Reflexes and Reaction Rates Lab

Biology Mr. Galego

Name: Name: ___________ _________________ ____________ ____________ ____________ ____________ ____________ _________ ___

Date: __________ ________________ ____________ _______ _ Sec: _____ 

Reflexes and Reactions Lab Introduction: Have you ever had to react to a situation situation where something was flying flying at your face? If so, you probably used two of the nervous system’s most important mechanisms for protecting your eyes: reflexes and reactions. You You automatically closed your eyes as the obect approached and you may have duc!ed your head out of the way. "losing your eyes automatically is a reflex. reflex. # reflex is an involuntary response to a stimulus. $eflexes are very rapid and of short duration since they do not rely upon the brain for %decision ma!ing&. 'his entire reflex response occurs in the spinal cord or brain stem. (ther types of reflexes reflexes happen all the time. In fact, your last visit visit to the doctor probably involved involved one. )hen struc! ust below the !nee with a small hammer, your lower leg %!ic!s& up to protect the ligaments inside the !nee and to !eep your *uadriceps muscle from being stretched too far. If you pic! up something very hot, you may drop it to prevent a serious burn. #ll of these are examples of reflexes. +uc!ing your head out of the way is a reaction. reaction . # reaction reaction is a voluntary response to a stimulus. 'his re*uires the brain to ma!e a decision about what your response will be. 'he reaction is the deliberate or voluntary changing of the body’s position to respond to the stimulus. $eactions may also be very *uic! and of short d uration, but they aren’t always. ur!ose:

to understand the difference between a reflex and a reaction to demonstrate some human reflexes to be able to calculate your reaction time

rocedure: 1.

atellar or "nee #er$ Reflex 'he subect is to sit on the edge of the lab table with the legs able to swing freely. -(ne -(ne partner will be the subect first and the other partner the tester, then you’ll switch. switch.

2.

(nce the legs are relaxed and swing freely, the tester should use the hammer to %tap& the subect ust below the !neecap. )hat happened? $ecord your results in the data table.

3.

$epeat steps / to 0. 'his time, try to stop your !nee from er!ing. $ecord your results in the data table.

4.

1witch places with your partner and repeat steps /0. $ecord the data for both partners in your data table.

5.

u!illary Reflex Have the subect cup their hand over their their eye for one minute -try to !eep as much light light out as possible. 2eep the other eye open.

6.

Have a group member shine the pen light close to the open eye for about /3 seconds. %&'(I)N: %&'(I)N: Do not shine light directly into the eye.

7.

4uic!ly remove your hand from the other eye.

8.

Have a group member observe what happens to the pupils of both the e ye exposed to light and the eye that remained in dar!ness. $ecord the observations in the data table.

Data for Reflex (esting: Stimulus 2nee 'ap -relaxed

2nee 'ap -trying to stop it

My Res!onse

artner*s Res!onse

5upil $esponse to 6ight 5upil $esponse to +ar! rocedure for Reaction (ime: /. Have the subect sit comfortably with their forearm resting on a des!. )ith their index finger and thumb about two inches apart. Hold a meter stic! at the 03 cm end and h ave the %7ero& -3 cm mar! lined up between your partner’s finger and thumb. 8. )ithout warning, release the ruler and have them grasp it as *uic!ly as they can. $ecord the distance the meter stic! traveled to where the thumb meets the stic!. $epeat the trial two more times and record your data. 0. 1witch roles and repeat steps / and 8. 9. +etermine the average distance that the meter stic! fell for all of the trials. sing that average, calculate the 'I;< it too! for you to react and grab the meter stic! using the e *uation below. Data for Reaction (ime: 'rial

+istance -cm of Call ;ine I 5artner’s

%alculation of Reaction (ime

t+ ,-da/

/

8

0

)here= t > reaction time d > average distance of fall -cm a > acceleration due to gravity > @3 cmAs8

 #verage B.

In the space below calculate your reaction time and your partner’s reaction time. 1how your wor!.

;ine:

5artner’s:

&nalysis /. "ould you prevent the !nee er! or pupil contraction?