Human Body: Cells to Systems

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Human Body Cells to Systems

• Chapter 10
• Mr. Saks
• General Science

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Words to Know

• Fetus A young mammal after fertlization of the
  egg but before birth
• Hormones Substances produced by certain glands
  in the body. These substances are circulated in
  the blood.
• Menopause Time in a womans life when
  menstruation stops
• Menstruation Monthly shedding of blood from
  uterus when an egg has not been fertilized

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• Neurons Cells throughout the body that carry
  signals to and from the brain (nerve cells)
• Organ Body tissues that form working unit, such
  as a heart or kidney.
• Ovaries the female organs that make egg cells
  and hormones
• Puberty the time in life when the reproductive
  organ develop
• System A group of organs working together

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• Tendons tough bands of tissue that attach muscle
  to bones
• Testes The male organs that make sperm cells and
  hormones.
• Tissue A group of cells that all do the same job
• Uterus The female organ in which a fertilized
  egg develops into a baby
• Ligaments are the tough bands that connect bone
  to bone.

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I. Being Human

• A. Humans are not the best at everything
• 1. Cheetahs run faster
• Birds can fly
• Dogs can smell better
• Elephants can hear better
• Many animals are stronger than us
• B. BUT we have a bigger brain
• Build fast cars
• Build airplanes
• Use glasses, telescopes, and microscopes to see
  better
• C. We are better because of our brains

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II. Organization of Cells

• Animals have specialized cells
• Cells that do one job are called tissue
• 1. Blood, muscle
• C. Organs are groups of tissue that work
  together
• Heart, stomach, lung
• Blood tissue and muscle tissue help the heart do
  its job

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• Systems are a group of organs working together
• Circulatory system moves the blood
• Digestive system breaks down food into simpler
  parts so the body can use it
• Respiratory system takes in oxygen and combines
  it with food to get energy
• Nervous system carries messages all over the body

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III. Five Senses

• Humans have five senses
• Sight, hearing, smell, taste, and touch
• Eyes are the organs of sight
• Light bounces off objects and enters the eye
• Light triggers nerves in back of eye
• These nerves send messages to your brain to form
  image

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• Many people depend on their sight
• Blind people depend on their hearing and touch
• Other senses in your body become much sharper
  (sensitive) when another sense is taken away
• Ears are the organs of hearing
• Sounds are made by vibrating air
• a. Plucking the string of a musical instrument
• Sound Waves are the moving sound vibrations you
  hear
• a. Sound waves are really molecules of air
  bumping into one another

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• 3. Ears stick out to catch sound waves
• a. They act like a satellite dish
• 4. Sound is reflected by your ear and
  directed toward your ear drum
• 5. Bones inside your ear are moved by the
  vibration
• 6. Vibrations are sent to the brain to be
  decoded

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• Tongue is the organ of taste
• Taste four flavors sour, sweet, salty, and
  bitter
• Tip of tongue tastes sweet and salty
• Side of tongue tastes sour
• Back of tongue tastes bitter
• Not all animals taste the same things
• Cats do not taste sweet things at all

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• Nose is the organ of smell
• Suppose you smell an onion
• Tiny molecules coming from the onion are what you
  are smelling
• These molecules drift up your nose
• These molecules trigger nerve cells to be decoded
  by your brain

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• Skin is the organ of touch
• Certain skin areas have a lot of nerve cells and
  are very sensitive
• Fingertips are very sensitive
• Touch helps protects the body
• a. Sharp or hot objects tell us to move away
• It is like an alarm system for us
• Skin is one of the most important organs
• a. Prevents us from drying out
• b. Keeps bacteria and other harmful organisms
  out
• Keeps your body temperature regulated (98.6)
• Sweat glands
• A gland is an organ that makes certain substances
• Sweat glands make sweat to keep the body at a
  comfortable temperature

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• Science Practice
• What do the eyebrows protect? How?
• What is the purpose of the hair on your head?
• What would you be unable to do if you didnt have
  fingertips?
• Do you think your toenails have a purpose?
  Explain.
• What would you be unable to do without
  fingernails?

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IV. Nervous System

• Human brain is larger and more developed than any
  other animal
• Brain is control center
• Neurons are the nerve cells in the body
• 1. Brain sends messages to all parts of the body
• 2. Brains receives messages from all parts the
  body
• 3. Brains controls many body functions and
  stores information

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• Spinal Cord is a big rope of neurons
• Messages travel to and from your brain by way of
  the spinal cord
• Spinal cord runs down the inside of your backbone
• Spinal cord connects all the neurons in your body
• The brain, spinal cord, sense organs, and neurons
  all work together to make the nervous system

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V. Support System

• Human body has 206 bones in it
• Skeleton are the bones working together
• Skeleton gives your body support
• Sit, walk, or stand
• Skeleton also protects
• a. Cage around your heart
• b. Skull protects your brain
• Bones are made of calcium
• Joints are were bones come together
• Wrist, knee, and in your fingers
• Ligaments connect bones

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VI. Muscles Help You Move

• Tendons help to connect muscle to bone
• These are tough bands of tissue that grip muscle
  and bone
• Muscles help your skeleton move
• Most muscles are called voluntary muscles
• This means you think to move them
• Arms, legs, hands,

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• Some muscles work without bones
• Swallow food, certain muscles push food down to
  your stomach
• Other muscles cause blood to move throughout your
  body
• They are not attached to your bones
• Involuntary muscles are those muscles that you do
  not think about
• a. Heart, lung, stomach

Voluntary Muscle
Involuntary Muscle
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VII. Reproduction and Growth

• Puberty is the time when the human reproductive
  system fully develops
• It is at this time that hormones are being
  produced by glands
• Testosterone for Men
• Estrogen for women
• These hormones are circulated by the blood stream
• Girls develop breasts and broader hips
• Boys develop broader shoulders and more muscles
• Both boys and girls grow hair under their arms
  and around their reproductive organs
• Boys voices get lower
• a. Puberty in girls happens between 10-13
• b. Puberty in boys happens between 13-16

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• During puberty Males and females begin producing
  sex cells
• Male sex cells are called sperm
• a. Made in testes
• Adult male make millions of sperm cells a day
• Female sex cells are called eggs
• a. Made in ovaries
• b. Adult females only make one egg cell a month

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• Each time the ovaries make an egg cell the uterus
  prepares for a fetus
• Uterus is the female organ in which a fertilized
  egg develops into a baby
• A fetus is an egg after fertilization but before
  birth
• Each month the walls of the uterus become thick
  with blood
• Blood will nourish a developing fetus
• Uterus, made of muscle, can stretch as fetus
  grows
• If egg is fertilized the fetus will grow inside
  uterus

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• An egg is not fertilized
• If the egg is not fertilized the blood lining the
  uterus leaves the body
• Menstruation is the monthly shedding of this
  lining
• As a woman grows older, menstruation will stop
• 1.) This usually happens around the age of 50
• The stopping of menstruation is called menopause
• People in science
• Dr. Bernadine Healy is a pioneer in health
  research especially for woman. She sees a lack
  of research into diseases affecting mostly women
  like asteoporosis.

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