Lecture 2 & 3 - Bone Biology

Question 1

list the important essential components of the skeleton

Answer 1

Mechanical component
- > it protects (soft tissue and organs)
- > anchors (ligaments)
- > rigid levers for movement
Physiological production center
- > blood cells
- > storage facilities for fat calcium
ITS NOT STATIC SCAFFOLDING OF THE BODY, IT’S ALWAYS ADAPTING AND CHANGING

Question 2

the skeleton makes up what percentage of your total body weight

Answer 2

20%

Question 3

what are the four factors of skeletal variation?

Answer 3

• > ontogeny (growth)
• > sexual dimorphism (xx vx xy)
• > geography (based on how population have adapted to their location/climate)
• > idiosyncratic (usually extra foramens/notches)

Question 4

explain Wolff’s Law

Answer 4

BONE IS DEPOSITED WHERE IT IS NEEDED AND RESORBED WHERE IT IS NOT NEEDED (use it or lose it)
- > 1869 Julius wold
- > bones are living highly vascularized structures that can change shape over time (remodel)
- > see slide 2 for graph

Question 5

liste the components of the MSK system and what they do/what they are

Answer 5

Joints
- > connections between different skeletal elements (articulation)
Cartilage
- > dense and elastic compressible connective tissue
Ligaments
- > bone to bone, stabilizing
Tendons
- > muscle to bone, movement of the joint

Question 6

disarticulation vs articulation

Answer 6

disarticulation means separated and articulated means together

Question 7

list the three main joint types

Answer 7

Synovial joints
- > mobile
Cartilaginous joints
- > semi-mobile
Fibrous/Syndesmoses Joints
- > immobile

Question 8

list the types of synovial joints

Answer 8

• > pivot joint
• > ball and socket
• > hinge joint
• > sellar joint
• > planar joint

Question 9

components of a synovial joint

Answer 9

• > hyaline cartilage
• > synovial fluid
• > joint capsule

Question 9

types of cartilagenous joints

Answer 9

synchondroses
- > articulating bones that are joined by cartilage
symphysis
- > cartilaginous joint with hyaline cartilage

Question 9

what are synchondroses

Answer 9

CARTILAGINOUS JOINTS
- > articulating bones that are joined by carlitage
- > have very little movement
- > temporary between growth centers, some persist into adult hood
- > i.e. ribs to sternum

Question 10

what are symphysis

Answer 10

• > type of cartilaginous joint with hyaline cartilage
  i.e. pubic symphysis

Question 11

what are fibrous/syndesmoses joints

Answer 11

• > tight inflexible joints
• > bones joined by bands of dense fibrous, tissue in the form of membrane or ligaments
  i.e. distal tibial connected to fibula or cranial sutures

Question 12

ratio of bone’s inorganic vs organic material

Answer 12

• > 90% organic (collagen)
• > 10% inorganic (hydroxyapatite)

Question 13

what do hydroxyapatite and collagen do/provide in reference to bone

Answer 13

• > H give bone the rigidity
• > C gives us the flexibility

Question 14

list the different bone classifications (shape)

Answer 14

• > long
• > short
• > flat
• > irregular
• > sesamoid

Question 15

list some examples of long bones

Answer 15

LONGER THAN WIDE
- > femur, humerus, fibula, tibia, ulna

Question 16

list some examples of short bone

Answer 16

AS WIDE AS THEY ARE LONG
- > carpals, tarsals

Question 17

list some examples of flat bones

Answer 17

STRONG FLAT PROTECTIVE
- > scapula, sternum, cranium, os coxae, ribs

Question 18

list some examples of irregular bones

Answer 18

• > vertebrae, sacrum, mandible

Question 19

list some examples of sesamoid bones

Answer 19

PROTECTS TENDONS
- > patella, pisiform (sometimes people have extra sesamoids in hands and feet)

Question 20

what are the difference sections of a long bone

Answer 20

• > 2 epiphyses on either end
• > 2 metaphyses, which house the growth plate
• > diaphysis, long section of the bone
• > medullary cavity, housed in the diaphysis

Question 21

list the different bone types (age & structure)

Answer 21

SEE SL. 24 TO SEE GRAPH
AGE
- > woven (immature)
- > lamellar (mature)
STRUCTURE (types of lamellar bone)
- > cortical/compact
- > cancellous/spongy/trabecular
ALL MATURE BONES ARE LAMELLAR BUT WOVEN MATURES TO LAMELLAR BONE

Question 22

how does the proportion of red/yellow bone marrow change as we age, why?

Answer 22

we start out with exclusively red marrow as infants (0-1yrs) then red marrow is converted into yellow marrow during childhood and into adolescence (1-20)
- > conversion begins at the centers of the long bone and extends axially and peripherally
- > red marrow makes blood cells, time of rapid growth needs more and more blood

Question 23

list the main bone cells and what they do

Answer 23

ALL OF THESE CELLS ARE FOUND IN OSTEOGENIC TISSUES osteoblasts - > bone formation osteoclasts - > bone destruction/resorption osteocytes - > bone maintenance - > signal the appropriate cell type (osteoblasts/clasts) depending on the needs of the body/bone

Question 24

what are osteogenic tissues and where are they

Answer 24

periosteum - > a sheath/membrane that covers the whole bone (not joint/articulation point endosteum - > lines the inside of the medullary cavity

Question 25

list all the structures/transport systems found in the bone that allow for nutruient and resource transport

Answer 25

- > haversian canals - > volkmans canals - > lacunae - > canaliculi

Question 26

which structures allow for horizontal and vertical transport across the bone

Answer 26

Haversian canals - > allow for the transport of nutrients VERTICALLY across the bone (freeway) Volkman's canals - > allow for the transport of nutrients HORIZONTALLY (off ramps) Canaliculi - > the smaller branches off of the volkmans canals, also help with communication

Question 27

what is a lacunae

Answer 27

are pockets where osteocytes are found - > osteoblasts lay down bone then trap themselves then they convert into osteocytes

Question 28

what is an osteon (primary vs secondary)

Answer 28

osteon - > functional unit of cortical bone - > primary and secondary mean the same thing, secondary is just laid on top of primary * this is a good way to tell age as we can see how many secondary osteons are laid down

Question 29

what are the different types of bone development

Answer 29

intramembranous ossification - > mineralization of vascular membrane - > primarily occurs before birth, create the bone/bone blueprint within the membrane Endochondral ossification - > bones are preceded by cartilage models - > nutrient artery - > buids upon previous previously made cartilage models, occurs after birth - > diaphysis is created first (primary ossification center) and usually are created in the womb but epiphyses (secondary ossification centers) form after birth *consider babies bones aren't fully formed at birth

Question 30

list both types of directional growth

Answer 30

- > linear growth - > appositional growth

Question 31

linear growth

Answer 31

growth plates, which are organized regions of rapid growth, contribute to an increase of bone length

Question 32

appositional growth

Answer 32

- > increases in bone size/width after endochondral growth has begun