Pathophysiology Of An Electrical Impulse Carrying A Neuronal Message

When neurotransmitter molecules are stuck to receptors located on a neuron 's dendrites, the part of a neuron which receives signals from other neurons, ion channels are opened. At an excitatory synapse, the opening of ion channels enable positive ions to enter the neuron and results in the loss of difference in the charge between the inside and the outside of the membrane, this is called depolarization. Sodium channels open first and sodium ions rush into the neuron. When potassium channels open, potassium ions rush out of the cell and the depolarization is reversed. Sodium ion channels begin to close which results in the action potential to go past -70 mV because the

When the neuron gets stimulated, the sodium ions flow in to the cell and the neuron gets depolarized. When the neuron reaches the complete depolarization, impulse is

A. Depolarization; excitatory postsynaptic potential. Sodium would depolarize the membrane and increase the likelihood that the post synaptic neuron would fire an action potential.

Epilepsy is one of the most common neurodegenerative disorder that is occuring in about 1% of the global population (WHO 2016). Epilepsy is defined as a tendency to have more than two recurrent of unprovoked, unpredictable seizures. Epileptic seizures are brief episodes of involuntary movements that involve the entire body (generalized; tonic-clonic) or one part of the body (partial). These seizures are a result of excessive electrical discharges in specific part of the brain (Shneker and Fountain 2003). Different regions of the brain can serve as a site of such unregulated discharges and form different type of seizures. Seizures can range from short lapses of attention and uncontrolled muscle jerks to severe and prolonged convulsions. Nonetheless, one seizure does not signify epilepsy, but more than two in frame time of two years is epilepsy. However, epileptic seizure is manifested with overlapped signs and symptoms with other disorders and disease, which makes it difficult to define specific seizure to epilepsy.

Partial seizures also referred to as focal seizures, have abnormal excited neuron activity on one part of the brain and in some cases it can increase to other parts of the brain. These specific areas are called the seizure focus. As the activity typically stays around where it started from, there is the potential for it to spread due to the failure of inhibitory mechanisms. Within the seizure focus, neurons experience depolarization, which is then followed by a line of action potentials. The activity involved is defined as proximal depolarizing

WHAT IS EPILEPSY Neurological disorder Primarily characterized by repetitive spontaneous seizures Many different types Wide range of symptoms that vary from person to person Characterized by abnormal electrical activity in brain CAUSES Caused by abnormal activity in brain cells

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

Action potentials act as ‘messengers’ to brain in the form of electrical signals. They are generated by depolarization which is a voltage change in the membrane of a neuron cell. An action potential is produced in each nerve cell and travels along the axon of the nerve cell. The action potential causes a release of a neurotransmitters to

In our brain we have neurons that communicate every second of the day with one other through their dendrite and axons. Most of the time incoming signals are received in the dendrites and outgoing signals travel down the axon to the nerve terminal. For the neuron to receive the rapid communication due to the long axon, the neuron sends electrical signals, from the cell’s body to the nerve terminal. This process is known as nerve impulses, or action potential. “Brain neurons can transmit signals using a flow of sodium(Na+) and potassium (K+) ions, that produces an electrical spike called an action potential (AP) (Forrest, 2014, P. 1). Action potential is essentially a slight reversal of electric polarity across the membrane. When an action potential takes place, the sodium -potassium pump resets the way sodium and potassium ions were back to their original positions. The sodium-potassium does this to the neuron so when it is then ready to relay another action potential, it will pump when called upon to do so. The Na+/K+ pump has a housekeeping role rather than a direct role in brain signaling (Forrest, 2014, P. 1). For an action potential to be generated the membrane voltage must be strong enough to bring the membrane voltage to a critical value called the threshold.

With a basic understanding of neurons and how the nervous system works, it should be known that the brain is a very delicate system; something seemingly minor can cause catastrophic complications. There are two key functions for the neurotransmitters of the brain, one is responsible for communication between cells the other is used to stop or slow it down. Sometimes this complex system becomes out of control and causes a “glitch” in the electrical system of the brain – resulting in what is known as epilepsy.

Excitatory post-synaptic potentials (EPSPs) depolarize the membrane and move it closer to the threshold for an action potential.

In physiology, an action potential is a short-lasting event in which the electrical membrane potential of a cell rapidly rises and falls, following a consistent trajectory. Action potentials occur in several types of animal cells, called excitable cells, which include neurons, muscle cells, and endocrine cells, as well as in some plant cells. In neurons, they play a central role in cell-to-cell communication. In other types of cells, their main function is to activate intracellular processes. In muscle cells, for example, an action potential is the first step in the chain of events leading to contraction. In beta cells of the pancreas, they provoke release of insulin.[a] Action potentials in neurons are also known as "nerve impulses" or "spikes",

The lipid bilayer is impermeable to charged ions, so ions have to pass through ion channels to get in or out of the neuron. When in the resting stage, the sodium channels are almost impermeable to sodium ions. Entry of sodium ions can only be accomplished if the voltage - gated Na+ channel allows it to. This means that there has to be a nerve impulse that results in a change of voltage to open the sodium ion channels allowing Na+ to enter the cell.

Action potential is an all-or-none response like firing a gun. It begins with a membrane that is outwardly positive and inwardly negative in terms of charge. Sodium is on the outside, and potassium is on the inside. When a stimulus occurs, depolarization takes effect and sodium diffuses into the cell. The reversed polarity initiates an action potential.

The first step of four is called the resting membrane potential, the resting membrane potential is also known as polarized. At this stage no ions move through the voltage-gated channels, both sodium and potassium gates are shut. A neuron (which is a specialized cell transmitting nerve impulses) is resting. At resting state, the membrane potential of a neuron is roughly -70mV (millivolts), so the cytoplasmic side (which is the inside) is negatively charged parallel to the outside. All gated Na+ and K+ channels are closed at this stage. A Na+ channel each has two gates, 1 being an activation gate which is closed at rest but swings open when depolarization occurs, the second being and inactivation gate that ceases the channel once swung open. Although for Na+ to enter both gates