Know the Difference Between Axon and Dendrite
The Human Nervous System is primarily divided into two components - the peripheral Nervous System (PNS) and the Central Nervous System (CNS). The CNS is essentially the hub of the organism’s body, which includes parts of the brain and spinal cord. The System is responsible for regulating command, coordination, information, and the integration which influences numerous activities of the body.
The other component of the Nervous System, as mentioned above, is PNS. The PNS is made up of Neurons, plus other parts that are outside CNS. The signals that are received by CNS are primarily from PNS which plays the supporting role. The Neurons are the components of PNS that are vital for processing as well as transferring information to muscles, glands, and Nerve Cells. There are various billions of Neurons that are present in the body that have extensions like Axons and the Dendrites.
The Neurons are Nerve Cells having the Cell body called soma. Neurons produce a significant chunk of protein and these proteins get absorbed in the soma. The Nerve Cells consist of two distinctive and important components - Axons and Dendrites. The processes of short branching are called Dendrites while the processes that are longer than Dendrites are called Axons. This is the fundamental structural difference between the Axons and the Dendrites.
The Dendrites are specialized forms of short fibrous branches which extend from the Nerve Cell body. The function of the dendron is to accept and process the incoming information that takes place within Dendrites. The incoming signals of dendron function belong to two categories - inhibitory which prevents the Neurons from taking the trigger and excitatory which makes the Neurons take the trigger.
The single Neuron might consist of multiple sets of Dendrites and it can receive a lot of information from input signals. The impulse is primarily dependent on the number of inhibitory and excitatory signals it receives. If a Neuron rejects the incoming trigger, the Nerve impulse is shifted down to the Axon.
What is the Axon?
The Axon is a tail-like projection of a Nerve Cell, also called the Nerve fiber which conducts electrical impulses within the body which is away from the soma or Nerve Cells. The impulses typically come from the Cell body at a special junction named as Axon hillock. The Axons are the main transition lines which bundle up for creating the Nerve. One of the differences between Dendrite and Axon is the fatty substance named myelin which only covers the Axon.
Some of the main differences between Axon and Dendrite are as follows. Axon originates from the discharging end of Neuron while Dendrite originates from the receiving end of Neuron. You can only find one Axon per Nerve Cell whereas there are various Dendrites within a Nerve Cell. The Axon has the long-tail structure and Dendrite has short, fibrous, root-like structure. The Axon has uniform thickness throughout its length while Dendrite consists of tapering end having root-like branches.
FAQs on Human Nervous System
1. What are the two main divisions of the human nervous system?
The human nervous system is broadly divided into two main parts:
- The Central Nervous System (CNS): This is the body's primary control centre, consisting of the brain and the spinal cord. It processes information received from the body and sends out instructions.
- The Peripheral Nervous System (PNS): This consists of all the nerves that branch out from the CNS and connect it to the rest of the body, including limbs and organs. It transmits messages to and from the CNS.
2. What is a neuron and what are its main components?
A neuron, or nerve cell, is the basic structural and functional unit of the nervous system. It is responsible for transmitting nerve impulses. Its main components are:
- Cell Body (Soma): Contains the nucleus and is the main metabolic centre of the neuron.
- Dendrites: These are short, branched extensions that receive signals from other neurons and transmit them towards the cell body.
- Axon: A long, single extension that carries nerve impulses away from the cell body to other neurons, muscles, or glands.
3. What are the different types of neurons based on their function?
Functionally, there are three main types of neurons:
- Sensory Neurons: These neurons transmit signals from sensory receptors (like those in the skin or eyes) to the central nervous system. They carry information about stimuli such as light, sound, or touch.
- Motor Neurons: These neurons carry signals from the central nervous system to the muscles and glands (effectors), instructing them to respond, for example, by contracting a muscle.
- Interneurons: Found exclusively within the central nervous system, these neurons act as connectors, transmitting signals between sensory and motor neurons.
4. How is a nerve impulse transmitted from one neuron to another?
A nerve impulse is transmitted between two neurons at a specialised junction called a synapse. The process involves several steps:
- An electrical signal (action potential) travels down the axon of the first neuron (presynaptic neuron).
- When it reaches the axon terminal, it triggers the release of chemical messengers called neurotransmitters into the synaptic gap.
- These neurotransmitters diffuse across the gap and bind to receptors on the dendrites of the next neuron (postsynaptic neuron).
- This binding generates a new electrical signal in the postsynaptic neuron, thus continuing the impulse transmission.
5. What is the difference between the Central Nervous System (CNS) and the Peripheral Nervous System (PNS)?
The key difference lies in their components and function. The CNS, consisting of the brain and spinal cord, acts as the integration and command centre. It processes information and makes decisions. In contrast, the PNS is a network of nerves that connects the CNS to the rest of the body. Its primary function is communication—relaying sensory information to the CNS and transmitting motor commands from the CNS to the body's muscles and glands.
6. What are the major parts of the human brain and their primary functions?
The human brain has three major parts, each with distinct functions:
- Cerebrum: The largest part, responsible for higher-level functions like thought, language, memory, and voluntary movements. It is divided into two hemispheres.
- Cerebellum: Located at the back of the brain, it is crucial for coordinating voluntary movements, posture, balance, and coordination.
- Brainstem: This connects the cerebrum and cerebellum to the spinal cord. It controls vital involuntary functions such as breathing, heart rate, and blood pressure.
7. What is a reflex arc and why is it important?
A reflex arc is the neural pathway that controls a reflex action, which is an involuntary and rapid response to a stimulus. For example, quickly pulling your hand away from a hot object. It is important because it allows for an extremely fast reaction to potentially harmful stimuli without waiting for the brain to process the information first. The signal travels from a sensory neuron to the spinal cord, which immediately sends a command via a motor neuron to a muscle, ensuring a swift, protective action.
8. What are some common disorders that affect the human nervous system?
Several disorders can affect the structure or function of the nervous system. Some common examples include:
- Alzheimer's Disease: A progressive neurodegenerative disorder that affects memory and other cognitive functions.
- Parkinson's Disease: A disorder of the central nervous system that affects movement, often including tremors.
- Epilepsy: A chronic neurological disorder characterised by recurrent seizures.
- Multiple Sclerosis (MS): An autoimmune disease where the body's immune system attacks the protective sheath (myelin) that covers nerve fibres.
