03.05 Nerve Conduction Case Study

1. Signal transmission across a myoneural junction that allows the nervous system to move the muscles of a football player during a game is depolarized and then repolarized again. This happens when sodium gates allow sodium to rush into the neuron, making the inside more positively charged. Then the sodium ion gate closes and the potassium gate opens, allowing potassium to rush out of the neuron. This makes the inside if the neuron more negative again

Neuromuscular junctions play a key role in skeletal muscle contractions, and they consist of axon terminals, synaptic clefts, and junctional folds. The contraction begins with the arrival of a nerve impulse at an axon terminal which causes acetylcholine (ACh) to be released into the synaptic cleft. ACh then diffuses across the synaptic cleft and binds with receptors on the sarcolemma of skeletal muscles. This binding creates electrical events that allow an action potential through muscle fiber which causes a muscle contraction. However, normal communication between a muscle and nerve can be interrupted due to the neurological disorder, myasthenia gravis. In Latin and Greek, Myasthenia gravis means “grave muscle weakness,” (fact sheet). As stated

In order for any sort of action to occur within a human body, or most any living body, neurons must send and receive signals to other cells within the body. Those signals, sent in the form of action potentials down the axon of a neuron, eventually reach their destination and typically cause a chemical or electrical change in the system being reached. In the case of a muscle fiber, a depolarization occurs, otherwise known as an excitation, and this excitation leads to the contraction of the muscle fiber (Hill et al, 2012). From this, physiologists coined the phenomenon excitation-contraction coupling. There are numerous steps involved in the overall process, with many variables that can adapt and change how the contraction occurs. One major aspect of the overall process is the

REVIEW SHEET EXERCISE 2 Skeletal Muscle Physiology NAME: Jasmine Young LAB TIME/DATE: 1. Define each of the following terms: • motor unit - A motor unit consists of a motor neuron and all of the muscle fibers it innervates. • twitch - Skeletal Muscle twitch is the mechanical response to a single action potential. It has three phases known as the latent, contraction, and relaxation phase. • threshold - the threshold is the minimal stimulus needed to cause a depolarization of the muscle plasma membrane (sarcolemma.) The threshold is the point at which sodium ions start to move into the cell (instead of out of the cell) to bring about the membrane depolarization. • treppe - the progressive increase in force generated when a muscle is

Muscle contraction begins when the nervous system generates a signal. A motor neuron conducts an action potential to the link with the muscle fiber at the neuromuscular junction a neurotransmitter called acetylcholine is released. This chemical then binds to receptors on the muscle fibers. Acetylcholine receptors are chemically gated ion channels. When Acetylcholine binds it opens and allows an influx of sodium ions into the muscle fiber. This stimulates the sarcolemma and generates another action potential that travels through tiny folds knows as transverse tubules the action potential reaches myofibrils within the muscle fiber, surrounding the myofibrils are membranous sacs called the sarcoplasmic reticulum. The arrival of the action potential

an action potential to pass down a neuron to the neuromuscular junction. It then stimulates the

Nerve and muscle twitch recruitment: External electrode stimulation of a nerve or muscle can lead to a twitch so long as the stimulus voltage is above the muscle or nerve’s threshold value. Electrical stimulation works to open ion channels without the muscle cells, leading to the firing of action potentials. After some time, however, a maximal stimulus voltage will be found. Voltages above this lead to no significant increase in the amplitude of the twitch. Our expectation was that twitch amplitude would increase steadily starting at threshold stimulus and level off at the maximal stimulus. These expectations were based on the results we obtained in previous labs as well as a basic understanding of action potentials, and they were met in this

Axons are surrounded by cell processed of oligodendrocytes inside the primary fearful gadget and Schwann cells inside the peripheral nervous gadget. Myelin sheaths are again and again wrapped round axon segments to form tightly wrapped cellular membranes. Myelin sheaths prevent nearly all electric current go with the flow through the cellular membrane. Gaps exist between the myelin sheaths known as the nodes of Ranvier. it can be visible approximately every millimeter between the oligodendrocyte segments or between man or woman Schwann cells. Contemporary flows effortlessly among the extracellular fluid and the axon on the nodes of Ranvier, and movement potentials can

A synapse is the space located between the motor neuron and the skeletal muscle which is also referred to as a neuromuscular junction. The motor neurons that originate from the spinal cord, help activate the skeletal muscle fibers. The innervation happens by the processes of the axon. The synapses are present along with these processes and are also known as motor endplate. The neuromuscular junction synapse has three characteristics. It consists of two membranes called the pre and post synaptic membranes and the space between the two membranes is known as the synaptic cleft. A high density of small spherical vesicles are present and they contain neurotransmitter substances. A thickened post synaptic membranes is present and it contains a high

Dehydration occurs when the body loses more fluid than its receiving. Intravenous fluids replace fluids lost through sweating, vomiting, diarrhea and constant urination. Dehydration has potential to affect the body’s concentration of electrolytes, causing an imbalance. Sodium is an electrolyte that is vital to the body’s fluid balance. Normal saline contains sodium chloride, so it replaces lost fluid and prevents some types of electrolyte imbalances

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.

Neurons are specialized cells that communicate through electrical signals throughout the body. Nerves are made up of neurons and are made of bundles of nerve fibers. In previous experiments, action potentials were observed. Action potentials are an all or nothing response and do not deteriorate as it travels down the length of the nerve. Action potentials are directed by voltage-gate pumps. One type of action potential is a compound action potential (CAP). CAP is an artificial response of a nerve when all the axons are simultaneously electrical stimulated. It is known that individual action potentials are voltage-dependent therefore it elicits an all-or-nothing response, but CAP are graded potentials. The amplitude of the CAP increases as the stimulus voltage increases. Each axon has its own threshold, so as the stimulus voltage increases it integrates more axons thus creating a larger response.

Neurons are throughout our entire body and are what allow our central nervous system and brain communicate with your whole body. Nerve impulses among motor neurons are what allow our bodies to move when we want to. A nerve impulse is an electrical signal that travels down the axon to transmit information to other neurons to allow movement. In order for a nerve impulse to be generated, a stimulus must be strong enough to cause an “all-or-nothing” response. If the signal is strong enough the reach the neuron’s threshold, then the neuron will “fire”, or send the impulse down the axon. Before this happens, the resting neuron must be polarized by having different charges on either side of the cell membrane. This is because the outside of the cell membrane is more positive due to the presence of sodium ions while the inside is more negative due to the presence of potassium ions. Normally the resting neuron has an electrochemical value of -70 mV. In order for the electrical balance to remain stable and for the cell the maintain homeostasis, the sodium/potassium moves sodium ions out of the cell and potassium ions into the cell using ATP. When the nerve impulse is generated the balance that was created by the cell membrane is reversed, causing sodium ions to go into the cell and potassium ions to leave the cell. The cell is now in a depolarized state due to a more positive charge inside the cell and a more negative charge outside the cell. This depolarization causes the

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

The action potentials of cardiac muscle are unusually sustained. This prevents premature relaxation, maintaining initial contraction until the entire myocardium has had time to depolarize and