Chapter 6 bone and bone tissue

bone. without it inorganic matrix

( minerals) cannot resit compression

Perforating fibers

(Sharpey's fibers) - made of collagen; anchors periosteum firmly to underlying bone surface by penetrating deep into bone matrix

epiphyseal plates

(growth plates); line of hyaline cartilage found in developing bones of children

-Medullary cavity

(marrow cavity) within diaphysis contains either red or yellow bone marrow, depending on bone and age of individual

Zone of calcification

(second to last region) - dead chondrocytes; some calcified

Zone of reserve cartilage

- (closest to epiphysis) cells that are not directly involved in bone growth but can be recruited for cell division if needed

Osteopetrosis ("marble bone disease")

- defective osteoclasts ( to degrade bone);

Flat bones

- thin and broad bones; include ribs, pelvis, sternum(breastbone), and most skull bones

•Skeletal system includes

-Bones, joints, and associated supporting tissues

endosteum

-Bony struts of spongy bone and all inner surfaces of bone are covered by thin membrane contain different populations of bone cells involved in maintenance of bone homeostasis

hormone estrogen

-Increases rate of longitudinal bone growth; inhibits osteoclast activity -When estrogen levels spike in teen years an accompanying "growth spurt" occurs in females -Accelerates closure of epiphyseal plate at much faster rate than testosterone; leads to average height differences between genders

3 types of cells found in bone

-Osteoblasts -Osteocytes -Osteoclasts

steps for bone remodeling

1. hematoma fills the gap between the bone fragments 2.fibroblast and chondroblast infiltrate the hematoma and soft callus forms 3.osteoblast build bone callus 4. the bone callus is remolded and primary bone is replaced with secondary bone

bone structure

5 classes despite diversity of bone appearance. All 206 bones fit into categories based on shape.

short bones

Also named for shape rather than size, Roughly cubed- shaped as long as they are wide; includes bones of wrist or carpals and ankle taraslas.

Bones

Main organ system

osteoblasts

Have a blast making cells

One of the main factors affecting bone growth is group of chemicals called

Hormones

5 different zones

Zone of reserve cartilage Zone of proliferation Zone of hypertrophy and maturation Zone of calcification Zone of ossification

Zone of proliferation (next region)

actively dividing chondrocytes in lacunae

most bones complete process by

age 7

Mineral storage and acid-base homeostasis

bone is most important storehouse for calcium, phosphorus, and magnesium salts; minerals are also present in blood as electrolytes, acids, and bases; critical for electrolyte and acid-base maintenance

Fat storage

bones also contain yellow bone marrow; made up of fat cells (adipocytes); storetriglycerides; fatty acids from breakdown of triglycerides can be used as fuel by cells

•(appositional growth)

bones grow in width

Blood cell formation

bones house red bone marrow - specialized connective tissue involved in formation of blood cells (hematopoiesis)

movement

bones serve as sites for attachment of most skeletal muscles; when muscles contract, they pull on bones; generates movement at joint

•Long bones lengthen

by longitudinal growth; involves division of chondrocytes (not osteocytes or osteoblasts) in epiphyseal plate

Zone of ossification (last region)

calcifiedchondrocytes and osteoblasts

What canals connect lacunae together?

canaliculi;

bones come from

cartilage

compact bone

cells are highly compacted not easily breakable

1.Protection-

certain bones (skull, sternum (breastbone), ribs, and pelvis) protectunderlying organs; Structure-Function Core Principle

Bonne without organic matrix

collagen is brittle and easily shatters

organic matrix (osteoid)

collagen--helps bone resist torsion (twisting) and tensile (pulling or stretching) forcesflexiable

Epiphyseal plate

composed of hyaline cartilage that did not ossify; five different zones of cells:

inorganic matrix

consists of a calcium hydroxyapatite, which is in a crystalline structure.

osteoblast

create osteocytes

Charlie has a break in the shaft of his thigh bone. He broke the:

diaphysis

The long, tubular shaft of a long bone is called __________.

diaphysis.

causes of osteoporosis

diet, vitam D defincay,

growth hormone

effects both longitudinal and appositional growth

central canal

endosteum-lined hole in center of each osteon; blood vessels and nervessupply bone

hormone estrogen

female sex hormone

Osteogenic cells

flattened cells; differentiate into osteoblasts when stimulated by specific chemical signals

spongy bone -

has no central or perforating canals supplying blood to trabeculae; obtain blood from vessels in bone marrow

Male sex hormone testosterone

has pronounced effect on bone growth

bone marrow transplant

have improperly functioning hematopoietic cells; benefit from bone marrowtransplantation ( hemotatis ) Makes new red blood cells

What is the function of red bone marrow?

hematopoietic

sinuses

hollow, air-filled spaces

Irregular bones

include vertebrae and certain skull bones; do not fit into other classes because of irregular shapes

yellow bone marrow

is a fat storage

Rings of each tree are made up of thin layers ofbone called

lamella

Which shape of bone contains a medullary cavity and epiphyseal lines?

long

Red bone marrow

loose connective tissue; supports islands of blood-forming hematopoietic( process of creating white and red blood cells.

osteoblast

makes bone

Crystalline structure

makes bone one of hardest substances in body; strong and resistant to compression Allows bone to be both protective and supportive; demonstrates

organic matrix

makes up remaining 35%; consists of collagen fibers and usual ECM components

yellow bone marrow is found

medullary cavity

red bone marrow is found where in children

medullary cavity because they need more to grow

Periosteum

membrane composed of dense irregular collagenousconnective tissue; rich with blood vessels and nerves; surrounds outer surface of long bones ( protection )

inorganic matrix

minerals make up about 65% of bone's total weight

Which of the following functions is associated with the skeletal system? Thermoregulation Vitamin D synthesis Movement

movement

Zone of hypertrophy and maturation

next region closer to diaphysis) - maturechondrocytes

Perforating canals (Volkmann's canals)

originate from blood vessels in periosteum; travel at right angles (perpendicular) to central canals of neighboring osteons;connect them to one another

Compact bone cross section resembles forest oftightly packed trees; each tree is a unit called

osteon

Circumferential lamella

outer and inner layers of lamellae just insideperiosteum; at boundary with spongy bone; add strength

bone / osseous tissue

primary tissue found in bone; composed mostly of extracellular matrix with a smallpopulation of cells scattered throughout

ossification or osteogenesi

process of bone formation

hematopoiesis

process of making new blood cells and platelets, which occurs in the bone marrow.

Functions of skeletal system

protection mineral storage and acid base homeostasis blood cell formation fat storage movement support

spongy bone

provides protective structure for bone marrow tissue

sesamoid bones

red bone marrow

osteoclasts

responsible for bone resorption. will destroy osteocytes, break down bone

Epihyseal lines

separate both proximal and distal epiphyses from diaphysis

Diaphysis

shaft of long bone; each end is epiphysis; covered with thin layer of hyaline cartilage (articular cartilage) found within joints (articulations) between bones

support

skeleton supports weight of body; provides its structural framework

Osteocytes in lacunae

small cavities between lamellae; filled with extracellular fluid

spongy bone

space within the cells things found inside

Sesamoid bones

specialized bones located within tendons; usually small, flat, and oval-shaped; give tendons mechanical advantage; give muscles better leverage; patella (kneecap) is example

Red bone marrow is found in

spongy bone

trabecuale

struts or ribs of bone; covered with endosteum

Bone growth

takes place at epiphysis on side closest to diaphysis

yellow bone marrow

triglycerides, blood vessels, and adipocytes

Internal structure of short, flat,irregular

two outer layers of thin compact bone with middle layer of spongy bone (diploë) and associated bone marrow

-Spongy bone

usually not weight-bearing like compact bone; much lessdensely packed

Osteoporosis

•Most common bone disease in United States; bones become weak and brittle due to inadequate inorganic matrix; increases risk of fractures with decreased rate of healing

Epiphyseal plate

•composed of hyaline cartilage that did not ossify; five different zones of cells:

Growth hormone

•secreted by anterior pituitary gland; enhances protein synthesis and cell division in nearly all tissues, including bone

bones

Dense regular, irregular collangeous tissue and bone marrow

Long bones

Named for overall shape not actual size( some are quite small). Longer then they are wide, includes most bones in arms and legs.

osteocytes

Osteoblasts eventually surround themselves with matrix in small cavities (lacunae); become osteocytes that no longer actively synthesize bonematrix