Stimulus and Response

Why animals and plants do what they do

ORA fancy way of saying cause and

effect in the animal world.

Describe a situation in which you were immediately scared and/or reacted quickly to something. Write at least 1 complete sentence describing your experience in your spiral.

http://www.youtube.com/watch?v=h6-evXswaQs

What is a stimulus?

any change in an organism’s environment that causes to the organism to react. It is a fancy way of saying “cause”.

Example: An animal is cold so it moves into the

sun.Example: Getting a drink when you are

thirsty.

What is a response?

how the organism reacts to a stimulus and results in a change in behavior. It is a fancy way of saying “effect”.

Example: An animal is cold so it moves into

the sun.Example: Getting a drink when you are

thirsty.

Examples of stimuli and their responses:

Circle the stimulus and underline the response:

• You are hungry so you eat some food

On your own, complete the rest of question 4

Plants also respond to their environment. They are called tropisms

phototropism thigmotropism

gravitropism

There are two types of stimuli:

External Stimuliand

Internal Stimuli

External Stimulus

a stimulus that comes from outside an organism.

Examples: 1. You feel cold so you put on a jacket.2. A snake lunges at a rabbit so it runs

away. 3. It is a very hot, sunny day so a dog

sits in the shade.

Internal Stimulus

a stimulus that comes from inside an organism.

Examples: 1. You feel hungry so you eat some food.2. A cat feels thirsty so it drinks water.3. A dog feels sick so it’s body triggers a

fever.

Animals can respond to stimuli in two ways:

1. In a way that they learned. We call this learned behavior.

OR

2. In a way that they were just born knowing how to do. We call this instinct.

Learned behavior: a response to a stimulus that

an animal was taught.

Examples: chimps bear teaching her

and monkeys cubs to fishlearning to use tools

Learned behavior: Pavlov’s Dog Famous dog experiment done

by Ivan Pavlov ring a bell

feed dog dog salivatesover time, the dog will

salivate when it hears the bell.

Instinct: an animal’s natural reaction

to a stimulus. It is an automatic reaction that the animal was not taught to do.

Examples: getting away from danger

Examples: finding or building a shelter

Homeostasis• An organisms response to internal

and external stimuli helps to maintain homeostasis– Homeostasis – balance or equilibrium

inside a living organism• Blood sugar levels• Sweating/shivering• Fever• Vomiting• Plant tropisms

Blood Glucose Levels• In order to maintain homeostasis,

your body tries to keep a certain blood glucose level

• When blood glucose is low, you should eat

• When blood glucose is high, your pancreas should release insulin

• Problems with this system can create diabetes

Pill Bugs• After watching the pill bug

demonstration, complete the activity.

http://youtu.be/p97-JHO-RNM