CH. 6 A&P

(NEED TO MOVE SOME OF THE FLASHCARDS FROM OTHER KNOWT)

ossification (osteogenesis)

The process of bone tissue formation

what is the four situation bone formation occurs

• Embryonic Formation of the skeleton (happens in month 2 of develop)

• Postnatal bone growth occurs until early adulthood (25yrs old)

• Bone Remodeling (lifelong)

• Fracture repair (lifelong, not exactly part of the cycle above)

is it cartilage before bone or no?

yes, cartilage before bone

intramembranous ossification

•begins within fibrous CT membranes formed by mesenchymal cells

•Forms flat bones of skull and mandible

•Four major steps involved

Endochondral ossification

•hyaline cartilage models are replaced by bone during fetal development

•forms most bones of the body

•Begins at primary ossification center in center of shaft

what is a fontanel

soft spots on fetal skull

(The parental cell, that can become different cells) Intramembranous Ossification begins with fibrous CT membranes formed by

mesenchymal cells

What are the four major steps involved with Intramembranous Ossification

1.Ossification centers are formed when mesenchymal cells cluster and become osteoblasts

2.osteoid is secreted, then calcified

3.Immature spongy bone (Woven Bone) is formed when osteoid is laid down around blood vessels, resulting in trabeculae

4.Compact bone replaces immature spongy bone, just deep to the periosteum, red marrow develops

When does endochondral ossification begin

at primary ossification center in center of shaft

what are the 5 steps of endochondral 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(spongey bone)

4. diaphysis elongates, and medullary cavity forms

5. epiphyses ossify (hyaline cartilage remains only in epiphyseal plates and cartilages)

where is the medullary cavity found in long bone

MIDDLE of bone

growth in length of bone growth

interstitial/longitudinal growth

Name the 5 zones of the epiphyseal plate

1. resting (quiescent)

2. Proliferation-divison (growth) zone

3. hypertrophic zone

4. calcification zone

5. ossification (osteogenic) zone

explain the resting (quiescent) zone of long bones

area of cartilage on epiphyseal side of epiphyseal plate that is relatively inactive

explain the proliferation (growth) zone of long bones

are of cartilage on diaphysis (below epiphyses) side of epiphyseal plate that rapidly divide; new cells formed move upward pushing epiphysis away from diaphysis causing lengthening

explain the hypertrophic zone of long bones

area with older chondrocytes closer to diaphysis

are newer cells closer to the plate or away from

closer to the plate

explain the calcification zone of long bones

surrounding cartilage matrix calcifies; chondrocytes die and deteriorate

explain the ossification zone for long bones

new bone is forming

what is the growth in width (thickness) called for bones

girth

what process does growth in width/girth occur

oppositional growth (occurs throughout life)

typically when growing do we see more building up then breaking down or more breaking down then building up

building up

bone remodeling consists of both of what

bone deposition and bone resorption

where does bone remodeling occur

occurs at surfaces of both periosteum and endosteum

in bone remodeling, what is Wolff’s Law

bones grow or remodel in response to demands placed on them

where does Trabeculae form

along stress lines

what does normal bone metabolism depend on

1. Minerals

   -large amts. of calcium and phosphorous

   -small. amts. of magnesium, fluoride, and manganese

2. Vitamins

   -Vitamin A

   -Vitamin C: Collagen Synthesis

   -Vitamin D: increases absorption of calcium

   -Vitamin K and B12

skeletal cartilage

made of highly resilient, molded cartilage tissue that consists primarily of water (DOES NOT HAVE BLOOD VESSELS OR NERVES)

Perichondrium

layer of dense connective tissue surrounding cartilage like a girdle (does contain blood vessels for nutrient delivery to cartilage)

what are the three types of cartilage

hyaline, elastic, and fibrocartilage

name the 7 functions of the bones

support, protection, movement, mineral and growth factor storage, blood cell formation, triglyceride (fat) storage, and hormone production osteocalcin

Bones are classified to four shapes

long bones, short bones, sesamoid, flat bones, and irregular bones

human bones are divided into two groups based on location which includes

axial skeleton- long (straight up and down); skull, vertebral column, rib cage

appendicular skeleton- bones of upper and lower limbs; girdles attaching limbs to axial skeleton

hematopoiesis occurs in

red marrow activities of certain bones

bone (osseous) tissue

predominates, but a bone also has nervous tissue cartilage, fibrous connective tissue, muscle cells, and epithelial cells in its blood vessels.

what is calcification initiated by

bone-forming cells

osteogenic cells are

stem cells that divide mitotically to produce osteoblasts

osteoblasts

immature bone-forming cells that make the ECM of bone tissue

osteocytes

mature bone cells in the lacunae

trabeculae

thin columns and plates of bone that create a spongy structure in a cancellous bone (contains red bone marrow)

ossification (osteogenesis)

the process of bone tissue formation

bone formation occurs in four situation which include

embryonic formation of skeleton(month 2 of development) , postnatal bone growth occurs until early adulthood, bone remodeling (lifelong), and fracture repair (lifelong)

hormonal controls

Growth factors (IGFs) produced by the liver are most important to childhood bone growth

Thyroid hormones promote what for the skeletal system?

bone growth by stimulating osteoblasts

Estrogen and testosterone have what effects on bone growth

growth spurt during puberty and cause skeletal differences between males & females

Parathyroid hormone

produced by parathyroid glands in response to low blood calcium level

calcitonin

produced by thyroid gland in response to high levels of blood calcium levels

three ways to classify fractures

•position of bone ends after fracture

•completeness of break

•whether skin is penetrated

comminuted fracture

bone fragments into three or more pieces

compression fracture

bone is crushed

spiral fracture

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

epiphyseal fracture

when the epiphysis and diaphysis separate along the epiphyseal (GROWTH) plate

depressed fracture

broken bone portion is pressed inward; type of skull fracture

greenstick

bone breaks incompletely, in a way a green twig breaks. only one side of the shaft breaks while the other side bends

name the four major stages of fracture repair

1. Hematoma formation-blood clots; site is swollen and painful

2. Fibrocartilaginous callus formation: fibroblasts invade the fracture site and produce collagen fibers bridging the broken ends of bone

3. Bony callus formation-osteo blasts begin to produce spongy bone joining portions of original bone fragment

4. bone remodeling- compact bone replaces spongy bone

cartilage is always before what

bone

what are the three major bone disorders

osteomalacia-bones are poorly mineralized

rickets (osteomalacia of children)-results in bowed legs and other bone deformities caused by malnutrition

osteoporosis- a group of diseases in which bone resorption exceeds deposit (bone mass declines)

two effects of aging increase susceptibility to fractures

1.) loss of bone mass (osteoporosis)

2.) Increased brittleness

periosteum covers what and endosteum covers what

periosteum covers outside of compact bone and endosteum covers inside portion of compact bone

what is cartilage

flexible connective tissue that protects joints and bones

what is a joint

part of the body where two or more bones meet to allow movement

what is a girdle

bony ring that connects limb to axial skeleton

where does primary bone ossification occur?

in the center shaft of center of shaft

How does intramembranous ossification differ from endochondral ossification?

Intramembranous ossification directly converts mesenchymal tissue into bone, while endochondral ossification begins with mesenchymal tissue transforming into a cartilage intermediate.