Generation, Conduction And Transmission Of Nerve Impulse: Process & Types

What Is The Nervous System?

The nervous system is a complex network of nerves and cells that transmit signals to and, at all places and times, correspond with other parts of the body. It regulates and collaborates the functions of the body which are related to each other, such as the movement and sensation of some cognitive functions among others. Understanding how the nervous system functions is important for one to appreciate the mechanisms through which different organisms respond to stimuli and how such internal functions maintain proper homeostasis.

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This Story also Contains

1. What Is The Nervous System?
2. Structure Of A Neuron
3. Generation Of Nerve Impulse
4. Conduction Of Nerve Impulse
5. Transmission Of Nerve Impulse
6. Types Of Neurotransmitters
7. Factors Affecting Nerve Impulse Transmission
8. Recommended Video On ‘Generation, Conduction And Transmission Of Nerve Impulse’

A nerve impulse is an electrical wave that sweeps down the length of a neuron. These impulses are how the nervous system communicates as the waves are how the information can travel to and from the body, through the brain and spinal cord. They allow for anything from a muscle to contract to perception.

Structure Of A Neuron

The neurones are the basic building blocks of the nervous system, particularly specialized for the communication of nerve impulses. The different parts primarily constituting one single neuron are described as follows.

• Cell Body (Soma): It contains the nucleus and other organelles that maintain the health and functioning of the neurone.

• Dendrites: The branches are supported extensions, specifically those that allow the receiving of signals by activity conducted through neurone transmissions towards the cell body.

• Axon: The second type of long and thin cellular projection that conducts impulses away from the cell body towards the neurons or the effectors.

• Myelin Sheath: A fatty layer that insulates the cell body from the axon, serving to increase speed during conduction.

• Nodes of Ranvier: gaps in between the myelin sheath, the action potentials will cause the signal to jump along the axon quickly.

Generation Of Nerve Impulse

The generation of a nerve impulse includes a series of electrical changes across the membrane of the neuron. The resting neuron initiates the process, and subsequently, several unique phases occur as an impulse is transmitted.

Resting Potential

• The voltage across the neuronal membrane in the neuron is not conducting an impulse.

• Average Value: -70 mV.

• Ion Distribution: Outside the neuron, there is a high concentration of Na+; while the inside the neuron contains a high concentration of K+.

Action Potential

• Depolarisation: opening of Na+ channels and entry of Na+ make the membrane potential positive.

• Repolarisation: The opening of K+ channels and the exit of K+ make the potential negative.

• Hyperpolarisation: a momentary increase in negativity before the membrane potential returns to the resting potential.

• Refractory Period: A period in which the neuron is not able to initiate another action potential

Conduction Of Nerve Impulse

After the nerve impulse is initiated, it needs to be conducted through the length of the neuron to properly send the message. A nerve impulse can be conducted down the length of a neuron in one of two ways, which depends on whether a neuron is myelinated or un-myelinated.

Saltatory Conduction

• Happens in myelinated neurons.

• Action potential jumps from one Node of Ranvier to the other.

• Raises the speed of impulse induction

Continuous Conduction

• Happens in un-myelinated neurons.

• Action potentials propagate along the axon without decremental

Transmission Of Nerve Impulse

The generation of the nerve impulse is an organized process of electrical changes across the membrane of the neuron. It is a process that initiates with the smallest and moves across all the degrees before a neuron is ready to send an electrical signal.

Synapse Structure

• Presynaptic Neuron: Neuron sending the signal.

• Synaptic Cleft: Gap between neurons.

• Postsynaptic Neuron: The neuron receiving the signal.

Neurotransmitter Release

• When the action potential reaches the axon terminal.

• When Ca2+ enters through calcium channels.

• The neurotransmitters are released by the vesicles into the synaptic cleft.

Neurotransmitter Reception

• The neurotransmitters bind with the receptors present on the postsynaptic membrane.

• The ion channels either open to lead to the depolarisation or hyperpolarisation of the postsynaptic neuron.

Types Of Neurotransmitters

The two types of neurotransmitters are:

Excitatory Neurotransmitters

• Examples are Glutamate and acetylcholine.

• Promote depolarisation and action potential generation.

Inhibitory Neurotransmitters

• Examples are GABA and glycine.

• Induce hyperpolarisation, preventing action potential.

Factors Affecting Nerve Impulse Transmission

• Temperature: Higher temperatures increase speed.

• Axon Diameter: Larger diameters conduct faster.

• Myelination: Myelinated axons conduct impulses more rapidly.

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