The Nervous System
Questions to Ponder
What is the function of the Nervous System?
What are the parts of the Nervous System?
How is the Nervous System related to the other systems that we have discussed?
circulatory
digestive
respiratory
skeletal
muscular
Learning Target
Describe characteristics of the Nervous System
Success Criteria
Explore Different ways the nervous system works in the human body
List foundational knowledge of the Nervous System
Identify features of the Nervous System
Nervous System 3 Part Lab
Introduction:
The human nervous system is composed of the brain and spinal cord (Central Nervous System, CNS) and the nerves which branch out from the CNS and the Peripheral Nervous System (PNS). Sensory neurons of the PNS carry information to the CNS. Signals from the brain are carried to motor neurons (PNS), which carry out responses by muscles.
In this lab, you will be comparing the rate at which sensory neurons, working through the brain, can elicit responses via motor neurons. We will also be mapping out the density of sensory neurons on the skin
Purpose:
To identify differences in the nervous system based on reaction response time and nerve density.
Roles
Learning Monitor
Reader
Recorder
Equipment Manager
Experiment 1: Reaction time
Part A – Arm and shoulder.
Get a meter stick. Select a group member, and use the same person for ALL of the following tests in Experiment 1.
Have the group member stand upright, with their arms extended straight out in front of the body, palms of the hands facing each other. The palms should be 10 cm apart. Place the meter stick exactly in the middle of the palms, with the 50 cm mark at the TOP of the index finger. The meter stick should be oriented so that “0” end is down and the “100” end is up.
Have another group member hold the top of the stick, and then let go (DO NOT WARN THEM OR COUNT DOWN). The meter stick’s fall should be stopped by bringing the hands together to stop the fall of the meter stick.
Record the distance that the stick fell by looking at the measurement lines on the meter stick that align with the index fingers as the palms hold the stick.
Use the equation, final position cm - 50.0 cm = Distance traveled
Repeat this process three more times, recording your data in the table you have on your lab.
Part B – Thumb and Index finger.
Have the same group member stand upright, with their right arm extended straight out in front of the body, with the thumb and index finger separated by 10 cm.
As before, place the meter stick at the 50 cm mark between the finger and thumb, with the 50 cm mark aligned with the top of the index finger.
Release the stick, and record the distance that the meter stick falls before the student catches it. Use the same equation as before to calculate the distance traveled.
Repeat this process three more times, recording the results in your data table.
Experiment 2: Mapping Nerve Endings
Obtain two toothpicks and a centimeter ruler. With these you will try to determine the distance between sensory neurons on several areas of the skin.
You may use the same group member that you used for Part 1, or you may choose a different group member. Have them sit in a chair with their eyes closed. Touch (don’t poke) the skin in each of the areas below with the two toothpicks, beginning 1 cm apart.
Move the toothpicks toward each other, lifting and touching each time, until the person (eyes still closed) reports that they feel the sensation of only one toothpick touching them.
Record the distance between the toothpicks in millimeters at which the person can no longer distinguish that there are two toothpicks touching them, and feel only one.
Repeat this three more times for each area of the body that you are to test.
Experiment 3: Temperature Effect on Neurons
One group member will get their hand wet and attempt to pick up as many pennies as they can in 30 seconds. They must pick them up from the desk with their finger tips, NOT slide them to the edge. They can only pick up one at a time.
If possible the person chosen should NOT have long fingernails.
Record the number on the data table. Next, have the same person immerse their hand in ice water for 1 minute 30 seconds. The sensations they feel should go from cold, to pain, to numbness.
Next, time them again for 30 seconds at picking up pennies.
Repeat with two other partners.
Average the times and compare the two counts.
The CNS and PNS
The nervous system has two different major parts. The two parts are the central nervous system and the peripheral nervous system. The central nervous system or the CNS contains the brain and the spinal cord. All together, the brain and the spinal cord serve as the nervous system's command station. When the sensory input reaches the CNS, the spinal cord and the brain figure out what it means. After, they quickly send orders out to the body parts that need to move.
Everything else but the CNS it is known as the peripheral nervous system. The peripheral nervous system or PNS contains the nerves, which leave the brain and the spinal cord and travel to certain areas of the body. The peripheral nervous system's main job is to send information gathered by the body's sensory receptors to the CNS as quickly as possible. Once the CNS has understood the information, the PNS will relay the specific orders back out the body. These nerves which carry information by way of nerve impulses to and from the brain are called cranial nerves. The nerves that carry information from the spine are called spinal nerves.
Diagrams
Study the following diagrams of the nervous system and the brain.
Damage to the Brain
Read The Story of Phineas Gage to find out what happens when a person suffers a traumatic injury to the brain.
Visit the Mayo Clinic Website to learn about the relationship between seizures and the Central Nervous System.
From Molecules to Organisms