Human Body


Digestive System - Breaks down food and absorbs nutrients (molecules your body needs) into the bloodstream

      Digestive Pathway:

  1. Mouth

    1. Saliva (chemical digestion) - contains enzymes

    2. Teeth (mechanical digestion)

  2. Esophagus - tube that leads from the mouth to the stomach

    1. Epiglottis - a flap that covers the trachea (windpipe) when you swallow

    2. Peristalsis - a wave-like series of muscular contractions that move food down the esophagus toward the stomach

  3. Stomach

    1. Breaks down food mechanically (with muscular churning) and chemically with acids and enzymes 

  4. Small intestine

    1. Continues digestion, but main function is nutrient absorption 

    2. Nutrients are absorbed through the capillaries (tiny blood vessels) that line the villi (finger-like protrusions that increase the surface area of the small intestine)

  5. Large Intestine

    1. Continues nutrient absorption, but the main function is to absorb water from the remaining food

    2. After the water is absorbed, the remaining waste is removed from the body as feces

  6. Liver

    1. When nutrients are absorbed in the small intestine, they are sent to the liver

    2. The liver acts as a sorting mechanism, sending nutrients to the general bloodstream and toxins to the excretory system for removal



Circulatory System - Main components are the blood, heart, and blood vessels.

  • Blood

    • Parts of blood:

      • Plasma - the liquid portion of the blood containing water, vitamins, salt, etc.

      • Platelets - cell fragments that help with blood clotting (healing wounds)

      • Cells

        • Red blood cells - carry oxygen and carbon dioxide

        • White blood cell - fight infection

  • Blood vessels

    • Arteries - carry blood away from the heart (mostly oxygenated)

    • Veins - carry blood back to the heart (mostly deoxygenated)

    • Capillaries - the smallest blood vessels, responsible for gas exchange

  • Heart

    • 2 main sides (oxygenated and deoxygenated)

    • Pumps blood throughout the body



Muscular System

  • 3 types of muscle

    • Cardiac - heart muscle that involuntarily contracts in a smooth, wave-like manner

    • Smooth muscle - muscles inside the body that involuntarily move substances throughout the body and control certain organs and structures in the body

      • Found in the digestive system, blood vessels, eyes, and other internal structures

    • Skeletal muscles - voluntary muscles that are attached to bones and are responsible for all the body’s purposeful movements



Skeletal System

  • Bone Functions

    • Assist with movement

    • Provide structure to the body

    • Store minerals

    • Makes blood cells

    • Protect important organs

    • Enable hearing

  • Bones are living tissue

    • Compact tissue - hard outer layer of the bone

    • Spongy tissue - includes bone marrow

      • Where the blood cells are made

  • Ligaments - connect bone to bone

  • Tendons - connect muscles to bone

  • Cartilage

    • Makes up joints, tendons, and ligaments

      • Also found in bones

    • Provides additional structure and protection

    • Is a template for bone development in infancy