphysis

tumors, infection

what is the shaft of bone

diaphysis

what part of the bone provides mechanical strength

diaphysis

what part of the bone contains bone marrow

diaphysis

what are the pathologies of diaphysis

multiple myeloma, ewing's sarcoma, leukemia

what are the cells of the bone

osteoprogenitor cell

osteoblast

osteoclasts

osteocytes

where do the osteoprogenitor/stem cells come from

from mesenchyme/embryonic connective tissue

mesoderm

where is are the osteoprogenitor/stem cells located

in periosteum and endosteum

what do the osteoprogenitor/stem cells become

fibroblasts

chondroblasts

osteoblasts

what is the function of the osteoblasts

secrete and synthesize osteoid

initiate bony mineralization

what enzyme is found in the cytoplasms of osteoblasts

aklaline phosphatase

what do active osteoblasts stain positively for

type 1 collagen

what are osteocytes

mature osteoblasts isolated in lacunae of bone

what is the function of the osteocytes

transport fluid through the canaliculi

regulate cell environment (Wolff's law)

what is wolff's law

bone grows or remodels in response to the demands placed on it

when do osteoblasts become osteocytes

when they become trapped in the matrix they secrete

what are osteoclasts

multinucleated cells responsible for bone resorption

where do osteoclasts originate from

circulating monocytes

where are osteoclasts found

Howship's lacunae on bone surface

osteoclasts can only function if the bone is what?

mineralized

how much of the diaphysis do you want to be cortical bone

1/3

how does hyperemia affect bone

increased blood flow --> increased osteolytic activity --> osteoporosis (bone loss)

how does osteoporosis appear on xray

radiolucent

how does ischemia affect bone

reduced blood flow --> increased osteoblastic activity --> bone sclerosis (bone growth)

how does bone sclerosis appear on xray

more bony prominences

are sesamoid bones primary or secondary growth centers

secondary

are apophysis primary or secondary growth centers

secondary

is diaphysis primary or secondary growth center

primary

when does ossification begin

in the 6th, 7th, and 8th week of fetal life

what makes up the embryonic skeleton

fibrous membranes and hyaline cartilage models

what is intramembranous bone formation

bone forms directly from osteoblasts clustered within fibrous membrane

where does intramembranous bone formation predominate

skull and facial bones where greater flexibility is needed

what is an essential process during natural healing of bone fractures

intramembranous bone formation

Is there a preexisting cartilage model for intramembranous bone formation?

no

what type of bone formation has a preexisting cartilage model that calcified and is replaced by bone

endochondrial bone formation

where is endochondrial bone formation seen

-in paired structures where a predetermined outcome is needed

-most long bones

what is the pathway of nutrient arteries in bone

enter cortex through the nutrient foramina

ascend and descend within the medullary cavity

what do the nutrient arteries supply in the bone

primary growth centers and diaphyseal region

what do the nutrient arteries in bone anastamose with

metaphyseal and periosteal arteries

where do periosteal arteries arise from

neighboring muscles

how do periosteal arteries enter the bone

enter periosteal fibrous layer and penetrate bone

what do the periosteal arteries supply

primary growth center, cortex, and periosteum

do periosteal arteries anastamose

yes

what do the metaphyseal arteries arise from

neighboring systemic vessels

what are metaphyseal arteries subject to prior to skeletal maturity

pooling/stasis at growth plate --> infections at bone ends

what do epiphyseal arteries arise from

vessels surrounding the joints

what makes epiphyseal arteries isolated

they are unable to cross cartilage growth plate prior to skeletal maturity

what does epiphyseal arteries being isolated put children at risk of

ischemic or avascular necrosis at bone ends

what does cartilage NOT contain

blood vessels, nerves, lymphatics

what are the types of cartilage

hyaline

fibrocartilage

elastic

what makes up cartilage

type 2 collagen fibers embedded in a jelly like ground substance

what cells are found in cartilage

chondroblasts and chondrocytes

what are the two types of cartilage growth

interstitial growth

appositional growth

what happens in interstitial growth

-cartilage expands from within via growth of new chondrocytes

-increases length

what type of cartilage growth predominates in young cartilage

interstitial growth

what is appositional growth

-new cartilage superimposed on old one

-increases width

what type of cartilage growth is seen in older cartilage

appositional

what is the least dense on xray and appears dark/lucent/radiolucent

air

how does fat appear on xray

dark

how does water appear on xray

light grey (muscle)

what is the most dense naturally occurring structure on xray and appears white/opaque/radioopaque/sclerotic or light gray

bone

what is the most dense not naturally occurring structure on xray

metal

how would you describe white density on xray

radioopaque

sclerotic

how would you describe dark density on xray

lucent

radiolucent

on a normal healthy patient can you see the periosteum on xray

no