Anatomy - Ch 7 Bone Tissues

made of dynamic tissues, full of cells, permeated with nerves and blood vessels

characteristics of a living skeleton

osteology

study of bone

bones, cartilages, ligaments

what is our skeletal system composed of

cartilage

forerunner of most bones; it covers many joint surfaces of mature bones

end of long bones have articular cartilage which is leftover hyaline cartilage from the formation of the bone

example of leftover cartilage from when bones were made

ligaments

holds bone together at joints (bone to bone)

tendons

attach muscle to bone

limb bones and vertebrae support body; jaw bones support teeth; some bones support viscera

example of support in the skeleton

protects brain, spinal cord, heart, lungs, and more

example of protection in the skeleton

limb movements, breathing, and other movements depend on bone

example of movement in the skeleton

calcium and phosphate levels; skeleton stores reserved/excess calcium

example of electrolyte balance in skeleton

buffers blood against large pH changes by altering phosphate and carbonate salt levels

example of acid-base balance in skeleton

red bone marrow is the chief producer of blood cells

example of blood formation in skeleton

bone (osseous) tissue

connective tissue with the matrix hardened by calcium and phosphate and other minerals

mineralization or calcification

hardening process of bone

tissue and organ

what can bone be classified as?

bone tissue, bone marrow, cartilage, adipose tissue, nervous tissue, fibrous connective tissue

what do individual bones (or organs) consist of?

long bones

at least twice as long as it is wide; they are levers acted upon by muscles; crucial for movement

short bones

less than twice as long as they are wide; glide across one another in multiple directions and are used for subtle movements

flat bones

thin, curved plates; protect soft organs

irregular bones

elaborate shapes that don’t fit into the other categories (temporal, maxilla, ethmoid, vertebra)

compact bone

dense protective outer shell of bone; covers spongy bone

spongy (cancellous) bone

loosely organized bone tissue

found in center of ends and shafts of long bones (epiphysis); flat bones are completely filled with it

where is spongy bone found?

spongy bone

where is most of our red bone marrow found

epiphyses

enlarged ends of a long bone; strengthens joint and anchors ligaments and tendons

diaphysis

shaft that provides leverage in a long bone

medullary cavity (marrow cavity)

space in the diaphysis of a long bone that contains bone marrow

epiphyseal plate (growth plate)

area of hyaline cartilage that separates epiphyses and diaphysis of children’s bones; it enables growth in length

epiphyseal line

a bony scar that marks where growth plate used to be found in adults

articular cartilage

layer of hyaline cartilage that covers joint surface; allows joint to move more freely

nutrient foramina

minute holes in bone surface that allows blood vessels to penetrate (all over)

endosteum

thin layer of reticular connective tissue lining marrow cavity and surrounds the trabeculae in spongy bone

some cells dissolve osseous tissue (calcium is released into blood) and others deposit it

what do the cells in the endosteum do

periosteum

external sheath covering most of bone; fibrous layer of collagen (some continuous with tendons); have perforating fibers that penetrate into the bone matrix

bone-forming cells that are important for bone growth and healing of fractures

what does the inner osteogenic layer of the periosteum house

two layers of compact bone enclosing a spongy middle layer; both surfaces are covered with the periosteum; endosteum lines marrow spaces

what is the structure of a flat bone

diploe; absorbs shock

what is the spongy middle layer in a flat bone and what does it do

long bone

what is the most common bone type of the appendicular skeleton

osteogenic cells

multipotent stem cells found in endosteum and inner layer of periosteum; arise from embryonic mesenchyme

they multiply continuously and give rise to most other bone cell types

what do osteogenic cells do

osteoblasts

bone-forming cells; form single layer of cells under endosteum and periosteum; synthesize soft organic material which hardens with mineral deposition

it stimulates osteogenic cells to multiply rapidly and increase the number of osteoblasts which reinforce bone

what does stress stimulate in bones

osteocytes

former osteoblasts that have become trapped in the matrix they deposited (bone maintenance cell)

lacunae

tiny cavities where osteocytes reside

canaliculi

little channels that connect lacunae; cytoplasmic processes of osteocytes reach through these

strain sensors

osteocytes act as what? so when they are stressed they produce biochemical signals that regulate bone remodeling

osteoclasts

bone-dissolving cells found on bone surface (in resorption bays), its ridged border faces the compact bone; helps maintain homeostasis and is part of bone remodeling

osteoclasts; they form from the fusion of multiple stem cells

what is one of the largest cell types in the body and why

collagen, carb-protein complexes

what is the organic matter synthesized by osteoblasts in osseous tissue

calcium phosphate salt mostly, calcium carbonate, other minerals

what is the inorganic matter in osseous tissue

stiffness

what does the mineral portion in bone provide

rickets

disease caused by mineral deficiency and resulting in soft, deformed bones

flexibility

what does the protein (collagen) portion in the bone provide

osteogenesis imperfecta

brittle bone disease; results from a defect in collagen deposition

osteon

structural and functional unit in compact bone

lamella

each individual ring that surrounds the central canal

central canal

where is most of the blood go through in an osteon

perforating canals

transverse or diagonal passages; connects blood vessels to adjacent central canals

trabeculae

individual bone filament found in spongy bone

red bone marrow

what are the spaces of spongy bone filled with

have a few osteons and no central canals

does spongy bone have osteons or central canals?

provides strength with minimal weight

what is the pro to spongy bone’s structure?

along bone’s lines of stress

what do trabeculae develop along?

bone marrow

soft tissue occupying marrow cavities of long bones and small spaces of spongy bone

red marrow (myeloid tissue)

contains hemopoietic tissue which produces blood cells

in nearly every bone of a child; in adults, skull, vertebrae, ribs, sternum, part of pelvic girdle, and proximal heads of humerus and femur

where is red bone marrow found

yellow bone marrow

marrow found in adults; fatty marrow that does not produce blood; can transform back into red marrow in the event of chronic anemia

ossification or osteogenesis

the formation of bone

intramembranous ossification and endochondral ossificiation

what are the two methods in which bone can develop in fetuses and infants

intramembranous ossification

used to thicken long bone throughout life; produces flat bones of skull and clavicle in fetus

endochondral ossification

turns cartilage into bone

spongy bone

during infancy and childhood, what do the epiphysis fill with

limited to articular cartilage covering each joint surface and the epiphyseal plate; a thin wall of cartilage separates the primary and secondary marrow cavities

what is the cartilage like during infancy and childhood

epiphyseal plate

serves as a growth zone for bone elongation; persists throughout childhood and adolescence

it has been consumed; the plate is replaced with a line

by late teens to early 20s, what has happened to all the remaining cartilage in the epiphyseal plate

gap between epiphysis and diaphysis closes; primary and secondary marrow cavities unite into a single cavity; bones can no longer grow in length

what happens in late teens and early 20s

ossification

what continues throughout life with the growth and remodeling of bones

length and width

what two directions can bones grow in

epiphyseal plate

where cartilage transitions to bone; has hyaline cartilage in the middle with transition zones on each side where cartilage is replaced with bone

metaphysis

zone of transition facing the marrow cavity in the epiphyseal plate

bone elongation (w/ the epiphyseal plate)

example of interstitial growth

interstitial growth

growth from within

marks site of former epiphyseal plate in which the epiphysis close once cartilage is gone; indicates that lengthwise growth is finished; it occurs at different ages in different bones

what is the epiphyseal line

achondroplastic dwarfism

long bones stop growing in childhood (normal torso, short limbs); failure of cartilage growth in metaphysis; mutant dominant allele by spontaneous mutation

pituitary dwarfism

caused by lack of growth hormone; normal proportions with short stature (diminished growth of bones for length and width)

appositional growth

growth occurs at bone surface; continual growth of diameter and thickness; occurs because osteoblasts of inner periosteum deposit osteoid tissue which becomes trapped as tissue calcifies

osteoblasts lay down matrix in layers parallel to surface and it forms circumferential lamella

how does appositional growth occur

enlarge the marrow cavity

what do osteoclasts in the endosteum do

microfractures are repaired, minerals are released into the blood, bones are reshaped in response to use and disuse

what occurs because of bone remodeling

architecture of bone is determined by the mechanical stresses put on it (ex: bony processes grow larger in response to mechanical stress)

what is wolff’s law of bone remodeling

osteoblasts and osteoclasts

what are the main cells involved in bone remodeling

it is involved in its own maintenance of growth and remodeling; it exchanges minerals with tissue fluid which exerts a profound influence over the rest of the body

in what ways does a mature bone remain a metabolically active organ

electrically active tissues like nervous and muscular

what does disturbance of calcium homeostasis especially disrupt

mineralization

process in which calcium, phosphate, and other ions are taken from the blood and deposited in bone

osteoblasts produce collagen fibers that spiral the length of the osteon; these fibers become encrusted with minerals; the first few crystals act as seed crystals that attract more calcium and phosphate from solution

how does mineralization occur

mineral resorption

process of dissolving bone and releasing minerals into the blood

performed by osteoclasts at ruffled border; hydrochloric acid dissolves bone minerals; acid protease enzyme digests collagen

how does mineral resorption occur

through resorption and deposit; osteoclasts dissolve bone ahead of tooth and osteoblasts deposit bone behind the tooth

how do orthodontic appliances such as braces reposition teeth

DNA, RNA, ATP, phospholipids, and pH buffers

what is a phosphate a component of