ch 7

Question 1

what are the most durable remains of a once living body

Answer 1

bones and teeth

Question 2

what is the study of bone

Answer 2

osteology

Question 3

what does the skeletal system consist of

Answer 3

bones

cartilage (forerunner of most bones, covers many joints/mature bone)

ligaments (bone to bone)

tendon (muscle to bone)

Question 4

what are the functions of the skeletal systme

Answer 4

support (jaw bones support teeth, limb/vertebrae support body)

protection

movement

electrolyte balance (charged particles, calclium and phosphate)

acid / base balance (buffers blood by altering phosphate and carbonate salt levels)

blood formation (red bone marrow)

Question 5

bone

Answer 5

osseous tissue

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

Question 6

what is mineralization/calcification/ossification

Answer 6

hardening process of bone

Question 7

what do individual bones consist of

Answer 7

bone tissue
bone marrow
cartilage
adipose tissue
nervous tissue
fibrous connenctvie tissue

Question 8

what are the 6 types of boen

Answer 8

flat (protect soft organs)
long (rigid levers)
short (glide across one another in many directions)
irregular (do not fit into other categories)
sutural (in face)
sesamoid (knee)

Question 9

compact bone

Answer 9

dense outer shell of bone

hard/calcified/organized collagen fibers

-3/4 skeleton weight

Question 10

spongy bone

Answer 10

• loosely organized bone tissue
• Found in center of ends and center of shafts of long bones and in middle of nearly all others
• Covered by more durable compact bone
• makes skeleton lighter/slightly protective
• makes up 1/4 of weight

Question 11

what are the features of long bone

Answer 11

diaphysis

• shaft that provides leverage
• contains MEDULLARY CAVITY (marrow cavity)=space in diaphysis of long bone that conatins bone marrow

epiphyses

• enlarged ends of a long bone
• strengthen joint and anchor ligaments and tendons

Question 12

articular cartilage

Answer 12

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

• located w/in joint =slick / absorptive
• hyaline cartilage covers ends of epiphyseas

Question 13

nutrient foramina

Answer 13

• minute holes in bone surface that allows blood vessels to penetrate
• usually along diaphysis
• bring nutrients/ take bone marrow

Question 14

periosteum

Answer 14

• external sheath covering most of bone
• heavier/thicker along diaphysis
• almost all bones
• two layers of cells
  1. outer fibrous layer of collagen
  2. inner osteogenic layer of bone forming cells

Question 15

what is the difference between outer fibrous layer of collagen and inner osteogenic layer of bone forming cells of the periosteum

Answer 15

outer fibrous layer of collagen

• some fibers continuous with tendons
• contains PERFORATING FIBERS (penetrate into bone matrix)
• parallel fibers to diaphysis

inner osteogenic

• layer of bone forming cells
• w/in periosteum
• important to bone growth and healing of fractures
• growth in diameter and length

Question 16

endosteum

Answer 16

thin layer of reticular connective tissue lining marrow cavity

has cells that dissolve osseous tissue and others that deposit it

osteoplasts? and osteoblasts present

Question 17

epiphyseal plate (growth plate)

Answer 17

• area hyaline cartilage that separates epiphyses and diaphysis of children’s bones
• where epiphyses and diaphysis meet
• enables growth in length
• epiphyseal line present
• grows in length and diameter at same rate

Question 18

what is the epiphyseal line

Answer 18

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

not calcified bone yet

adults = 1-2 cells thick left

Question 19

what is bone

Answer 19

connective tissue

consists of:

• cells
• fibers
• ground substance

Question 20

four principle types of bone cells

Answer 20

osteogenic cells
osteoblasts
osteocytes
osteoclasts

Question 21

what are osteogenic cells

Answer 21

stem cells found in endosteum and inner layer of periosteum

• multiply quickly and give rise to most other bone cell types
• produce osteoblasts
• periosteum, endooosteum, plate

Question 22

osteoblasts

Answer 22

bone forming cells

• Form single layer of cells under endosteum and periosteum
• Nonmitotic = centrioles
• Synthesize soft organic matter of matrix which then hardens by mineral deposition
• Stress stimulates osteogenic cells to multiply rapidly and increase the number of osteoblasts which reinforce bone
• lots of rough ER + Golgi complex to help make new matrix/collagen fibers/semisolid matrix = new bone

Question 23

osteocytes

Answer 23

former osteoblasts that have become trapped in the matrix they deposited

• lacunae and canaliculi present
• some reabsorb bone matrix/others deposit it
• act as strain sensors (when stressed, produced biochem signals that regulate bone remodeling (shape and density changes)
• you know it is a cyste and not a blast by it being completely surrounded by solid matrix
• can go back to blast if injury occurs

Question 24

what is lacunae and canaliculi

Answer 24

lacunae=
tiny cavities where osteocytes reside

canaliculi=
little channels that connect lacunae
similar to gap junctions that allow passage of nutrients, waste, and signals

Question 25

what causes osteoporosis

Answer 25

if osteoblasts do not stay at same rate at osteoclasts = pourous bones= lighter= too much can lead to osteroporosis

Question 26

osteoclasts

Answer 26

bone dissolving cells found on bone surface develop from same bone marrow as stem cells that give rise to RBC = different origin than other bone cells (aka cant become osteoblast or cyte) - dissolving bone= part of remodling - has its own stem cells - unorganized matrix

Question 27

what is the matrix of bone tissue

Answer 27

it is 1/3 organic and 2/3 inorganic matter by dry weight mostly calcium but some magenesium and potassium

Question 28

what does the organic matter consist of in bone tissue matrix

Answer 28

synthesized by osteoblasts collagen, carbohydreates, protein complexes such as glycosaminoglyancs/glycoproteins

Question 29

inorganic matter of bone tissue matrix

Answer 29

85% hydroxyapatite (crystallized calcium phosphate salt) 10% calcium carbonate Other minerals (fluoride, sodium, potassium, magnesium)

Question 30

what does the histology of compact reveal

Answer 30

it reveals osteons = mature bone cells - CONCENTRIC LAMELLAE which surround a CENTRAL CANAL running longitudinally - PERFORATING CANALS: transverse or diagonal passageways - CIRCUMFERENTIAL LAMELLAE: fill outter region of dense bone -INTERSITIAL LAMALAE fill irregular regions between osteons

Question 31

spongy bone

Answer 31

consists of Lattice of bone covered with endosteum Thin plates of bone called trabeculae =Spaces filled with red bone marrow few osteons and no central canals (all osteocytes are close to bone marrow provides small amount strength (trabeculae develop along lines of stress) open air organization = light weight

Question 32

bone marrow

Answer 32

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

Question 33

red marrow

Answer 33

= myeloid tissue - Contains hemopoietic tissue—produces blood cells - In nearly every bone in a child - In adults, found in skull, vertebrae, ribs, sternum, part of pelvic girdle, and proximal heads of humerus and femur - mostly found diaphysis of long bones

Question 34

yellow marrow

Answer 34

found in adults - Fatty marrow that does not produce blood - Can transform back to red marrow in the event of chronic anemia - as we age, red replaced with yellow = adipose - thought to be due to lack of need for immune function