The skeletal systemprovides support, protection, and facilitates movement. It is composed of bones, cartilage, and ligaments.

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  Bones:
  
  Provide the framework of the body and attachment points for muscles.
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  Cartilage:
  
  Cushions joints and provides flexibility.
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  Ligaments:
  
  Connect bones to each other.

The muscular system enables movement, maintains posture, and produces heat. It consists of three types of muscle tissue.

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  Skeletal Muscle:
  
  Responsible for voluntary movement.
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  Smooth Muscle:
  
  Found in the walls of internal organs and is responsible for involuntary movements.
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  Cardiac Muscle:
  
  Found in the heart and responsible for pumping blood.

The nervous system controls and coordinates body functions. It consists of the brain, spinal cord, and nerves.

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  Brain:
  
  The control center of the body.
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  SpinalCord:
  
  Transmits signals between the brain and the rest of the body.
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  Nerves:
  
  Carry signals throughout the body.

The respiratory system facilitates gas exchange (oxygen and carbon dioxide). It includes the lungs, airways, and diaphragm.

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  Lungs:
  
  Where gas exchange occurs.
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  Airways:
  
  Trachea, bronchi, and bronchioles transport air.
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  Diaphragm:
  
  Muscle that aids in breathing.

The digestive system breaks down food and absorbs nutrients. It includes the mouth, esophagus, stomach, intestines, and accessory organs.

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  Mouth:
  
  Where digestion begins.
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  Stomach:
  
  Churns and mixes food withgastric juices.
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  Intestines:
  
  Where nutrient absorption occurs.

The urinary system filters waste from the blood and eliminates it as urine. It includes the kidneys, ureters, bladder, and urethra.

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  Kidneys:
  
  Filter waste from the blood.
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  Ureters:
  
  Transport urine from the kidneys to the bladder.
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  Bladder:
  
  Stores urine.