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The Human Body

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Pre-Lesson Activity

Can you name any organs that are in the human body?

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That’s right! Some include:

Heart

Lungs

Eyes

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The Human Body

  • Includes about 78 organs that are part of 11 different body systems
    • You’ll learn about some of these systems soon!
  • These organs are made of tissues, which are made of cells

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The Respiratory System

  • This is the system used for gas exchange (which we do by breathing)
  • Converts oxygen to carbon dioxide through a process called respiration
    • The body gets energy from this
  • The main parts are the lungs, airways, and blood vessels

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The Respiratory System

  • The left lung is typically smaller than the right lung to make space for the heart
  • The lungs are the only organs that can float on water
  • Some people can actually hold their breath for more than 20 minutes

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The Cardiovascular System

  • Allows blood to circulate through the body in order to blood transports nutrients, oxygen, hormones, and so on
  • Regulates the body’s temperature
  • Consists of the heart and blood vessels

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The Cardiovascular System

  • The average heart is the size of a fist in an adult
  • An electrical system controls the rhythm of your heart
  • The heart can continue beating even if it is disconnected from the body

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The Cardiovascular System

  • Your heart pumps about 2,000 gallons of blood each day
  • Newborn babies have the fastest heartbeats
  • This system stretches 66,000 miles
    • This is more than 2.5 times the circumference of the Earth!

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The Nervous System

  • Coordinates your actions and sensory information (like touch) by transmitting signals throughout the body
  • The center of learning, thought, and memory
  • Along with the endocrine system, makes sure the body remains balanced (in homeostasis)

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The Nervous System

  • Consists of the central nervous system (brain and spinal cord) and peripheral nervous system (nerves branching off from the spinal cord)
    • All made of neurons (nerve cells)
  • There are more nerve cells in the brain than stars in the Milky Way!

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The Endocrine System

  • Releases certain amounts of hormones into the bloodstream
  • The hormones help control things like mood, metabolism, the way organs work, and etc
  • Consists of various glands that make different hormones
    • There are 8 major glands

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The Endocrine System

  • Some important hormones are:
    • Insulin - helps to reduce glucose (sugar) levels in your blood
    • Glucagon - helps to increase glucose levels in your blood
    • Melatonin - controls sleep and wake cycles
    • Adrenaline - increases blood pressure, heart rate, and metabolism in reaction to stress

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The Muscular System

  • Allows the body to move
  • Maintains posture
  • Helps to circulate blood through the body
  • Mostly controlled by the nervous system, although some can act automatically
  • Consists of muscles

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The Muscular System

  • Your body contains more than 600 muscles
  • The heart is actually a muscle!
  • Muscles make up about 40% of your body weight
  • Muscles are made of muscle fibers that can shorten and lengthen as needed

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The Muscular System

  • There are three types of muscles:
    • Smooth - involuntary muscles in your gut, blood vessels, and etc that move without you thinking
    • Cardiac - in your heart
    • Skeletal muscles - attached to bones

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The Skeletal System

  • The internal framework of the body
  • Provides body support
  • Protects internal organs
  • Stores minerals and fat
  • Blood cells form here
  • Consists of bones

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The Skeletal System

  • You have about 270 bones when you are born, but some bones fuse together as you grow
    • By the time you’re an adult, this number has decreased to around 206 bones
  • Bones are filled with spongy tissue

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Fun Facts

  • Your heart beats about 100,000 times per day
  • Every second, your body produces 25 million new cells
  • You’re taller in the morning than when you go to sleep

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Post-Lesson Activities

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