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levels of organization
chemical cellular tissue organ organ systems
functions of skeletal system
support protection movements mineral storage- homeostasis and calcium red and white blood cell leverage 

triglyceride storage (function of the S.S)
-adipose tissue -98% of all body energy reserves insulates protect
hemopoiesis( functions of s.s)
blood cell production
composition of the skeletal system
cartilage- runs from 1 end to another ligaments- reinforce joints, allow movements
axial skeleton
midline, longitude skull auditory ear bones hyoid ribs sternum vertebral 80bones thorax
appendicular skeleton
-126 bones arms legs femur pectoral girdles upper limb pelvic girdle lower limbs 

classification of bones
long bones- greater length shortbones- equal width and length flat bones- thin flat surface irregular bones- complex shapes sesamoid- patella pneumatized sutural
long bones
-humerus radius ulna femur tibia fibula metacarpals metatarsals phalanges
flat bones examples
skulls ribs sternum carpal tarsal bones protect organs scapula
irregular bones
- vertebrae hips - calcaneus
Gross Anatomy of a Long bone
Epiphysis - head of the long bone Diaphysis - shaft of long bone(middle) Medullary Cavity - hollow, no bone, has fat (YBM) Periosteum - double layered (outer - dense irregular tissue // inner - rich osteoblast)*** bone growth Endosteum - lines the medulla cavity**bone growth Articula…
sutural
- suture of the skull
pneumatized
cavities in vertebrae -----allow penetration by air sacs - ethmoid bone
periosteum
-- connective tissue covers external surface of bone contains blood vessels doesn't cover joints two layers outer fibrous** inner osteogenic**
endosteum
-inside lining marrow cavity spongy bone compact bone osteogenic cells
bone develops fatigue damage
detect location and magnitude of damage remove damage replace it with new bone restore bones material composition, micro and macro architecture
gross anatomy of flat bones
yellow marrow found in medullary cavity, severe blood loss = conversion of yellow marrow back to red marrow to increase blood cell production
What are the four types of cells found in bone tissue?
Osteoprogenitor cells Osteoblasts Osteocytes Osteoclasts
Osteoprogenitor cells Osteoblasts Osteocytes Osteoclasts
maintain bone strength by removing damaged bone
during growth modeling /remodeling
achieve the skeleton peak strength
achieve the skeleton peak strength
- achieve strength for loading and lightness for mobility strategically deposit bone where it is needed remove bone from where it is not needed to avoid
bone remodeling
reconstruction when bone is resorbed by osteoclasts
bone modeling
construction formed by osteoblasts without prior bone resorption produces change in bone size and shape
osteoclasts
break down bone bone resorption release proteolytic enzymes and acids
osteocytes
maintenance of bone found in lacunae
osteoblasts
-bone formation synthesize organic components of matrix builds bone repair and remodel initiate calcification- take calcium from blood and deposit it within matrix exocytosis
osteogenic cells
develops into an osteoblast stem cells formed from mesenchyme can differentiate and become other bones mitosis form in osteoblasts
Extracellular Martix
The stuff outside of and between cells Connective tissue (e.g., dermis, below epidermis) is typically of lower cell density than epithelial and glandular tissue
osteology
-study of the skeleton
sesamoid bones
protects tendons form excessive wear -patella
spongy bone
- light weight -strong - end of long bones -calcellous -irregular shape
primary weakness of compact bone
-connects blood vessels
osteocyte
-bone cell
lacuna
- containing bone cells containing osteocytes -space in bone
canaliculi
- connects lacunae -supplying nutrients ao cells
osteons compact bones
contains passage ways 4 blood central canal-blood vessels and nerves lamellae - layers of tissue caniliculi allows osteocyte to maintain bone
compact bone function
- withstand forces along longitudinal axis -keeps bone strong
compact bone location
-diaphysis of long bones -arms and legs
compact bone organization
- solid networks of ring structures -osteon
spongy bone location and function
epiphyses of long bone surrounding marrow cavities flat, short, regular function strength contains blood vessels bone marrow pelvis ribs sternum vertebra skull
organization of spongy boneTerm
-thin plates trabecullae osteocytes are housed in lacunae
bones need both collagen and minerals for maximum strength
...
minerals
provide firmness
collagen
strong and flexible
scurvy
- lack of vit c - bones can fracture easily -weakens collagen
rickets
-lack of vitamin d
hydroxyapatite
-lack of vitamin d
organization of mineral
collage fiber contains mineralized fibrils fibrils contain small mineral plates bound by helical non collagenous
type 1 collagen
- connective tissue provides structure and support
inorganic components
hydroxyapatite mineral salts ca10(P04)6(OH)2 ADDS strength water MAKES UP 25% ATTRACTED TO GROUND SUBSTANCE
organic components ecm
type 1
collagen fibers
-resist stretching but bend easily contain fibrils ligaments and joint capsules most common protein in the body strong connective tissue
describe each component of the matrix
-organic component resists twist and stretch
glycosaminoglycans
negative sulfate attracts water and cation
list components of the extracellular matrix
glycosaminoglycans glycoproteins negatively charged proteins fibers proteoglycans
purpose of its organization osteon
compact bone made up of osetons
bone formation
fontanels- soft spots on skull epiphyseal plates stay as cartilage until adult hood
intramembranous process
flat bones of skull facial bones mandible sternum clavicles medial parts
intramembranous ossification
-within membrane mesenchyme bone
ossification
- cartilage is converted to bone during human development beings during the second month of dev.
bones before birth
-loose connective tissue -mesenchyme hyaline cartilage bones start as cartilage
heterotropic bone formation
sesamoid bones abnormal stress can stimulate bone formation in areas where bone is not normally found
order of events of intramembranous
dev. of center calcification- formation of trabeculae and periosteum dev. of compact bone collar
calcification
osteoblasts deposit calcium in matrix differentiate into osteocytes deposition of calcium
development of ossification center
-dev. of the bone mesenchymal cells cluster together an differentiate into osteogenic cells and later osteoblast osteoblasts secrete bone to matrix
development of periosteum
-remodeling of spongy bine to compact bone
formation of trabecullae
strands of bone spongy bone
process of appositional growth
ridges in periosteum create groove 4 periostesl blood vessel Per. ridges fuse forming endosteum osteoblasts in endosteum build new concentric lamellae inward bone grows outward
appositional growth of bone
growth in width periosteal osteoblasts build bone on outer surface - divide and secrete additional matrix endosteal osteoclasts increase diameter of marrow cavity - deep layer
epiphyseal plate
cartilage growth plate on long bones during childhood diaphyseal osteoclasts break down calcified cartilage osteoblasts lay down spongy bone chondroblasts will cont to form cartilage matrix at the proliferating cart. region growth in length
interstitial growth
chondroblasts build matrix and diff into chondrocytes chondrocytes divide chondrocytes build matrix and spread apart cartilage tissue growths within
interstitial growth
growth within the tissue - growth in length
appositional growth
growth at the edge increases bone thickness occurs in the periosteum of all bones
secondary ossification
l- epiphyses near time of birth epiphyseal cartilage is transformed into bone and cartilage remains at the joint in the end no marrow cavity
primary ossification
- marrow cavity formed replaces all cartilage w/bone occurs b4 birth l- diaphysis
Endochondral ossification
Primary ossification center Secondary ossification centers epiphyseal plate process of cartilage turning into bone
Endochondral Ossification Summary Step
Cartilage model forms Growth of cartilage model Blood vessels penetrate model and stimulate differentiation of osteogenic cells into osteoblasts Osteoblasts form bone on the outer surface of the bone Osteoblasts create a primary ossification center (bone replaces cartilage) Osteoclas…
**bones formed by intramembranous
-skull bones, -mandible -clavicle -patella -flat bones
role of parathyroid hormone
- causes increase in blood calcium - -increased bone resorption by osteoclasts
role of calcitonin
from thyroid decreases blood calcium level target tissues- bone,kidney, intestine decreased bone resorption by ostclst.
osteoporosis prevention
no smoking caffeine consumpiton exercise high foods on Ca andVIT D
risk factors for development of osteoporosis
-high fat diets -low intake of fruits and veggies -old age - females - low on calcium -low on vit d
define osteoporosis
-bones become weak and porous -increase risk of fractures -decrease bone strength
estrogen/ testosterone
- sex hormones -bone growth bone formation -levels decrease with older age
skeletal disorders( conditions affecting muscles or bones )
pituitary d.- children w/low levels of growth hormone slow epiphyseal (short) pituitary giantism- accelerated growth tall acromegaly- thickening of bone skull, hands, feet, mandible epi. played of long bone already closed
sex hormones in modulating bone mass
- causes osteoblasts to produce bone faster than the rate and overtime stops growth - at puberty bone growth accelerates dramatically
role of thyroxine
- increase metabolic rate -reg growth & dev
**roles of hormones
maintains of homeostasis growth n dev. sexual drive
role of exercise
exercise early in life helps increase peak bone mass exercise later in life- prevent bone loss improve strength and balance and coordination reach the feature threshold later in life fall prevention
***recommended CA2
- young adults 19-50 yrs old need 1000mg calcium from diet and supplements to avoid bone loss
role of calcium in bone dev.
-bone remodeling -regulates blood muscle contraction nerve transmission
role of calcitriol in calcium homeostasis
increase calcium absorption increase resorption by kidneys reduces pth, works great with pth controls how calcium is absorbed from bone to blood
Describe Vitamin D
Called sunshine vitamin Vitamin D is synthesized in the body by sunlight. inactive converted to circulating form in liver, to active form in kidneys. Active form acts as a hormone. Regulates calcium and phosphorous. maintains healthy blood levels and build/maintain bones. May preve…
describe the vitamin D pathway
vit D from skin precursor dehydrocholesterol plus UV light blood cholecalciferol liver cholecalciferol 25 hydroxy kidney1,25 to dihydro chol.
calcium homeostasis
-keep blood calcium in normal range 8.5-11.0mg/dl -important 4 membrance intracellular activity blood clotting
dietary factors that influence the bone
Vit vit A-activity 4 osteoblasts vit C- needed 4 collagen vit D- calcium absorption Vit- K & b12- bone proteins Minerals - cal & phosphorus exercise hormones
****bones formed by endochondral ossification
-most bones in the body(vertebrae,pelvis, limbs, digits,

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