the skeletal system. basics skeletal system – bones and connective tissue that holds them together...
TRANSCRIPT
The Skeletal System
Basics
• Skeletal system – bones and connective tissue that holds them together
• Human skeleton has 206 bones
• Cartilage – flexible connective tissue found between bones
http://www.msnucleus.org/classes/images/skeleton_dancing_lg_nwm.gif
More Basics
• Joint – place where two bones meet
• Ligament – long flexible band of connective tissue that connects two bones at a joint
“Divisions” of the Skeletal System
Appendicular• Allows body
movement
• Bones in the limbs that extend from trunk: legs, arms, feet and hands
Axial• Bones found
in head and trunk
• Includes vertebrae that protect the spinal cord
Major Bone Structure• Spongy bone: less
dense & surrounded by compact bone.
• Compact bone: hard & dense with calcium rings
• Periosteum: layer of connective tissue that covers/protects the bone.
Compact Bone Structure
• Made of calcium-rich rings maintained by bone cells (osteocytes).
• At the center of the rings are channels called Haversian canals, containing a small blood vessel.
Functions of the Skeletal System• Provides support• Allows for movement• Protects internal organs• Storage bank for minerals
(calcium)• Location for blood cell
formation– Red bone marrow is found
in the spongy bone and produces blood cells
– Yellow marrow is mostly fat but can change back to red marrow if necessary (forms from red marrow)
Different types of cells / cell parts produced in bone marrow
Bone Growth
• Bones grow from their ends.
• They grow longer, thicker & wider.
• Human embryos start out with skeletons mostly made of cartilage.
• Osteoblasts – cells that secrete collagen and calcium phosphate to cause hardening – this is called ossification.
Broken Bones
• Osteoblasts heal damaged/broken bones after growth has ended.
• Bones are strongest between 18 and 30. After that, calcium may be taken from the bones and used elsewhere in the body -so drink your milk!