bone Flashcards

1
Q

what are the 4 functions of bone

A

weight bearing/support for the mechanical function of joints and muscles
protection e.g. skull and vertebral column
mineral store - Ca
blood formation in the red bone marrow - it is the supporting tissue for haemopoiesis

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2
Q

gross anatomy of bones

A
compact bone (cortical)
spongy bone (trabecular)
blood vessels
medullary cavity (found in the shaft of long bones and filled with bone marrow)
bone marrow
membranes surrounding the surface
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3
Q

what are the 2 membranes surrounding the bone surfaces

A

periosteum (on the outside)

endosteum (covers the internal surface of the bone)

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4
Q

osteons/Haversian system

A

found in compact bone
organisation of bone in circular structures
central Haversian canal with blood vessel running through and horizona perforating/ Volkmann’s canals (connect the Haversian canals and also filled with blood vessels)

osteocytes and concentric rings of bone matrix - lamellae - around Haversian canals

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5
Q

spongy bone

A

also called cancellous or trabecular bone or diploe
less dense than compact bone, more porous
network of lamellated trabeculae filled with bone marrow
NO HAVERSIAN SYSTEMS
orientation of trabeculae reflect main directions of mechanical forces

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6
Q

What are the 6 types of bones

A
flat bone (frontal - skull)
short bone (carpal)
sesamoid bone (patella) 
sutural bone 
irregular bone (vertebrae)
long bone (femur)
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7
Q

what are the 2 types of bone formation

A

endochondral

intramembranous

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8
Q

endochondral bone growth

A
most common - long bones
endochondral ossification: 
1. bone forms as cartilage model first
2. blood vessels invade cartilage
3. cartilage replaced with bone
4. cartilage remains in epiphyseal growth plate to allow further growth (eventually ossifies when growth is complete)
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9
Q

intramembranous bone growth

A

flat bones of skull, mandible, maxilla and clavicles
more straightforward than endochondral ossification
NO CARTILAGINOUS PHASE
1. mesenchymal cells develop into osteoprogenitor cells
2. these mature into osteoblasts that start depositing bone
3. residual mesenchyme cells develop blood vessels and bone marrow
4. this also occurs in adult cortical bone and doesnt stop when you stop growing

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10
Q

what makes up bone

A

cells - osteoblasts, osteocytes, osteoclasts

extracellular matrix

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11
Q

what makes up the ECM in bone

A

~45% hydroxyapatite crystals - make bone stiff and supportive, high strength under compression
~35% type I collagen - provides some flexibility and reduces risk of fraction, high strength under tension
~20% water

bone is a composite material and a very dynamic tissue

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12
Q

bone turnover

A

constant process, even in adults
healthy bone has a balance between bone removal and formation

main cells involved are osteoclasts and osteoblasts

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13
Q

osteoblasts

A

immature bone cells created from osteoprogenitor cells in periosteum and endosteum

derived from mesenchymal lineage

produce bone matrix and initiate calcification

become osteocytes once surrounded by the matrix that they have created

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14
Q

osteocytes

A

mature bone cells found inside lacunae

numerous processes lying in canaliculi

canaliculu connect lacunae to each other - allows communication between cells

function - may maintain bone matrix and sense mechanical forces

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15
Q

osteoclasts

A

fairly large cells with ruffled border, mutlinucleated cell derived from haematopoietic stem cells

found on bone surface

function: resorb bone matrix

Howship’s lacunae: resorption pits

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16
Q

how do osteoclasts resorb bone

A

release acids from the ruffled border onto the mineral which dissolves the minreals in the bone in order to break it down, forms resorption pit

17
Q

osteoporosis

A

resorption>formation
fairly common, weaker spongy bone structure

bone structure is weaker and struts are thinner

seen in elderly patients

much more likely to fracture a bone

18
Q

paget’s disease

A
increased resorption/formation
much less common than osteoporosis 
both processes are in XS
bones aren't formed properly 
tissue is weaker and it is painful
19
Q

osteopetrosis

A

reduced resorption
bone becomes stone like
too dense and brittle
NOT THE SAME AS OSTEOGENESIS IMPERFECTA

20
Q

differentiation between osteoblasts and osteoclasts is regulated by…

A

specific regulatory molecules

21
Q

osteo

A

bone

22
Q

chondro

A

cartilag

23
Q

arthro

A

joints

24
Q

how many bones are there in the human skeleton

A

270 at birth

206 in adults

25
Q

axial skeleton

A

trunk of the body
skull, vertebral column, ribcage
maintains upright posture
transmits weight from trunk to lower limbs

26
Q

appendicular skeleton

A

appendages - upper and lower limb bones

locomoter and protective functions