Reaction Time: How Things in Your Body Communicate

Unit Name: Science in Sports

Lesson Name: The Nervous System (Reaction: Voluntary and Involuntary)

Lesson Objectives: To introduce the idea that nerves carry messages throughout the body and there is some delay associated with this process (reaction time)

Target Age Group: 2-4 graders

Materials Needed: At least one foot rulers; hammers for hitting the knees

Introduction/Lecture:

We talked before about muscles and using your muscles in sports to say hit a ball (in baseball). How do we know when to hit the ball?

We see the ball, etc.

How does what the eye see get through to the muscle? Where does this message travel through the body?

Eye sees the ball. The message is carried by special cells in the body (Does anyone know what these cells are called? … nerve cells.

Message goes to the central nervous system… brain and spine

Brain or spine process what to do

Nerve cell carries message to the muscles

Muscles contract and you swing at the ball.

This process is made possible by the nervous system; which we’re going to talk about the nervous system and how it relates to sports.

90mph fast ball in baseball takes about 0.5 seconds to reach home plate

usually the batter has to react at least within 0.25 seconds to hit the ball successfully

Parts of the nervous system

Nerves

Spinal Cord

Brain

(Central nervous system is brain and spine)

Neuron:

Cell body: contain the organelles that keep the cell alive

Dendrites: receive information from another cell

Axon: conduct messages away from cell body

Three types of neurons:

Sensory neuron: connect sensory organs to central nervous system

(what are sensory organs? Give examples… like eyes, ears, tongue?)

Motor neuron: connect central nervous system to muscles

What muscles?

Interneurons: connect neurons with neurons

Voluntary versus involuntary reaction

In voluntary reaction, you require a conscious processing of information. (signal goes all the way to brain and we actually think about what to do and then control the muscles with thinking)

What are some examples of voluntary reaction??

In involuntary reaction, you react without thinking.

What affects reaction time? Age.. how awake you are, how much you practice? What are other examples of impairments? (fatigue, dizziness, etc)

Reaction time versus age: shortens from infancy into late 20s and then gets longer to the 50s and 60s

Does this explain why most athletes are pretty young? 20s-30s

Mean age of gymnasts is 14-15

Why? Due to slower nervous speed; also old people tend to be careful

Does practicing make you faster at reacting? (Yes.. theoretically up to a certain point)

Now do worksheet…

At the end, come back and look at results…. Who got better? Tutor versus kid reaction time?

Distance to time conversion is t = sqrt(2*d/a) d is distance in cm

Nervous System and Reaction Time Worksheet

Voluntary Reaction

A batter has less than 0.25 seconds to react to a fast ball. How fat can you react?

Instructions: One student hold a ruler in the air with 0 inch marking closer to the ground. A second student holds thumb and forefinger around the ruler at the 0 inch mark. The first student drops the ruler without warning and the second student tries to catch it as fast as possible. Repeat 10 times and record the measurement where the ruler is caught.

Draw the path through your body that the signals travel that allow you to catch the ruler.

Convert the distance dropped to a reaction time using the table:

My Reaction Time Data:

My Tutor’s Reaction Time Data:

Would you be able to see the baseball and swing the bat in time? With more practice could you do it?