Skeletal System

SupportAll living organisms need a support

structureOne-cell organisms have cytoskeletonArthropods have exoskeleton (exo = out) (i.e.

insects, snails)Vertebrates have endoskeleton (endo = in)

Skeletal System PartsBones and other connective tissues, such

as cartilage and ligaments, form the skeletal system.

FunctionsOur skeletal system and its joints

allows special movementsHips allows us to walk upright on 2

legsHands allow us to have an opposable

thumb = ability to grasp objects.Size of skull says we have a well

developed brain. (Remember evolution of late ancestors. Small skull, big jaw.)

FunctionsThe skeleton supports the body,

protects internal organs, provides for movement, stores mineral reserves, and provides a site for blood cell formation.

Examples:Skull protect brainRibs and sternum protects lungs, kidneys,

liver, stomach, heart, etc.

DivisionsThere are 206 bones in 2 parts

Axial – supports the central axis of the body

Skull, vertebrae and ribs

DivisionsAppendicular Skeleton

The bones of the arms and legs, along with the bones of the pelvis and shoulder area, form the appendicular skeleton.

StructureThe bone is surrounded by a tough layer of

connective tissue called the periosteumBlood vessels pass through here to supply bone

w/ oxygen and nutrientsBelow periosteum is compact bone. (Really dense,

but not solid)Running through compact bone are tubes called

Haversian canals that have blood vessels and nerves.

Spongy bone is less dense found inside the outer layer of compact bone.Its not soft or spongy. Its pattern provides strong

support without adding too much mass.

Structurehttp://www.pearsonsuccessnet.com/snpapp

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StructureOsteocytes

Mature bone cellsOsteoclasts

Break down boneOsteoblasts

Build up boneBone remodel even when we stop growing.

Example: Exercise puts stress on our bones and forces bone to become stronger. Broken bone need to rebuild. Also, if not used, bones become weaker and break down.

StructureBone marrow are in cavities within our

bones2 types:

Yellow – made up of fat cellsRed – makes RBCs, WBCs and platelets

Bone Marrow

Bone DevelopmentEmbryo is almost entirely cartilage.Cartilage is replaced by bone by

ossificationStarts 7 months before birth. Here’s where

osteoblasts come into play.

Types Of JointsPivot Hinge

Ball & Socket Gliding

Top of the neck

Shoulder/Hip

Elbow/Knee

Intercarpal joints

Structure of JointsCartilage covers surfaces where bone

meet. Bone on bone hurts!

A capsule surrounds the joint made of 2 layers1. ligaments2. cell that make synovial fluid (reduces

friction)

DisordersResearch and find a disorder of the skeletal

system. Name, how it affects a person and how to

treat it.Write 1 paragraph about it. Will count as 1 homework and 1 project grade.

Cranium

Mandible

Sternum

Rib

Vertebral ColumnPelvisSacrum

Coccyx

Clavicle

Scapula

Humerus

Ulna

Radius

Carpals

Metacarpals

PhalangesFemur

Patella

Tibia

Fibula

Tarsals

MetatarsalsPhalanges