Chapter 6: Bone Tissue Flashcards
Bone
specialized CT
- made up of different tissues working together
- cartilage
- dense CT
- epithelium
- blood forming tissues
- adipose tissue
- nervous tissue
functions of skeletal system
- support
- protection
- movement
- mineral homeostasis
- hemopoiesis
- triglyceride storage
skeleton as support
- framework for soft tissues
- serves as POA for muscles
- maintains posture
skeleton for protection
brain, heart, lungs, spinal cord
skeleton for movement
motion
skeleton for mineral homeostasis
stores calcium and phosporous which are critical to nerve activity and muscle contraction
skeleton for hemopoiesis
examples
blood cell production:
- stem cells located in red bone marrow of flat bones
- ex: scalpula, sternum, skull, ribs, vertebral body, ilia
skeleton for triglyceride storage
store fat in yellow bone marrow
long bone parts
bones and areas on bone
humerus, femur, tibia, fibula, ulna, radius,
diaphysis, epiphysis, metaphysis, articular cartilage, periosteum, endosteum, marrow, medullary cavity
diaphysis
shaft, long and cylindrical
epiphysis
extremities, end of bone, proximal and distal
metaphysis
- includes epiphyseal plate in growing bone
- region where diaphysis joins epiphysis in mature bone
epiphyseal plate
calcified cartilage is replaced by bone as bone lengthens
articular cartilage
description
location
function
- covers epiphysis
- thin layer of hyaline cartilage covering ends of bone that enter joint
- absorb shock and reduce friction
periosteum
- CT membrane made up of fibrous layer and osteogenic layer
- covering bone surfaces but not articular cartilage
- important in bone growth, nutrition, repair, provides attachment surface for muscles + ligaments + tendons
periosteum: fibrous layer
dense irregular CT has blood vessels, lymphatic vessels, nerves
- outer layer
periosteum: osteogenic layer
layer of elastic fibers
- contains blood vessels and bone forming cells (osteoblasts)
- inner layer
tendons
muscles to bone
marrow or medullar cavity
contains yellow bone marrow in adults (none in infants)
- necessary to produce blood cells
ligaments
bone to bone
endosteum
- lining of medullary cavity
- contains bone destroying cells (osteoclasts)
matrix of bone chemical makeup
- 50% inorganic salts
- 25% collagen fibers
- 25% water
responsible for hardness of bone
mineral salts
how does bone get tensile strength?
collagen fiber
4 types of bone cells
- osteogenic cells
- osteoblass
- osteocytes (bone corpuscles)
- osteoclasts
osteogenic cells
actively mitotic, precursors to osteoblasts
osteoblasts
- bone building cells
- contain extensive ER & ribosomes
osteocytes or bone corpuscles
mature bone cells, most prevalent
osteoclasts
function
- break down bone
- derived from macrophages
- important in healing bone fractures
- has modified microvilli
types of bone
compact and spongy
compact bone
arranged in unites called osteons or haversian systems
osteons
- central or haversian canal
- lamella
- lacunae
- canuliculi
- perforating or volkmanns canals
central or haversian canal
- contains blood + lymph vessels + nerves
- circular canal in center of osteon that runs longitudinally through the bone
lamella
- concentric rings of calcified matrix
- circumfrential and interstitial
- very thin
- encircles central canal
circumferential lamellae
around periosteum
interstitial lamellae
- fill intervals btwn osteons
- remnants of old osteons left over from bone remodeling
lacunae
- contain osteocytes
- cavities btwn lamella
canaliculi
- minute canals containing osteocyte processes
- radiate in all directions from lacunae
- connect with each other
- provide passageway for nutrients and wastes to reach central canal/each other
perforating (volkmann’s) canal
small blood vessel canals that connect Haversian canals of neighboring osteons
where are nerves most numerous?
- at the end of bones that enter into joints
- large flat bones
spongy bone
- doesn’t contain osteons
- contains trabeculae and lamella
- large spaces contain red bone marrow
trabeculae
thin columns of bone with pointed spicules (spongy)
how is the hardened matrix arranged?
in concentric lamellae
is bone supplied with blood?
YES
steps in blood supply to bone (4)
- periosteal arteries pass volkman’s canal to supply outer compact bone
- nutrient artery passes through nutrient canal into Haversian canal to provide for osteocytes
- nutrient veins follow nutrient artery in diaphysis
- periosteal veins exit with periosteal arteries
nerves in bone
- follow vessels into bone tissue and the periosteum where they sense damage + transmit pain
- rich nerve supply in periosteum + epiphysis
bone formation
osteogenesis or ossification
intramembraneous ossification
formation of bone directly from or within loose fibrous CT membranes
endochondral ossification
- formation of bone from hyaline cartilage models
- begins at 6-7 weeks (embryonic)
steps for intramembranous ossification
step 1
ossicfication center forms from mesenchymal cells as they are converted into osteoblasts and lay down osteoid (non-calcified) matrix
steps for intramembranous ossification
step 2
matrix surrounds cells and calcifies as the osteoblasts become osteocyctes
steps for intramembranous ossification
Step 3
calcifying matrix centers join to form bridges of tribeculae that constitue spongy bonewith red marrow btwn
steps for intramembranous ossification
step 4
on the periphery, mesenchyme condenses and develops into a collar of spongy bone and then compact bone (periosteum)
steps for endochondrial ossification
steps 1-5
- development of cartilage model
- growth of cartilage model
- primary ossification center develops in diaphysis; medullary (marrow) cavity develops and fills with red marrow
- development of secondary ossification centers in epiphysis
- formation of articular cartilage and the epiphyseal plate
formation of bone within hyaline cartilage
mesenchyme become chondroblasts
- hyaline cartilage model which ossifies to bone
how can you tell if a bone is fully ossified?
its epiphyseal plate becomes epiphyseal line around age 25
in which direction is bone growth?
length and width
4 zones of the epiphyseal plate
- zone of resting cartilage
- zone of proliferating cartilage
- zone of hypertrophic cartilage
- zone of calcified cartilage
zone of resting cartilage
- nearest epiphysis
- small scattered chondrocytes that anchor the epiphyseal plate to the bone of epiphysis
- doesn’t function in bone growth
zone of proliferating cartilage
- larger chondrocyte
- arranged like stack of coins that will divide and replace dead cells of epiphyseal plate
zone of hypertrophic cartilage
- zone of maturing cartilage
- larger chondrocyte arranged in columns
- actively maturing
zone of calcified cartilage
- few cells thick
- consist of mostly cells that are tracked in calcified matrix which is then
- taken up by osteoclasts then invaded by osteoblasts
- cements epiphyseal plate to bone of diaphysis
what is the only way diaphysis can increase in length?
epiphyseal activity
how can bones grow in thickness(diameter)?
appositional growth
- periosteum cells differentiate into osteoblasts that secrete collagen fibers and organic molecules to form the matrix
- ridges fuse and periosteum becomes the endosteum
- new concentric lamellae are formed
- osteoblasts under periosteum form new curcumferential lamellae
- bone tissue lining medullary cavity is destroyed by osteoclasts in the endosteum and the medullary cavity inc in diameter
