The Human Skeleton
Composed of the body’s
Bones
Ligaments ( bone -- bone )
Tendons ( bone -- muscle )
Cartilage
Infants have more than 300 bones at birth
Bones fuse as babies develop
206 bones in the adult human body (can be less)
1. Structure and Support
Leg bones, pelvis, and vertebrae
Supports the body’s weight
2. Protection
Skull protects the brain
Ribs and sternum
(breastbone) protects the lungs and heart
Functions of the Skeletal System
Movement
Muscles attach to bones and use them as levers to move the body
Storage
Calcium and Fat (Stored E)
Blood Cells Production :
Bone marrow produces millions per second
Bone Classification
Each bone belongs to one of two major groups:
Axial Skeleton
Skull, vertebral column, and rib cage
Involved in protection, support, and carrying other body parts
Appendicular Skeleton
Bones of upper & lower limbs
Involved in locomotion
Types of Bones :
Long Bones
Longer than they are wide
All limb bones except the patella (kneecap) and the bones of the wrist + ankle
Short Bones
Roughly cube shaped
Bones of the wrists and ankle
Flat Bones
Thin; flattened, and usually a bit curved
Scapula (shoulder blade)
Sternum (breast bone), ribs, and most bones of the skull
Irregular Bones
Have weird shapes that fit none of the 3 previous classes
Vertebrae, hip bones, 2 skull bones - mandible, and maxilla
Long Bone Structure:
Periostern : Hard outer covering
Epiphysis : Ends of the bones
Diaphysis : The shaft of the bone
Articular Cartilage : Cushions the ends of the bones and allows for smooth movement
Epiphyseal Plate : Areas made of cartilage allowing for the growth of the bone growth plate
Collagen (protein) -- provides strength and resillience
Calcium -- provides hardness and resistance to crushing
Three Types of Bone Cells
Osteocytes --
Mature bone cells suspended in matrix [ cytes = basic cells ]
Osteoblasts --
Build new bone by adding Collagen and Calcium to matrix [ blasts = build ]
Osteoclasts --
Breakdown matrix to replace stored Calcium; can also clean up unhealthy or unwanted bone
Yellow Marrow:
Largely fat
In emergencies -- massive blood loss -- convert to red bone marrow
Red Marrow
Medullary Canal
All bones consist of a dense, solid layer known as compact bone and an inner layer spongy bone
Composed of the body’s
Bones
Ligaments ( bone -- bone )
Tendons ( bone -- muscle )
Cartilage
Infants have more than 300 bones at birth
Bones fuse as babies develop
206 bones in the adult human body (can be less)
1. Structure and Support
Leg bones, pelvis, and vertebrae
Supports the body’s weight
2. Protection
Skull protects the brain
Ribs and sternum
(breastbone) protects the lungs and heart
Functions of the Skeletal System
Movement
Muscles attach to bones and use them as levers to move the body
Storage
Calcium and Fat (Stored E)
Blood Cells Production :
Bone marrow produces millions per second
Bone Classification
Each bone belongs to one of two major groups:
Axial Skeleton
Skull, vertebral column, and rib cage
Involved in protection, support, and carrying other body parts
Appendicular Skeleton
Bones of upper & lower limbs
Involved in locomotion
Types of Bones :
Long Bones
Longer than they are wide
All limb bones except the patella (kneecap) and the bones of the wrist + ankle
Short Bones
Roughly cube shaped
Bones of the wrists and ankle
Flat Bones
Thin; flattened, and usually a bit curved
Scapula (shoulder blade)
Sternum (breast bone), ribs, and most bones of the skull
Irregular Bones
Have weird shapes that fit none of the 3 previous classes
Vertebrae, hip bones, 2 skull bones - mandible, and maxilla
Long Bone Structure:
Periostern : Hard outer covering
Epiphysis : Ends of the bones
Diaphysis : The shaft of the bone
Articular Cartilage : Cushions the ends of the bones and allows for smooth movement
Epiphyseal Plate : Areas made of cartilage allowing for the growth of the bone growth plate
Collagen (protein) -- provides strength and resillience
Calcium -- provides hardness and resistance to crushing
Three Types of Bone Cells
Osteocytes --
Mature bone cells suspended in matrix [ cytes = basic cells ]
Osteoblasts --
Build new bone by adding Collagen and Calcium to matrix [ blasts = build ]
Osteoclasts --
Breakdown matrix to replace stored Calcium; can also clean up unhealthy or unwanted bone
Yellow Marrow:
Largely fat
In emergencies -- massive blood loss -- convert to red bone marrow
Red Marrow
Medullary Canal
All bones consist of a dense, solid layer known as compact bone and an inner layer spongy bone