16 Nervous Systems

Summary

This script delves into the intricacies of the human nervous system, highlighting its three main divisions: the central nervous system (CNS), which includes the brain and spinal cord; the peripheral nervous system (PNS), encompassing nerves outside the CNS; and the autonomic nervous system (ANS), which controls involuntary actions. The ANS is further split into the sympathetic, responsible for 'fight or flight' responses, and the parasympathetic, which manages 'rest and digest' functions. The script promises a deeper exploration of these systems, particularly the CNS, in upcoming lectures.

Takeaways

• 🧠 The human body has multiple nervous systems, not just one.
• 🌐 The Central Nervous System (CNS) consists of the brain and spinal cord, controlling the mind and behavior.
• 🌿 The Peripheral Nervous System (PNS) includes all nerves outside the CNS, extending throughout the body.
• 🔍 The PNS is further divided into the Somatic Nervous System and the Autonomic Nervous System.
• 🏃‍♂️ The Somatic Nervous System is responsible for voluntary control of body movements through skeletal muscles.
• 🫀 The Autonomic Nervous System manages visceral functions that occur below the level of consciousness, such as heart rate and digestion.
• 🛑 The Autonomic Nervous System is further split into the Sympathetic and Parasympathetic Nervous Systems.
• 💨 The Sympathetic Nervous System activates the 'fight or flight' response during crises or perceived threats.
• 🛌 The Parasympathetic Nervous System takes over during rest and recovery, promoting digestion and relaxation.
• 🔁 Only one of the two branches of the Autonomic Nervous System is active at a time, depending on the body's needs.

Q & A

What is the central nervous system (CNS) and what does it control?

The central nervous system (CNS) includes the brain and spinal cord, and it controls the mind and behavior.

What is the peripheral nervous system (PNS) and how is it different from the CNS?

The peripheral nervous system (PNS) consists of nerves that extend outside of the brain and spinal cord. It controls all other nerves in the body not directly connected to the CNS.

How is the peripheral nervous system divided?

The peripheral nervous system is divided into the somatic nervous system, which controls voluntary movements, and the autonomic nervous system, which manages involuntary functions.

What does the somatic nervous system do?

The somatic nervous system is responsible for voluntary control of body movements through skeletal muscles, such as writing, walking, or tapping your foot.

What are the key functions of the autonomic nervous system?

The autonomic nervous system controls involuntary functions like heart rate, digestion, respiration, and perspiration, which occur below the level of conscious awareness.

What is the role of the sympathetic nervous system?

The sympathetic nervous system activates the body's 'fight or flight' response during crisis situations, increasing heart rate, blood pressure, and preparing the body for action.

How does the parasympathetic nervous system function in contrast to the sympathetic nervous system?

The parasympathetic nervous system is responsible for 'rest and digest' functions. It promotes recovery by slowing the heart rate and aiding in digestion when the body is not in a state of crisis.

Can the sympathetic and parasympathetic nervous systems be active at the same time?

No, only one of the systems can be active at a time. If the sympathetic nervous system is engaged, the parasympathetic system is inactive, and vice versa.

What are examples of modern-day scenarios that can trigger the sympathetic nervous system?

Modern scenarios like anxiety over sending an important email or facing a stressful work situation can trigger the sympathetic nervous system, causing symptoms like increased heart rate and blood pressure.

How does the sympathetic nervous system affect digestion and sleep?

When the sympathetic nervous system is activated, it diverts energy away from non-essential functions like digestion and sleep, which is why stress can cause digestive issues and difficulty sleeping.

Outlines

00:00

🧠 Overview of the Nervous System

This paragraph introduces the concept of the nervous system, explaining that there is a common misconception that humans have just one nervous system, when in fact there are several. The central nervous system (CNS), which includes the brain and spinal cord, is responsible for controlling the mind and behavior. The peripheral nervous system (PNS) consists of nerves that extend beyond the CNS, and it is further divided into the somatic nervous system, which controls voluntary movements through skeletal muscles, and the autonomic nervous system, which oversees visceral functions such as heart rate, digestion, and respiration. The autonomic nervous system is further broken down into the sympathetic and parasympathetic systems, which are responsible for the 'fight or flight' response and restorative processes, respectively.

05:00

🔄 The Autonomic Nervous System: Sympathetic vs. Parasympathetic

The second paragraph delves deeper into the autonomic nervous system, highlighting the interplay between the sympathetic and parasympathetic systems. It explains that these two systems are mutually exclusive, meaning only one can be active at a time. The sympathetic nervous system activates during stressful or dangerous situations, preparing the body for 'fight or flight' by increasing heart rate and diverting energy away from non-essential functions like digestion. Conversely, the parasympathetic system takes over during rest and recovery, promoting digestion and relaxation. The paragraph also touches on how chronic activation of the sympathetic system due to stress can negatively impact digestion and sleep, illustrating the body's prioritization of immediate survival needs over restorative processes.

Keywords

💡Central Nervous System (CNS)

The Central Nervous System is composed of the brain and spinal cord, and it controls the mind and behavior. This system processes information and coordinates activities across the body. In the script, the CNS is referred to as the system responsible for managing thoughts, voluntary actions, and decision-making processes, playing a central role in controlling body functions.

💡Peripheral Nervous System (PNS)

The Peripheral Nervous System includes all nerves located outside the brain and spinal cord. It connects the CNS to the rest of the body, transmitting sensory and motor signals. In the video, the PNS is mentioned as a system that includes all nerves except those in the brain and spinal cord, ensuring communication between the body and CNS.

💡Somatic Nervous System

The Somatic Nervous System controls voluntary movements through skeletal muscles, such as walking or writing. It coordinates the transfer of signals between the CNS and muscles. In the transcript, this system is discussed in the context of voluntary control of body movements, allowing humans to consciously interact with their environment.

💡Autonomic Nervous System

The Autonomic Nervous System regulates involuntary bodily functions like heart rate, digestion, and respiration. This system operates below the level of consciousness. The video explains that the autonomic nervous system is divided into the sympathetic and parasympathetic systems and governs automatic functions essential for survival.

💡Sympathetic Nervous System

The Sympathetic Nervous System is part of the autonomic nervous system responsible for the 'fight or flight' response. It activates during stressful or dangerous situations, increasing heart rate and preparing the body to respond to threats. In the transcript, it is mentioned in contexts ranging from physical dangers like animal attacks to modern-day stressors like sending a stressful email.

💡Parasympathetic Nervous System

The Parasympathetic Nervous System is the counterbalance to the sympathetic system, focusing on 'rest and digest' activities. It helps the body relax and recover after stress, promoting digestion and restful states. The video contrasts this system with the sympathetic system, explaining that it manages bodily functions when a person is not in crisis.

💡Fight or Flight Response

The fight or flight response is a physiological reaction triggered by the sympathetic nervous system during a threat. It prepares the body to either confront or flee from danger. In the transcript, this concept is discussed in relation to both real physical threats, such as encountering a wild animal, and modern psychological stressors, like anxiety over sending an important email.

💡Rest and Digest

Rest and digest refers to the body's ability to relax, recuperate, and focus on processes like digestion and sleep, which are regulated by the parasympathetic nervous system. The video explains how this system helps balance the stress response, allowing the body to recover after the sympathetic nervous system is activated.

💡Visceral Functions

Visceral functions are automatic, unconscious activities like heart rate, digestion, and respiratory rate, governed by the autonomic nervous system. In the script, they are described as processes managed without conscious effort, with the autonomic nervous system handling these life-sustaining functions.

💡Nerves

Nerves are bundles of fibers that transmit signals between the CNS and the body, allowing communication within the nervous system. The video describes the PNS as including all nerves outside the CNS, highlighting their role in relaying information between the brain, spinal cord, and peripheral organs or muscles.

Highlights

The body has several nervous systems, not just one.

The central nervous system (CNS) controls the mind and behavior, specifically the brain and spinal cord.

The peripheral nervous system (PNS) includes all nerves outside the brain and spinal cord.

The peripheral nervous system can be broken down into the somatic and autonomic nervous systems.

The somatic nervous system involves voluntary control of body movements through skeletal muscles.

The autonomic nervous system controls visceral functions below the level of consciousness, such as heart rate and digestion.

The autonomic nervous system is divided into the sympathetic and parasympathetic nervous systems.

The sympathetic nervous system activates during crisis situations, responsible for the fight-or-flight response.

The sympathetic nervous system can also be triggered by non-life-threatening situations, such as anxiety from sending an email.

The parasympathetic nervous system takes over when the sympathetic nervous system is not engaged, focusing on rest and digestion.

Only one of the sympathetic or parasympathetic systems is active at a time.

When the sympathetic nervous system is active, resources are diverted away from rest and digestion.

Anxiety or stress can lead to issues with digestion and sleep due to sympathetic nervous system activation.

The parasympathetic nervous system helps the body recover from stress, promoting rest and restoration.

A detailed exploration of the central nervous system will follow in subsequent lectures.

Transcripts

so when it comes to our body there's

kind of this belief that we just have

one nervous system but technically we

have several different nervous systems

so I want to briefly talk about them

here so first we have the central

nervous system or the

CNS the central nervous system controls

the mind and our

behavior and specifically we're talking

about the brain as well as the spinal

cord then we have the peripheral nervous

system or the

pns and the peripheral nervous system

involves nerves in the body that extend

outside of the central nervous system so

any nerves that we have in our body

other than you know where our spinal

cord is or where our brain

is the peripheral nervous system can

then be broken down into the sematic

nervous system as well as the autonomic

nerv nervous system so the sematic

nervous system involves voluntary

control of body movements through our

skeletal

muscles and then the autonomic nervous

system

involves visceral functions uh which

really occur below the level of

Consciousness so this includes things

like our heart

rate

digestion perspiration

our respiratory rate so how fast we're

breathing

Etc so essentially we have this whole

thing so we have our nervous system so

we have the central nervous system brain

and spinal cord we have the peripheral

nervous system now this slide breaks

them down a little bit more um into a

sensory nervous system for sensory

information and then the motor nervous

system uh which gets into then the

somatic and the autonomic nervous

systems

but essentially what we were just

talking

about

so and then we'll talk about the anomic

a little bit more than a minute so for

the sematic nervous system like I said

this controls um and coordinates

volunteer movement so anytime we are

moving something through our skeletal

muscles you know any Movement we choose

to do essentially writing tapping a foot

walking around Etc that involves our

sematic nervous system and really it has

to De with information between our

central nervous system you know our

brain and our spinal cord and our

body and then the autonomic nervous

system which like it says more

responsible for those visceral uh

reactions and all of that can then be

broken down into the sympathetic nervous

system and the parasympathetic nervous

system so so the sympathetic nervous

system is what controls us when we're

engaged in a

crisis so if we're in a situation that

requires essentially like fight ORF

flight or a body goes into like that

fight ORF flight response that's our

sympathetic nervous system taking

over and so that's going to rev us up to

deal with whatever the situation is now

in the past I was more along the lines

of you know we thought we were in danger

because we might be attacked by like a

bear nowadays that still might be the

case you know if we walking in the woods

you know maybe uh we are in the presence

of something that could attack us so our

sympathetic nervous system is going to

take over them um or if we're in the

situation where there could be a human

that might attack us you know our

sympathetic nervous system is going to

take over but since that sympathetic

nervous system will take over for more

kind of mundane things in a way compared

to like trying to outrun a beer um so

maybe you have an email you need to send

out but for whatever reason sending out

that email is giving you a lot of

anxiety you know you're really nervous

about how people are going to react to

whatever the message is and you start

feeling your heart rate increasing and

you start maybe not feeling your blood

pressure increase but you can kind of

feel that response it's still your

sympathetic nervous system kicking in so

your body is

still sensing that there's danger nearby

even though the danger here in this case

is an Emil versus a

beer we also have a parasympathetic

nervous system so the parasympathetic

nervous system is basically what takes

over when the sympathetic nervous system

is not engaged so this tends to deal

with things like rest

you know when we're trying to rest and

recoup from a sympathetic nervous system

take over um as well as things like

digestion uh so when it comes to the

autonomic nervous system specifically

the sympathetic and the

parasympathetic only one nervous system

takes over at a

time so if the sympathetic nervous

system is active the parasympathetic is

not and vice

versa um so only one is actually engaged

at a time it just depends on what the

situation

is and this is why you know like I say

the parasympathetic has to De with like

rest and digestion think about if you're

really stressed how you might not be

hungry or if you do eat it might not sit

with you well or you might not be able

to sleep it's because your sympathetic

nervous system is

activated and the sympathetic nervous

system doesn't have time to basically

devote resources to rest resources to

digestion and so that's why you can have

those issues if you're really anxious

about something or if you feel like you

are in absolute

danger so that's essentially what's

going on with the different nervous

systems like I said it's a very brief

explanation of everything um but we will

spend more time talking about especially

the central nervous system over the next

few lecture videos so I will end this

one

here