Bones

# of bones in the body

206

weight of the skeletal system

20 lbs

functions of skeletal system

-provides the framework/support of the body
-produces blood cells
-provides protection for the organs
-helps us breathe
-stores minerals

production of blood cells

hematopoiesis

minerals that bones store

calcium and phosphorus

osteocytes

mature bone cells

% of bone weight that comes from mineral content

60-70

% of bone weight that comes from collagen and water

30-40

collagen

a protein that makes bones flexible

reason children's bones are more flexible than adults

they have a higher collagen and water levels

shapes of bones

-long bones
-short bones
-flat bones
-irregular bones

long bones

longer than they are wide

examples of long bones

arms and legs

short bones

cube shaped; made mostly of trabecular bone

examples of short bones

wrist and ankles

flat bones

flat or curved, or platelike

examples of flat bones

sternum, skull, and ribs

irregular bones

fit together like a jigsaw puzzle

examples of irregular bones

vertebrae and hips

types of bone tissue

cortical and trabecular

cortical bone

-dense
-outer layer of the bone (hard, protective)
-higher mineral content
stronger than trabecular bone

trabecular bone

-spongy bone
-porous
-makes up the interior bone
-more flexible than cortical
-makes bone lighter in weight

periosteum

outer covering of the bone

epiphysis

ends of the bone

diaphysis

middle part of the bone (shaft)

epiphyseal plate

growth plate

medullary cavity

hollow area in diapysis

endosteum

lines the medullary cavity

parts of periosteum

-blood vessels
-lymph vessels
-nerves

parts of epiphysis

-trabecular bone tissue
-filled with red marrow
-covered with articular cartilage

yellow marrow in an emergency

converts to red bone marrow to help in RBC production

parts of diaphysis

is hollow

parts of medullary cavity

-filled with yellow bone marrow
-blood vessels
-stores fat

function of epiphyseal plate

bone fuses together when you are done growing