Nervous System :reflex Function and Sensory System

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Department of Biology

Faculty of Science and Mathematics

Universiti Pendidikan Sultan Idris

Experiment 1

Nervous System :Reflex Function and Sensory System

Name                         : Nadzatul Elya bt Md Fuad

Matric No                : D20141066881

Group                         : A        

Lecturer’s name        : Profesor Madya Dr. Syakirah binti Samsudin

Experiment 1: Nervous System: Reflex Function and Sensory System

Introduction

The nervous system coordinate actions and transmit signals between different parts of the body from a network of cells called neurons that coordinate actions.

Normally, the brain coordinates the response when it receive the signal from the central nervous system (CNS) that involve brain and spinal cord and the signal receive by CNS from stimulated receptor. However, sometimes we realize there is some action that has very quick response when needed. This action does not involve brain and known as reflex action (adapted from www.bbc.co.uk/schools/gcsebitesize/science). This action happen rapid and we do not have time to thinking. The simple example of reflex action is when we pull our hand away from the hot flame without thinking about it. In this experiment, the investigation involve several types of human reflexes to demonstrate their investigate function at several levels of investigation in the body like eye reflex, spinal reflex, ciliosinal reflex and Plantar reflex and Babinski’s reflex.

As we know the nervous system also include a sensory system that responsible for processing sensory information. There are sensory receptors, neural pathways and parts of the brain involved in sensory perception that was include in sensory system. Usually vision, hearing, taste, touch and smell are commonly known. In this experiment, the study investigate the sensory system (taste, smell, cutaneous sensation, proprioception and hearing).

Materials

• Torchlight
• Reflex mallet
• Chopstick
• Sugar
• NaCl
• 6-n-propylthiouracil (PROP)
• 1 sen coin
• 50 sen coin
• 10 sen coin
• Pins
• Banana flavour
• Orange flavour
• Pandan flavour
• Rose flavour
• Vanilla flavour
• Cold water
• Warm water
• Water bath (room temperature)
• Tuning forks
• Tubes
• Alcohol
• Pencil/ pen

Methods

A. Reflex Functions

a) Eye reflex

1. Pupillary Reflex

1. The size of your partner’s pupils was observed in a given intensify of light.

2. A light was flashed into one eye and the papillary responses was observed. (The length of eye and light source was identified).

3. The diameter of the pupils in a given light was observed.

4. Without changing either the light intensity or the focus, the hand was placed over one eye.

5. The change in the uncovered pupil was explained.

1. Accommodation Reflex

1. The size of your partner’s pupils was observed when the eyes are focused on a distant object (more than 20 ft. away, the length was identified).

2. While the focus is shifted to a near object it was carefully watched.

3. The light intensity does not changed.

b) Spinal reflex

Patellar Reflex

1. Partner was sat in a chair or on a laboratory stool with legs crossed.

2. The patellar tendon of the crossed leg was gently tapped with a reflex mallet and the response was noted.

3. The responses of the right and left knees was compared.

c) Ciliospinal Reflex

1. The skin on one side of the nape of your neck was pinched and the dilation of the pupil of the eye on the ipsilateral (location at the same part) side noted.  

2. This was a reflex response mediated over the sympathetic nervous system in response to a painful stimulus.

d) Plantar Reflex and Babinski’s reflex

1. The sole of foot was scratch or stroked sharply near the inner side, using a blunt probe.

2. The normal adult reflex response was a plantar (downward) flexion of all toes.

3. If the toes fan out with a big toe reflexes dorsally (upward), the response is referred to as the positive Babinski’s reflex: this reflex is often associated with damage to the pyramidal tract fibres.

4. Babinski’s reflex was the normal response of a child in its first year because the nerves were still undergoing myelination at this time.

B. Organization and Function of the Nervous System Ii- sensory system

a) Taste ability

1. Sugar, NaCl and a chemical called 6-n-propylthiouracil (PROP) were tasted and smelled, which are placed in cups or bottles at each of the lab desks.

2. Each of the solutions were sip and spit out, with or without nose clips in place, and each on intensity was rated on specially constructed scales.

3. For the smell portion bottles of the solutions was sniffed, and the intensity of these was rated as well.

4. The observation does not make out loud until the experiment is over.

5. It was perfectly normal to have reactions to these taste that differ from other people’s reactions.

6. People were differ in their ability to taste PROP.

7. At the end of this experiment the fungiform papillae on the tongues of people who were classified as non-tasters [of PROP], medium, and super-tasters was demonstrate.

8. The differences among these tongues was observed.

b) Two Point Discrimination

1. Three coins of difference sizes (RM 1 sen, 5 sen and 10 sen) was found.

2. Eyes was closed and the partner placed one of the coins on the back of forearm.

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