Skeletal system part 1
What are the different types of tissue that bones are made up out of?
Bone
Cartilage
Nervous tissue
Dense connective tissue proper
Muscle
Epithelial
What are the three types of cartilage in the skeleton
Hyaline
elastic
fibrocartilage
Hyaline characteristics and locations
most abundant and provides support with flexibilty and resistance
LOCATIONS: articular, costal, respiratory, nasal
elastic cartilage characteristics and location
more elastic fiber, is able to handle repeated bending
LOCATIONS: external ear and epiglottis
Fibrocartilage characteristics and locations
great tensile strength and restsits tension (being pulled apart)
LOCATIONS: menisci of knee
intervertebral dics
Functions of bone
support
protect
anchor
mineral/growth factor storage
blood cell formation
TG(fat) storage
Hormone production
Compact VS Spongy bone
COMPACT: dense outer layer and appears smooth and solid
SPONGY: internal layer that consits of marrow. honey comb structure
Red VS Yellow marrow
RED: blood cell production and located in medullary cavities of long and flat bones
YELLOW: fat storage and can turn back into red in adults in severe anemia
MICROSCOPIC ANATOMY OF COMPACT BONE: Osteon (haversian system)
Structural unit of compact bone
group of rings/full system
paralell to axis of bone
Types of Lamellae
1) complete: covers single osteon
2) interstitial: grouped, spaces between osteon
3) circumferential: travels circumference of the bone
Haversian (central) canal
core of each osteon that containss nerves/blood vessels
travels longitudal axis of the bone
Volkmans (perforating) canals
connects harversian canals to outer vessels
travels towards the cent of the bone
Canaliculi
canals connecting adjacent lamellae in an osteon
Bone growth: Bone cells
Osteogenic cell: primordial bone cell that grows into different types, miotically active
Osteoblast: builds more bone, matrix-synthesizing cell
Osteocyte: measures how much bone is needed, monitors and maintains mineralized bone matrix
Osteoclast: gets rid of bone, reabsorbs minerals and uses them elsewhere
Two methods of ossification
Endochondrial: Bone replaces hyaline cartilage
Intramembranous: bone develops from fibrous membrane, clavicles, bone of skull
Steps for endochondrial ossification
1) bone collar forms around the diaphysis of the hyaline cartilage model
2) Cartilage in the center of diaphysis calcifies and then develops cavities
3) The periosteal bud invades the internal cavities and spongy bone forms
4) diaphysis elongates and medullary cavity forms , secondary ossification appearls in the epiphyses
5) epipyses ossify, hylaine cartilage only appearns in epiphyseal plates and articular cartilage
Bone remodelling
spongy: replaced every 3-4 years
compact: replaced every 10 years
Two sites of control
Hormonal: stimulates bone creation
Mechanical stress: Specific to certain bone or region that makes it stronger when put under a lot of stress
Fractures
Position
completeness of break
Skin penetration
Fractures: position of bone
Non-displaced: bone ends retain normal position
Displaced: bone ends are out of alignment
Fractures: completeness of bone
Complete: bone is broken through
Incomplete: bone broken only part way through
Fractures: Skin penetration
Simple (closed): bone does not penetrate skin
Compound (open): bone penetrates skin
Type of fracture: communited
bone fragments into thrhee or more pieces, common in aged who's bones are brittle
Type of fracture: compression
bone is crushed, common in porous bones, subject to extreme trauma
Type of fracture: spiral
common sports fracture, excessive twisting forces
Type of fracture: Epiphyseal
separates from diaphysis along epiphyseal plate, when cartilage cells are dying and calcification is occuring
Type of Fracture: depressed
typical skull fracture, broken bone portion is pressed inward
Type of Fracture: Greenstick
bone breaks incompletely, only one side of the shaft breaks and the other bends
Fracture repair
external reduction: Physician manually coaxes bone ends back into position
Internal Reduction: bone ends are secured surgically with pins or wires
Fracture Healing
1) hematoma forms
2) fibrocartilangous callus forms
3) bony callus forms
4) bone remodelling occurs
Bone disorders: osteomalacia
soft/weak bones due to poor mineralization
diet related or dietary digestive disorder
Bone disorder: Rickets
analogous disease in children
due to malnourishment the cartilage do not become bone fast enough and the become too long and excessively weak
epiphyseal plate cannot calcify
calcium and Vitamin D defficient
Bone disorder: osteoporosis
common in older adults after menopause
when bone resorption is greater than bone building
Treatment: calcium, vitamine D and hormone replacement therapy
Prevention: adequate nutrition, load-bearing exercise