Lab Report- Neurophysiology of Nerve Impulses Essays

Lab Report- Neurophysiology of Nerve Impulses Essays Lab Report- Neurophysiology of Nerve Impulses Paper Lab Report- Neurophysiology of Nerve Impulses Paper Neurons (also known as neurons, nerve cells and nerve fibers) are electrically excitable and the most important cells in the nervous system that functions to process and transmit information. Neurons have a large number of extensions called dendrites. They often look likes branches or spikes extending out from the cell body. It is primarily the surfaces of the dendrites that receive chemical messages from other neurons. One extension is different from all the others, and is called the axon. Although in some neurons, it is hard to distinguish from the entries, in others it is easily distinguished by its length. The purpose of the axon is to transmit an electro-chemical signal to other neurons, sometimes over a considerable distance. Longer axons are usually covered with a myelin sheath, a series of fatty cells which have wrapped around an axon many times. They serve a similar function as the insulation around electrical wire. At the very end of the axon is the axon ending. It is there that the electro-chemical signal that has traveled the length of the axon is converted into a chemical message that travels to the next neuron. (Dry. C. George Before, 2009). Axons are what make up nerves. A nerve is a bundle of neurons fibers or processes wrapped in connective tissue that extends to and/or from the CONS and visceral organs or structures of the body periphery (Marine Mitchell, 2009). In this experiment we will work with a nerve The action potential we will see on this experiment reflects the cumulative action potentials of all the neurons in the nerve, called a compound nerve action potential. Although an action potential follows the all-or none law within a single neuron, it does not necessarily follows the all-or-none law within an entire nerve. When you electrically stimulate a nerve at a given voltage, the stimulus may result in deportation of most of the neurons but not necessarily all of them. To achieve deportation of all of the neurons, a higher stimulus voltage may be needed ( Marine Mitchell, 2009). Seaplanes in the body all begin with the resting membrane potential. This is the natural state of a nerve before it is presented with a stimulus (Martini, Nathan Bartholomew, 2012). Resting membrane potential is important because it is necessary in order for a synapse to occur (Marine Mitchell, 2009). This resting Tate stands at -map because of three factors. First the ionic composition of the extracurricular and intracellular fluid varies in their charge. The Extracurricular fluid has a negative charge because of the An+ ion that exist, just as the intracellular fluid has a negative charge because of K+ ions and negatively charged proteins (Martini, Nathan Bartholomew, 2012). Second the cells have an uneven distribution because of the existence of sodium and potassium leak channels. This allows the creation of an electrochemical gradient, which ultimately is the force that guides the conduction of an action potential. The electrochemical gradient is created by sodium-potassium pump which is responsible for exchanging 3 An+ ions out while bringing in 2 K+ ions (Martini, Nathan Bartholomew, 2012). Third, the resting membrane potential varies in permeability based on the type of ion. Membranes are more easily permeable by K+ ions because of their size, which is responsible for the negative charge during the resting state (Martini, Nathan Bartholomew, 2012) Without a resting potential, we would not have a threshold to conduct an action potential. When a stimulus is presented, it requires a certain excitability, or popularization level of at least map to map (Martini, Nathan Bartholomew, 2012). The action potential depends on the threshold stimulus because of the all or none principle. This states that if a stimulus does not break the required threshold level, no action potential will occur (Martini, Nathan Bartholomew, 2012). However, if a threshold does uphold this principle, an action potential is created and a synapse begins. When membrane is exposed to a certain chemical, its response is either excited or inhibited. When a membrane is excited deportation begins. When the membrane depilatories the resting membrane potential of -70 NV becomes less negative. When the membrane potential reaches 0 NV, indicating there is no charge difference across the membrane. The sodium ion channels start to close and potassium ion channels open. By the time the sodium ion channels finally close. The membrane potential has reached +35 NV. The opening of the potassium channels allows K+ to flow out of the cell down its electrochemical gradient ( ion of like charge are repelled from each other). The flow of K+ out of the cell causes the membrane potential to move in a negative direction. This is preferred to as revitalization. ( Marine Mitchell, 2009). As the transmigrate potential comes back down towards its resting potential level and the potassium channels begins to close, the transmittance potential level goes just below -map, causing a brief period of hyperventilation (Martini, Nathan Bartholomew, 2012). Finally, as the potassium channels close, the membrane turns back to its resting potential until it is excited or inhibited again. In this experiment we will be dealing with two chemicals that intend to inhibit a nerve impulse. Curare is a toxic substance that interferes with the neural remission between motor neurons and skeletal muscles. Curare competes with acetylenes -or Ach- for receptors on muscle cells. Acetylenes is a chemical messenger that normally transmits nerve impulses and activates muscles receptors. Schaeffer, 2010). Loading is a chemical substance that inhibits the transmission of nerve impulses by blocking An ion flux across nerve membranes. In other words Loading is a local anesthetic that blocks voltage- gated An channels at low concentrations, it would make it harder to reach the threshold for firing action potential at high concentrations, and it would stop the action potential entirely. Materials/ Methods This experiment was conducted using the lab manual Human Anatomy Physiology by Marine Mitchell, 2009. Exercisers neurophysiology of Nerve Impulses on Physiology 8. 0 page 131 The activities that were used in this exercise were o Activity 6- testing the Effects of curare page 131 o Activity 7- Testing the Effects of Loading page 131 Results Effects of Curare versus Loading on a Nerve Voltage (NV)Action Potential Notes Curare 2. 0 NV Inaction potential begins at 3. NV Amplitude increases by very little and remains constant soon after. 3. 0 NV Yes 4. NV yes Loading 2. 0 NV No No action potential is recognized 3. NV No 4. NV No Using a frog nerve, two inhibitory chemicals were place onto the nerve to determine what inhibitory properties were seen after stimulating at the threshold voltage for this nerve. Discussion To have a better understanding of the respond to a stimulus and action potential of a nerve (In this case a frog sciatic nerve) we executed this experiment, and realized that numerous physical and chemical factors can impair the ability of a nerve to function. On the first exp eriment we used Curare that at 3. NV created an action attention on the nerve. At the neuromuscular junction, the action potential occurs in the presentation motor neuron, which releases acetylenes during an action potential. Synapses is a junction between two neurons. The presentation neuron terminal is the one that releases a neurotransmitter in response to an action potential. The posthypnotic neuron is the one that receives the neurotransmitter and may undergo an action potential (and become a presentation to the next nerve cell) if the neurotransmitters stimulate the cell enough. When curare is present, it will block acetylenes from binding to its acceptors on the muscle fiber, in turn stopping the muscle from contracting. They key point is that this effect is exclusively post synaptic. The presentation neuron still fires the identical action potential with or without the drug, it still release neurotransmitter. When curare is present, only the downstream effect is blocked. Loading showed success by having an inhibitory effect on a nerve impulse. With a range of electrical voltages from 2. NV to 4. 0 NV, no action potential was shown. This is what an inhibitory chemical intends to do inhibit any response by binding to the axon terminals of the presentation neuron. Specifically, it blocks the voltage-gated sodium channels that allow the influx of sodium when the nerve reaches the threshold voltage thus preventing an action potential. No action potential means no nerve impulse. A nerve must be stimulated and that stimulation must meet or exceed the threshold le vel required for activity to follow. Then as an impulse occurs, such as the nerve with loading being stimulated there must be either a period of inhibition or excitement that causes the membranes permeability to change. If a stimulation was intended to be excitatory the process of generating an action potential would occur, followed by revitalization and hyperventilation. However, in inhibitory responses, the goal is to see no action potential. If the intention is to prevent a stimulus from occurring, creating an action potential is not desired. It is important to understand the properties of substances such as these to better understand their intended effect. In order for them to be used properly one must know what intention of these substances to then provide a proper use for them. For example, one WOUld not propose to administer loading to someone who has regular heart function, because that would suppress their art levels below the threshold level. In conclusion nerve impulses all begin with a stimulus that either causes excitement or inhibition from a certain stimulus (Marine MitcheIl, 2009). If a nerve is excited the process of creating an action potential follows in order to achieve a chemical synapse. In other words, when a nerve is stimulated certain messages able to be transported in and out of the cell. However, in an inhibitory response such as the one witnessed with loading. This experiment determined the difference in excitatory versus inhibitory stimuli in a nerve. It allowed us to visualize the synaptic activity occurring based on a certain chemical which allows us to better understand the effects certain substances have on nerves.