Crayfish Lab Report Essays

Crayfish Lab Report Essays Crayfish Lab Report Paper Crayfish Lab Report Paper Frequency vs.. Stretch a) In our classroom experiment, after dissecting and preparing our crayfish ail, we sucked up a MR.. Receptor neuron with our electrode to record firing of the nerve as we adjusted the length of the crayfish tail using a string attached to both the uncomplimentary and the end of the tail. Unlike our classroom experiment, the methods for Delicacy and Crevice and Van Gilders experiment dealt directly with the MR.. Strand, to be more specific -the isolated abdominal stretch receptors of the crayfish. In Deletions experiment, the MR.. Strand was held at each end by forceps and a microelectronic was inserted into the cell body of the sensory neuron. Gentle manipulations of the forceps caused a stretch in the MR.. Generating a generator potential in the strand that caused a spike potential in the sensory neuron. As stated earlier, methodically, Crevice and Van Gilders experiment didnt differ significantly because they too interacted directly with the MR.. Receptor neuron. The independent variable in each experiment was the stretch applied to the neuron. The dependent variable for our classroom experiment and Deletions experiment was the firing rate, but Crevice and Van Gilders experiment contained an additional dependent arabletension (which is linearly related to the firing rate). B) According to Crevice and Van Gilders Figure 7, stretch and tension are linearly related. The graphs reveal that with increasing tension, firing rate and tension increase progressively faster. The relationship of both tension and firing rate to stretch are exponential (Crevice and van Gelded, 1961). Because of the differences in our methodical approaches, our classroom experiment is not directly comparable to Delicacy or Crevice and van Gilders. The authors data is much more comparable because Delicacy and Crevice applied stretch erectly to the MR.. Strand, so the stretch in mm is directly comparable for the two. In our classroom experiment, we have a much bigger range because we dealt with the entire crayfish tail, so mulch of the movement in millimeters goes into lifting the tail itself. C) The best-fit curve for my results of firing rate vs Trench applied is exponential. Similarly to Deletions results, my stretch is linearly related to the firing for the first three data points. For the last two values, my scale begins to increase exponentially and starts to resemble Crevice and van Gilders results. Operational errors that could account for differences in the class data would be recordings incorrectly taken before the neuron has adapted (values would be higher). The class dat a supports Deletions linear results, but it could be that our classroom experiment would have increased exponentially with increased stretch. Deletions data is linear in his experiment, but the range of stretch values is considerably smaller than Crevices. Similarly to my experiment, Crevices data also follows this linear trend until it reaches a level of stretch that causes an increase in tension and thereby and increase in the firing rate. In Figure 7 of Crevice and Van Gelded, it is at the two largest values for stretch that the firing rate increases from linear to exponential. The fact that Crevice obtains values for firing rate at larger values of stretch could explain why his results showed exponential growth after a certain value. ) There is a huge amount of variance in the stress vs Frequency relation for the class. Simple biological factors like individual variance could account for the variance in the data. In Table 1 of Crevices paper, he acknowledges that he differences in the receptor taken from the same cross section could have contributed to inaccuracies in his experiment (Crevice 1961 Another biological fac tor that might influence the slope of the stretch frequency curve could be tension. For instance, a less flexible crayfish (i. E. More tense) would have a faster firing rate for a given stretch than a more flexible crayfish would. . Frequency vs.. Time a. In our particular experiment, a spike potential is the action potential of the sensory neuron that is driven by the generator potential. A generator potential n the MR.. Is driven by a net inward current of An+ and Ca++ or an PEPS, after activation of the anchorperson. This generator potential gets the membrane potential to threshold and thereby causes an Action Potential (spike potential). The contributions of the generator adaptation and spike adaptation could be separated experimentally by application of a spike inhibitor, which in Crevices experiment is represented by determination. ) In slowly adapting neurons, spike adaptation makes a greater contribution to overall adaptation. In Figure IA, the spike potential has been isola ted and according to this experiment, the behavior of the neurons spike potential is consistent with what we know about tonic receptors. Under a constant current, the slow adapting neuron transitions from a rapid firing of action potentials to the slower fire represented by larger enterprise intervals. In Figure B, the spike adaptation for the fast adapting receptor, too, is consistent with our knowledge of aphasic receptors. There was an initial firing rate at the onset of the current, but while the current was still applied, we see a drop to zero for the aphasic acceptors firing rate. (Making 1964). Conversely, in Figure AAA and B, where both aphasic and tonic generator potentials are isolated, there is essentially no difference between the two potentials behavior(Making 1964). This suggests that the generator potential has no effect on the behavior of the neurons and its adaptation mechanism. D) In both Figure 10 and my own, the adaptation over some duration to a constant stimulus is logarithmic. According to our overall adaptation result the rate of firing of a slowly adapting neuron slows when exposed to a constant tumulusFigure 10 of Making follows the same form because our classroom experiments also follow a logarithmic curve. ) In my analysis of whether the ion concentration model accounts for both adaptation and the immediate recovery from overstretch, I conclude that this model only partially applies because of its plausible explanation for spike adaptation. According to the Unrest equation (log Anal/Amount), the An concentration inside and outside of the cell could chemically equilibrate. Based on where ANA is determines the deportation of the action potential and if ANA were to drop below threshold (due to equilibration of An concentrations and sm aller influx of An ions), we would not get firing. Conversely, application of the ion concentration model to immediate recovery from overstretch doesnt directly apply because it cant explain how the ion concentrations would immediately become more available extracurricular to provide the ANA needed to cause firing of the action potential. The process of generating a concentration gradient could not logically occur that quickly. Ii) In order to test the sensitivity of a particular ion channel, we could use the attach clamp method and analyze its response to a constant stimulus and see whether or not we get a change in ion influx over time (thats not due to ion concentration).