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