Human Body Systems
Unit 2
Skeletal System
• Skeleton- made up of all the bones in your body – 206 bones. 5 major functions:– Shape and support for body– Protects internal organs– Movement – attached to major muscles– Blood cells are formed in red marrow at center of
bones– Stores minerals like calcium for later use.
Skeletal SystemDay #2
Bone Structure
• Bones are alive, and therefore grow and develop.– Periosteum – tough membrane covering surface– Compact bone – hard, strong layer under periosteum– Spongy bone – found towards ends of long bones; with
many small spaces within it:• Marrow: soft, connective tissue found in spaces. red marrow
produces blood cells; yellow marrow stores fat as energy reserve.
– Cartilage – rubbery layer of tissue found at ends of bones where they form joints.
Joints• Any place where two or more bones come
together is a joint, held in place by tough band of tissue – ligament (bone to bone). Tendon connects muscle to bone.– Immoveable Joint – allows little or NO movement– Pivot Joint – one bone rotates around another– Ball and Socket – rounded end of one bone fits into
cup-like structure of another– Hinge Joints – back and forth movement– Gliding Joint – one part of bone slides over another.
Type of Joints
BALL & SOCKET HINGE
Day #2
Type of Joints
GLIDING PIVOT
Day #2
Muscular System• Muscle: an organ that can
relax and contract, providing the force to move the body.– Voluntary muscle: muscles
you are able to control• Examples: bicep, abdominal
– Involuntary muscle: muscles you CANNOT control• Examples: muscles in
organs, heart.
Types of Muscle Tissue• Skeletal Muscle: Mostly Voluntary
muscles attached to bones of skeleton. Tire easily.– Tendons: strong connective tissue
attaching muscle to bone.• Smooth Muscle: Involuntary
muscles found in internal organs. React and tire more slowly.
• Cardiac Muscle: Involuntary muscle found ONLY in the heart. Does NOT get tired; contractions are your heartbeats.
Types of Muscles
Cardiac Smooth
Skeleton
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Working Together• Muscle cells can only
contract, not extend. Therefore, skeletal muscles must work in pairs.– One muscle contracts (flexor), – The other muscle relaxes to its
original length (extensor)