External Vs. Internal Stimulus

Homeostasis...

• A stimulus from inside an organism
• How an organism reacts to a change
• The ability to maintain a stable internal environment (type of equilibrium or balance)
• A stimulus from outside an organism

Stimulus...

• A change that prompts an action-the cause
• The ability to maintain a stable internal environment (type of equilibrium or balance)
• How an organism reacts to a change and results in a change in behavior- the effect
• Constant and balanced environment

Which of the following is an example of an external Stimuli?

• Becoming dehydrated and then taking a drink of water
• Getting a headache and then taking Excedrin
• Having hunger pains and then eating a sandwich
• Smelling Pizza and then eating a piece

Jackson is around his friend who is constantly sick. Jackson begins coughing and sneezing the next day at school. What is the possible stimulus and response?

• Internal stimulus is coughing, the response is getting sick
• External stimulus is coughing, the response is getting sick
• Internal stimulus is germs/bacteria, the response is coughing
• External stimulus is germs/bacteria, the response is coughing

A cheetah's water levels are becoming too high, and its thirst is quenched. In response to this, the cheetah's body will send internal signals...

• Of hunger, since the cheetah needs food
• Of thirst, since all living things need water
• To sweat, so the organism can shed some of the water
• Of quenched thirst, so the organism will stop drinking water

There is high temperature outside. What type of response can a person's body have to regulate body temperature?

• Wearing a jacket
• Sweating
• Taking an ice bath
• Wearing a visor

Which of the following is an example of internal stimuli?

• Smelling pizza and then eating a piece of pizza
• Seeing ice cream on television and then eating a bowl of ice cream
• After working out feeling sore in your legs and then placing ice on the sore spot
• After working out seeing a bottle of water and drinking water

Many birds migrate long distances when the seasons change. Which of the following is an environmental stimulus that would signal to the birds the changing seasons?

• Changes in the length of daylight
• Increases in the population of edible plants
• Decreased number of offspring per hatching event
• Increase in annual precipitation levels

Bobby is singing at a concert for 80,000 people. Bobby had meal of chicken which was not cooked all of the way. Bobby is starting to feel "butterflies" in his stomach, which is making him nauseous. The feeling of nausea is an...

• External stimulus because the crowd is super loud from back stage
• Internal stimulus because the crowd is super loud from back stage
• Internal stimulus telling Bobby to get rid of the food that he ate because it is bad for him
• External Stimulus telling Bobby to get rid of the food the he ate because it is bad for him

What type of stimulus?
Increasing pH levels in blood

• Internal
• External