The Skeletal System

Question 1

Components of the skeletal system

Answer 1

bones
articulations
associated c.t. (tendons and ligaments)

Question 2

Functions of the skeletal system

Answer 2

support
protection
movement
blood cell production
mineral storage
energy storage

Question 3

Bone is considered a subtype of which of the 4 basic types of tissue?

Answer 3

connective tissue

Question 4

What characteristic of c.t. differentiates if from other tissues?

Answer 4

tends to consist of relatively few cells and a great deal of material between the cells – extracellular matrix

bone is no exception

Question 5

4 types of bone cells

Answer 5

1. osteoprogenitor
2. osteoblasts
3. osteocytes
4. osteoclasts

Question 6

Osteoprogenitor Cells

Answer 6

stem cells that are found in embryonic c.t. (mesenchyme)

Question 7

Osteoblasts

Answer 7

bone-forming cells, derived from osteogenic cells

they secrete components of matrix and initiate the process of ossification

Question 8

Osteocytes

Answer 8

mature bone cells

develop as osteoblasts become encased in mineralized matrix

maintain bone tissue and have roles in actions such as minerals balance and nutrient exchange in mature bone

Question 9

osteoclasts

Answer 9

huge cells formed by the fusion of many white blood cells known as monocytes

they release powerful enzymes and acids that digest the matrix of bone

important to maintain calcium balance and reshape bones

Question 10

What forms the bulk of bone mass?

Answer 10

extracellular matrix, as bones are widely separated from each other

Question 11

Extracellular matrix of consists approximately:

Answer 11

50% mineral salts
25% water
25% collagen fibers

Question 12

prominent mineral in bone matrix

Answer 12

calcium; mostly combined with phosphorus to form calcium phosphate

Question 13

what do proteins do within bones

Answer 13

proteins – collagen fibers— provide a framework for mineralization of bone and provide strength and flexibility

Question 14

ground substance

Answer 14

fills spaces between minerals and collagen fibers and consists of mostly water and proteoglycans (proteins and polysaccharides)

this creates the FLUID ENVIRONMENT within the bone

Question 15

types of bone

Answer 15

compact - makes up about 80% of bone mass

spongy - makes up about 20% of bone mass

Question 16

Compact bone

Answer 16

has relatively few spaces - a dense arrangement of bone cells and matrix

very solid and strong

Question 17

the outer layer of any bone is…

Answer 17

arranged in a compact bone fashion

Question 18

Haversian system

Answer 18

a cylindrical unit of bone consisting of a central Haversian canal surrounded by concentric layers of lamella

Question 19

Spongy bone

Answer 19

also known and cancellous bone or trabecular bone and contains far larger spaces than compact bone

very strong and supportive

lighter than compact bone

Question 20

Trabeculae

Answer 20

fingerlike projections of the bone

give the spongy bone it’s spongy appearance

great spaces between trabeculae

Question 21

spongy bone makes up

Answer 21

the inner layer of any bone, deep to compact bone

Question 22

Types of bones based on shape

Answer 22

long
short
flat
irregular
sesamoid

Question 23

long bones

Answer 23

longer than they are wide and make up many bones of the extremities

Question 24

short bones

Answer 24

tend to be somewhat cube-shaped

many of the carpal and tarsal bones are short bones

Question 25

flat bones

Answer 25

relatively thin and provide protection and serve as large areas for muscle attachments include cranial bones, the sternum, ribs, and in some classifications the scapula

Question 26

irregular bones

Answer 26

do not neatly fit into one of the previous categories vertebrae, coral bones, most facial bones, and in some classifications the scapula

Question 27

sesamoid bones

Answer 27

develop within tendons and protect them from excessive wear and tear and may provide mechanical advantage to the direction pull of tendons number varies, especially around the hands and feet, but would def. include the patellae

Question 28

Parts of bones

Answer 28

diaphysis medullary cavity epiphysis metaphysis articular cartilage periosteum endosteum

Question 29

diaphysis

Answer 29

the shaft of the long bone

Question 30

medullary cavity

Answer 30

a long space in the diaphysis and one spot where bone marrow is found

Question 31

epiphysis

Answer 31

refers to the ends of long bone

Question 32

articular cartilage

Answer 32

a layer of hyaline cartilage on the end of bones at moveable joints not limited to long bones, this cartilage reduces friction and adds some shock absorption

Question 33

periosteum

Answer 33

a fibrous "sheath" around the outside of bones, except over articular cartilage roles in bone growth/repair, acts as a pathway for blood vessels and nerves and serves as an attachment site for tendons and ligaments

Question 34

endosteum

Answer 34

lines the medullary cavity and has roles in bone growth and repair

Question 35

Red bone marrow

Answer 35

site of BLOOD CELL PRODUCTION (hemopoiesis). in adults, tends to be limited to the SPONGY LAYER OF MANY FLAT BONES such as the ILIUM, sternum, and ribs

Question 36

yellow bone marrow

Answer 36

consist mostly of adipose tissue and serves as site of energy storage replaces red marrow in many adult bones, such as the medullary cavity of long bones

Question 37

blood supply in bones

Answer 37

bone has a very RICH BLOOD SUPPLY, as it is a very living tissue often HEALS much better than structures without a good blood supply, like cartilage

Question 38

bones and nerve supply

Answer 38

bones have GOOD NERVE SUPPLY, which means that sensations such as pain may be quite pronounced if bone is damaged

Question 39

endochondral ossification

Answer 39

bone forms within the cartilage model (cartilage ossifies into bone)

Question 40

Intramembranous ossification

Answer 40

bone forms directly from embryonic c.t (mesenchyme) to form sheet-like layers of bone WITHOUT A CARTILAGE MODEL involved

Question 41

bone growth in length

Answer 41

to avoid having to add bone directly to ends of bone at moving joints, a primary site of bone growth in length is at the EPIPHYSEAL PLATES (growth plate) via ENDOCHONDRAL OSSIFICATION eventually the epiphyseal plate ossifies and BONE GROWTH IN LENGTH STOPS

Question 42

bone growth in width

Answer 42

occurs via INTRAMEMBRANOUS OSSIFICATION, with no cartilage model that ossifies new bone is ADDED TO THE OUTSIDE OF THE BONES, BY OSTEOBLASTS, under the periosteum (like adding a new growth ring to a tree) spaces are HALLOWED OUT by OSTEOCLASTS NO DEFINITE END POINT for this process bone does not continue to get wider, but the capability does remain

Question 43

Bone remodeling

Answer 43

the process of bones continually to grow and be reshaped, based upon many factors including the stresses that we put on them

Question 44

What factors influence bone growth?

Answer 44

genetic age gender diet - minerals such as calcium, fluoride, magnesium. Vitamins such as A, C, D, K and B12 injuries/disease hormones physical stress