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Homeostasis and Behavior

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Kaylah H.

on 21 November 2014

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Transcript of Homeostasis and Behavior

Homeostasis and Behavior
What is an internal stimulus?
An internal stimulus is a stimulus that comes from inside an organism's body. An example is if you are sleepy, you take a nap or rest. Certain responses to internal stimuli are controlled by hormones such as the main change during insect metamorphosis or puberty in humans. In animals, the hormones are released into the blood stream by the endocrine system while in plants, the movement of certain hormones causes growth and tropisms, others cause fruit to mature.
Where do responses come from?
Animal's sensory receptors send messages along the nervous system when identifying stimuli. Sound, which is a stimulus, causes fast moving electrical signals to be sent along nerves to the brain. The brain then clarifies the sensory information and sends signals along nerves to "tell" the body how to respond in that situation. An animal can behave a certain way when muscles may be triggered by electrical signals. Plants also have an electrical message system. Responses are caused by hormones. Hormones are chemical signals produced in one part of an organism that affects cell activity in another part of the organism. Hormones actually move slower than electrical signals. An organism's response is usually the result of action from both hormones and electrical signals.
What is Behavior?
Every organism is constantly interacting with its environment. A stimulus is anything that causes a reaction or change in an organism. A response is an organism’s reaction to a stimulus. A set of actions taken by an organism in response to a stimulus is a behavior. Homeostasis is maintaining a stable balance in the body.

By:Kaylah H.
What is an external stimulus?
An external stimulus is any stimulus that comes from outside the body of an organism and that influences the behavior of the organism. Examples are temperature, sound, light, and other organisms are external stimulus. Taxis is the movement of organisms toward or away from an external stimulus. An organism can show a positive taxis when it moves toward a stimulus. An example is organisms will usually move toward a food source. A negative taxis is the movement away from a stimulus that is threatening. An example is cockroaches will run away from a bright light which they don't like. Tropism is the movement of a plant in response to an external stimulus, such as light or gravity. Phototropism is a plant's response to light. Geotropism is a plant's response to gravity. An example of this is roots show a positive geotropism because of how they grow in the direction of gravity while stems show a negative geptropism because they grow in the opposite direction of gravity.
How are stimuli detected?
All organisms are able to recognize changes in their environments and respond to them. Multicellular organisms have sensory cells in their bodies that identify specific stimuli. Sensory receptors are found in sensory organs. Sensory organs include eyes, noses, skin, whiskers, and ears. Sensory receptors are easily affected to changes in specific stimuli. Some examples are sensory receptors in the ears detect sound and the sensory receptors in eyes detect the light. Plants also identify stimuli such as light and to by the movement of certain materials inside their cells.
A stimulus can be an environmental factor such as temperature.
Response example- some animals respond to cold temperatures by growing extra fur to stay warm, while others respond by moving to warmer environments.
Behaviors include birds building nests and moles and gophers digging underground tunnels.
Organisms’ bodies constantly respond to stimuli to maintain homeostasis.

Organisms must continually respond to external and internal stimuli to maintain homeostasis. A change in blood pressure or filtering of wastes by the kidneys are responses that an organism may not be informed of. The homeostatic responses allow individual cells and complete body systems to function properly. Many of the homeostatic processes are contained by hormones. Illness or disease may develop if the body does not maintain homeostasis.
How does homeostasis work?
What are some behaviors that improve survival?
To survive, organisms must avoid predators and find food and space. Learning how to hunt is a required behavior. Finding a mate, reproducing, and raising young are other behaviors of the overall survival of species.
What behaviors help animals survive environmental changes?
People would often add more layers of clothes when they are cold and remove layers as they become warmer. Shivering is a response to cold temperatures that many animals have. Shivering generates more warmth in the body. Many reptiles usually lie in the morning sun to make themselves warmer. Migration and hibernation are long-term behaviors that some animals have in response to environmental changes.
What behaviors help plants survive environmental changes?
Plants can't move another location to avoid harsh conditions while animals can. Plants maintain homeostasis and conserve energy in other ways. They have behaviors to survive each day and behaviors to survive changing seasons. Tropisms are behaviors that plants have in response to an external stimulus, such as light or gravity. Movement or growth is directed toward or away from the stimulus. A response to touch is another type of tropism, this allows plants, vines for example, to coil around objects. Food storage and dormancy are other plant behaviors.
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