Human Nervous System (Part 1) - Spinal Cord and Periphery (Animation)
Summary
TLDRThis animation delves into the intricacies of the human nervous system, highlighting the central and peripheral components. It explains the roles of nerve cells, spinal nerves, and the synaptic process, including the function of neurotransmitters. The script also explores sensory receptors in the skin and their connection to the spinal cord, illustrating how stimuli are translated into electrical impulses and processed by the brain, culminating in reflex actions.
Takeaways
- 🧠 The human nervous system is a complex network composed of numerous nerve cells that process environmental stimuli.
- 🌐 It is divided into the central nervous system (CNS), which includes the brain and spinal cord, and the peripheral nervous system (PNS).
- 💛 The CNS is well-protected within the skull and spinal column, while the PNS extends throughout the body, as depicted in yellow in the animation.
- 🦴 The spinal cord is housed within the spinal canal, surrounded by vertebrae, fatty and connective tissue, and is covered by three protective membranes.
- 🔁 The spinal nerves of the PNS connect to the CNS, with afferent fibers carrying impulses to the CNS and efferent fibers carrying impulses to muscles and glands.
- 🔋 Nerve cells, or neurons, consist of a cell body, dendrites, and an axon. Dendrites receive stimuli, while the axon conducts electrical impulses.
- 🔗 At the end of an axon are terminal buttons, which form synapses with other neurons or cells, and are involved in neurotransmitter release.
- 🚀 The conduction speed of impulses is increased by myelination, where Schwann cells wrap around the axon, forming nodes of Ranvier.
- 💊 Neurotransmitters are stored in vesicles within terminal buttons and are released into the synaptic cleft through a process called exocytosis.
- 🔄 The process of synaptic transmission allows nerve cells to communicate with each other, converting neurotransmitters back into electrical impulses at the post-synaptic cell.
- 🔬 Sensory receptors in the skin, such as Meissner's corpuscles, Merkel cells, and Ruffini corpuscles, convert mechanical stimuli into electrical impulses for transmission to the CNS.
- 🔄 The spinal cord processes sensory information and can also facilitate reflex actions, such as muscle contractions, in response to stimuli without brain involvement.
Q & A
What is the human nervous system?
-The human nervous system is a complex network composed of countless nerve cells that process stimuli from the environment and control various functions such as movement, sensation, and cognition.
How is the nervous system divided?
-The nervous system is divided into the central nervous system (CNS), which includes the brain and spinal cord, and the peripheral nervous system (PNS), which extends throughout the body.
What are the main components of the CNS?
-The CNS is primarily composed of the brain and spinal cord, which are well protected by the skull and spinal column, respectively.
What is the role of the peripheral nervous system in the body?
-The PNS is responsible for transmitting nerve impulses from various parts of the body to the CNS and from the CNS to the muscles and glands.
What are the different types of nerve fibers in the PNS?
-The PNS contains afferent (sensory) fibers that carry impulses from sensory receptors to the CNS, and efferent (motor) fibers that carry impulses to muscles and glands.
What is the function of the spinal ganglion or dorsal root ganglion?
-The spinal ganglion or dorsal root ganglion is a thickening where the cell bodies of sensory neurons are located, receiving and transmitting sensory information to the CNS.
What is the significance of the myelin sheath in nerve fibers?
-The myelin sheath, formed by Schwann cells, encloses nerve fibers and increases the conduction speed of nerve impulses by allowing for saltatory conduction at the nodes of Ranvier.
How do nerve cells transmit signals to each other?
-Nerve cells transmit signals through synapses. When an action potential reaches the terminal button of an axon, it triggers the release of neurotransmitters into the synaptic cleft, which then bind to receptors on the post-synaptic cell, converting the signal back into an electrical impulse.
What are the different types of skin receptors mentioned in the script?
-The script mentions Meissner's corpuscles, Merkel cells, and Ruffini corpuscles as types of skin receptors that respond to different types of mechanical stimuli.
How does a reflex arc work in the spinal cord?
-A reflex arc is a neural pathway that allows for a rapid response to a stimulus. Sensory neurons transmit impulses to interneurons in the spinal cord, which then activate motor neurons to cause a response, such as muscle contraction.
What is the difference between white and gray matter in the spinal cord?
-White matter in the spinal cord consists of nerve fibers that transmit information, while gray matter contains the cell bodies of neurons where processing of information occurs.
Outlines
🧠 Central and Peripheral Nervous Systems Overview
This paragraph introduces the human nervous system, emphasizing its complexity and function in processing environmental stimuli. It distinguishes between the central nervous system (CNS), which includes the brain and spinal cord, and the peripheral nervous system (PNS), which extends throughout the body. The CNS is well protected within the skull and spinal column, while the PNS is depicted in yellow in the animation. The paragraph also explains the structure of the spinal cord, including the vertebrae, spinal canal, and the protective membranes known as the dura mater and arachnoid mater. Additionally, it describes the function of spinal nerves, which are part of the PNS and connect to the spinal cord, and differentiates between afferent (sensory) and efferent (motor) nerve fibers.
🌱 Nerve Cell Structure and Synaptic Transmission
The second paragraph delves into the structure of nerve cells, also known as neurons, which are the fundamental units of the nervous system. It describes the components of a neuron, including the cell body, nucleus, dendrites, axon, and terminal buttons. The paragraph explains the role of dendrites in receiving stimuli and the axon in conducting electrical impulses. It also discusses the myelin sheath, which is formed by Schwann cells and increases the conduction speed of impulses through a structure known as nodes of Ranvier. The process of synaptic transmission is highlighted, detailing how neurotransmitters are released from vesicles in the terminal buttons and interact with receptors on the post-synaptic cell membrane to continue the nerve signal. The paragraph also touches on the variety of dendritic spines and their role in post-synaptic signal reception.
🔁 Sensory Processing and Reflexes in the Spinal Cord
The final paragraph focuses on the sensory processing within the spinal cord and the concept of reflexes. It describes how sensory impulses are transmitted from receptors in the skin and other organs to the CNS via sensory neurons. The cell bodies of these sensory neurons are located in the spinal ganglion, which is why the corresponding part of the spinal nerve is thicker. The paragraph explains the types of sensory receptors found in the skin, such as Meissner's corpuscles, Merkel cells, and Ruffini corpuscles, and their respective roles in responding to mechanical stimuli. It also discusses the direct processing of sensory information in the spinal cord, leading to reflex actions such as muscle contraction or relaxation in response to stimuli like a burn, without the need for brain intervention.
Mindmap
Keywords
💡Nervous System
💡Central Nervous System (CNS)
💡Peripheral Nervous System (PNS)
💡Spinal Cord
💡Nerve Cells
💡Axon
💡Synapse
💡Neurotransmitters
💡Dendrites
💡Nodes of Ranvier
💡Reflex
💡Sensory Neurons
💡Motor Neurons
Highlights
The human nervous system is a complex system made up of countless nerve cells that process stimuli from the environment.
A distinction is made between the Central and peripheral nervous systems, with the peripheral nervous system running through the entire body.
The brain and spinal cord are part of the central nervous system, well protected by the skull and spinal column.
The spinal cord is enclosed in three membranes, including the outer membrane called dura mater.
Spinal nerves of the peripheral nervous system lead into the spinal cord, divided into afferent and efferent fibers.
Afferent nerve fibers conduct impulses from sensory receptors to the central nervous system.
Efferent nerve fibers carry impulses to affect organs, mainly muscles and glands.
The spinal ganglion or dorsal root ganglion is a thickening where blood vessels and many nerve fibers are part of a spinal nerve.
Fascicle nerve fibers are enclosed by a connective tissue layer, with Schwann cells located underneath.
Schwann cells can increase the conduction speed of an impulse by forming nodes of Ranvier.
Nerve cells consist of a nerve fiber, cell body, nucleus, dendrites, and terminal buttons.
Terminal buttons possess calcium channels that open and close, allowing neurotransmitters to be released via exocytosis.
Neurotransmitters are absorbed by receptors on the post-synaptic cell membrane, converting them back into electrical impulses.
Dendrites have spines with post-synapses that can receive signals from terminal buttons.
Terminal buttons can form synapses with other axons or terminal buttons, facilitating nerve impulse transmission.
Sensory neurons' cell bodies are located in the spinal ganglion, making that part of the spinal nerve thicker.
Neurons in the dorsal root ganglion are pseudo unipolar neurons with axons divided into two branches.
Unmyelinated nerve fibers lack a myelin sheath, meaning there is no increase in conduction speed.
Sensory receptors on fingertips convert mechanical stimuli into electrical impulses transmitted to the brain.
Different types of skin receptors, such as Meissner's corpuscles, Merkel cells, and Ruffini corpuscles, respond to various stimuli.
Action potentials generated by skin receptors are transmitted to the brain via nerve fibers and the spinal cord.
The spinal cord can process impulses directly through reflexes, such as when we burn ourselves.
Transcripts
[Music]
in this animation we want to explain the
human nervous system with the help of
incredible never-before seen
images the body's nervous system is a
complex system made up of countless
nerve cells that serve among other
things to process stimuli from the
environment a distinction is generally
made between the Central and peripheral
nerve nervous system the peripheral
nervous system runs through the entire
body and is shown here in
[Music]
yellow the brain and spinal cord are
part of the central nervous
[Music]
system they are well protected by the
skull and spinal
column
our spinal column consists of individual
vertebrae that have a spinal canal
containing fatty and connective tissue
and the spinal cord like the brain the
spinal cord is enclosed in three
membranes the outer membrane of the
spinal cord is called dura moer the
arachnoid modder is located directly
under the dura modder this arachnoid
modder is connected to the P Mo via
arachnoid
tcul
[Music]
the spinal nerves of the peripheral
nervous system lead into the spinal cord
whereby the spinal nerve is divided into
afferent and ephant fibers the afferent
nerve fibers conduct nerve impulses from
the sensory receptors to the central
nervous system while ENT nerve fibers
carries impulses to affect our organs
mainly muscles and glands we will take a
close closer look at the thickening that
we call spinal gangion or dorsal root
gangion in a
[Music]
moment blood vessels and many nerve
fibers are part of a spinal nerve
several nerve fibers form a nerve
[Music]
faasle nerve fibers are enclosed by a
connective tissue layer of endorian
Schwan cells are located under this
protective layer if these cells are
wrapped around the axon several times
they are able to increase the conduction
speed of an Impulse the increase in
conduction speed is achieved by regular
interruptions which are known as nodes
of
ronier the cell uses an axon to conduct
electrical
impulses
let us first take a look at the basic
structure of a nerve cell nerve cells
consist of the nerve fiber mentioned
earlier which originates from a cell
body inside we see the glowing cell
nucleus dendrites mainly used to receive
stimuli also originate from the cell
[Music]
body at the end of an axon are terminal
buttons
[Music]
these small knobs form the first part of
a synapse and are therefore called press
synaptic
terminals terminal buttons possess
calcium channels that can open and
close these calcium channels open via an
electrical
impulse as soon as the action potential
reaches the terminal button the calcium
channels open and allow calcium ions to
flow
in
there are vesicles in the terminal
button these vesicles contain
neurotransmitters which are shown here
as red spheres there are approximately
200 to 500 such vesicles in the synaptic
terminal
buttons the calcium ions enable these
vesicles to fuse with the outer layer
that is the membrane of the
cell
[Music]
the fusion of the vesicle with the
membrane allows the neurotransmitters to
be transported out of the cell this
process is known as
exocytosis the neurotransmitters are
absorbed by receptors located on the
post synaptic cell membrane which
convert the neurotransmitters back into
an electrical impulse with the help of
such a chemical synapse a nerve cell can
transmit its signal to an another nerve
[Music]
[Applause]
[Music]
cell for this purpose the dendrites have
spines which possess the post synapses
mentioned before spines can take many
forms including stubby and
[Music]
[Applause]
thin
[Music]
terminal buttons can not only transmit
impulses via the spines of dendrites
they can also transmit their action
potential directly to the cell it is
also possible for a terminal button to
form a synapse with another axon or
terminal button nerve cells can and must
also be able to transmit impulses to
other cells such as our muscle cells so
that we can
move but now let's get back to the
spinal cord and nerves the impulses are
transmitted via the nerve fibers on one
side impulses come from the spinal cord
on the other side they are transmitted
to the spinal cord the cell bodies of
the sensory neurons are located in the
spinal gangion that is why this part of
a spinal nerve is thicker than the other
part the neurons in the dorsal root
gangion are pseudo unipolar neurons in
which the Axon is divided into two
branches One Branch goes to the
periphery for example to the skin and
the other to the central nervous
system impulses are transmitted from the
skin to the central nervous system via
the
axon depending on the function neurons
can also have unmyelinated nerve fibers
in that case non-m milina Schwan cells
and sheath the axon that means that
there is no increase in conduction
[Music]
speed let's take a look at the process
with the help of a highly simplified
image on the fingertips in particular we
have numerous receptors at the ends of
sensory nerve fibers if the receptors of
a sensory neuron receive a mechanical
stimulus this stimulus is converted into
an electrical impulse and transmitted
via the a on to another neuron in the
spinal
cord the neuron in the spinal cord
transmits the action potential to the
brain where another neuron finally
transmits the impulse to the somato
sensory cortex the impulse is then
[Music]
processed as already mentioned there are
numerous receptors in the skin some
receptors are are located in the upper
layer of the skin the epidermis which is
made up of dead and living
keratinocytes mner cor pusles and Merkel
cells are found here other receptors are
located in deeper layers of the skin
such as rufini cor pusles which are
found in the
dermis there are many other receptors
but only these three will be briefly
described here let's start with the
meisner's cor
pusle as soon as pressure is applied to
the er's core pusle for example by
pressing on the skin an action potential
is triggered this action potential only
occurs when there is a change in
pressure meisner's cor pusles are
therefore rapidly adapting mechano
receptors Merkel cells on the other hand
belong to the slowly adapting mechano
receptors as they trigger an action
potential in response to both Dynamic
and static
stimuli
rufini cor pusles trigger an action
potential when the tissue is stretched
rufini cor pusles also belong to slowly
adapting mechano receptors of the
skin let's take another look at the
spinal cord and the spinal
[Music]
nerves the axons of the sensory nerves
end at nerve cells in the spinal cord
nerve fibers which can be seen here as
thin threads extending into the brain
originate from the cell bodies of these
nerve
cells the nerve fibers are referred to
as white and the cell bodies as gray
matter when The receptors of the skin or
organs generate an action potential they
transmit this action potential via the
nerve fibers to the gray matter after
which the action potential is
transmitted to the brain via the white
matter
[Music]
from above we can see the
butterfly-shaped structure of the gray
[Music]
matter however impulses can also be
processed directly in the spinal cord
the sensory fibers transmit impulses
directly or indirectly to motor nerve
fibers which can then contract or relax
a muscle this is called
[Music]
reflex such a reflex occurs when we burn
ourselves receptors then transmit
impulses via Sensory neurons to
interneurons which then cause motor
neurons to contract
[Music]
muscles
[Music]
浏览更多相关视频
Organizzazione del Sistema Nervoso | NEUROSCIENZE - Lezione 9
BIOLOGI Kelas 11 - Sistem Koordinasi (Saraf & Hormon) | GIA Academy
#controlandcoordination full chapter | cbse Class 10th Biology | NCERT class 10 science chapter 7
Coordination & Control | Mdcat Biology Lecture || Mdcat 2023
SISTEMA SENSORIAL: Receptores sensoriais, Vias aferentes e Centros de processamento | MK Fisiologia
Nervous System
5.0 / 5 (0 votes)