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...in a myelinated axon.
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Which of the following types of nerve fiber possesses the fastest speed of impulse propagation?
Type A
How does myelination affect nerve conduction velocity?
Myelination will speed the nerve conduction velocity considerably. Myelin is found in Schwann cells which encircle a given axon. It acts mainly as an insulator so that depolarization in one cell does not set off depolarizations in adjoining cells. When a neural membrane is depolarized, local currents are set up between positive and negative ions causing membrane conduction. In myelinated fibers, the local currents go from one internode (or node of Ranvier) in between two Schwann cells to the next internode. Thus we have "salutatory conduction" where a neural impulse actually jumps from one internode to the next without being conducted down the entire cell membrane.
1 List the physiological events that occur between delivery of the stimulus and the start of the recorded response?
The speed of nerve impulse transmission changes as the body ages. In infants, the transmission speed is only about half that seen in adults. By age five, most people have attained the adult velocity. A gradual decline in conduction velocity begins as people reach their 20s, and continues for the remainder of life. Another factor that influences conduction velocity is the length of the nerve itself. An impulse that has to travel a longer distance will take longer. Some nerves are naturally longer than others. Measurement of nerve conduction takes into account the length of the target nerve. Some other factors are: · Initiation of action potential in nerve fibers; · Conduction of impulse; · Release of acetylcholine from the nerve terminals; · Binding of acetylcholine to receptors of the motor end plate; · Depolarization of the end plate; · Initiation of action potential in muscle fibers; · Muscle contraction.
How fast do nerves impulses travel?
Nerve impulses travel through nerve fibers via a action potential and the speed at which the impulse travels depends on the type of nerve fibre. This can range from 100m/s in the case of touch to 20-30 m/s when you're thinking.
What two factors increase the nerve conduction speed?
Whether the nerve fiber is myelinated or unmyelinated effects speed of a nerve impulse. A myelinated nerve impulse is faster. Also the diameter of the nerve fiber effects nerve impulse speed.
Which of the following types of nerve fiber possesses the fastest speed of impulse propagation?
Type A
Would conduction speed of a nerve fiber be the fastest in a large or small myelinated fiber?
Yes. Myelinated fibers have a myelin sheath around them which keeps the impulse from scattering and on a direct path. This makes the impulse travel faster than unmyelinated fibers.
How to calculate the speed of propagation of the nerve impulse in a nerve fiber?
The velocity of nerve conduction is usually assessed by dissecting out a nerve fiber from an animal such as a frog. The nerve is placed in a chamber containing stimulating and recording electrodes. The responses of the nerve can be monitored using an oscilloscope. More detail on this procedure can be found in the related link.
What do nerve conduction velocity studies?
Nerve conduction velocity studies (NCV) are used to measure the speed with which an electrical signal is transferred along the nerve.
What is electroneurography?
The measurement of the speed of conduction of impulses down a peripheral nerve.
What is Nerve conduction testing?
Procedure that measures the speed at which impulses move through the nerves.
What are the factors which affect the nerve conduction velocity?
The factors affecting nerve conduction velocity are as follows:(i) Axon diameter:An axon with a larger diameter conducts faster. In an unmyelinated fiber, the speed of propagation is directly proportional to the square root of the fiber diameter (D), i.e.,Conduction velocity a D(ii) Myelination and saltatory conduction:Myelination speeds up conduction. Thus, the action potential travels electrotonically along the long myelinated segments, and fresh action potentials are generated only at the nodes. This is called saltatory conduction. In a myelinated neuron, the conduction velocity is directly proportional to the fiber diameter (D).(iii) Temperature:A decrease in temperature slows down conduction velocity, (iv) Resting membrane potential. Effect of RMP changes on conduction velocity is quite variable. Usually, any change in the RMP in either direction (hyper polarization or depolarization) slows down the conduction velocity.
What is the effect of the myelin sheath on synaptic transmission?
Myalin sheath gives insulation to the neurons. They also hasten the nerve conduction by saltatory conduction.
What is involved in electromyographic and nerve conduction velocity testing?
These tests involve stimulating the median nerve with electricity and measuring the resulting speed and strength of the muscle response, as well as recording speed of nerve transmission across the carpal tunnel.
What is fastest download speed network in the world?
Commercially available is the draft-N speed.
How fast nerve impulses travel?
Nerve impulses travel through nerve fibers, and the speed of which they travel depends on the type of nerve fiber. They travel usually around 86 miles per hour.
What is the myelin sheath's function?
The function of the myelin sheath is to insulate the axon of the neuron. When there are gaps in the sheath, known as nodes of Ranvier, the nerve impulse can jump from gap to gap, thus increasing greatly the speed of conduction of the nerve impulse. This is known as saltatory conduction.
