API06 BONES
AND SKELETAL TISSUE
I.
Skeletal Cartilages
a. High
water content
b. Surrounded
by layer of dense irregular CT
i. Perichondrium
ii. Vascular
iii. Chondrocytes
in lacunae
c. Most
are hyaline cartilage
i. Support,
flexibility, resilient
ii. Fine
collagen fibers
iii. Articular
iv. Costal
d. Elastic
cartilage
i. Elastic
fibers
ii. External
ear
iii. Epiglottis
e. Fibrocartilage
i. Compressible
and great strength
ii. Thick
collagen fibers
iii. Heavy
pressure and stretch
iv. Menisci
in knee joint
v. Intervertebral
discs
II.
Functions of bone tissue (osseous tissue)
A.support
1.whole body
2.other organs
B.protection
1.vertebrae - spinal cord
2.rids - lungs, heart
3.skull - brain
C.movement
1.works with skeletal muscle
2.bones as levers by muscle
D.storage
1.fat for energy in cavities
2.minerals can be removed is
required for other body
functions
E.blood cell formation
1. Hematopoiesis
a.process of blood
cell formation
b.occurs in red
bone marrow
` c. in adults
1.limited
to head of femur and humerus
2.sternum
and hip bone diploe
d. in severe
anemia
1.can
revert medullary cavity to hematopoietic tissue
III.Classification
of bones
A.composition
1.compact
a.dense
2.spongy (cancellous)
a.formed of many
pieces - trabeculae
B.shape – long, short, irregular, flat
IV.Structure
A.Long bone
1.Diaphysis
a. shaft
b. compact bone
2.Epiphysis
a.on proximal and
distal ends
b.spongy bone
3.Metaphysis
a. epiphyseal
plate/line
4.articular cartilage
a.on ends of bone
b.makes junction
with other bones (articulates)
5. medullary cavity
a.center of
diaphysis
b.in adults
storage site for fat
c.yellow marrow
6. Draw and label a long
bone:
6.linings
a.dense irregular
connective tissue membrane with
(1)cells
(2)blood
vessels, nerves, lymph vessels enter
bone via nutrient foramina
b.periosteum
(1)covers
the outside surface of bone
(2)dense
connective tissue
c.endosteum
(1)lines
inside of medullary cavity
(2)lines
inside of trabeculae
B.Short, Irregular, Flat
1.periosteum, compact,
spongy, endosteum
2.diploe
a.spongy layer
VI.Bone
Composition
A.organic
1.cells
a.osteogenic
cells- unspecified stem cells produce osteoblasts located in blood vessel
canals in bonesn, inner side of perisoteum and endosteum
b.osteoblasts – produce matrix and initiates
calcification
b.osteocytes
–mature and maintain bone tissue
c.osteoclasts
–form from fusion of monocytes (type of WBC phagocyte) and releases enzymes,
acid to destroy matrix
2.osteoid
a.organic part of
bone matrix secreted by osteoblasts
(1)proteoglycans
(2)glycoproteins
(3)collagen
fibers
B.inorganic
1.hydroxyapatite
a.mineral salts
(1)calcium
(2)phosphorus
2.arrangement
of trabeculae allows nutrients to circulate
(3)hydroxide
(a)fluoride
replaces to strengthen
2. 85% is calcium phosphate
3.10% calcium carbonate
4.magnesium salts also
present
5.salts allow bones to last
after death
VII.
Histology
A.compact
1.dense with many canals
2.structural unit
a.Haversian system
(canal)
b.Osteon -tube of
bone matrix
3.Draw and label an osteon
a.lamella
b.lacunae
c.Haversian canal
d.Volkman's cannal
e.canaliculi
(1)permits
nutrients to enter all levels
4.osteocytes
a.lie at junction
of lamella
b.in lacunae
B.spongy
1.no true osteon
VIII.Bone
development
A.ossification = osteogenesis
1.process of bone formation
2.growth
3.remodeling of bone
B.Embryonic skeleton
1.hyaline cartilage
a.forms into bone
by ENDOCHONDRAL ossification
b.chondroblasts
become osteoblasts
(1)mature
to osteocytes
2.fibrous membranes
a.forms into bone
by INTRAMEMBRANOUS ossification
b.skull and
clavicle
C.Process of bone formation
1.osteoblasts
a.secrete matrix
substances
b.become trapped
in lacunae of bone matrix
c.mature into
osteocytes
2.osteoclast activity
a.breakdown of
bone for growth
b.bone breaks at
epiphyseal plates
for lengthening
c.osteoblast
activity increases
d.appositional
growth
(1)increases
width
D.factors to regulate bone growth
1.hormones
a.growth hormone
b.thyroid hormone
c.testosterone
d.estrogen
2.calcium
3.Vitamin D
4. vitamin K
E.Calcium in bone matrix
1.calcification
a.laying down of
calcium salts initiated by osteoblasts
b.occurs to add
bone strength
c.at injured site
2.resorption
a.breakdown of
matrix and reabsorption of minerals
to bloodstream
(1)Calcium
(a)for
other functions as needed
(b)pregnancy
b.action of
osteoclasts
3.hormones regulate bone
resorption and deposition
a.parathyroid
hormone (PTH)
(1)signal
is low blood calcium
(2)calcium
released from bones
b.calcitonin (thyroid
cells)
(1)signal
is high blood calcium
(2)stores
in bone
1.growth in response to
external stimulus
2.gravity
a.loss of bone
density in space
3.exercise
4.electrical stimulation
a.speed repair
process
G. Fractures
1.breaks in bone
a.realign with reduction
2.repair
a. hematoma
(1)blood
clot at site
b.
fibrocatillagenous callus
(1)granulation
tissue
(2)fibroblasts
move in and secrete collagen
c.bony callus
(1)osteoclasts
and osteoblast active
(2)osteoblasts
move in from periosteum to secrete bone matrix
d.calcification
(1)remodeling
to change bony callus
over several months
IX.Bone
Disorders
A.osteoporosis
1.bone resorption > bone
deposition
2.bone mass less
3.normal composition
B.osteomalacia
1.soft bones more fragile
2.rickets in children
a.bowed legs
b.deformed pelvis