Ch 6, bones & skeletal system

Question 1

Where is hyaline cartilage mainly found on the skeleton

Answer 1

• articular joints (covers end of joints)
• costal cartilages (connects ribs to sternum)
• respiratory cartilages (skeleton of larynx)
• nasal catilages

Question 2

what are the main descriptive properties of hyaline cartilage

Answer 2

Resilience and flexibility

Question 3

What bones are included in the axial skeleton?

Answer 3

long axis of the body, includes bones of skull, vertebral column, and rib cage

Question 4

What bones are included in the appendicular skeleton?

Answer 4

included bones of upper and lower limbs and the girdles that attach them ex: arms legs shoulder hip bones ect

Question 5

Briefly describe long bones, short bones, flat bones, and irregular bones:

Answer 5

• long bones: have a shaft and 2 expanded ends
• short bones: cube shaped (ankles wrists)
• flat bones: thin, flattened, usually curved (sternum, scapulae, ribs and most skull bones)
• irregular bones: complicated shapes (vertebrae, hip bones)
• sesamoid bones: special bone that forms in tendon (patella). can act to change pull of tendon.

Question 6

List the 7 major functions of bones

Answer 6

1) support 2) protection 3) mineral homeostasis 4) movement 5) Hemopoiesis (production of blood cells and platelets which occurs in the marrow) 6) triglyceride (fat) storage 7) hormone production

Question 7

What hormone does bones produce and what is its function

Answer 7

bones produce osteocalcin: regulates bone formation; protects against obesity, glucose intolerance, and diabetes mellitus (high blood sugar levels)

Question 8

What are the main minerals associated with bones

Answer 8

Calcium (Ca) and phosphorus (P) calcium phosphate and calcium carbonate

Question 9

where is triglyceride stored in bones

Answer 9

in the yellow marrow in bone cavities

Question 10

what is the matrix on bone

Answer 10

25% water, 25% protein fibres, 50% mineral salts

Question 11

Describe trabeculae

Answer 11

honeycomb like collection of small flat needles. Are filled with red (flat, irregular) or yellow (long) bone marrow. *in flat bones trabeculae is called dipole.

Question 12

Where is the diaphysis located on the bone

Answer 12

forms the long axis of bone, the medullary cavity is located in this area. medullary cavity contains yellow bone marrow.

Question 13

Where is the epiphysis located on the bone

Answer 13

the bony ends, joint surface is covered with hyaline cartilage

Question 14

Describe the periosteum

Answer 14

• double-layered membrane that covers the entire external surface of bone, minus joint surfaces.
• fibrous outer layer is made of dense irregular connective tissue
• supplied with nerve fivers and blood and lymphatic vessels, which enter the bone though nutrient foramina
• inner osteogenic layer is composed of osteoblasts (forming) and osteoclasts (destroying)
• Sharpey’s fibers - collagen fibres that brake through bone securing periosteum to the underlying bone

Question 15

Describe the endosteum

Answer 15

• delicate membrane that covers internal surfaces of bones
• covers trabecular of spongy bone and lines canals that pass though compact bone.
• contains osteogenic (undifferentiated stem) cells

Question 16

what are the 5 bone cells

Answer 16

1) Osteogenic cells: mitotically active undifferentiated cells, found in peritoneum and endosteum.
2) Osteoblasts: bone FORMING cells that secrete the bone matrix
3) Osteoclasts: facilitate DESTRUCTION of bone matrix, found at sites of bone reabsorption
4) Osteocytes: spiderylike mature bone cells that conform to lacunae spaces they occupy and function to monitor and maintain bone matrix.
5) Bone lining cells: flat cells found on bones surfaces when remodelling; similar function to osteocytes.

Question 17

What is one structural unit of bone called

Answer 17

Osteon or Haversian system

-Osteon = a group of elongated hollow tubes (lamellae) of bone matrix.

Question 18

What is the function of the central canal or Haversian canal

Answer 18

runs though the core of each osteon allowing small blood vessels and nerve fibres to service the osteon

Question 19

what is the function and location of perforating canals or Volkmann’s canals

Answer 19

they lie at right angles to the central canal and connect the blood and nerve supply of the periosteum to those in the central canals and medullary cavity

Question 20

what are lacunae

Answer 20

hollow spaces at the junctions of the lamellae *siper shaped osteocytes occupy these hollow spaces

Question 21

what are canaliculi

Answer 21

hair like canals that connect the lacunae to each other and the central canal. *canaliculi connect tie all the osteocytes in a mature osteon together facilitating communication and waste and nutrients exchange.

Question 22

what are the organic components of bones

Answer 22

ALL the bone CELLS: osteogenic cells, osteoblasts, osteoclasts, bone lineing cells, osteocytes.
-Osteoid= organic part of matrix consisting of round substance (proteoglycans and glycoproteins) and collagen fibres (provides flexibility and tensile strength) *

Question 23

what are the inorganic components of bones

Answer 23

HYDROXYAPATIES or Mineral Salts account for 65% of bone mass
-mostly calcium phosphate which is present as tightly packed crystals providing exceptional hardness and resistance to compression *

Question 24

what is osteogenesis

Answer 24

= ossification = process of bone formation

Question 25

what does osteogenesis lead to

Answer 25

• bony skeleton of embryos
• bone growth until early adulthood
• bone thickness, remodelling, and repair
• early fetal skeleton is made of hyaline cattily and fibrous membranes - ossification doesn’t start until week 8

Question 26

what are the two main patterns of bone growth

Answer 26

1) intramembraneous ossification: bone development from fibrous membranes = membraneous bone
2) Endochondral ossification: bone developed by replacing cartilage = endochondral bone = most bones

Question 27

Describe the steps of Intramembranous ossification

Answer 27

• formed by fibrous membranes
  1) ossificiation centre forms from osteoblasts
  2) Bone matrix secreted by ossification centre and is mineralized by hydroxyapatite formation tapping osteoblasts in lacunae
  3) bone matrix forms around blood vessels and periosteum forms trabulae are formed
  4) outer trabeculae thicken and form compact bone; trabeculae remain in spongy bone which then becomes heavily vascularized and red marrow forms

Question 28

what is the most common type of bone formation called

Answer 28

endochondral ossification (forms hyaline cartilage)

Question 29

what are the five stages of endochondral ossification

Answer 29

1. formation of bone collar
2. cavitation (formation of an empty space in a solid) of hyaline cartilage
3. invasion of internal cavities by periosteal bud and spongy bone formation
4. formation of the medullary cavity; appearance of secondary ossification centre in the epiphyses
5. ossification of the epiphyses with hyaline cartilage remaining only in the epiphyseal plates.

Question 30

briefly describe growth in length of long bones

Answer 30

• cartilage on the side of the epiphyseal plate closest to the epiphysis is relatively inactive
• cartilage abutting the shaft of the bone organizes into a pattern that allows fast, efficient growth
• cells of the epiphyseal plate proximal to the resting cartilage form four functionally different zones

Question 31

what are the four functional zones in long bone growth

Answer 31

1. proliferation zone
2. hypertrophic zone
3. calcification zone
4. ossification zone

Question 32

describe the four zones in long bone growth

Answer 32

1. proliferation: cartilage cells undergo mitosis
2. hypertrophic: older chondrocytes enlarge
3. calcification: the matrix becomes calcified, chondrocytes die, and the matrix begins to deteriorate
4. ossification: new bone formation occurs

Question 33

steps of Appositional (width) bone growth (4)

Answer 33

1. osteoblasts beneath the periosteum secrete bone matrix, forming ridges that follow the course of periosteal blood vessels
2. As the bony ridges enlarge and meet, the groove containing the blood vessel becomes a tunnel
3. the periosteum lining the tunnel is transformed into an endosteum and the osteoblasts just deep to the tunnel endosteum secrete bone matrix, narrowing the canal
4. as the osteoblasts beneath the endosteum form new lamellae, a new odeon is created. Meanwhile new circumferential lamellae are elaborated beneath the periosteum and the process is repeated, continuing to enlarge bone diameter.

Question 34

what happens to bones during remodelling

Answer 34

bone is resorbed and added by appositional growth.

• adjacent osteoblasts deposit bone and osteoclasts resorb bone at the periosteum and endosteum surfaces.
• bone is removed from the inside and added to the outside - this maintains bone proportions between epiphysis and diaphysis

Question 35

what is needed to bone deposition

Answer 35

• occurs where bone is injured to extra strength is needed

- requires a diet rich in protein, vitamins c,d and a, calcium, phosphorus, magnesium, and manganese

Question 36

what mineral is essential for mineralization of bone

Answer 36

alkaline phosphatase

Question 37

sites of new matrix deposition are revealed by:

Answer 37

1. osteoid seam: unmineralized band of bone matrix

2. calcification front: abrupt transition zone between the osteoid seam and the older mineralized bone

Question 38

what are the common types of fractures

Answer 38

1. open: bone penetrates skin
2. closed: skin not perforated
3. incomplete: doesn’t extend across the bone
4. complete: does
5. displaced: bone ends are out of normal position
6. nondisplaced: bone ends stay in place