Action Potentials And Its Effects On The Body

Action potentials can occur more frequently as long there is a continued source of stimulation, as long as the relative refractory period has been reached, which in experiment 2 the refractory period was complete.

Extracellular recording electrodes were used to measure the compound action potentials (CAPs) in a cockroach leg nerve. CAPs are the summations of all present action potentials (APs) in the individual axons of the nerve. When an AP is conducted along an axon, sodium channels open and positively charged sodium ions enter the axon. Therefore the inside and the outside voltage changes. The voltage changes in the extracellular fluid were measured. A depolarisation of the axonal membrane causes a local negative charge in the extracellular fluid. The summation of all the voltage changes in the extracellular fluid at a specific position is measured by the recording electrodes.

If the nerve impulse is not released than it will not cause an action potential.

As well as these there are also the axon of the cell which is covered in myelin sheaths which carried information away from the cell body and hands the action potentials, these are small short bursts of change in the electrical charge of the axon membrane through openings of ion channels, off to the following neurons dendrites through terminal buttons at the end of the axons. Whenever an action potential is passed through these terminal buttons it releases a chemicals that pass on the action potential on to the next neuron through the terminal button and dendrite connection. The chemicals that are

To send a message, a neuron will send a ripple of electrical energy down its axon. This ripple is called "action potential." The way it works is by changing the chemical makeup of the axon's negatively charged interior. Positively charged sodium ions move into the cell and negatively charged potassium ions move out, then the ions move to their original positions. This produces a wave of positively charged

Once a presynaptic neuron is passive, an electrical current is spread along the length of the axon (Schiff, 2012). This is known as action potential (Pinel, 2011). Action potential happens once an abundant amount of depolarisation reaches the limit through the entry of sodium, by means of voltage gated sodium channels

CAP or compound action potential is a measure of the sum of the "all or none" single action potential of a group of fibers in a single nerve. The single action potentials are events that occur when sodium channels are activated causing the depolarization of a neuron. Single Action potentials are considered to be all or none responses, they travel down the length of the axon and then release a neurotransmitter into the synapse.

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?

The nervous system operates using an electrochemical process (see Video Clip: The Electrochemical Action of the Neuron). An electrical charge moves through the neuron itself and chemicals are used to transmit information between neurons. Within the neuron, when a signal is received by the dendrites, is it transmitted to the soma in the form of an electrical signal, and, if the signal is strong enough, it may then be passed on to the axon and then to the terminal buttons. If the signal reaches the terminal buttons, they are signaled to emit chemicals known as neurotransmitters, which communicate with other neurons across the spaces between the cells, known as synapses.

Single action potentials follow the “all or none” rule. The “all or none” rule being that if a stimulus is strong enough to depolarize the membrane of the neuron to threshold, then an action potential will be fired. Each stimulus that reaches threshold will produce an action potential that is equal in magnitude to every other action potential for the neuron. Compound action potentials do not exhibit this property since they are a bundle of neurons and have different magnitudes of action potentials. Compound action potentials are also graded, meaning the greater the stimulus, the greater the action potential.

Depolarization in membrane potential triggers an action potential because nearby axonal membranes will be depolarized to values near or above threshold voltage.

Whenever the balance is altered, the process of transmitting electrical signals, which is called action potential initiates by carrying information across a neuron’s axon; which is called resting membrane potential. This process occurs as uneven ions distribution flow across cell membrane, creating electrical potential. As a result, the duration of active potential can be as fast as 1 ms. Similarly, the average resting membrane is between -40 mV and -80 mV. Since the membrane from inside is more negatively charged than the outside, it reflected on the negative average voltage readings of the resting membrane.

The electrical event that projects the signal along these distances is known as an action potential. The action potential runs from the axon hillock to the end of the axon where more synaptic contacts are made. Target cells of neurons include nerve cells in your brain, spinal cord, cells of your muscles and various glands.

The compound action potential adds up all the action potentials that each individual neuron experiences in the sciatic nerve. Different stimulus amplitudes cause different neurons to fire an action potential; this is due to the fact that each neuron has a different threshold potential, or the minimum voltage the neuron needs to fire an action potential. The individual neuron action potential is an ‘all-or-nothing’ event, but the CAP, as a summation of different individual neurons, is not. The CAP amplitude will increase with larger stimulus potentials because more neurons with higher individual thresholds will be recruited. For this frog sciatic nerve, there are three fiber types, A, B, and C. A fibers are further divided, in the order of decreasing diameter, into α, β, γ, and δ fibers. There is an inverse relationship between the diameter of the nerve fiber and the threshold potential: the larger the diameter, the lower the threshold. Thus, as the largest fibers, the Aα neurons will be the first to be stimulated at a low stimulus potential, and the Aδ neuron fibers will be the last to be recruited. Because the sciatic nerve is mostly composed of A fibers, the recruitment of A-subtype nerve fibers are more readily distinguishable from the data. The minimum potential required to stimulate the Aα fibers was between 75 mV and 80 mV. Once the stimulus potential reached 90 mV, Aβ neurons were recruited and contributed to the increase in amplitude of the CAP. At a stimulus

Reaction time is the time between the presentation of a stimulus and the initiation of the muscular response to that stimulus ( the free dictionary [26/07/14].The purpose of this test was to identify what happens to reaction times as different independent variables are applied. The nervous system helps all parts of the body to communicate with each other, it is responsible for making sure all of the body’s parts coordinate properly. The nervous system is the centre of all the body’s activity (better health channel [26/07/14]). The brain and spinal cord make up the central nervous system and all the other nerves in the body part of the peripheral nervous system. Inside nerves lie neurons, neurons are found in the brain, spinal cord and the peripheral nerves (PubMed Health [26/07/14]). They are also known as nerve cells. These neurons have the same structure as plant and animal cells (differencebetween.net [27/07/14]). Neurons are made up of a cell body, dendrites, a nucleus, an axon and a myelin sheath (the nervous system [27/07/14]). The myelin sheath surrounds the nerve fibre of axon and protects the body from the electrical charge that nerves have (GCSE Bite size [27/07/14]). There are two types of neurons: sensory neurons and motor neurons. Sensory neurons send signals to the brain and spinal