Extracellular Recording Electrodes Used For Measure The Compound Action Potentials

In this lab we apply the technique known as a two point discrimination test. This test will allow us to determine which regions of the skin are best able to discriminate between two simultaneous sensory impulses. According to (Haggard et al. 2007), tactile discrimination depends on the size of the receptive fields located on the somatosensory neurons. However receptive fields for other types of sensations are located elsewhere. For vision we find that the receptive fields are located inside the visual cortex, and for hearing we find receptive fields in the auditory cortex. The ability for the body to discriminate two points depends on how well that area of the body is innervated with neurons; and thus conferring to the size of the

3. A nerve is a bundle of axons, and some nerves are less sensitive to lidocaine. If a nerve, rather than an axon, had been used in the lidocaine experiment, the responses recorded at R1 and R2 would be the sum of all the action potentials (called a compound action potential). Would the response at R2 after lidocaine application necessarily be zero? Why or why not?

Both electrical and chemical forces combine to determine the resting membrane potential of the cell. Although the resting membrane potential of most cells is normally negative, the selective permeability of the membrane allows certain ions in and out, causing the neuronal membrane voltage to become depolarized (more positive), or hyperpolarized (more negative). Key ions involved in muscle membrane potential are sodium, potassium, and chloride, which move via passive or active diffusion through ion channels and transporter pumps (Baierlein et al. 2011). The Nernst equation predicts the membrane voltage based on the assumption that the membrane is only permeable to one type of ion. In this investigation, we are seeking to understand the basis for how different ions interact to produce the membrane potential of DEM, DEL1, and DEL2 crayfish muscle

11.A. The stimulus is the hypothalamus sensing that the temperature is too low or too high and sends out signals to cool the body. The response is that the blood vessels in the skin dilate to radiate heat and the sweat glands increase sweat production.

Conduction occurs when that action potential transmits along the periphery up to the cell bodies in the dorsal root ganglion in the spinal cord. (2) The action potential from Linda’s ankle injury is travelling up the periphery via the primary afferent nociceptor.

The peak of the CAP changes with different strength stimulus because the sizes and thresholds of the nerve fibres within the nerve is different. Larger nerve fibres have lower threshold stimuli than smaller ones, hence larger fibres were activated first, followed by smaller ones. As stimulus strength increased, the larger nerve fibres began firing followed by the activation of the smaller ones (refer to Figure 2). At the maximal stimulus a constant pattern was formed. This was because all the nerve fibres were now firing and there were no further fibres to be activated.

An eel was placed in a naturalistic experimental environment with other fish and the fishes’ response to high-voltage pulses was observed. If there was a strong enough discharge, the fish was unable to move on its on accord and was captured by the eel. A pitched fish was placed behind an agar barrier, which received the same discharge as the eel directed toward earthworms placed in the same environment. In order to determine if the discharges induced the muscle movement by initiating action potentials or by activating the motor neurons in the fish, two fishes were pitched; one of the fish was injected with an AcH antagonist and the other was injected with a placebo. To test doublet and triplet discharges

(Heldmaier,1981; Kronfeld-schor et al. 2000; Bao et al. 2002; Jefimow et al. 2004; Li and Wang, 2005; Zao and Wang, 2005). These experiments helped discover the many different thermoregulation responses in endotherms and specifically, rodents. Knowing the depth of these studies given above makes investigating this relationship very interesting because we have the ability to discover not only more knowledge about this relationship, but also about the other possible thermoregulatory responses that may occur in endotherms that has not yet been exhibited. R.P. Stated in the Investigating Biology lab manual these variety of responses can also include “photoperiod, ambient temperature, food availability…”(French, 2015). In order to test this relationship and its responses we will test the hypothesis as stated above: Endotherms have a more active metabolic rate when exposed to temperatures above or below ambient due to the thermoregulatory responses to the extreme environment. This study is different from any other that preceded it because it directly compares the responses of thermoregulation in different atmospheres. The study also has the possibility of being published in JIBI. For this new path of experimenting to be published, and

During phase 1 and the beginning of phase 2, the variables measured were relatively stable as the body was in a homeostatic state and skin temperature was within a thermoneutral zone (34°C). Thus, thermoregulatory responses could be regarded as passive.

The findings of this experiment reinforced the hypothesis that the resting membrane potential is most influenced by the ion potassium. We were able to deduce this through the collection of a multitude of intracellular and extracellular recordings, such as the one shown below in Figure 1. This shows how this experiment was able to record every single resting membrane potential in all three different muscle groups under all six solutions.

Every organism has thousands of these junctions that control the movements of the body and cause the heart to beat. The neuromuscular junction is a chemical synapse consisting of the point of contact, between the axe on terminals of a motor neuron and the motor endplate other skeletal muscle fiber. The events at the neuromuscular occur in seven coordinated steps. 1. The action potential arrives at the axon terminal. 2. Voltage-regulated calcium channels open allowing calcium ions to enter the axon terminal. 3. Presence of calcium ions in the axon terminal cause synaptic vesicles to fuse with the membrane. 4. Acetylcholine is released into the synaptic cleft and calcium ions are pumped out of the axon terminal. 5. Acetylcholine binds to receptor sites on the motor end plate, causing an influx of sodium ions and a small efflux of potassium ions, which results in a local depolarization of the motor end plate. 6. An action potential is generated which propagates along the sarcolemma in all directions and down the T tubules. 7. The action potential causes the release of calcium ions from the terminal cisternae into the

Initially the temperature sensations start from receptors in the skin and based on the neocortex for their conscious appreciation .

After viewing and running through the experiment, there was a question that was formed from it. The question was: could this be done with another animal or organism? With understanding, there are certain animals that could show signs when the temperature has been changed. With different types of canine, the sign of heat could be shown by having their tongues out and panting when the environment’s temperature increase. While some organisms could be more tired or tend to be less active because of the heat. When setting up the experiment, a person should use two rooms that contains the temperature of 20 to 25℃. Although, the temperature should be equal for both rooms since the temperature will be the neutral. The control variables should be the

Temperature affects all aspects of physiology, and animals use their thermosensory systems to achieve optimal temperatures for growth and reproduction and to avoid damaging thermal extremes [1]. The fruit fly Drosophila melanogaster being a small animal makes thermoregulation very difficult, but their responses to temperature as a stimulus is subtle and robust, able “with milli-degree per second temperature changes triggering readily assayed behavioral responses “[2]. This sensitivity makes them perfect to study sensory processing and behavior. Both the larva and the adult fly provide different aspects of thermosensitivity that can be observed [3]. Flies have at least 3 classes of thermoreceptors: “warm receptors respond to innocuous (moderate)

In the research paper “The Role of Calcium in the Rapid Adaption of an Insect Mechanoreceptor”, researchers aimed to identify whether calcium entry into the cell is correlated with neuronal adaption. To address this question researcher varied the concentration of calcium in the extracellular space of the cell in addition to applying calcium blocking agents (cobalt and cadmium), and by applying a calcium ionophore (antibiotic A23187). Three primary findings pertaining to these substances were derived from the experiment. The most important finding was that increasing the extracellular concentration of calcium did not increase the rate of adaption and instead reduced the rate of adaption. Secondly, researchers found that the presence of cobalt reduced the rate of adaption, the opposite of what they had originally expected. Lastly, no significant difference in adaption rate was found for solutions containing the antibiotic A23187.