Integumentary System

• Synthesizes vitamin D₃, essential for calcium and phophorus absorption (bone maintenance and growth)
• Provides structural support

Muscular System

• Stabilizes bone positions; tension in tendons stimulates bone growth and maintenance
• Provides calcium needed for normal muscle contraction; bones act as levers to produce body movement

Nervous System

• Regulates bone position by controlling muscle contractions
  
• Provides calcium for neural function; protects brain, spinal cord; receptors at joints provide information about body position

Endocrine System

• Skeletal growth regulated by growth hormone, thyroid hormones, and sex hormones; calcium mobilization regulated by parathyroid hormone and calicitonin
  
• Protects endocine organs, especially in brain, chest, and pelvic cavity

Cardiovascular System

• Provides oxygen, nutrients, hormones, blood cells; removes waste products and carbon dioxide
  
• Provides calcium needed for cardiac muscle contraction, blood cells produced in bone marrow; axial skeleton protects heart and great vessels

Lymphoid System

• Lymphocytes assist in the defense and repair of bone following injuries
  
• Lymphocytes and other cells of the immune response are produced and stored in bone marrow

Respiratory System

• Provides oxygen and eliminates carbon dioxide
  
• Movements of ribes important in breathing; axial skeleton surrounds and protects lungs

Digestive System

• Provides nutrients, calcium, and phosphate
  
• Ribs protect portions of liver, stomach, and intestines

Urinary System

• Conserves calcium and phosphate needed for bone growth; disposes of waste products
  
• Axial skeleton provides some protection for kidneys and ureters; pelvis protects urinary bladder and promix urethra

Reproductive System

• Sex hormones stimulate growth and maintenance of bones; surge of sex hormones at puberty causes acceleration of growth and closure of epiphyseal cartilages
  
• Pelvis protects reproductive organs of female,, protects portion of ductus deferens and accessory glands in males