Nervous System and Reflex Arc

Topics: Nervous system, Central nervous system, Reflexes Pages: 2 (679 words) Published: December 8, 2012
Nervous systems are composed of circuits of neurons, highly specialized cells that communicate with each other and with other types of cells by electrical or chemical signals.—The central nervous system (CNS) is composed of brain and a nerve cord. The peripheral nervous system (PNS) consists of all neurons and their projections that are outside and connect with the CNS. The most basic circuits is a reflex arc, which occurs rapidly in response to inputs from the sensory neurons and consist of only one or a few afferent and efferent cells. Such a response is very quick and automatic. Reflexes are among the oldest and most important features of nervous systems, because they allow animal to respond quickly to potentially dangerous events. Materials

Reflex hammer with rubber head or mallet
Laboratory partner
I. Knee Reflex
1. Allow your partner to sit on the table with the legs suspended or crossed. Put hands outward with the fingers locked infront. 2. Tap gently below the knee cap or patella with the mallet II. Biceps Reflex

1. Hold the elbow of your partner with the thumb, pressed over the tendon of the biceps brachii. 2. Strike a sharp blow on the first digit of your thumb with the mallet. 3. If no reaction is elicited, ask your partner to clench his/her teeth or let him/her squeeze him/her thigh with the other hand and repeat the procedure in number one. III. Achilles Reflex

1. Grip the foot of your partner with the left hand and position it upward. Let the subject relax and then strike the Achilles tendon. IV. Plantar Reflex
1. Strike the sole of the foot of your partner with your pen point from the big toe to the other toes or upward from the heel to the big toe.

Results and Discussions
Test Subject| Knee Reflex| Biceps Reflex| Achilles Reflex| Plantar Reflex| Ramos| There’s a knee-jerk response when tapped.| There’s no response at the first attempt but when she clench her teeth...
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