1three main structures of skeletal system
bones, ligaments, cartilage
2Functions of the skeletal system
protects inner organs, anchor for muscle attachments , aids in movement, supply leverage, stores minerals, blood cell reproduction
3Four basic bone shapes
long (skinny), short (cube shaped), flat (thin plate like, slightly curved), irregular (varying shapes)
43 types of cartilage
hyaline, elastic, fibrocartilage
5the three types of cartilage are different
due to their fibers
6what kind of fibers does hyaline cartilage have?
few fibers
7what kind of fibers does elastic cartilage have?
elastin (stretches)
8what kind of fibers does fibrocartilage have?
collagen (strong)
9Bone is a
connective tissue
10Bones are made up of
30% cells and 70% matrix
113 kinds of bone cells
osteoblasts, osteocytes, osteoclasts
12Osteocytes
most mature bone cell, most numerous in adult bone, maintains bone density, repairs bone
13Osteoblasts
immature cells, builds new bones, produces matrix in bones, stresses bone to activate these cells
14Osteoclasts
breaks down bone matrix, important for remodeling & growth
15osteogenic cells
stem cells
16Blastic activity ---> clastic activity
bone thickens, strengthened
17clastic activity ---> blastic activity
bone thins, weakens
18Two types of bone tissue
compact and spongy
19Compact bone
forms hard outer shell of bones composed of osteons
20Osteon system (haversian system)
contains blood vessels and nerves at the center of our bones
21Lacunae
small cavities in bone that contain osteocytes, arranged in concentric rings around a central canal
22In compact bones
nutrients and waste materials diffuse through the canal system between blood vessels in the central canal and bone cells
23spongy bone (cancellous bone)
porous, honeycomb like bone that is less dense than compact bone but strong; 20% of skeleton
24Wolff's law of bone
A bone grows or remodels in response to forces or demands placed upon it
25Diaphysis
shaft of a long bone that is composed mainly of compact bone and yellow bone marrow
26Epiphysis
End of a long bone; exterior on compact bone; interior on spongy bone
27When do bones develop in utero?
6 weeks as hyaline cartilage
28osteogenesis
process of bone formation
29Ossification
bony skeleton developing to replace the cartilage
30Bone lengthening occurs
epiphyseal plate
31intersitial growth
Growth in length; occurs at epiphyseal plates.
32When does the epiphyseal plate close?
around 18 in women and 20 in men
33growth spurts occur
when sex hormones stimulate chondroblasts and osteoblasts
34bone remodeling
ongoing replacement of old bone tissue by new bone tissue
35bones become thicker and stronger
in areas of stress
36growth in bone thickness is due to
osteoblasts beneath the surface and osteoclasts on endosteal surface
37two processes of bone replacement
bone deposition (osteoBLASTS) and bone resorption (osteoCLASTS)
38What triggers bone growth?
weight bearing exercises
39bone remodeling occurs
every year, around 10% of the human skeleton is broken down and replaced
40dietary calcium is needed for
blood clotting, muscle contraction, and nerve function
41Factors that affect bone remodeling
mechanical stress, hormones, nutrition, and age
42bone's response to mechanical stress
increase in strain = stimulates osteoblastic activity
decrease in strain = increase in osteoclastic cell activity