What are Nerve Cells, Neurons & Synapses? | Physiology | Biology | FuseSchool

Summary

This script delves into the intricate workings of the nervous system, highlighting its role as a vast communication network. It explains the function of sensory, relay, and motor neurons in transmitting signals from receptors to effectors. The script also details the structure of neurons, emphasizing the importance of dendrites, cell bodies, and axons. Furthermore, it describes the synaptic process, where neurotransmitters facilitate the passage of electrical impulses between neurons, ensuring unidirectional signal flow and controlling signal speed. The video promises to explore reflex reactions and quick responses in future content.

Takeaways

• 🧠 The nervous system is a complex body-wide communication system that relays messages through sensory neurons to the central nervous system and then to motor neurons for a response.
• 🔍 Sensory neurons detect stimuli through receptors and send electrical impulse messages to the central nervous system.
• 📡 The central nervous system processes the sensory input and uses motor neurons to communicate with effectors, such as muscles or glands, to elicit a response.
• 👨‍🔬 There are three main types of neurons: sensory, intermediate or relay, and motor neurons, each with a specific role in the nervous system.
• 🌐 Sensory neurons carry signals from receptors to the spinal cord and brain, serving as the input pathway for the nervous system.
• 🔄 Intermediate or relay neurons facilitate communication within the central nervous system, passing messages from one part to another.
• 🏃 Motor neurons transmit signals from the central nervous system to effectors, initiating actions such as muscle contractions or hormone secretion.
• 🏢 Neurons consist of a cell body with a nucleus, dendrites, and axons, with dendrites receiving information and axons transmitting signals away from the cell body.
• 🛡️ Axons are insulated by a sheath that accelerates the conduction of nerve impulses, making them travel faster.
• 🔗 Synapses are junctions between neurons where electrical impulses are converted into chemical signals via neurotransmitters, allowing the signal to continue its journey to the next neuron.
• ➡️ Synapses ensure that nerve signals travel in one direction and control the speed of the signal transmission.
• 🔍 The video script also mentions that synapses will be discussed in more detail in another video, focusing on reflex reactions and quick responses.

Q & A

What is the primary function of the nervous system?

The primary function of the nervous system is to act as a complex body-wide communication system, relaying messages throughout the body.

How do sensory neurons contribute to the nervous system?

Sensory neurons detect stimuli through receptors and send electrical impulse messages along to the central nervous system.

What is the role of the central nervous system in processing sensory input?

The central nervous system processes the sensory input it receives and then relays the message via motor neurons to effectors for a response.

What are the three main components of a neuron?

The three main components of a neuron are the cell body with a nucleus, dendrites, and axons.

How do dendrites function in a neuron?

Dendrites receive information from other neurons or the external environment and transfer this information to the cell body.

What is the purpose of the myelin sheath surrounding axons?

The myelin sheath surrounding axons serves as an insulating layer that speeds up the rate of conduction, making nerve impulses travel faster.

How do motor neurons differ from sensory neurons in terms of their structure?

Motor neurons have motor end plates at the end of their fibers, which cause muscle fibers to contract or glands to secrete hormones, unlike sensory neurons that have receptors at the end of their fibers.

What is a synapse and why is it important in the nervous system?

A synapse is a junction between two adjacent neurons, allowing the electrical impulse to cross and continue its journey. It is important because it enables nerve signals to travel in one direction and controls the speed of the signal.

How do neurotransmitters function at a synapse?

Neurotransmitters are released when an electrical impulse arrives along an axon, they diffuse across the synapse, and bind with receptors on the next neuron, stimulating it to generate a new electrical signal.

What are the three types of neurons mentioned in the script?

The three types of neurons are sensory neurons, which detect signals; relay or intermediate neurons, which carry messages within the central nervous system; and motor neurons, which trigger responses.

How do synapses contribute to the one-way transmission of nerve signals?

Synapses ensure that nerve signals are transmitted in one direction by allowing the electrical impulse to cross the junction from one neuron to the next, but not in reverse.

Outlines

00:00

🧠 Nervous System Overview

The nervous system is described as a complex communication network throughout the body. It involves sensory neurons that detect stimuli and relay messages to the central nervous system (CNS). The CNS then uses motor neurons to send responses to effectors, such as muscles, to execute actions like running. This video aims to delve deeper into the nervous system's components, including the different types of nerve cells: sensory, intermediate (or relay), and motor neurons. These cells, known as neurons, transmit information in the form of electrical impulses and consist of a cell body, dendrites, and axons. Dendrites receive information, while axons carry signals away from the cell body, often insulated to speed up conduction.

🔬 Neuron Structure and Function

This section focuses on the structure and function of neurons, the nerve cells of the nervous system. Sensory neurons are responsible for carrying signals from receptors to the CNS, while intermediate or relay neurons facilitate communication within the CNS. Motor neurons, on the other hand, transmit signals from the CNS to effectors to initiate responses. Each neuron has a cell body containing a nucleus and dendrites that receive information and pass it to the cell body. Axons, which are often myelinated for faster signal transmission, carry the signal away from the cell body. Specialized structures like receptors at the end of sensory neurons and motor plates in motor neurons are highlighted, indicating their roles in stimulus detection and response triggering, respectively.

🔄 Synaptic Transmission Mechanism

The script explains the concept of synapses, which are junctions between adjacent neurons that allow electrical impulses to continue their journey across neurons. When an impulse reaches a synapse via an axon, it triggers the release of a chemical neurotransmitter. This neurotransmitter diffuses across the synapse and binds to receptors on the next neuron, stimulating it to generate a new electrical signal. Synapses are crucial for unidirectional signal transmission and controlling the speed of the nerve signals. The explanation sets the stage for further exploration of reflex reactions and quick responses in future videos.

Keywords

💡Nervous System

The nervous system is the body's complex communication network, responsible for transmitting signals throughout the body. It is central to the video's theme as it explains how the system operates as a whole. In the script, it is described as 'a massive complex body-wide communication system' that relays messages through sensory and motor neurons.

💡Sensory Neurons

Sensory neurons are specialized nerve cells that detect external stimuli and transmit this information to the central nervous system. They are key to the video's narrative as they initiate the communication process. The script mentions that 'messages are relayed to the central nervous system through sensory neurons' and that they 'carry signals from receptors to the spinal cord and brain'.

💡Central Nervous System (CNS)

The central nervous system, consisting of the brain and spinal cord, is the command center for processing and interpreting sensory information. It is integral to the video's theme as it is where sensory input is processed. The script describes it as the system that 'relays the message via motor neurons to effectors'.

💡Motor Neurons

Motor neurons are responsible for sending signals from the CNS to the muscles and glands, triggering a response. They are crucial for the video's message on how the body reacts to stimuli. The script states that motor neurons 'carry signals from the central nervous system to effectors', such as telling 'your legs to run'.

💡Neurons

Neurons, or nerve cells, are the fundamental units of the nervous system that transmit information in the form of electrical impulses. They are central to the video's educational content. The script defines neurons as having 'three main components' and being of 'three different types', emphasizing their role in the nervous system.

💡Receptors

Receptors are specialized structures that detect changes in the environment and initiate a response by sending signals to the nervous system. They are mentioned in the script as the starting point of sensory neuron activity, where 'stimulus is detected by a receptor', which then sends an 'electrical impulse message'.

💡Dendrites

Dendrites are branching extensions of a neuron that receive signals from other neurons and transmit this information to the cell body. They are part of the neuron's input system. The script describes dendrites as 'the input of the neuron' that 'receive information from other neurons or the external environment'.

💡Axons

Axons are long, slender projections of a neuron that carry electrical signals away from the cell body to other neurons or effectors. They are vital for the video's explanation of signal transmission. The script notes that axons are 'surrounded by an insulating sheath' which 'speeds up the rate of conduction'.

💡Synapses

Synapses are the junctions between neurons where electrical impulses cross to continue their journey. They are a key concept in the video as they explain how neurons communicate. The script describes synapses as 'a junction between two adjacent neurons' where 'the electrical impulse arrives along an axon' and triggers 'the release of a chemical neurotransmitter'.

💡Neurotransmitters

Neurotransmitters are chemical messengers that transmit signals across synapses from one neuron to another. They are essential for the video's explanation of how signals are passed between neurons. The script explains that neurotransmitters 'diffuse across the synapse and bind with the receptors on the membrane of the next neuron'.

💡Effectors

Effectors are the muscles or glands that respond to the signals from motor neurons, resulting in an action or response. They are important for the video's theme as they represent the endpoint of the nervous system's communication process. The script mentions that motor neurons send signals to 'effectors which provide a response', such as muscle contraction or hormone secretion.

Highlights

The nervous system is a complex body-wide communication system.

Messages are relayed to the CNS through sensory neurons after stimulus detection.

The CNS processes the message and relays it via motor neurons to effectors for a response.

Nerve cells, known as neurons, are the fundamental units of the nervous system.

There are three types of neurons: sensory, intermediate or relay, and motor neurons.

Sensory neurons carry signals from receptors to the CNS.

Intermediate or relay neurons facilitate message transfer within the CNS.

Motor neurons transmit signals from the CNS to effectors.

Neurons consist of a cell body, dendrites, and axons for information processing and transmission.

Dendrites receive information and transfer it to the cell body.

Axons carry signals away from the cell body, aided by an insulating sheath for faster conduction.

Sensory neurons have receptors at the end of their fibers for stimulus detection.

Motor neurons have motor plates that trigger muscle contraction or gland secretion.

Synapses are junctions between neurons, allowing electrical impulses to cross.

Neurotransmitters are released at synapses to stimulate the next neuron.

Synapses ensure nerve signals travel in one direction and control signal speed.

Upcoming video will cover reflex reactions and quick responses needed in certain situations.

Understanding the roles of sensory, relay, and motor neurons is crucial for grasping nervous system function.

Synapses play a vital role in transmitting impulses between neurons.

Transcripts

from our introduction to the nervous

system video you should already know

that the nervous system is essentially a

massive complex body-wide communication

system

messages are relayed to the central

nervous system through sensory neurons

so stimulus is detected by a receptor

which sends the electrical impulse

message along a sensory neuron to the

central nervous system

the central nervous system then relays

the message via motor neurons to

effectors which provide a response such

as telling your legs to run

in this video we are going to look at

the nervous system in more detail

including the different nerve cells and

the structure

to clarify nerve cells are known as

neurons and they are three different

types

sensory intermediate or relay and motor

neurons

these specialized cells carry

information as tiny electrical impulses

and make up the nervous system

sensory neurons carry signals from

receptors to the spinal cord and brain

intermediate or relay neurons carry

messages from one part of the central

nervous system to another

the motor neurons carry signals from the

central nervous system to effectors

they all have three main components a

cell body with a nucleus

dendrons and dendrites which are the

input of the neuron they receive

information from other neurons or the

external environment and transfer this

information to the cell body

and axons which carry the signal away

from the cell body

axons are surrounded by an insulating

sheath which speeds up the rate of

conduction

it makes the nerve impulses travel

faster

because the sensory neurons are the ones

that detect the stimulus they have

receptors at the end of their fibers

whereas because motor neurons trigger

the reaction they have motor in plates

which cause muscle fibers to contract or

glands to secrete hormones the relay

neurons make connections with other

neurons across gaps that are called

synapses

so let's have a look at how synapses

work

synapses are a junction between two

adjacent neurons

and the electrical impulse has to cross

the junction to carry on its journey

the electrical impulse arrives along an

axon this triggers the release of a

chemical neurotransmitter which diffuses

across the synapse and binds with the

receptors on the membrane of the next

neuron

this stimulates the second neuron to

generate a new electrical signal

synapses not only connect two or more

adjacent neurons together but they also

allow the nerve signals to travel in one

direction only

and they also control the speed of the

signal

in another video we will look at reflex

reactions and what happens when a very

quick response is needed

so from this video you should know that

there are three different types of

neuron or nerve cells

the sensory neuron which detects the

signal the relay or intermediate neuron

and the motor neurons which trigger the

response

you should also know how synapses work

transmitting the impulse between neurons