the skeletal system. types of skeletons exoskeleton: outside the body arthropods (lobster) ...

The Skeletal System

Types of skeletons

Exoskeleton: outside the body Arthropods (lobster)

Endoskeleton: Inside the body Vertebrates such

as humans

Regions of the skeleton

Axial skeleton- consists of the

skull, backbone, and rib cage

Appendicular skeleton consists of the

bones of the forelimbs and hind limbs, shoulder girdle and pelvic girdle

Functions of the skeleton

Provides support Gives the body shape Protects fragile organs-brain & heart Movement (working w/ muscular system) Stores minerals-calcium Site of blood cell formation

Blood cells are formed in bone marrow, deep within the bone.

Bone is living!

Composition of Skeletal System

The skeletal system consists of bones and special types of connective tissues,

206 bones - light, but strong Cartilage – flexible, but strong

Babies skeleton (350 ‘bones’) Why is this a benefit at this age? Eventually replaced by bone. Adults: Nose, ears, ribs, throat made of

cartilage Ends of long bones are cartilage

Composition of Skeletal System continued

Tendons: Connect muscle to

bone. Ex: achilles’ tendon

Ligaments: Connect bone to

bone Ex: ACL (anterior

crutiate ligament)

Composition continued

Joints - where bones meet

Types: Immovable - ex.

bones in the skull Slightly movable -

ex. vertebrae Freely movable -

ex. knee, elbow, shoulder

Types of Bones 5 basic types of bones:

long = compact short = spongy except

surface flat = plates of compact

enclosing spongy irregular = variable sesamoid = develop in

tendons or ligaments (ex.patella)

Sutural bones = in joint between skull bones

Skeletal disorders

Arthritis- inflammation of the joints Osteoporosis- bones become

thinner, more porous, easily broken

miscellaneous

Your skeleton is replaced every two years

Osteocyte – “bone cell” Bone is 5 times stronger than a

steel bar of the same weight. The knee is the body’s largest joint

The Muscular System

Types of Muscles

Skeletal Attached to bones Voluntary - we

consciously control Smooth

In internal organs and blood vessels

Involuntary - we do NOT consciously control

Cardiac Heart muscle Involuntary

Functions of Muscles

Movement Posture Joint stability Heat production

Muscular System Composition

656 different muscles Usually work in pairs (one relaxes while

the other retracts) Some remain partially contracted at all

times (muscle tone) Allows us to keep our head up even

when relaxed Regular exercise increases muscle tone

Muscle Miscellaneous

40% of our body weight

Cells are specialized to contract (shorten) when stimulated

The number of muscle cells you have never changes.

Repetitive muscle activity increases the size of the cells, not the number.