A/P Lec 6 Bone and Bone tissue

7 functions of bones

shape, support, protection, movement, blood production, electrolyte balance, acid-base balanceand mineral storage.

How strong and light is bone

as strong as steel and as light as aluminum

What percent of an adults body weight is bone

14%

Bone composition (basic anatomically) includes

blood vessels, nerves, and living cells

5 classifications of bone types

long, short, flat, irregular, sesamoid

long bone description

longer than they are wide, typically working like levers to move limbs

long bone examples

humerus and femur

short bone description

as long as they are wide, tend to be cube shaped

short bone examples

carpals and tarsals

flat bone description

thin, flat, and often curved. typically protect organs and have large surface area for attachment

flat bone examples

skull and scapula

irregular bone description

grouped, and come in various shapes and sizes

irregular bone examples

vertebrae, facial bones

sesamoid bone description

small bones embedded in tendons

sesamoid bone example

patella

what is the diaphysis of a bone

the center shaft. it is hollow, made of compact bone, and gives the bone strength

what is the epiphysis of the bone

the head of each end of the bone. strengthens the joint and is an area of attachment

what is the medullary cavity of the bone

the central hollow portion

what color is bone marrow in children

red

what color is bone marrow in adults

yellow

what is the endosteum of the bone

the epithelial membrane lining the medullary cavity (endo - in)

what is the periosteum of the bone

dense fibrous membrane covering the diaphysis

what is the function of the periosteum

some fibers penetrate the bone, some fibers mesh with tendons for strong bone-muscle connection, and contains bone-forming cells and vessels to keep bone alive

what is the epiphyseal plate

a layer of cartilage in children that grows the bone (growth plate)

what happens to the epiphyseal plate in adults

once growth stops, the plate is replaced by an epiphyseal line

what is the study of bone

osteology

what kind of tissue is osseous tissue

a type of connective tissue

bone cells include

osteoblasts, osteoclasts, osteocytes

what is the function of osteoblasts

create bone by secreting substances that comprise the bones matrix

what is the function of osteoclasts

dissolve unwanted or unhealthy bone

general function of osteocytes

they are mature osteoblasts that sit in the bone matrix. they contribute to the maintenance of bone density/formation, and assist with regulation of blood Ca and PO4

what does the bone matrix consist of

consists of collagen fibers and crystalline salts made of calcium and phosphate

what is the name of calcium salts in bone

hydroxyapatite

what forces are bone resistant to

tensile and compressional forces

how are bones resistant to tensile forces

collagen fibers in the matrix make bone resistant to stretching

how are bones resistant to compressional forces

calcium salts allow bones to resist strong squeezing forces

why cant bone resist torsional forces

bone lacks the ability to endure twisting which is why most fractures result from twisting

what are the two types of bone tissue

compact and spongy (cancellous) bone tissue

what is compact bone

it is dense and solid, and forms shafts of long bones and surfaces of other bones

what is spongy bone

it is light and consists of a latticework of bone, and is found in the end of long bones and middle of other bones

T/F: spongy bone is soft

false, it is still hard

what is the name of the lattice work of spongy bone

trabeculae

what is the key function of the trabeculae

it has maximum strenth-weight ratio, and if a bone is stressed the trabeculae will realign to compensate

what fills the cavities in the trabeculae lattice structure

bone marrow

what are the lamellae in compact bone

layers of matrix arranged in concentric rings

what is the haversian canal in compact bone

the central canal of the lamellae, contains blood vessels

what is the osteon in compact bone

the basic structural unit consisting of the lamellae and haversian canal

what are the lacunae in compact bone

tiny gaps between rings of lamellae that contain osteocytes

what are canaliculi in compact bone

microscopic passageways that connect the lamellae to each other and feed osteocytes (cracks)

what are volkmanns canals in compact bone

transverse passageways that connect the haversian canals and transport blood and nutrients from the bone exterior to osteocytes

T/F bone is vascular and heals quickly

T

what is bone marrow

a type of soft tissue that fills the medullary cavity of long bone and spaces of spongy bone

red bone marrow function

produces red blood cells

where is red bone marrow found in children

in nearly all of a childs bones

where is red bone marrow found in adults

mostly in the axial skeleton

yellow bone marrow function

it is now saturated with fat, and in cases of severe blood loss, it can change back to red marrow

two types of ossification processes

intramembranous ossification and endochondral ossification

intramembranous ossification function

fibrous connective tissue becomes bone and applies to the bones of the skull and face

endochondral ossification function

cartilage becomes bone, and affects most bones in the fetal skeleton

what are fontanels

soft spots of fibrous connective tissue on the fetal skull

fontanels function

allow safe compression of skull during birth, and allow skull to expand readily as the brain grows after birth

how long does it take a babys skull to ossify

2 years

what is bone lengthening

process that occurs at the epiphyseal plate where chondrocytes multiply and move towards the shaft and minerals are deposited and calcifies

at what age is the epiphyseal plate replaced with spongy bone

between 16 and 25

what is an epiphyseal fracture

overstress of the epiphyseal plate can cause separation from the diaphysis or epiphysis and affect future bone growth

bone widening/remodeling description

osteoblasts in periosteum lay new layers outside of bone, and osteoclasts in the cavity dissolve bone, making it wider

bone remodeling replaces how much of the skeleton every year

about 10%

resorption process

osteoclasts dissolve old bone and reduce the mass of unused bones

ossification process

osteoblasts deposit new bone tissue on heavily used bones making them thicker

when is bone grown faster than it is resorped

during childhood and adolescence

when are ossification and resorption in balance

during early and middle adulthood

when is resorption greater than ossification

after age 40

besides maintaining bone, what else is remodeling used for

trauma repair, calcium homeostasis, and bone marking development

how are bone markings developed by remodeling

occurs as bone is stimulated by the pull of powerful muscles

what factors affect bone growth and maintenance

heredity, nutrition, growth/sex hormones, exercise

closed reduction fractures are

fractures that can be reduced without surgery

open reduction fractures are

fractures that require surgery to be reduced

pathologic fractures are

fractures that happen in diseased or weakened bones that wouldnt happen in healthy bones

5 common fracture types

simple, compound, greenstick, comminuted, spiral

simple fracture description

fractured bone remains aligned and surrounding tissue is intact

compound fracture description

a fracture where bone has pierced the skin and there is damage to the surrounding tissue

greenstick fracture description

a fracture that has an incomplete break, and typically occurs in young children

comminuted fracture description

a fracture where bone is broken into pieces, typically from crushing forces

spiral fracture description

a fracture line that spirals around the bone from a twisting force. creates jagged ends on bone

uncomplicated fractures heal in

8-12 weeks

complex fracture healing time

longer in bones that have a poor blood supply

step 1 in fracture repair

initial hematoma transforms into granulation tissue

step 2 in fracture repair

granulation tissue turns into soft callus

step 3 in fracture repair

a hard callus forms around the fracture and splints the two ends together

step 4 in fracture repair

remodeling replaces the callus tissue with bone