Homeostasis Activity

Organisms are constantly trying to maintain homeostasis. Stimuli cause your body systems to respond to regain balance. Stimuli may be internal (inside the body) or external (outside the body). Review the examples below. Examples:  A person eats moldy bread (Internal stimuli) o The person vomits (response of the Digestive System)  Someone jumps out of the closet and scares you (External stimuli) o The adrenal glands release adrenaline. (response of the Endocrine System) Read the stimuli and determine if they are internal (inside the organism) or external (outside the organisms). Explain how the organism would respond.

# Stimulus Internal Response or External 1 A person touches a hot stove.

2 Sunlight is shining into a window onto a plant.

3 Gravity pulls on a plants root.

4 A person eats a candy bar.

5 A plants cell vacuoles are lacking water.

6 A microorganism is swallowed when a person eats with dirty hands. 7 A person swallows a bite of a cracker while upside down.

8 A person has just been confronted with a grizzly bear on a narrow mountain trail. 9 A pig cannot sweat, but is hot.

# Stimulus Internal Response or External 10 Gravity pulls on a plants stem.

11 A plants cell vacuoles are full of water.

12 A turtle is exothermic and is cold.

13 A person’s body has elevated levels of fluid.

14 A person is working out and it muscles have produced and excess amount of carbon dioxide. 15 A person’s body has a large amount of waste collecting in the large intestines. 16 In an area where monarch butterflies live temperatures get cold and food becomes hard to find. 17 A rabbit sees and hears a predator in the bushes nearby.

18 A person walks outside while it is snowing wearing shorts.

19 A person’s temperature increases during a workout.

20 A dog eats a piece of food that is contaminated with a poisonous substance.

A person has to go to the restroom The plant bends toward the light and demonstrates phototropism. The plant bends toward the light and A person’s temperature increases and demonstrates phototropism. then vomits. A person’s temperature increases and The pig wallows in the mud to cool then vomits. down. The pig wallows in the mud to cool The plant stem stands upright because down. of turgor pressure. The plant stem stands upright because A person’s breathing rate increases to of turgor pressure. get rid of excess carbon dioxide. A person’s breathing rate increases to The plants stem grows away from get rid of excess carbon dioxide. gravity and demonstrates negative geotropism. The plants stem grows away from A person begins to sweat to cool itself gravity and demonstrates negative down. geotropism. A person begins to sweat to cool itself The organism responds by vomiting. down. The organism responds by vomiting. The esophagus squeezes to pushes the cracker to the stomach. The esophagus squeezes to pushes the The plants root grow toward gravity cracker to the stomach. and demonstrate positive geotropism. The plants root grow toward gravity A person’s body sends a message to and demonstrate positive geotropism. move their hand. A person’s body sends a message to The plant’s stem begins to wilt or move their hand. bend. The plant’s stem begins to wilt or bend. The turtle lies on a rock out in the sun. The turtle lies on a rock out in the sun. The organism responds with migrating. The organism responds with migrating. A person gets chill bumps and begins to shiver. A person gets chill bumps and begins to The organisms responds with flight. shiver. The organisms responds with flight. The intestines break down the candy bar and absorb nutrients. The intestines break down the candy A person secretes adrenaline to enact bar and absorb nutrients. the fight or flight response. A person secretes adrenaline to enact A person’s bladder fills up. the fight or flight response. A person’s bladder fills up. A person has to go to the restroom