VHS+Science+Lesson+14

Today we are going to learn about how living things respond to their environment. What is happening inside these people? How are they responding to their environment? How does your body respond to the world around you?

Every living thing receives stimuli from its environment. Every living thing responds. Living things also defend themselves against infection.

media type="youtube" key="BquIPYo7CQE" width="420" height="315" Let's watch this video of the fire alarm being pulled...

Pretty loud huh? Did you cover your ears at all?

All living things work to maintain equilibrium ( or to keep everything in balance).

When a living thing receives new information from it's senses, it receives a stimulus. For example, a loud noise is a stimulus. To maintain equilibrium, the living thing reacts to the stimulus. The reaction is called a response. Covering your ears might be a response to a loud noise.

What are some of the ways we are stimulated? What senses are we using?

Organisms keep a steady internal environment. This steadiness is called equilibrium. It keeps the body healthy.



When the equilibrium is disturbed, a stimulus will alert the body. The body responds to bring itself back to equilibrium. The body is always checking and changing it's internal environment to stay balanced.

(video of eye reacting to light stimulus) media type="youtube" key="utlTrMTgmMg" width="420" height="315"

One way an organism stays balanced is by controlling its body temperature. When you get hot, the sweat on your skin helps to keep your body cool.

Some animals grow thick fur or feathers to stay warm in cold weather. They loose fur and feathers during the hot summer.

Organisms respond to changes in the amount of fluid in their bodies. Plants pull in water through their roots. Animals respond to thirst by getting a drink.

Part 2:

= Responding to the Outside Environment =

The outside world always changes. Animals and plants perceive the external environment through their senses. When this animal senses danger, it responds very quickly.

Plants bend towards sunlight.

When this animal senses danger, it responds very quickly. Most animals have a nervous system to help them do this. A nervous system receives information from your senses. It sends signals to your body to tell it how to respond.

Plants respond to light stimulus. If you put a houseplant near a window, cells in the leaves and stems will grow so that the plant bends towards the light.

Sunlight attracts animals too. Heat from the sun can make you feel warm and comfortable. However, the stimulus of sun shining in your eyes will cause you to squint. Your eyes will start to close so that less light will come in. Too much light can harm your eyes, squinting protects them.

= Reflexes = Reflexes are automatic responses that happen too quickly to think about. Reflexes are great for emergencies. If you touch a hot plate, you will quickly move your hand. This protects you from getting burned. There is a reflex that makes your foot and leg jump when something hits your knee.

media type="youtube" key="eCrY0-m5TFU" width="420" height="315"

Let's try this with the teacher...and a staff.

Can you think of some ways that your nervous system can protect you from getting hurt?