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Skeletal for An. Lecture Exam 2
Skeletal for Exam 2
56
Anatomy
Undergraduate 1
10/28/2010

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Term
osteoprogenitor cells
Definition
undifferentiated cells; can divide to replace themselves or become osteoblasts
Term
osteoblasts
Definition
form matrix and fibers, but cannot divide
Term
osteocytes
Definition
mature cells that were osteoblasts, but have enclosed themselves in matrix and can not longer secrete matrix.
Term
osteoclasts
Definition
huge cells from fused monocytes (WBCs); function in bone reabsorption at surfaces like the endosteum
Term
fracture hematoma formation
Definition
first step in healing of fractures; damaged blood vessels produce a clot in 6-8 hours, bone cells die;
inflammation brings in phagocytic cells for clean-up duty;new capillaries grow into damaged area
Term
fibrocartilagenous callus formation
Definition
second step in healing of fractures; fibroblasts invade and lay down collagen fibers; chondroblasts produce fibrocatilage to span the broken ends of the bone.
Term
bony callus formation
Definition
third step in healing of fractures; osteoblasts secrete woven bone that joints 2 broken ends of the bone; lasts 3-4 monts.
Term
bone remodeling
Definition
fourth and last step in healing of fractures compact bone replaces tech spongy in the bony callus; surface is remodeled back to normals shape
Term
bone remodeling
Definition
Term
Ilizarov Fixator
Definition
Gavriil Ilizarov;
a) deformed bone is cut
b) fixator is attached and slowly pulls and/or rotates the cut ends of the bone
c) osteoblasts lay down new matrix, and bone is remodeled
Term
fracture
Definition
break in a bone
Term
Why is healing faster in bone than in cartilage?
Definition
Cartilage is avascular.
Term
Even though healing of bone is faster than healing of cartilage, why is healing of bone still a slow process?
Definition
Because of vessel damage.
Term
closed reduction
Definition
clinical treatment for a fracture; restoring pieces to original position by external manipulation
Term
open reduction
Definition
clinical treatment for a fracture; surgery
Term
bone remodeling (in general):
Definition
osteoclasts carve out small tunnels and osteoblasts rebuild osteons
Term
bone remodeling (specific steps):
Definition
-osteoclasts form leak-proof seals around edge of cell, secrete enzymes and acids beneath themselves, and release calcium and phosphorus into interstitial fluid.
-then osteoblasts take over bone remodeling
Term
There is continual redistribution of bone matrix where?
Definition
Along lines of mechanical stress.
Term
What is an example of continual redistribution of bone matrix along lines of mechanical stress?
Definition
The distal femur is fully remodeled every 4 months.
Term
What hormone prevents bone loss?
Definition
Calcitonin
Term
mechanical stress
Definition
pull on bone by skeletal muscle and gravity
Term
What does mechanical stress increase?
Definition
Mechanical stress increases deposition of mineral salts and production of collagen.
Term
What does lack of mechanical stress result in?
Definition
Lack of mechanical stress results in bone loss.
Term
How does bone length growth happen?
Definition
Cartilage cells are produced by mitosis on the epiphyseal side of the growth plate; then they are destroyed and replaced by bone on the diaphyseal side of the plate.
Term
When do growth plates close?
Definition
Ages 18-25.
Term
When does bone length growth stop?
Definition
Age 25.
Term
How do epiphyseal growth plates close?
Definition
Cartilage cells stop dividing and bone replaces cartilage; epiphyseal line created.
Term
Epiphyseal line
Definition
marks the fusion of diaphysis and epiphysis
Term
Name the zones of growth in the epiphyseal plate.
Definition
Resting, Proliferating, Hypertrophic, Calcified.
Recess Produces Hyper C(k)ids.
Term
Zone of resting cartilage
Definition
1st layer: anchors growth plate to bone
Term
Zone of proliferating cartilage
Definition
2nd layer: rapid cell division (stacked coins)
Term
Zone of Hypertrophic cartilage
Definition
cells are enlarged, remain in columns
Term
Zone of calcified cartilage
Definition
-thin zone
-mostly dead cells, since the matrix is calcified
-osteoclasts remove matrix
-osteoblasts and capillaries move in to create bone over calcified cartilage
Term
Appositional growth
Definition
bone growth by width; at bone's surface
Term
How does appositional growth happen?
Definition
Periosteal cells differentiate into ostoblasts and form bony ridges, then tunnel around periosteal blood vessels; then concentric lamellae fill int the tunnel to form an osteon.
Term
Periosteal cells
Definition
in appositional growth: differentiate into osteoblasts and form bony ridges, then tunnel around periosteal blood vessels.
Term
How do concentric lamellae play a role in appositional growth?
Definition
Concentric lamellae fill in the tunnels created by periosteal/osteoblasts around periosteal blood vessels to form an osteon.
Term
Factors affecting bone growth (2)?
Definition
Nutrition - adequate levels of minerals and vitamins
Hormones - sufficient levels of specific hormones.
Term
Factors of bone growth: Nutrition.
What's needed?
Definition
Calcium and phosphorus - growth
Vit C - collagen formation
Vit K and Vit B12 - protein synthesis
Term
Calcium and phosphorus
Definition
growth
Term
Vitamin C
Definition
collagen formation
Term
Vitamins K and B12
Definition
protein synthesis
Term
Hormones for growth needed?
Definition
hGH - growth
thyroid (T3 and T4)
insulin
Term
What hormones are present at puberty related to growth?
Definition
sex steroids
Term
At puberty, sex steroids result in...
Definition
growth spurt and closure of epiphyseal plate.
Term
During puberty, what specific bone growth takes place in females and what hormone causes it?
Definition
Estrogen promotes female changes like a wider pelvis.
Term
giantism
Definition
produced by oversecretion of hGH during childhood
Term
short stature
Definition
produced by the undersecretion of gHG or thyroid hormone during childhood
Term
men and women growing taller than normal?
Definition
They lack estrogen receptors on cells.
Term
Why does the lack of estrogen receptors on cells relate to people growing taller than normal?
Definition
Estrogen is responsible for the closure of growth plates.
Term
Skeleton = resevoir of...
Definition
calcium and phosphate.
Term
What are some body processes that calcium ions are involved in (3)?
Definition
-nerve and muscle cell function
-blood clotting
-enzyme function in many biochemical reactions
Term
Plasma level usually maintained
Definition
9-11 mg/100mL
Term
Small changes in blood levels of _____ can be deadly.
Definition
Ca+2
Term
If the plasma levels of Ca+2 are too high, this results in...
Definition
cardiac arrest.
Term
If the plasma levels of Ca+2 are too low, this results in...
Definition
respiratory arrest.
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