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Anatomy chapter 6

Terms in this set (48)

Appositonal
Cells secrete matrix against the external face of existing cartilage. growth on the edge.
interstital
chondrocytes divide and secrete new matrix, expanding cartilge from within.
perichondrium
Dense irregular connective tissue membrane covering cartilage
Axial skeleton
bones of skull, vertabral column, and rib cage
appendicular skeleton
bones of upper and lower limbs and the pectoral and pelvic grodles
bones function
support
protection
movement
storage
blood cell formation
compact bone
Hard, dense bone tissue that is beneath the outer membrane of a bone
spongy bone
Layer of bone tissue having many small spaces and found just inside the layer of compact bone. looks like honeycomb of trabeculae
periosteum
covers compact bone on the outside
endosteum
covers spongy bone within
diploe
spongy bone in flat bones
osteogenic cells
stem cells in periosteum and endosteum that give rise to osteoblasts
osteoblasts
bone-forming cells
osteocytes
mature bone cells that maintain bone matrix
osteoclasts
cells that break down resorb bone matrix
spongy bone anatomy
trabeculae align along stress lines, no osteons, Osteocytes interconnected by canaliculi, nutrients reach osteocytes via diffusion from capillaries in the endosteum.
chemical composition of bone
organic and inorganic
organic
bone cells. ground substance (proteoglycans, glycoproteins)
Collagen fibers- tensile strength
inorganic
calcium salts. hydroxyapatities (mineral salts)
65% of bone by mass
mainly calcium phosphate crystals.
osteogenesis(ossification)
bone tissue formation
stages of osteogenesis
bone formation
Postnatal bone growth
Bone remodeling and repair
bone formation
begins in the 2nd month of development
postnatal bone growth
until early adulthood
Bone remodeling and repair
is a life long process
Intramembranous ossification
forms flat bones e.g. cranial bones.
membran bone develops from fibrous membrane.
endochondral ossification
cartilage (endochondral) bone forms by replacing hyaline cartilage.
forms most of the rest of the skeleton
more complexed than intramembranous ossification. Start n teh diaphysis of long bones.
interstitial growth
growth from within a bone during endochondral ossification, resulting in an increase in the bone's length
Appositional growth
growth at the outer surface of a bone during endochondral ossification, resulting in an increase in the bone's thickness
Hormonal regulation of bone growth
growth hormone stimulates mitosis of cartlage cells in proliferation zone. thyroid hormone modulates hypertrophy. testosterone and estrogens.
bone remodeling
occurs continuously. 5%-7% bone mass replaces each week.spongy bone replaces every 3-4 years. Compact bone every 10 Years. Prevents bone from becoming brittle. Also important for self- repair of broken bones. involves bone deposit and bone resorption.
bone deposit
Occurs where bone is injured or added strength is needed; Requires a diet rich in protein; vitamins C, D, and A; calcium; phosphorus; magnesium; and manganese
Bone resorption
the breakdown of bone extracellular matrix by osteoclasts that is part of the normal development, maintenance, and repair of bone tissue
hormonal mechanisms that maintain calcium homeostasis in the blood
Ca2+ is important in transmisson of nerve impulses, muscle contraction, blood coagulation, secretion by glands and nerve cells, and cell division.
blood Ca2= is maintained between 9-11 mg/dl
wolff's Law
A bone grows or remodels in response to forces or demands placed upon it
Classifications of fractures
1. position of bone ends after fracture:
(Non-displaced or Displaced)
2. Completeness of the Break:
(Complete or incomplete)
3. Orientation of the break to the long axis of the bone:
(linear or transverse)
4. Wether or not the bone end penetrated the skin:
(Compound(open) or simple(closed)
Stages in healing of a bone fracture
1)Hematoma forms
• Torn blood vessel hemorrhage
• Clot (hematoma) form
• Site became swollen, painful, and inflamed
2)Fibrocartilaginous callus forms
• Phagocytic cell clear debris
• Osteoblasts begin form spongy bone within week
• Fibroblast secrete collagen to connect bone end
• Mass of repair tissue now called fibrocartilaginous callus
3)Bony callus formation
• New trabeuclae form a bony (hard) callus
• Bony callus formation continue until firm union is formed in - 2month
4)Bone remodeling
• In response to mechanical stressor over several months
• Final structure resemble original
Osteomalacia and rickets
• Calcium salts not deposited
• Rickets (childhood disease) causes bowed legs and other bone deformities
• Cause: vitamin D deficiency or insufficient dietary calcium
Osteoporosis
loss of bone mass- bone resportion outpaces deposit
spnongy bone of spine and neck of femur become most susceptible to fracture
comminuted fracture
bone fragments into three or more pieces
spiral fracture
ragged break occurs when excessive twisting forces are applied to a bone
compression fracture
bone is crushed
epiphyseal fracture
epiphysis separates from the diaphysis along the epiphyseal plate
depressed fracture
broken bone portion is pressed inward
greenstick fracture
bone breaks incompletely much in the way a green twig breaks.
1st stage of healing bone fracture
Hematoma Forms: Torn blood vessels hemorrhage, Clot (hematoma) forms, Site becomes swollen, painful, and inflamed
2nd stage of healing bone fracture
Fibrocartilaginous callus forms: Phagocytic cells clear debris, Osteoblasts begin forming spongy bone within 1 week, Fibroblasts secrete collagen fibers to connect bone ends, Mass of repair tissue now called fibrocartilaginous callus
3rd stage of healing bone fracture
Bony Callus Formation: New trabeculae form a bony (hard) callus, Bony callus formation continues until firm union is formed in ~2 months
4th stage of healing bone fracture
Bone Remodeling: In response to mechanical stressors over several months, Final structure resembles original
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