Chapter 6 Flashcards
What does the skeletal system contain?
Bones, cartilage, ligaments, other connective tissues relating to bones
What are the categories of bones?
Sutural, irregular, short, long, sesamoid, flat
What are sutural bones?
Small, flat, irregularly-shaped bones between the flat bones of the skull, individual variations between people
What are irregular bones?
Bones with irregular shapes like the vertebrae
What are short bones?
Boxy bones like the carpals and tarsals
What are flat bones?
Bones that are thin with parallel surfaces like bones of the skull
What are long bones?
Long bones are long and slender, like the femur
What are sesamoid bones?
Small, round, flat bones like the patella, individual variations between people
What are the three major types of bone markings?
Projections, openings, and depressions
What do projections do?
Allow for attachment of muscles, tendons, and ligaments, and part of joint articulations
What are openings and depressions?
Sites where blood vessels or nerves lie alongside or penetrate bones
What is an example of a projection?
Ramus of the mandible, head of the femur
What is an example of an opening?
Paranasal sinuses
What is an example of a depression?
Coronoid fossa of the humerus
What is the general structure of the long bone?
Diaphysis (shaft), Epiphysis (ends made mostly of spongy bone), and Metaphysis (narrow connective area)
What is the general structure of a flat bone?
Core of spongy bone between two layers of compact bone
What is bone tissue?
Supporting connective tissue
What causes the density of the bone matrix?
Calcium salts and collagen fibers
Where do osteocytes occur?
Lacunae
What are canaliculi?
Narrow passageways that allow osteocytes to exchange nutrients and communicate
What does the periosteum do?
Covers the outer surfaces of bones
How much bone weight is calcium phosphate?
About 2/3 of bone weight
How is hydroxyapatite made?
Calcium phosphate and calcium hydroxide interact and form crystals of it
What is 1/3 of bone weight?
Collagen fibers
What do collagen fibers do for hydroxyapatite crystals?
Provide a framework
What are the four types of bone cells?
Osteogenic, osteoblasts, osteocytes, and osteoclasts
What are osteogenic cells?
Mesenchymal stem cells that produce osteoblasts
What are osteoblasts?
Immature bone cells
What are osteocytes?
Mature bone cells
How many osteocytes per lacuna?
Only one
What are osteoclasts?
Large, multinucleate cells that absorb and remove bone matrix in osteolysis
Where does osteolysis occur?
Osteoclastic crypts
Are osteoclasts related to the other three types of bone cells?
No, they are basically a specialized type of macrophage
What is the basic unit of compact bone?
Osteon
What is the central canal of an osteon called?
Haversian canal
What do haversian canals do?
Contains blood vessels that carry blood to and from the osteon
What are perforating canals?
Perpendicular canals that also contain blood vessels for deep osteons and the medullary cavity
What are the three types of lamellae?
Concentric, interstital, and circumferential
What does concentric lamellae do?
Form osteons
What does interstitial lamellae do?
Fill spaces in between osteons in compact bone
What does circumferential lamellae do?
Occur at outer and inner bone surfaces
What is different about spongy bone?
No osteons, no blood vessels, trabeculae matrix
How does spongy bone get blood vessels?
Red bone marrow with diffusion and cannaliculi
In some parts of the body, spongy bone contains what, and why?
Yellow bone marrow, energy reserve for adipose tissue
Where is yellow bone marrow found?
Some spongy bone and medullary cavities of long bones in adults
What do medullary cavities contain in children?
Red bone marrow
What is the endosteum?
Incomplete cellular layer that lines inner surfaces of bone that’s active during bone growth, repair, and remodeling.
What is the endosteum made of?
Flattened layer of osteogenic cells that covers bone matrix
What is ossification?
Bone formation
What is calcification?
Deposition of calcium salts during ossification
What are the two ossification processes?
Endochondral and intramembranous
What happens in endochondral ossification?
Bone replaces existing cartilage, occurs during fetal development
Is the timing of epiphyseal closures the same?
No. Toes may complete ossification around age 11, while the wrist may not complete until around age 25
What is appositional growth?
How wide bones grow
What is intramembranous ossification?
Bone develops directly from mesenchymal cells, occurs during fetal development, occurs mostly in flat bones
What are spicules?
Bone grown in small struts
