Ged Science Worksheets

							                              GED SCIENCE LESSON 5

                    THE NERVOUS SYSTEM AND BEHAVIOR

Competency: Explore the human nervous system.

Learning Objectives:

    1. Summarize the basic functions of the brain, spinal cord, and nerves.
    2. Examine the basic unit of the nervous system, the neuron.

Learning Activities:

___1. Read pgs. 66-73 Steck-Vaughn GED Science text and answer all the questions.

___2. Log on at http://www.myskillstutor.com and complete the Humans I exercises
under
      Science II –Biology.

___3. Utilize the BBC Science and Nature website to participate in an interactive brain
      map activity.

http://www.bbc.co.uk/science/humanbody/body/interactives/organs/brainmap/index.shtm
l

___4. Read the Essay Homeostasis on page 2.

___5. Choose a survey or psychology test to find out more about your brain and
      personality at the BBC Science and Nature website

http://www.bbc.co.uk/science/humanbody/mind/index_surveys.shtml


___6. Discuss how a unicellular organism that does not have a central nervous system
      might respond to a change in its environment.

___7. Describe the functions of the three types of neurons found in the human nervous
      system.

___8. Explain the difference between an innate behavior such as a reflex and a behavior
      that is learned.




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                   LESSON 5 – The Nervous System and Behavior

                               ESSAY: HOMEOSTASIS

All living organisms interact with their environment and respond to stimuli. This is a
major characteristic of life. Being able to sense how they are doing and make changes
accordingly is known as feedback. Feedback involves signaling, sensing, and reacting.
This process of feedback occurs at every level of biological organization and is
responsible for how we regulate factors such as heart rate, blood pressure, and cholesterol
levels. Feedback also governs when our cells divide, how much energy we require, and
how we respond to stimuli.

The process of feedback requires that there be some kind of device to measure the
differences between the current state of affairs and some preset state. For example, our
body temperature is maintained at 37º C by sensors in the brain that measure blood
temperature. If the blood temperature drops below this set point, signals from the central
nervous system are sent to skeletal muscles and shivering occurs. Shivering generates
heat, which will eventually cause the body temperature to return to 37º C. This type of
negative feedback control brings about a response that is opposite to the present
conditions. Living things maintain a constant internal environment despite an external
environment that can vary considerably. Feedback controls are necessary to maintain this
internal state of stability or homeostasis.

In multicellular organisms most organ systems contribute to homeostasis. For example,
the respiratory system adds oxygen to the blood and removes carbon dioxide. The
amounts of these gases can be regulated by feedback controls involving the nervous
system. Chemicals made in cells called hormones act as messengers and help sense blood
sugar levels, for example. Ultimately, it is the nervous system however that controls
homeostasis and ensures that things are running smoothly within the organism.




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