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118 Cards in this Set

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Dynamic tissue that continually remodels itself
Bone tissue
bone or _____ tissue is a _______ tissue with a matrix hardened by minerals called ________
osseous

connective

calcium phosphate
Individual bones are made up of:
1. bone tissue
2. marrow
3. catilage
4. periostem
Functions of the skeletal system
• SUPPORT– hold up body, muscles & organs
• PROTECTION - organs & bone marrow
• MOVEMENT – muscle attachment
•BLOOD FORMATION - bone marrow -> RBCs/WBCs
•MINERAL RESERVOIR - stores calcium & phosphate
•pH BALANCE - buffers blood by absorbing or releasing alkaline salts
• DETOXIFICATION – removes heavy metals from blood; can later slowly release
Structure of flat bone from most SUPERFICIAL to DEEPEST layer:
1. Suture
2. Outer compact bone
3. Spongy bone (dipole)
4. Trabeculae
5. Inner compact bone
Flat bones:
• Most cranial bones
• Ribs
• Sternum (breastbone)
• Scapula (shoulder blade)
• Os coxae (hipbone)
Which layer of a flat bone contains no marrow cavity?
the spongy bone (dipole)
Lever acted upon by muscles
long bones
Bones that glide across one another in multiple directions
short bones
These bones protect soft organs
flat bones
Layer of fibrous connective tissue covering the bone
periosteum - long bone
Refers to hyaline cartilage over ends of bone for lubrication
articular cartilage (long bones)
Lines internal surface of a long bone
endosteum
Long bones include:
• Humerus
• Radius
• Ulna
• Metacarpals
• Phalanges
• Femur
• Tibia
• Fibula
• Metatarsals
• Phalanges
Short bones include:
– Carpals (wrist)
– Tarsals (ankle)
Irregular bones include:
– Sphenoid & Ethmoid bones of the cranium
– Vertebrate (backbone or spine)
Cylinder of compact bone

Marrow cavity lined with endosteum
shaft (diaphysis)
Enlarged ends

Spongy bone covered by compact bone

Enlarged to strengthen joint and attach ligaments
epiphyses (enlarged ends of bone)
Covers bone

– outer fibrous layer _________
– inner osteogenic layer important for growth & healing
periosteum

continuous with TENDONS
An elevated ridge on the surface of a mature bone which marks the point of fusion between the epiphysis and diaphysis.
epiphyseal plate or line
reside in endosteum or periosteum - multiply continuously & differentiate into osteoblasts
osteogenic cells
form organic matter of matrix & help to mineralize it in response to stress or fractures
osteoblasts
osteoblasts that have become trapped
osteocytes
Osteocytes reside in _______ and are connected to each other via _______
lacunae (little leg)

canaliculi
What do osteocytes do?
– signal osteoclasts & osteoblasts about mechanical stresses
bone-dissolving cells that develop in bone marrow by the fusion of the same stem cells that give rise to monocytes of the blood
osteoclasts
______ will reside in pits called _____ ______that they have eaten into the surface of the bone
osteoclasts

resorption bays
Osseous Tissue is made up of ______ organic matter and _______ inorganic matter
1/3 organic

2/3 inorganic
What is the organic matter found in osseous tissue?
collagen, glycosaminoglycans, proteoglycans & glycoproteins
What is the inorganic matter found in osseous tissue?
– 85% hydroxyapatite (crystallized calcium phosphate salt)
– 10% calcium carbonate
– other minerals
The combination of organic and inorganic matter provides ______ & _______
strength and resilience

minerals resist compression; collagen resists tension
No collagen in bone results in :
Osteogenesis imperfecta

"brittle bone"
No minerals in bone results in :
"bendy" bone (too flexible)
Rickets is a result of :

Causes? Targeted group?
• In children
• Insufficient sunlight or vitamin D
• Dietary deficiency in calcium or phosphate
• Liver or kidney disease
is the softening of the bones due to defective bone mineralization secondary to inadequate amounts of available phosphorus and calcium.

mainly found in _______
osteomalacia

adults
Compact bone:

_________ are arranged in concentric circles around _______ canals. This is the basic structural unit of compact bone, collectively called an _______.
Lamellae

haversian canals

osteon
Compact bone:

Within the lamellae lie the _______ with osteocytes. _________ extend between adjacent lamellae.
lacunae

Canaliculi
Compact bone:

___________ canals enter the bone from the outside and inside, and feed into the haversian canals, carrying nerves and blood vessels.
Perforating (Volkmann's)
spongy bone:

spongelike appearance formed by rods and plates of bone called:
trabeculae
Spongy bone is made up of:

Spaces are filled with:
spines, rods, and plates

red bone marrow
These have few osteons or haversian canals (found in spongy bone)
trabeculae
What is the benefit of TRABECULAE?
Provides strength with little weight
trabeculae develop along bone’s lines of stress
Red marrow is found in :

Red marrow produces blood cells, this is known as:
Red marrow is a mesh of reticular fibers and immature cells

in adults found in axial skeleton & girdles

hemopoietic means produces blood cells
yellow marrow is found where?
fatty marrow of long bones in adults
yellow marrow replaced with reddish jelly
gelatinous marrow
intramembranous ossification forms which bones?
the sternum, the frontal and parietal bones of the skull, the temporal & occipital bones and the mandible and maxillae
How does intramembranous ossification occur?
- mesenchyme condense in soft sheet of tissue - becomes network
- osteoblasts gather on trabeculae to form osteoid tissue
- Calcium phos. is deposited in matrix (osteoblasts-> osteocytes)
-osteoclast remodel center to contain marrow
-osteoblasts remodel & form compact bone
-mesenchyme --> periosteum
endochondral ossification takes place in what bones?
mostly long and short bones
How does endochondral ossification take place?
- mesenchyme differentiates into hyaline cartilage
- cartilage -> broken down, reorganized & calcified
- primary ossification center forms in cartilage model from chondrocytes
- matrix becomes weak here
- primary marrow space is formed by periosteal bud
cartilagenous material that remains as growth plate between medullary cavity & secondary ossification centers in the epiphyses
Metaphysis
layer of resting cartilage
no sign of transformation
(zone)
zone of reserve cartilage
In this zone, chondrocytes multiply forming columns of flat lacunae
zone of cell proliferation
In this zone, chondrocytes push other cells closer to the ends
zone of hypertrophy
This zone shows mineralization between columns of lacunae
Zone of calcification
In this zone, chondrocytes die and each channel is filled with osteoblasts and blood vessels to form a haversian canal & osteon
zone of bone deposition
Explain the process of secondary ossificaiton:
- Begin to form in the epiphyses near time of birth
- Same stages occur as in primary ossification center
result is center of epiphyseal cartilage being transformed into spongy bone
-Hyaline cartilage REMAINS on joint surface as articular cartilage and at junction of diaphysis & epiphysis (epiphyseal plate)
bones increase in length at epiphyseal plate
interstitial growth
bones increase in width (mature bone only)
appositional growth
how does appositional growth occur?
similar to intermembraneous growth
osteoblasts lay down matrix in layers parallel to the outer surface & osteoclasts dissolve bone on inner surface
During appositional growth, if one process OUTPACES the other, bone deformities occur known as:
osteitis deformans
Achondroplastic Dwarfism
Short stature but normal-sized head and trunk
long bones of the limbs stop growing in childhood but other bones unaffected
How does achondroplastic dwarfism occur?
Result of spontaneous mutation when DNA is replicated
mutant allele is dominant
What is pituitary dwarfism?
has lack of growth hormone
short stature with normal proportions
evels of calcium & phosphate in tissues must reach a point (_________) before crystallization can occur
solubility product
most tissues have inhibitors to prevent crystallization
_________ neutralize the inhibitors
osteoblasts
Abnormal calcification

Where does this occur?
ectopic ossification

may occur in lungs, brain, eyes, muscles, tendons or arteries
Process of dissolving bone & releasing minerals into the blood
mineral resorption
Explain how mineral resorption occurs:
performed by osteoclasts “ruffled border”
hydrogen pumps in the cell membrane secrete hydrogen ions into the space between the osteoclast & the bone
chloride ions follow by electrical attraction
hydrochloric acid (HCl) with a pH 4 dissolves bone minerals
secrete an enzyme (acid phosphatase) that digests the collagen
Phosphate is a component of :
DNA, RNA, ATP, phospholipids, & acid-base buffers
Calcium is needed for :
communication between neurons
muscle contraction
blood clotting
exocytosis – movement of substances out of a cell
____% if the body's calcium is in the bones
99%
______% of body's phosphorus is in the bones
85-90%
What percentage of calcium does the adult skeleton exchange with the blood each year?
18%
What happens when the bones experience HYPOCALCEMIA?

When does this occur?
causes excessive excitability of nervous system leading to muscle spasms, tremors or tetanus
laryngospasm  suffocation
caused by vitamin D deficiency, diarrhea, pregnancy, lactation, underaction/removal of parathyroid glands
What happens when the bones experience HYPERCALCEMIA?
depresses nervous system  muscle weakness, sluggish reflexes, cardiac arrest
Homeostasis in the bones depends on :
calcitriol, calcitonin & PTH
carpopedal spasm is often seen in patients experiencing:
hypocalcemia (overexcitability of nerves)
What is calcitriol?
Activated vitamin D
How is calcitriol produced?
UV radiation penetrating to the dermal blood vessels converts a cholesterol derivative (7-dehydrocholesterol) to D3
liver converts it to calcidiol
kidney converts it to calcitriol (active form of vit D)
How does calcitriol function?
behaves as a hormone
stimulates small intestine to absorb calcium & phosphate
Reduces urinary secretion of calcium & phosphate
promotes osteoclast activity
Parathyoid hormones are released from which gland and under what circumstances?
parathyroid glands on the posterior surface of the thyroid gland

when calcium blood level is TOO LOW
What is the function of the parathyroid hormone?
inhibits activity of osteoblasts
_Stimulates osteoclast multiplication & activity
reduces calcium secretion & increases phosphate secretion in the urine
stimulates production of an enzyme in the kidneys that carries out the last step in calcitriol synthesis
Where is calcitonin released from and when?
secreted from the thyroid gland when calcium concentrations RISE
What is the function of calcitonin?
Promotes bone deposition of calcium
reduces osteoclast activity by 70% in 15 minutes
increases the number & activity of osteoblasts
Important aspect of CALCITONIN:
Important role in children, but little effect in adults
calcitonin deficiency is not known to cause any disease in adults
may be useful in reducing bone loss in osteoporosis
a break caused by abnormal trauma to a bone
stress fracture
a break in a bone weakened by some other disease
pathological fracture
break in which skin is NOT broken
closed (simple)
break where bone protrudes from skin
open (compound)
Fracture where bone is broken into 2 or more pieces
complex
Break that extends only partway (pieces remain joined)
incomplete
break where one side is bent with an incomplete fracture on other
greenstick fracture
fine crack in bone
hairline fracture
Bone broken in 3 or more pieces:
comminuted fracture
break that is parallel along the long axis of the bone:
linear fracture
break that is perpendicular to the long axis of the bone
transverse fracture
diagonal break (between linear and transverse)
oblique
Break that is a result of a twisting stress
spiral fracture
How long does it normally take for a fracture to heal?
8-12 weeks
Stages of healing from a fracture:
1. Fracture hematoma
2. Granulation tissue
3. Callus formation
4. Remodeling
1st stage of healing from fracture:
Fracture hematoma (1)
broken vessels form a blood clot
2nd stage of healing from a fracture:
granulation tissue (2)

fibrous tissue formed by fibroblasts and infiltrated by capillaries
3rd stage of fracture healing:
Callus formation (3)
soft callus of fibrocartilage replaced by hard callus of bone in 6 weeks
4th stage of fracture healing:
remodeling (4)

occurs over next 6 months as spongy bone is replaced with compact bone
treatment where fragments are aligned with manipulation & casted
closed reduction
treatment for fracture involving surgical exposure & repair with plates & screws
open reduction
This treatment is not used in elderly due to risks of long-term confinement to bed ;

What does it involve?
traction

hip fractures are pinned & early walking is encouraged
This treatment is used on fractures that take longer than 2 months to heal
electrical stimulation
This is a branch of medicine that deals with the prevention & correction of injuries and disorders of the bones, joints & muscles
orthopedics
This disease may lead to fatal complications such as pneumonia. Can also cause widow's hump
osteoporosis
alson known as brittle bone and is a result of the bone losing mass from loss of organic matrix and minerals
osteoporosis
Who's at the greatest risk for osteoporosis?
postmenopausal white women

by age 70, average loss of 30% bone mass
What's the best treatment for osteoporosis?
prevention

exercise and calcium intake (1000mg/day) between ages 25 and 40
bacterial infection causes inflammation of osseous tissue and bone marrow
fatal before widespread use of antibiotics
osteomyelitis
Benign bone tumor
osteoma
benign tumor of the bone and cartilage
osteochondroma
most common and deadly form of bone cancer

often found in :
osteosarcoma

males between 10-25 yrs
slow-growing cancer of hyaline cartilage
chondrosarcoma