IMAT Biology Lesson 6.13 | Anatomy and Physiology | Immune System Part II

Summary

This video from Med School EU delves into the intricacies of the immune system, focusing on the innate and adaptive responses to infection. It explains the roles of macrophages and neutrophils as first responders, the inflammatory response, and the activation of the adaptive immune system by dendritic cells. The video also highlights the lymphatic system's role and the production of specialized antibodies by plasma cells, concluding with a comparison of innate and adaptive immunity, emphasizing their differences in speed, specificity, and memory.

Takeaways

• 🛡️ The immune system is complex and consists of two main parts: the innate and the adaptive immune system.
• 👨‍⚕️ The innate immune system is the first line of defense and includes cells like macrophages and neutrophils that perform phagocytosis.
• 🚨 Histamine is released by damaged cells and acts as an alarm to recruit immune cells to the site of infection, promoting inflammation.
• 🔬 Macrophages are considered the 'captains' of the innate immune system, controlling the immune response and directing other cells.
• 💥 Neutrophils are aggressive 'warriors' that engulf bacteria and undergo apoptosis to prevent further damage, forming pus as they die.
• 📈 The body produces and destroys about a hundred billion neutrophils daily, highlighting the scale of the immune response.
• 🔄 Inflammation is a universal response to damage or perceived threats, characterized by pain, redness, swelling, heat, and loss of function.
• 🚫 Inflammatory responses are limited in certain delicate areas like the brain and spinal cord to prevent damage to nerve cells.
• 🔗 Dendritic cells bridge the innate and adaptive immune systems by capturing antigens and presenting them to T cells in the lymphatic system.
• 🔬 The lymphatic system is a network of vessels and nodes that transport large proteins and fats, and is integral to the adaptive immune response.
• 🛠️ Helper T cells activated by dendritic cells enhance the activity of phagocytes and promote a more specific immune response against pathogens.

Q & A

What is the main focus of the video script provided?

The video script focuses on explaining the immune system, particularly the innate and adaptive immune responses, using a hypothetical example of how the body responds to an infection.

What are the first responders of the innate immune system?

The first responders of the innate immune system are phagocytes, specifically macrophages and neutrophils, which are responsible for identifying and engulfing pathogens.

How do neutrophils identify harmful bacteria?

Neutrophils identify harmful bacteria through glycoproteins on the bacterial cells that correspond to what the neutrophils are looking for, unlike the glycoproteins on healthy cells.

What role does histamine play in the immune response?

Histamine is an inflammatory chemical released by healthy cells that have been killed due to an injury or infection. It promotes inflammation in the affected area, signaling an alarm for immune cells to respond.

What is the function of macrophages in controlling the immune response?

Macrophages act as the captains of the innate immune system, telling other cells what to do, activating neutrophils, and regulating the immune response to prevent further damage by ordering neutrophils to undergo apoptosis when necessary.

How do neutrophils contribute to the inflammatory response?

Neutrophils, when activated, engulf several bacteria and, once exhausted, undergo apoptosis, forming pus. This process contributes to the inflammatory response by increasing the presence of white blood cells at the site of infection.

What is the role of the dendritic cell in the immune system?

The dendritic cell captures snapshots of the battlefield by taking parts of the bacteria or their glycoproteins and delivers them to the adaptive immune cells, specifically T cells, activating them and bridging the innate and adaptive immune responses.

What is the purpose of the lymphatic system in the immune response?

The lymphatic system serves as a network of vessels and nodes that transport lymph, a fluid containing immune cells and proteins, throughout the body. It helps in the circulation of immune cells and the removal of interstitial fluid.

How do helper T cells contribute to the adaptive immune response?

Helper T cells, once activated by dendritic cells, arrive at the site of injury and use cytokines to activate phagocytes, enhancing their ability to fight off pathogens and promoting a more effective immune response.

What is the significance of memory T cells and memory B cells in the adaptive immune response?

Memory T cells and memory B cells are crucial for long-term immunity. They remember previous infections and can respond more quickly and effectively to the same pathogen if encountered again, preventing or reducing the severity of future infections.

How does the specificity of the immune response differ between innate and adaptive immunity?

Innate immunity is unspecific, providing a broad response to various pathogens, while adaptive immunity is highly specific, with immune cells and antibodies tailored to target specific antigens of the pathogens encountered.

Outlines

00:00

🧬 Introduction to the Immune System: Part 2

In this video, Andre continues the discussion on the immune system, focusing on the innate and adaptive immune responses. He emphasizes the importance of understanding the first video for a complete grasp of the topic. The video will use a hypothetical scenario to explain how the body responds to bacterial or viral infections, highlighting the roles of macrophages, neutrophils, and histamine.

05:02

🛡️ Innate Immune Response: First Line of Defense

Andre explains the initial activation of the innate immune system, focusing on macrophages and neutrophils. He describes how these cells respond to a skin-piercing event, identifying and attacking bacteria through phagocytosis. The role of histamine in signaling inflammation is also discussed, along with the behavior of neutrophils and macrophages during an infection.

10:02

⚔️ Macrophages and Neutrophils: The Battlefield Commanders

The video distinguishes between macrophages and neutrophils. Macrophages act as captains, controlling the immune response and signaling neutrophils to action. Neutrophils, as the frontline warriors, engage in phagocytosis and apoptosis to fight infections. The section also covers the process of inflammation and its symptoms as part of the body's defense mechanism.

15:04

🧠 Specialized Areas: Limited Inflammation

Andre explains that inflammation is generally universal in the body but limited in delicate areas like the brain, spinal cord, eyes, and testicles to prevent irreversible damage. He describes how cells dying unnaturally trigger inflammation, highlighting the role of mast cells, histamine, cytokines, and the dilation of blood vessels in the inflammatory response.

20:07

🌐 Linking Innate and Adaptive Immunity

The video introduces the dendritic cell as a crucial link between the innate and adaptive immune systems. Dendritic cells capture antigens from pathogens and present them to T cells in the lymphatic system, initiating the adaptive immune response. Andre briefly explains the lymphatic system's role in transporting these antigens and supporting the immune response.

25:09

🦠 Adaptive Immune Response: The Second Wave

Andre describes the activation of T cells by dendritic cells, emphasizing the role of helper T cells in enhancing the phagocytic activity of macrophages and neutrophils. The production of specific antibodies by B cells and the formation of memory cells are explained as key components of the adaptive immune response, which provides long-term immunity against pathogens.

Keywords

💡Innate Immune System

The innate immune system is the body's first line of defense against pathogens, providing an immediate and non-specific response. It includes various cells like macrophages and neutrophils that are the 'first responders' to an infection. In the video, the innate immune system is highlighted as the initial reaction to a nail piercing the skin, where it quickly deploys macrophages and neutrophils to engulf and destroy bacteria.

💡Adaptive Immune System

The adaptive immune system is a more specialized and slower response to pathogens compared to the innate system. It involves cells like T cells and B cells, which can recognize specific antigens and produce a tailored response. In the script, the adaptive immune system is described as being activated later in the immune response, with dendritic cells bridging the innate and adaptive responses by presenting antigens to T cells.

💡Macrophages

Macrophages are large white blood cells that play a crucial role in the innate immune system. They are phagocytic cells that engulf and digest cellular debris and pathogens. In the video, macrophages are depicted as 'captains' of the innate immune system, coordinating the immune response and signaling other cells when to activate or slow down.

💡Neutrophils

Neutrophils are another type of phagocytic white blood cell that are essential for the innate immune response. They are rapidly produced and have a short lifespan, often dying after engulfing bacteria. The video describes neutrophils as 'suicidal warriors' that self-destruct after fighting off pathogens, contributing to the formation of pus.

💡Histamine

Histamine is an inflammatory chemical released by damaged cells, which promotes inflammation at the site of injury or infection. In the context of the video, histamine acts as an 'alarm' signaling the presence of pathogens and attracting immune cells like neutrophils and macrophages to the area.

💡Inflammation

Inflammation is the body's response to harmful stimuli, including pathogens, characterized by symptoms such as pain, redness, swelling, and heat. The video explains that inflammation is a universal response to any threat and is part of the innate immune system's strategy to restrict infection to a specific area.

💡Dendritic Cells

Dendritic cells are antigen-presenting cells that link the innate and adaptive immune systems. They capture parts of pathogens and present them to T cells, initiating the adaptive immune response. In the video, dendritic cells are described as 'snapshots of the battlefield,' essential for activating T cells with specificity to the pathogen.

💡Lymphatic System

The lymphatic system is a network of vessels and nodes that transport lymph, a fluid containing white blood cells, throughout the body. It plays a role in immune response by circulating immune cells and removing interstitial fluid. The video mentions the lymphatic system as the pathway through which dendritic cells travel to find and activate T cells.

💡T Cells

T cells are a type of white blood cell central to the adaptive immune response. They can be activated by dendritic cells to become helper T cells, which in turn activate other immune cells. The video describes helper T cells as enhancing the activity of phagocytes and promoting a more effective immune response at the site of infection.

💡Antibodies

Antibodies, also known as immunoglobulins, are proteins produced by B cells that bind to specific antigens, marking them for destruction by other immune cells. The video explains that antibodies are part of the adaptive immune response and become more specialized over time, providing targeted defense against pathogens.

💡Memory Cells

Memory cells are immune cells that 'remember' previous encounters with pathogens, allowing for a faster and more effective response upon subsequent exposures. The video discusses memory T cells and memory B cells as a key feature of the adaptive immune system, providing long-term immunity against specific pathogens.

Highlights

Introduction to the second part of the immune system series on Med School EU, emphasizing the complexity of the immune system.

Explanation of the innate and adaptive immune systems, using a hypothetical infection scenario to illustrate their responses.

Discussion on the role of the innate immune system as first responders, particularly macrophages and neutrophils in phagocytosis.

Description of how neutrophils patrol and identify harmful bacteria through glycoproteins, leading to phagocytosis.

Release of histamine by damaged cells to promote inflammation as part of the innate immune response.

Role of macrophages as the 'captains' of the innate immune system, controlling the immune response and directing other cells.

Life cycle of neutrophils, highlighting their rapid death and birth rates in maintaining the body's health.

Inflammatory response triggered by the innate immune system, including symptoms like pain, redness, and swelling.

Exclusion of certain delicate body areas from significant inflammation to protect vital structures like the brain and eyes.

Factors promoting inflammation, such as unnatural cell death and release of histamine and cytokines by mast cells.

Mechanism of the lymphatic system in transporting large proteins and fats, and its role in the immune response.

Introduction of dendritic cells as a bridge between the innate and adaptive immune systems, presenting antigens to T cells.

Activation of the adaptive immune response through T cells, particularly helper T cells, enhancing the activity of phagocytes.

Explanation of antibodies' structure, function, and their specificity in binding to antigens.

Transformation of B cells into plasma cells and memory B cells, producing specialized antibodies for a specific pathogen.

Summary of the innate and adaptive immune systems, comparing their response speed, memory, specificity, and activation.

Conclusion of the lecture on the immune system, moving on to the topic of excretion.

Transcripts

[Music]

hello everybody my name is andre and

welcome back to med school eu

in today's video we are going to talk

about the immune system once again

because the immune system is so complex

and we're going to have to do two videos

on it so this is the second part if you

haven't watched the first part please be

sure to do that because in the first

part i talk about the cells of the

immune system which will be

crucial to know for this part of the

course

now in part two of the immune system

that we're going to talk about today

we will discuss primarily the innate and

the adaptive immune system so we're

going to compare the two with a

hypothetical example of what would

happen

and how would the body respond to an

infection

by bacteria or viruses or other

pathogens so let's begin

now i'm going to go over this immune

response in terms of a chronological

order of what would happen and how the

body would react in case of an infection

so the first thing that gets activated

and the first responders are the innate

immune system and i discussed this

briefly in the first

video however in this one i'm just going

to go into a little bit more detail and

just a disclaimer that for the imac

course and in terms of just high school

knowledge you are not obligated to know

most of these details they will be

listed here but i read a book recently

on the innate uh immune system and the

adaptive immune system

and how they interchange and i thought

it was really fascinating so i'm going

to share that with you today and i will

be pointing out the parts that you do

need to know for the imad exam

so starting off with the innate immune

system they are going to be the first

responders we talked about macrophages

and neutrophils so the response would be

from phagocytes

and phagocytes are of course cells that

do phagocytosis

the ones who that we described

in great detail in the first video were

the macrophages and the neutrophils

so let's talk about those in more

detail now if we're talking about our

scenario here we've got a nail piercing

through the skin so these are the skin

cells on the surface

and then

because the nail of course it's got

bacteria on it it's got probably viruses

on it all kinds of pathogens and once it

pierces through the skin

it's going to the the bacteria are going

to enter

the the body

and the the first responders that are

going to be macrophages and neutrophils

so these would be

are neutrophils that are simply flowing

underneath the skin they are remember

that

the neutrophils are pretty much patrol

cells they are there to us they're

scavengers they're they're patrolling

around and they're looking for

things to eat things that are

going to be harmful for the body and

they're able to identify that through

glycoproteins so they're going to look

at healthy cells and the glycoproteins

will not correspond to what they should

be attacking

however the glycoproteins of the

bacteria that are presented on the

bacterial

cells

they are going to be correspondent to

the neutral what the neutrophils are

looking for and as you can see here the

bacteria are just being are eaten alive

by these neutrophils

and of course the macrophages that will

be around will join the fight as well

now all of these little yellow dots that

i have presented here

they would be typically much much

smaller than the bacteria so this is not

an accurate depiction of them however

these molecules

are going to be released by the healthy

cells that were just killed due to the

piercing

of the of the nail

and they would release chemicals called

histamine

now many of you may know that histamine

is an inflammatory chemical so it

promotes inflammation

of that specific area this is why we

take antihistamine drugs when we have an

allergic reaction or we have seasonal

allergies typically you're given

antihistamine drugs so that the

histamine doesn't spread around the body

and you don't have these reactions going

on however when you do have danger when

cells are dying all of these

healthy cells

have have died because of the

piercing of the nail

inside

the body

they are going to release the histamines

the histamines are basically going to

sound an alarm it's like

an alarm is being

is being uh brought up by

these healthy cells that something's

going on there's a breach and

this needs to be fixed this needs to be

cleaned up we need our fighters here to

the front lines and the fighters are

neutrophils and macrophages they are the

first responders as mentioned

and they are part of the innate immune

system

so let's distinguish neutrophils and

macrophages we're going to begin with

the macrophages that are considered to

be the captains of the innate immune

system because they tell other cells

what to do they tell the neutrophils to

activate

and they activate other cells around

them

and basically telling them

uh what to do they can increase or slow

down the immune response

at the battlefield to prevent further

damage so if this has all been cleaned

up and the macrophages can sense that

there's less histamine being released

and they can sense that the battle is

being won

because the bacteria are now being

destroyed then the macrophages will

pause the immune response and they will

slow it down they will order the

neutrophils to do apoptosis so

self-destruction they're gonna kill

themselves in order to stop further

damage because when the neutrophils come

in they are these crazy warriors that

are gonna just wreak havoc on the

battlefield and they're going to destroy

healthy cells and they're going to

destroy

the the harmful bacteria as well

so the macrophages are responsible for

controlling

how much innate immune response is

happening now the neutrophils are

nothing as special they are just crazy

suicidal warriors their only purpose is

to float around find bacteria and eat

the bacteria or

pathogens or viruses or or what not

and so

when they are activated by the

macrophages or by the histamines

they

they would go ahead and

engulf several bacteria and as soon as

they reach their maximum so they are

exhausted from

engulfing the bacteria they would do

apoptosis they would kill themselves and

form pus we talked about this

in the previous video so there's some

some

crazy numbers

just to show you the scale of of what's

happening daily when a person is healthy

is we have about a hundred billion

neutrophils that die

on a daily basis and we have one billion

per kilogram of body mass that are born

daily so

you can decide what that means for you

but as you can see neutrophils rapidly

die and they rapidly

are born

now another thing to mention about the

macrophages is that they are generally

are going around the body and they're

going to be patrolling

they're going to be eating dead cells

and when they are activated they're also

vicious fighters just like the

neutrophils their lifespan is longer

than than the neutrophil

however

they would still be depleted of energy

and as soon as they are

that they have used their maximum

capacity of dna to immune response then

they would also perform apoptosis and

they would also

do self destruction

now these two cells the neutrophil and

the macrophages are going to be involved

in

creating an inflammatory response and

that is something that we're going to

talk about next

however i just wanted to bring that up

here because there's going to be

multiple factors that cause

inflammation in the body one of them is

the histamine molecule being released so

histamine is of course inflammatory

chemical gonna cause inflammation

then we got the neutrophils and the

macrophages if they see that the battle

is not going in their favor

and of course there's a big mess there's

uh something big going on

then they're going to call for an

inflammatory response which is a

universal response of the immune system

to any threat or any damage whether it's

real or perceived so a lot of the times

when you know you have a perceived

threat of a cut or wound

there's going to be inflammation in that

area because of the way

our our bodies work

now some of the symptoms of inflammation

is pain redness swelling heat and loss

of function

and the purpose of inflammatory response

is to restrict infection to an area and

stop the spread

so we're going to talk about um what

happens and what is an immune response

in terms of the

cellular level now an important part to

mention

is that

the inflammatory response is universal

throughout the body except in several

areas where

inflammation is very very limited and if

not completely absent because they're

very delicate structures so things like

the brain the spinal cord

parts of the eyes and the testicles if

you happen to have those

they would

would exclude that area from

inflammation because inflammation is

very damaging

uh to the the cells and of course we

cannot recover our nerve cells

so if if the brain cells are are going

to die due to inflammation

then it cannot be recovered therefore

the inflammation there

is

it exists it happens in some places but

it is very very

mild compared to inflammation for

example like on your skin let's talk

about some factors

that would promote inflammation and

cause inflammation to happen within an

area and

the first one is cells dying

in unnatural ways

so what's incredible about the immune

system is it's able to tell in itself

are able to tell

if the healthy cells the regular healthy

cells are dying a natural death from

just being old

or

they are dying unnaturally from damage

or an infection and so when they when

they do die from damage or an infection

they release chemicals like i mentioned

histamine is is the most prominent one

that will cause inflammation to occur

in the area now we also have mast cells

that typically lie

right underneath the skin and they are

they're found all over the body and

these mast cells release histamine and

cytokines

so they also would release these yellow

tiny little histamines but they would

also have cytokines now because of the

release of the histamines the

neutrophils and the macrophages coming

along and the mast cells releasing their

cytokines

the blood vessels within the area are

now going to dilate they're going to

increase the blood flow and they're

going to be more permeable now what this

means is that other cells other white

blood cells so these are going to be

white blood cells like other neutrophils

they are going to seep through the

endothelium and they're going to go on

to the area

in order to to fight now what this also

does is it increases the fluids

in the tissues so the tissue fluid the

volume of it is now going to increase

and it basically just floods the area

with a huge tsunami of extracellular

fluid

that seeps through from from the blood

and that's why we get the swelling we

get the redness we get the heat because

there's so much pressure being built up

in the area and it is very an

uncomfortable environment for the

pathogens so the bacteria or the virus

it is uncomfortable it's unnatural and

is very difficult to survive such an

onslaught of of an attack by the innate

immune system and that's why most of our

cuts and and most of our infections just

end right there because the neutrophils

the macrophages and the inflammatory

response is going to be able to

combat this in a in a timely manner

however if we do have

an infection that is more serious so the

bacteria are able to combat the

neutrophils and the macrophages

and maybe the neutrophils are not able

to detect them

whatever happens to be but it is a more

serious infection maybe the viral load

is is extremely high

that the innate immune system is not

able to handle it

and so what happens then

the next thing that occurs we got to

talk about more cells of the immune

response and

the cell that we're going to talk about

is the dendritic cell

the dendritic cell is one of the

connections that occurs between the

innate and the adaptive response so what

did dendritic cell do is that it

captures snapshots of the battlefield

and it takes parts of the enemy so the

the bacteria or or the glycoproteins of

the bacteria

and it delivers it to the adaptive

immune cells using the lymphatic

system and lymphatic system we haven't

talked too much about yet but we will

discuss it in this video now the

dendritic cell is quite fascinating and

there's so much detail in terms of how

these things work but i'm not going to

get much into it since it's not part of

our course but i just wanted to create a

connection between the innate immune

system

and the adaptive immune system and that

connection is typically done through the

dendritic

cell the dendritic cell brings these

snapshots of the battlefield to

the t cells and that's its drop and it

finds these t cells within the lymph

nodes or other organs like the spleen or

the tonsils of

the lymphatic system and now we're gonna

discuss

that in greater detail but in general

you you should know that the dendritic

cell will leave the site of battle

and it's going to enter the lymphatic

system and it's going to circulate all

around continuously looking for the

correct t cell that will match the

pathogens antigen

so it's going to have antigens

of the pathogen

and the t cells are going to have have

antibodies or the b cells will have its

antibodies

and it's going to look for the right

match within the lymphatic system and

once this happens

basically just clicks and it activates

the t cells to do their job and that's

how the adaptive immune response is

activated in a nutshell there's a lot

more detail to it there's there's so

much

physiology involved in it but this is as

far as we're going to go

in terms of this course so let's talk a

little bit about lymphatic system it is

basically just a collection of these

cities which would be the lymph nodes

and these highways

that is the tubes that connect these

lymph nodes that go all around the body

and what's interesting about the

lymphatic system is it's much slower of

course the lymph it moves around much

slower than the the blood because blood

has a heart to pump

pump things around but how lymphatic

system moves is it's got these valves

as you can see these valves are going to

be contracting and they're going to be

pushing the fluid in the direction that

it's supposed to go

now what's the purpose of the lymphatic

system well

it is uh wide enough to allow proteins

to be passed around so the lymphatic

system is spread all around the body

and as you can see here in the thoracic

duct and lymphatic vessels from the

villi of the small intestine we talked

about

the the villi

and how they're composed and how they're

able to collect

all these

macro molecules now the fat and the

large proteins are going to settle in

the lymphatic vessels and they're going

to be carried all around

the body until they reach the major

veins and some of those would be

the subclavian vein

so it's going to dump its contents into

the subclavian vein which is wide enough

to carry those large

proteins and as you can see this is just

a one-way

valves so the fluid can enter in inside

that is collected from the extracellular

fluid that fluid can go inside the lymph

and it becomes a fluid called lymph

which is just exactly the same as the

extracellular fluid except it is in

these compartments

and it's going to be it's going to be

able to carry

the large proteins and

the fat all around the body

to

the large veins where then it could be

circulated or used by the organs now

we're going to talk about the adaptive

immune response so our t cells which are

part of the adaptive immunity

have been activated by the dendritic

cell that travel through

the

lymph

and now of course there's different

kinds of t cells and they do different

things but we're going to talk a little

about a little bit about the helper t

cell

which is now going to be activated by

the dendritic cell and is going to

arrive at the site

of injury and so this is our helper t

cell and what this helper t cell does is

it activates the phagocytes

using cytokines

so it arrives at the site of injury and

it it's basically going to make the

macrophages and the neutrophils fight

harder it's going to give them this

little touch and it's going to

basically command them

to fight longer fight harder and

kill more viciously so

it's going to promote

doing more damage more inflammation in

the area and it's not a specific

response at this point these

antigens

that are on the t cell they're not going

to be extremely specific to

the

pathogen that we have they are going to

be specific for it because the dendritic

cell did find a close enough match but

they're not going to be 100

efficient and we will discuss the the

other b cells that will produce um

antibodies that are

extremely specific

for the pathogen that we're fighting but

at this point it's just a general

response so it's going to promote uh the

phagocytes to fight harder using

cytokines once again

and then uh there's going to be a

a large army of these

antibodies that are going to arrive at

the injury site as well as part of the

adaptive immune response and they're

going to help the immune cells so the

neutrophils and the macrophages to

detect the enemies

by being attached to them they're

basically going to be like markers

displaying this is the bacteria this is

the enemy go and kill it so anybody's

have a role of just

going all around the bacteria and

attaching all around them so it's easy

for the neutrophils and the macrophages

to find the enemies we're gonna go

through a little bit of the labeling

because this is something you should

know for the imat test you should know

what the parts of

the antibodies are

and

what they're responsible for these long

chains right here are going to be called

heavy chains

they're heavy polypeptide chain these

are just proteins but in general

these longer ones are going to be called

heavy polypeptide chains

now the tips here of the

antibodies

these are going to be antigen binding

sites

so this is where the bacteria would be

bind binding to

on the side of the antibodies these

smaller ones right here

are going to be called light chains

now because the antigen binding sites

are going to be different for pretty

much every bacteria that the body is

going to encounter so the antibodies are

going to be specific for the antigen

that they are going to bind to and

antigens could be there's millions of

different

varieties of antigen that

could happen and therefore these regions

the red ones i pointed out they're going

to be variable regions and what that

means is that they could be changed

based on the demand

of the antigen that they're binding to

so they could become specific to the

antigen and bind

very precisely and another important

aspect to point out here is these bonds

that are right in the middle and the

bonds here that connect the light and

the heavy chains

these bonds are called disulfide bonds

and these disulfide bonds create

something called a hinge region

hinge region promotes flexibility for

the antibody to open up further and to

be able to attach to the antigen

in the precise manner now there's

several several things that could

happen once these things arrive at the

battlefield so if the battle is won the

helper t cells become memory t cells and

there are gonna stop the immune response

to prevent further damage and then

they're gonna promote healing but if

further stimulation is needed the t

cells are going to activate b cells so b

cell

activation leads to production

of plasma cells now these are the plasma

cells

and the purpose of plasma cells is to

produce specialized antibodies

so these antibodies are specifically

made

for the pathogens

antigens that we have encountered so

it's specifically brought up and

specifically

made just to respond to that

pathogen that we are fighting

and these uh antibodies are going to be

way more efficient than the ones we've

gotten at the beginning of the adaptive

immune response

because they're coming off the plasma

cells that were originally b cells

and in the end the b cells are then

going to become memory b cells and that

is how typically the battle

would be won so i wanted to go over a

quick summary of the innate and the

adaptive immunity and

their similarities and the differences

in terms of these

six features so the response speed of

the innate immune system is going to be

immediate as we saw with the response

speed of our of the nail cutting through

the innate immune system was right there

immediately

catching the bacteria that have entered

now in terms of the adaptive immunity

it's going to be prolonged it's not

going to be

responsive right away it's going to take

several days

two weeks so again talking about the

kinetics

this is going to be a fast response

within minutes

uh two hours

it's going to produce swelling uh

inflammation all of all of those

symptoms that's part of the innate

immunity however production of

specialized b cells and all of those

things they're gonna take days

two weeks now the innate immunity is

short-lived typically we're gonna have

a short response of the innate immunity

in terms of swelling and that that

immediate

uh first responder

effects and adaptive immunity

is going to be

long the duration because it's going to

produce these memory t cells and memory

b cells

which will then be able to activate much

sooner when a similar infection comes

along

for next time for example you caught the

flu you're probably not going to have

the flu for another several years

before

before your immunity is going to go away

so for example if you've had the flu or

any other seasonal virus

you've had covid you're not going to

catch covet immediately again why is

that because of the adaptive immunity

that creates t cells and memory b cells

that will then be able to respond to the

same pathogen

much quicker and you will probably not

even notice whether you had contact with

the flu or you had contact with covet

because you already have natural

adaptive immunity that has produced

those memory t cells in those memory b

cells

and they are able to combat it without

you experiencing any severe symptoms now

in terms of memory innate immunity of

course does not constitute memory

uh the adaptive immunity

provides uh

t cells memory t cells and memory b

cells now in terms of activity uh the

innate immunity is going to be

always ready but the adaptive immunity

is normally

silent

so it's going to be

normally dormant until

it is needed until it is activated and

there is a reason why active activation

of the adaptive immunity takes this long

is is because the body always wants to

conserve energy and of course the body

does not want to cause more harm than

good we don't want our adaptive immunity

to turn on because it causes lots of

harm to the area

and it causes lots more inflammation

than needed therefore

it is very difficult to activate

adaptive immunity and our body has made

sure

to only activate adaptive immunity when

it is really needed when the innate

immunity cannot handle

the task

and in terms of specificity the innate

immunity is unspecific and adaptive

immunity is highly specific so this is

the complete summary this is something

you should also know

in terms of the imat exam uh i would

encourage you to memorize this chart so

you know the difference between innate

and adaptive

immunity so this concludes our lecture

on the immune

system we're now done with the immune

system and we're going to move on to

excretion

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you