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Body Lab 3-5 / Week 10 / Wednesday
3/6
Week 10 · Skin, Touch, Smell and Taste

Wednesday

Touch receptors
// The senses that touch, sniff and sample the world
⏱ about 15 min

Wednesday: Touch Receptors

Rocket hands Raven a lumpy sock. "Guess what is inside without looking!" he says.

Raven squeezes it. "Hmm. What do you notice?" she asks herself. "It is smooth, cool and round."

Rocket bounces. "Just guess!"

Nova dips lower. "Your fingers are full of tiny messengers," she says. "Let them report one clue at a time."

How you feel things

Your skin is full of tiny sense cells called receptors.

Different receptors pick up different things. Some feel light touch. Some feel pressure.

Others feel hot and cold.

When a receptor is touched, it sends a signal along a nerve.

The signal travels to your brain. Then your brain tells you what you feel.

FROM TOUCH TO BRAIN
  • ?Your finger touches a smooth stone.
  • ?Touch receptors in your skin pick it up.
  • ?A signal travels along a nerve.
  • ?The signal reaches your brain.
  • ?Your brain says, "That is smooth and cool."
WHY THIS EXERCISEReceptors send signals along nerves, and the brain makes sense of them.

Some spots feel more

Touch receptors are not spread out evenly.

Compare a fingertip with the same size patch of skin on your back.

The fingertip has about 100 times more touch receptors!

That is why fingertips are great at feeling tiny details.

Scientists test this with two points that touch the skin at once.

They find the smallest gap where a person still feels two points.

Body partSmallest gap to feel two points
Fingertip2 to 3 millimeters
Palm10 millimeters
Forearm35 millimeters
Back39 millimeters
READ THE TOUCH DATA
  • Read the question.
  • Tap your answer.
Which part can feel two points closest together?
Which part needs the biggest gap to feel two points?
Why are fingertips so good at feeling?

Mystery sock test

  1. A grown-up puts one safe object in a sock.
  2. Close your eyes. Feel the object through the sock.
  3. Say one clue: smooth or rough, hard or soft, warm or cool.
  4. Guess the object. Then peek!
  5. Try three more objects.
Safety first
A grown-up picks the objects. Nothing sharp, hot or breakable.
Good objects: a spoon, a sponge, a cotton ball or a smooth stone.
Nothing goes in your mouth.
StatementTrue or false?
Some receptors feel hot and cold.?
Touch receptors are spread out evenly all over the body.?
Touch signals travel along nerves to the brain.?
WHY THIS EXERCISEDifferent receptors feel different things, and some body parts have many more of them.
A touch signal travels along a ____ to the brain.
Fingertips have ____ touch receptors than the back.
What do we call the tiny sense cells in skin that pick up touch?
WHY THIS EXERCISEReceptors pick up touch, pressure, heat and cold and send signals to the brain.

Super sensing! Tomorrow we follow our noses into the world of smell.

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