Difference Between Sensory and Motor Neurons

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Difference Between Sensory and Motor Neurons Difference Between Sensory and Motor Neurons

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Introduction

Our bodies are made up of many organs that help us function. Our work is dependent on the body's ability to function. Neurons are the cells that control our body’s functions. The nervous system in our body is controlled by two types of neuron cells: sensory and motor. Sense Neurons are neuron cells that activate sensory cells in response to their surroundings. Through sensory neurons, the actions of the environment enter our bodies. It then sends signals to the nervous system informing it of the information it has acquired. Sensory Neuron cells were discovered in the spinal cord.

Now, the nerve cells that make up the Nervous System are known as Motor Neurons. Motor Neurons aid in the modulation of a variety of downstream targets. Motor Neurons control all muscular motions in a living body by connecting to muscles, organs, and glands. The section of the Nervous System that occurs in the spinal cord is Motor Neurons.

Sensory Neurons vs Motor Neurons

Sensory Neurons and Motor Neurons are distinguished by the fact that Sensory Neurons are activated by environmental input. Motor neurons, on the other hand, are found in the nervous system and control a variety of downstream targets. Sensory and Motor Neurons have diverse structures and processes (Difference Between Sensory and Motor Neurons.

Difference Between Sensory and Motor Neurons in Tabular Form

Table: Sensory Neurons vs Motor Neurons
Parameters of Comparison
Sensory Neuron
Motor Neuron
The meaning
In a live body, sensory neurons are the cells that operate.
Motor Neurons are the cells that regulate how the body works.
The location
Sensory Neurons were implanted in the dorsal ganglia of a person's spinal cord.
Motor Neurons are found in the spinal cord, which connects the nervous system to the brain.
The commands
Sensory Neurons govern the cells that help the spinal cord identify the sensations.
Muscles, organs, glands, and muscle motions are all controlled by motor neurons.
The functions
Sensory Neurons respond to their surroundings by activating and sending signals to the nervous system, informing it of the information they have received.
Motor Neurons in the nervous system send signals to organs and glands, as well as control all muscular motions.
The axon
Sensory nerve cells have a short axon and perform a different purpose.
When compared to Sensory Neurons, Motor Neurons have a longer axon.

What are Sensory Neurons?

So, A sensory neuron (also known as an afferent neuron) is a type of nerve cell that perceives and reacts to external stimuli. Sensory neurons take information from their receptors, which are located throughout the peripheral nervous system, and transform it into electrical impulses. These impulses are transmitted to the central nervous system as signals. This information is then received and processed by the spinal cord and brain.

Also, Sensory neurons come in a variety of shapes, sizes, and locations, as well as the stimuli they respond to.

Neurons are nervous system cells that may conduct electrical impulses to allow the brain and the rest of the body to communicate. Sensory neurons, relay neurons, and motor neurons are the three main types of neurons.

Relay neurons permit motor neurons and sensory neurons to communicate with one another. Motor neurons govern movement, sensory neurons allow us to perceive experiences.

The brain depends on the information provided by sensory neurons to appropriately respond to inputs. Sensory neurons detect environmental stimuli, convert them to signals (electrical impulses), and send them to the brain and the spinal cord, in which a response can be created. Sensory neurons react to a variety of stimuli; for example, some detect temperature, while others perceive pain, and still, others are specialized for taste.

Dendrites, an axon, as well as a cell body make up a typical neuron, and sensory neurons are no different. The majority of sensory neurons are pseudounipolar, meaning that they have a single axon that extends from the cell body and splits into two extensions: dendrites and axons.

Structure

Because the signal is received from the external world, the sensory neuron "begins" with the dendrites. The signal is received by the dendrites' branch-like projections. The dendrites of sensory neurons are often relatively lengthy. The signal from the dendrites' receptors travels along with the nerve fiber until it reaches the cell body. The nucleus, cytoplasm, and other organelles are all found in the cell body. The cell body of pseudounipolar sensory neurons is found in a side branch of the nerve fiber.

Now, the axon is the fiber that transmits the signal away from the cell body. The axon in sensory neurons is short. The axon even communicates with the spinal cord, and the neuron terminates at the end of the axon.

Moreover, A fatty cushion called a myelin sheath protects, insulates, and nourishes nerve fibers. A layer of Schwann cells makes up the myelin sheath.

Location

The cell bodies of sensory neurons congregate in areas of the spinal cord known as the dorsal ganglia, sometimes known as the dorsal root ganglia. The term ganglia simply refer to a grouping of cell bodies.

Sensory neurons are found in the periphery of the brain. Because of the sensory neurons placed at the surface of the skin, humans may receive tactile stimuli that detect touch, discomfort, and cold. This information is subsequently sent to the cell body and axon via the sensory neuron. This information is sent by the axon to the spinal cord, where it also ends. After that, the information in the spinal cord is sent to the brain. If sensory information triggers a reflex response, the spinal cord can send the signal directly to the motor neurons. Signals from the spinal cord, for example, control the knee-jerk reflex.

Functions

Sensory neurons make up all of the senses in the body, including those you aren't aware of! Sensory neurons receive and transmit signals from a peripheral area in the central nervous system to a more central place in the central nervous system, such as the spinal cord or the brain.

Now, the sensory receptor at the dendritic end of the neuron is where the signal is transduced. When a stimulus, such as a scent, touch, or taste, is detected, a new signal is created.

The stimulus causes the sensory neuron to send a signal, which subsequently transports information to the brain. Depolarization begins at the sensory receptors and travels through the dendrites to the cell body, where it is subsequently conveyed to the axon. The signal at the axon terminal triggers the release of chemicals into the synapse. These substances are what cause the spinal cord to respond.

Types of Sensory Neurons

Sensory neurons are categorized in a variety of ways, including by their anatomy, location, and the input they perceive. Here are some instances of sensory neurons that can be categorized based on the type of stimuli they respond to.

  • Bipolar sensory neurons in the nasal cavity are known as olfactory sensory neurons. They provide us with our sense of smell by being activated by odor molecules in the air.
  • Now, Gustatory receptors, often known as taste receptors, detect molecules in food and provide humans with a feeling of flavor.
  • Also, Light is converted into electrical signals by photoreceptors, which are a type of neuroepithelial cell. As a result, they communicate with the brain, allowing us to perceive the world. Rods and cones are the two main types of photoreceptor cells in the human eye.
  • Temperature changes in the environment are detected by thermoreceptors. Some thermoreceptors are sensitive to cold, whereas others are sensitive to heat.
  • Changes in pressure or mechanical stress are detected by mechanoreceptors. The activation of a motor neuron, for example, causes the knee-jerk reflex to be triggered. When a mechanoreceptor in the knee is stimulated, the motor neuron is activated.
  • Proprioceptors, also known as position sensors, transmit data about the relative positions of our body parts to other body parts. These are what allow us to be spatially aware and coordinated. It is also necessary for our feeling of equilibrium.
  • Agony and temperature sensations, such as the pain in your mouth after eating spicy meals, are controlled by nociceptors (McLaughlin, 2020).

What are Motor Neurons?

A motor neuron is a central nervous system cell. To govern their functional output, motor neurons send signals to muscle cells or glands. Motor neuron illness can develop when these cells are injured in any way. Muscle wasting (atrophy) and motor function loss characterize this condition.

Neurons are individual cells. As a result, they contain the nucleus, cell membrane, ribosomes, mitochondria, and other basic eukaryotic organelles.

Structure

The dendrites, cell body (soma), and axon are the three components that make up the structure of a motor neuron. They have a single axon and many dendrites, making them multipolar in structure.

The branch-like extensions located at one end of a neuron are known as dendrites. These are the components that collect information from other neurons and send it to the cell body, where the signal is transmitted, and the cell is activated. The average number of dendrites per neuron is five to seven, however some, such as the Purkinje neurons in the brain, including over a thousand.

The organelles are found within the cell body. It is responsible for all of the cell's operations, and it is also where the majority of protein synthesis takes place.

Now, the axon is a protrusion from the cell body that can be quite prolonged. It has a tube-like or cable-like architecture that transports information from the dendrites to the opposite end of the cell, known as the axonal terminal, via the cell body. So then,  the information is then passed on to the next call, which may be an additional neuron or an effector cell such as a muscle cell.

Although each neuron has just one axon, it can have several branches and terminals, allowing it to communicate with a variety of cells. Axons can be exceedingly long; in fact, the axons that make up the sciatic nerve have the longest axon in the human body. These can be over a meter long and reach from the base of the lumbar spine to the big toe.

So basically, Synapses are the points at which neurons communicate with one another. They are the information transfer sites between the axon terminal and the dendrite.

Some neurons are also covered with a myelin sheath, which protects the cell from external stimuli that could disrupt signal transmission.

The function of Motor Neurons

Motor neurons are responsible for sending messages from the brain and spinal cord to muscle cells. As a result, they are in charge of all of our muscle cells' voluntary and involuntary activities.

To create these effects in our cells, motor neurons rapidly conduct electrical messages. The position of the cell body within the nervous system determines its specialized function.

Also, the spinal cord, brain stem, and motor cortex of the brain, a part of the cerebral cortex, are all home to motor neuron cell bodies. The motor cortex is engaged in voluntary action planning and execution.

Their projections then stretch outward to connect with effector organs, particularly muscles and glands, throughout the body, either directly or indirectly.

Types of Motor Neurons

Upper motor neurons convey signals from the brain to interneurons and lower motor neurons, and they begin in the brain's motor cortex or brain stem. These are the primary cells that connect the cerebral cortex to the brain stem or spinal cord to initiate voluntary movement throughout the body.

Lower motor neurons are present in the brain stem and spinal cord and are responsible for interacting directly with effector organs like muscle cells. They stimulate upper motor neurons' activity by receiving signals from them (directly or via interneurons) (McLaughlin, Motor Neuron, 2020).

Main Differences Between Sensory and Motor Neurons In Points

  • Sensory neurons carry signals from the sensory organs to the central nervous system. The dorsal root ganglion, which are specialized clusters situated at the dorsal roots of the spinal cord, gives rise to sensory neurons.
  • Motor nerves help initiate activities by transmitting signals from the CNS to the sensory organs.
  • Axons and dendrites are absent in sensory neurons.
  • A lengthy axon and many dendrons make up motor neurons.
  • Sensory neurons are equipped with receptors.
  • Motor neurons are devoid of receptors (Difference Between Sensory and Motor Neurons

Conclusion

Henceforth, we got to know the major differences between sensory and motor neurons.

References

  • McLaughlin, K. (2020, May 16). Motor Neuron. Retrieved from biology dictionary: https://biologydictionary.net/motor-neuron/
  • McLaughlin, K. (2020, June 14). Sensory Neuron. Retrieved from biology dictionary: https://biologydictionary.net/sensory-neuron/

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"Difference Between Sensory and Motor Neurons." Diffzy.com, 2022. Sun. 27 Nov. 2022. <https://www.diffzy.com/article/difference-between-sensory-and-motor-neurons-461>.



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