A&P 1 - Chapter 6

osteoclast activation involves

PTH (parathyroid hormone) and immune T cell proteins

compression fracture

bone is crushed

classification of bones

long, short, sesamoid, flat, irregular

thyroid hormone

modulates activity of growth hormone, ensuring proper proportions

osteocyte

monitors and maintains the bone matrix

bone remodeling

ongoing replacement of old bone tissue by new bone tissue

Five main steps in the process of ossification

1. Bone collar forms around diaphysis of cartilage model 2. Central cartilage in diaphysis calcifies, then develops cavities 3. Periosteal bud invades cavities, leading to formation of spongy bone • Bud is made up of blood vessels, nerves, red marrow, osteogenic cells, and osteoclasts 4. Diaphysis elongates, and medullary cavity forms • Secondary ossification centers appear in epiphyses 5. Epiphyses ossify • Hyaline cartilage remains only in epiphyseal plates and articular cartilages

5 zones of the growth plate

1. resting zone 2. proliferation zone 3. hypertonic zone 4. calcification zone 5. ossification zone

How many bones are in the human skeleton

206

at what age are all bones completely ossified

25

what percent of bone mass is recycled each week

5-7%

leptin

A hormone released by white adipose tissue to reduce hunger

Serotonin

Affects mood, hunger, sleep, and arousal

Treating Osteoporosis

Calcium Vitamin D supplements Weight-bearing exercise Hormone replacement therapy

Perforating (Volkmann's) canals

Connect blood vessels and nerves of periosteum, medullary cavity, and central canal

Epiphysis

End of a long bone that consists of compact bone externally and spongy bone internally

Estrogen

Female sex hormone

Canaliculi

Hairlike canals that connect lacunae to each other and the central canal

Repair involves four major stages

Hematoma formation, fibrocartilaginous callus formation, bony callus formation, bone remodeling

inorganic components of bone

Hydroxyapatites (mineral salts)

axial skeleton

Long axis of body: Skull, vertebral column, rib cage

long bones

Longer than they are wide Limb bones

Calcitonin

Lowers blood calcium levels

Testosterone

Male sex hormone

nutrient foramen

Narrow tunnel through the diaphysis that allows blood vessels into the medullary cavity

Control of Remodeling

Occurs continuously but regulated by genetic factors and two control loops

bone deposit

Occurs where bone is injured or added strength is needed

functions of bones: hormone production

Osteocalcin secreted by bones helps to regulate insulin secretion, glucose levels, and metabolism

resorption is function of

Osteoclasts

compact bone consists of

Osteon (Haversian system) Canals and canaliculi Interstitial and circumferential lamellae

functions of bones: protection

Protect brain, spinal cord, and vital organs

hyaline cartilage

Provides support, flexibility, and resilience

Hydroxyapatites (mineral salts)

Responsible for hardness and resistance to compression

functions of bones

Support Protection Movement Mineral and growth factor storage Blood cell formation Triglyceride (fat) storage Hormone production

wolf's law of bone

The shape of a bone reflects the stress it endures

flat bones

These bones are thin, flat, and curved. They form the ribs, breastbone, and skull.

hematoma formation

Torn blood vessels hemorrhage, forming mass of clotted blood called a hematoma

growing bones widen as they lengthen through apposition growth (can occur throughout life) T or F

True

what is the cause of rickets

Vitamin D deficiency

Response to Mechanical Stress

Wolff's law: A bone grows or remodels in response to forces or demands placed upon it

Osteoporosis

a condition in which the bones become fragile and break easily

fibrocartilaginous callus formation

a mass of repair tissue

primary ossification center

a region where bone tissue will replace most of the cartilage

excesses or deficits of any hormones cause

abnormal skeletal growth

osteomalacia

abnormal softening of bones in adults

calcification front

abrupt transition zone between osteoid seam and older mineralized bone

testosterone and estrogen promote

adolescent growth spurts

two ways in which cartilage grows

appositional and interstitial

fractures

are breaks

trabeculae of spongy bone

are like cables on a suspension bridge, they confer strength to bone

when does bone lengthening in females cease?

around 18 years of age

when does bone lengthening in males cease?

around 21 years of age

osteoid seam

band of unmineralized bone matrix that marks area of new matrix

skeletal cartilage contains no

blood vessels or nerves

epiphyseal plate thins, then is replaced by

bone

greenstick fracture

bone breaks incompletely. common in children

comminuted fracture

bone breaks into many fragments

intramembranous ossification

bone develops from a fibrous membrane

displaced fracture

bone ends are out of normal alignment

non-displaced fracture

bone ends retain their normal position

Osteoblasts

bone forming cells

endochondral ossification

bone forms by replacing hyaline cartilage

periosteal cells

bone lining cells on the external bone surface

endosteal cells

bone lining cells on the internal bone surface

what is scattered throughout spongy bone

bone marrow

osteoprogenitor cells

bone stem cells

irregular bones

bones of the vertebrae and face

short bones

bones of the wrist and ankles

appendicular skeleton

bones of upper and lower limbs: girdles attaching limbs to axial skeleton

Depression (bone marking)

bowl or groove like cut out that can serve as passageways for vessels and nerves, or plays a role in joints

closed (simple) fracture

break that does not penetrate the skin

sacrificial bonds

break under stress to dissipate shock and quickly reform

bone resorption

breakdown of bone

complete fracture

broken all the way through

open (compound) fracture

broken bone penetrates through the skin

depressed fracture

broken bone portion is pressed inward

functions of bones: mineral and growth factor storage

calcium and phosphorus, and growth factors reservoir

cartilage is made up of

chondrocytes

Lamellae

contain collagen fibers that run in different directions in adjacent rings

Endosteum

covers inside portion of compact bone

Periosteum

covers outside of compact bone

Bisphosphonates

decrease osteoclast activity and number

gross anatomy of compact bone

dense outer layer on every bone that appears smooth and solid

sustained high blood calcium levels can lead to

deposits of calcium salts in blood vessels or kidneys and formation of kidney stones

Where is yellow marrow found?

diaphysis

some risk factors for osteoporosis

diet poor in calcium and protein, smoking, genetics

what does resorption do?

dig depressions or grooves as they break down matrix

closed reduction

doctor manipulates to correct position

osteoclasts remove bone on

endosteal surface

How often is compact bone replaced?

every 10 years

how often is spongy bone replaced

every 3-4 years

functions of bones: triglyceride (fat) storage

fat used for an energy source is stored in bone cavities

interstitial lamellae

fill spaces between osteons

bone lining cells

flat cells on bone surfaces believed to also help maintain matrix

functions of bones: support

for body and soft organs

levels of bone structure

gross, microscopic, chemical

interstitial growth

growth from within

postnatal bone growth

growth in length of long bones

appositional growth

growth in width

epiphyseal plate

growth plate

epiphyseal fracture

growth plate (epiphyseal plate) separates from shaft of bone (diaphyses)

In adults, red marrow is located

heads of femur and humerus

circumferential lamellae

help long bone to resist twisting

functions of bones: blood cell formation

hematopoiesis occurs within the marrow cavities of bones

hypercalcemia

high levels of calcium cause nonresponsiveness

fibrocartialge

highly compressible, forms cushion-like discs between vertebrae

Opening (bone marking)

hole or canal in bone that serves as passageways for blood vessels and nerves

two control loops of remodeling

hormonal controls and response to mechanical stress

What covers area of bone that is part of a movable joint

hyaline cartilage

what makes up 65% or bone by mass?

hydroxyapatite

when can yellow marrow convert to red marrow?

if the person becomes anemic

Denosumab

improves bone density in elderly

parathyroid hormone

increases blood calcium levels

osteogenic layer

inner layer abutting bone and contains primitive osteogenic stem cells that gives rise to most all bone cells

immobilization

is needed for healing by a cast

compact bone is also called

lamellar bone

functions of bones: movement

levers for muscle action

Hypocalcemia

low levels of calcium cause hyper excitability

skeletal cartilage

made of high resilient, molded cartilage tissue that consists primarily of water

gross anatomy of spongy bone

made up of a honeycomb of small, needle-like or flat pieces of bone called trabeculae

Osteocytes

mature bone cells

growth hormone

most important hormone in stimulating epiphyseal plate activity in infancy and childhood

bones thicken in response to increased stress from

muscle activity or added weight

incomplete fracture

not broken all the way through

capillaries in endosteum supply

nutrients

New bone matrix is deposited by

osteoblasts

bony callus formation

osteoblasts begin to produce spongy bone trabeculae joining portions of the original bone fragments

Types of bone cells

osteocytes, osteoblasts, osteoclasts

Cells of bone tissue

osteogenic cells, osteoblasts, osteocytes, bone lining cells, osteoclasts

organic components of bone

osteogenic cells, osteoblasts, osteocytes, bone-lining cells, osteoclasts, and osteoid

bone disorders

osteomalacia, rickets, osteoporosis

Projection (bone marking)

outward bulge of bone

remodeling units

packets of adjacent osteoblasts and osteoclasts coordinate remodeling process

Fracture Classification

position of bone ends after fracture, completeness of break, whether skin is penetrated

Ossification (osteogenesis)

process of bone tissue formation

Three types of bone markings

projection, depression, opening

spiral fracture

ragged break occurs when excessive twisting forces are applied to a bone

open spaces between trabecular are filled with

red or yellow bone marrow

fracture treatment involves

reduction

osteoblasts

responsible for bone growth

sesamoid bones

round bones found near joints

Central (Haversian) Canal

runs through the core of the osteon that contains blood vessels and nerve fibers

sharpey's fiber

secures periosteum to bone

elastic cartilage

similar to hyaline cartilage but contains elastic fibers

bone markings

sites of muscle, ligament, and tendon attachment on external surfaces

Lacunae

small cavities that contain osteocytes

rickets

softening of bones in children

Where is red marrow found?

spongy bone

where is red marrow found in newborns?

spongy bone and medullary cavities

mesenchymal cells

stem cells that respond to injury or infection

osteon

structural unit of compact bone

trabeculae

supporting bundles of bony fibers in spongy bone

open reduction

surgical pins or wires secure ends

resorption bays (osteoclasts)

the depressions that the cells are located when active

paget's disease

the excessive breakdown of bone tissue, followed by abnormal bone formation

reduction

the realignment of broken bone ends

diaphysis

the shaft of the bone

Hematoma

tumor of blood

Osteoid

unmineralized bone matrix

How do Canaliculi form?

when matrix hardens and cells are trapped