The nervous system and the peripheral nervous system

The Investigation ofthe Response time of the Dominant and Non-Dominant HandIntroduction:The nervoussystem is made up of the central nervous system and the peripheral nervoussystem which work together to enable the body to respond to environmental stimuli,this response is done by motor control. Specialised receptors transform thestimuli to which they are specific to into electrical nerve impulses.Specialised cells known as nerve cells or neurons form the central nervoussystem, these cells come together to form nerve fibres. Neurons respond to andinterpret the stimuli received and react appropriately, such reactions arecarried out by effectors, as discussed by (Technologies, 1999-2018). Response to a stimulus is produced by effectors. Whenneurons are stimulated by stimuli, the information is transmitted by “a series of electrical impulses passingalong the length of the neuron.

” (Chemistry, 2004) Electric impulses only travel in onedirection in a neuron.There arethree types of neurons, all neurons stimulate cells, and transmit electricalimpulses. Motor neurons retrieve information from other neurons, and cause reactionsto occur, as discussed by (Academy, 2018). A neuron contains a nucleus, and cytoplasm; thiscytoplasm produces Dendron’s.

Dendron’s branch off into finer structures knownas Dendrite’s which are stimulated by the electrical impulses from otherneurons. The axon is formed by the extension of cytoplasm, it transmitsimpulses away from the cell. Nerves consist of many axons from many neurons. Axonsend in synaptic knobs which stimulate nerves. Some axons are surrounded bymyelin sheath, “Glial cells producemyelin, which is a fatty substance that protects the nerves.

” (SparkNotes, 2017) Schwann cellsline and wrap around axons, which speed up the transmission of pulses and actas an insulator. A neuron lined with Schwann cells is known as being myelinated.Neurons havea membrane potential established across the cell membrane, meaning there is anunequal distribution of ions between the outside of the cell membrane and theelectrical field inside. The most abundant ions in extracellular fluid aresodium (Na+) and chloride (Cl-). Potassium (K+) is the main positive ion withinthe cell, neutralized by organic anions. The extracellular fluid and cytoplasmare electrically neutral, being a potential difference in comparison to thenegative interior. The interior is negative when the neuron is not conducting asignal, known as the resting potential, as discussed by (Rajakumar & Kiernan, 2013) The cell ispolarised as it has an unequal distribution of ions on either side. Thepermeability of the cell transfers Na+ and Cl- by pumps which carry out activetransport, ensuring that at any given time there are more Na+ ions outside, andmore K+ ions inside, as discussed by (Biologist, 2018) When a nervecell membrane is stimulated, the action potential occurs rapidly causing thesodium pumps to open, allowing more Na+ ions inside the cell meaning the insidebecomes more positive than the outside.

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This is known as depolarisation ascharge distribution has changed. Potassium pumps then proceed to open, allowingthe ions to flow out meaning the charge returns to its original state, aprocess known as repolarisation. “A reflex is the simplest, quickest form ofactivity in the nervous system. It is an automatic, involuntary, unthinkingresponse to a stimulus.” (Teacher, n.d.) Examples include, moving your finger away from aflame, breathing and blinking.

To catch a falling object includes a degree ofreflex action, as your brain is reacting to the visual stimuli. Aim of the InvestigationMy aim is toinvestigate the speed of the reflexes of both a person’s dominant andnon-dominant hand in response to the external stimuli of a ruler being dropped.I will test reaction time by timing how long it takes to catch a ruler in eachhand.A similarinvestigation was carried out by (Dana Badau, 2014) in which thegoal was to record the difference of simple reaction time between the left andright hand to the visual stimuli with regards to the dominant hand of eachstudent that took part.

This was done so using the ruler test with both hands,consisting of the ruler being caught twice with each hand and an average thencalculated as the result. The overall results shown that there were significantdifferences between both hands, especially when cerebral dominance wasaccounted for.Whileresearching possible outcomes of this investigation, it was discussed by (Reaction TIme Ruler, n.d.

) that it can be expected that the dominant handwill be faster as it is used more regularly, meaning neurons carry alongmessages along a well-worn pathway. Such repetitiveness results in improvedmotor skills. Hypothesis:I expectthat the response time of the participants dominant hand to the visual stimulusof a dropped ruler will be faster in comparison to the nondominant hand, due tothe daily repetitive and more frequent usage of the dominant hand which equatesto improved motor skills and greater dexterity than that of the nondominant.  Therefore, the distance that the ruler drops shouldbe smaller when caught by the dominant hand. Apparatus: ·       30cm ruler ·       Table·       Chair·       Pencil·       Paper to record data Method:1.     I will get my participant(s) to sitdown in a chair and place their dominant arm flat across the table top, withtheir wrist aligned with the edge of the table. Their hand will not be indirect contact with the table top. 2.

     I will be stood in front of theparticipant, holding the ruler between my thumb and forefinger. The ruler’szero mark (0cm) will be level with the table top.3.     I will get the participant to enclosetheir thumb and forefinger around either side of the zero mark, ensuring thatthey are approximately 2cm apart with the ruler in the centre.

4.     I will say “Ready” and will drop itwithin 5 seconds of saying so. The participant is to catch the ruler with theirforefinger and thumb once I’ve said this.5.     I will record the distance the rulerdropped (in centimetres) in a table by reading where the participant has caughtthe ruler. 6.

     I will repeat the above steps twiceagain to receive more measurements. 7.     I will get the participant to switchto their non-dominant and repeat steps 1-6.8.     Once all my readings are completedfor both hands, I will calculate the mean dropping distance of each hand byadding up the three results and dividing them the number of trials (3).9.

     I will gather the results of all the participantsand find the average for the dominant and non-dominant hands overall. Independent Variable:HandDominance is the only way in which to vary this variable, is by switching thehands to catch the ruler after three turns with each. From the dominant hand tothe nondominant hand.Dependent Variable: This is thetime of reflex response to catch the ruler.

To collect this data, I will bemeasuring and recording the distance the ruler has dropped when it has beencaught. I will be measuring in centimetres from a fixed height. Each hand willcatch the ruler three times so as to increase the reliability of my results. Iwill be calculating the mean response time by dividing the sums of all threeresults by the number of trials carried out.Control Variables:·       Caffeine Intake: It is important to ensure that this stimulant is not ingested betweenthe switching of the dominant and nondominant hand, or between trials carriedout.

Caffeine will affect the results of reaction times, especially over timeas it takes effect.·       Warning of Stimulus: I will warn the participant by saying “Ready”, and will proceed to dropthe ruler within a five second limit.·       Distance of Participants Thumb and Forefinger from Ruler: It is important to try to ensurethat the Thumb and Forefinger are approximately 2cm apart with the ruler in thecentre. This is slightly difficult to regulate as one’s fingers tend to shakein anticipation of a falling object.

If the fingers get closer to the rulerwhile shaking, it causes a smaller distance, meaning the ruler will be caughtquicker and subsequently lowering the reaction time. And vice versa if thefingers move outwards.·       Distance from Which the Ruler is dropped: The distance needs to be the samewith each test, to ensure this happens the participants will rest their armflat on the table top so their hand level will not change. I will hold theruler so that the zero mark (0cm) is at level with the hand.

 Ethical Assessment: ·       I will not carry out theinvestigation until I have the consent of the participants to partake.·       I will explain the investigation tothe participants, so they can partake in it with full knowledge of thesituation.·       I will ensure all results will beconfidential and anonymous in my recordings of data. ·       Participants may withdraw from theexperiment at any stage. ·       All participants shall be treatedequally and fairly. Risk Assessment: ·       Trip & Collison: I will ensurethere is nothing on the floor, for example, a schoolbag to collide with.

I willadvise participants to store bags and belongings safely to remove this hazard.

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