Stimulus and Response

1
Stimulus and Response

• Why animals and plants do what they do
• OR
• A fancy way of saying cause and effect in the
  animal world.

2

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

3
What is a stimulus?

• any change in an organisms 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.

4
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.

5
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
6
Plants also respond to their environment. They
are called tropisms
gravitropism
phototropism
thigmotropism
7
Think Pair - Share

• Turn to your table partner and share two other
  stimuli and their responses.

8
There are two types of stimuli

• External Stimuli
• and
• Internal Stimuli

9
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.

10
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 its body triggers a
• fever.

11
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.

12
Learned behavior

• a response to a stimulus that an animal was
  taught.
• Examples chimps bear teaching her
• and monkeys cubs to fish
• learning to use
• tools

13
Learned behavior

• Pavlovs Dog
• Famous dog experiment done by Ivan Pavlov
• ring a bell
• feed dog
• dog salivates
• over time, the dog will
• salivate when it hears
• the bell.

14
Instinct

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

Examples finding or building a shelter
Examples getting away from danger
15
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

16
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