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.

Day #2 Skeletal System

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.

Day #2 Type of Joints BALL & SOCKET HINGE

Day #2 Type of Joints GLIDING PIVOT

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.

Smooth Cardiac Skeleton Day #2 Types of Muscles Smooth Cardiac Skeleton

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)