Sci 6 Act 9 Text Analysis

Text: Gathering Information. You use your senses to gather information about your environment. Your senses include sight, hearing, taste, smell, and touch. To understand how you feel the objects you touch, you need to know a little about your nervous system. Your nervous system includes your brain, spinal cord, and nerves. Nerves are made up of bundles of nerve cells, or neurons, and are found throughout your body.

Question: What is a bundle?

Text: The human body contains over 100 billion neurons, which take in information from the world. The nerve cells that sense this information are called sensory neurons. Sense receptors are located at the end of your sensory neurons. On your tongue and in your nose, you have receptors that detect chemical inputs, which allow you to taste and smell. Sensory receptors in your eyes detect light waves, allowing you to see, and sensory receptors in your ears detect sound waves, allowing you to hear. In other parts of your body, you have sensory receptors that detect mechanical inputs. For example, these sensory receptors have helped you collect information about the weight of your backpack when you pick it up and think, “It’s heavy!”

Question: What kinds of information do sensory neurons detect?

Transmitting Information. Information travels from sensory neurons all over your body along nerves to your spinal cord before continuing to your brain. The sensory neurons that connect to the nerve cells in your spinal cord are called interneurons. Interneurons are also found in your brain. The interneurons in your brain connect to millions of interconnected sensory neurons.

Question: "Inter" means between. Why are neurons in the spinal cord called interneurons?

They analyze all of the information from the interneurons and help you understand what your sensory neurons have detected. For example, the interneurons help you identify the object at your feet as a dog. As a result, your brain can then provide directions to other nerve cells called motor neurons. Motor neurons send signals to your muscles that cause you to move in response to a stimulus.

Question: Where is interneuron information about the dog analyzed?

Sometimes there is a need for a reflex action, such as when you touch a hot stove. In this case, you react before the message gets to your brain. The interneurons in your spinal cord directly signal the motor neurons of your arm and hand to move your hand away fast. When the original message does get to your brain, it helps to form a memory of what has happened so that you know next time not to touch a hot stove.

Question: Where are the interneurons that signal the body to take a reflex action?

What is the order from sensory reception to possible arm movement based on this diagram.

• sensory neuron

• brain interneuron

• motor neuron

• arm muscle

Based on the text at the top of page 38, what are the five functions of the brain?

Text: The parts of your brain have various functions. The largest and wrinkled part of the brain that you see is called the cerebrum. The folds or wrinkles increase the surface area of the brain, allowing more room for neurons and making it more efficient. This is where all of the thinking and reasoning you do takes place

Question: What is a benefit of the cerebrum having folds and wrinkies?

Which of these functions in the cerebrum does not require sensory neurons to collect information?

Differences in Sensitivity. Now you know how you sense information from the outside world and react to it. You may have noticed that some parts of your body are more sensitive than others. When something touches your arm, you feel it only if it is detected by the nerve endings (or sensory receptors) in your skin. You have sensory nerves in your body that detect pressure, heat, sounds, smells, and light. The nerve endings that detect pressure on your skin are called touch receptors. They help carry a message from your skin to your brain.

Question: Describe a situation where your touch receptors were needed.