- [Instructor] With all those pathogens out,
we have to figure out how our body defends itself.
One of the biggest defenses is our lymphatic system.
One of the main functions of lymphatic
is the maintenance of blood volume
in the cardiovascular system.
And you're saying "Well, hold on,
"how does that have anything to do with defense?"
Your white blood cells are in the blood volume.
That's part of your defense system.
The lymphatic system can transport fats,
fat-soluble materials, helps with moving particles around
through the blood is not as easy to move around with.
Filter out, or get rid of the foreign particles,
whether that's gonna be pathogens that are living,
pathogens that are non-living, simply particles
of cells that have broken down.
Here's a snapshot of your lymphatic system.
The heart has the thymus gland on it.
Thymus is gonna help out with immunity.
Your throat, you have your tonsils.
There's a ring of tonsils all around your throat,
which helps to try and deter any pathogens
from coming in through either your mouth or your nose.
Your spleen, most of your spleen will pull out
dead blood cells or damaged blood cells.
But it also helps through moving micro organisms.
Then we have our lymph nodes.
Every kind of green dot you see in the body there,
each one of those green dots is a lymph node.
And there's even more than that.
lymph nodes are meant to clean out the lymph or the fluid.
This way they can filter out any
bacteria, particles, pathogens, you name it.
It goes into the lymph node
and then if it's foreign,
good chance it's not coming back out again.
Maybe when you've really been sick,
you've noticed your lymph nodes are swollen.
Lymph nodes are around your neck,
and if you're really sick your underarm.
So there's a bunch of lymph nodes all around.
Then we have the vessels.
The lymphatic capillaries, right next to blood vessels.
Let's start with how
the first line of defense of your body works.
The skin, it really is your first line of defense.
It's a pretty good deterrent,
things really can't get through it very easily.
We also have tears and saliva.
They contain things called lysosomes.
Then lysosomes contain enzymes,
specifically antibacterial enzymes.
So any bacteria that ends up going
into your tears or your saliva,
good chance is those bacteria
are going to have a real problem,
some will get through,
but quite a bit will be killed off.
Ear wax, might think of it as more of an annoyance,
But the ear wax, because of it's nature,
actually entraps microorganisms
not allowing them to proceed,
not allowing them to live.
Mucus...
you're going to have mucus
throughout your entire oral cavity, nasal cavity,
all down through your digestive track and respiratory.
Mucus is meant to trap microorganisms,
but it is also meant to trap
any particles that are entering the body.
It is a way to try to prevent foreign objects
from getting into the system.
Your stomach, you wouldn't necessarily think of that
as the first line of defense,
but really the inside of your stomach
is getting things directly from outside environment.
When you're eating,
you're swallowing that outside component
right down into your stomach.
So, it is very acidic, pH of two a lot of times.
And that pH of two can inhibit
quite a few different microorganisms.
The vagina, obviously female specific,
but were talking it's a little bit acidic.
Now, this acidity helps to inhibit
certain microorganisms from forming and developing.
Vomiting, urination, defecation.
These are all ways of removing objects from the body.
They could be removing normal waste,
defecation, urination.
It could be a way of getting out
any foreign particles, any bacteria.
A lot of times vomiting,
or more too frequent defecations with looser stool,
is trying to remove microorganisms from the system.
Your body is trying to flush out.
Get rid of things.
But, yet for all these defenses you have resident bacteria,
bacteria that live in and on your systems.
Your skin is covered with bacteria that should be there.
Your intestines, specifically the large intestines,
have tons of bacteria that are supposed to be in there.
And these bacteria that are living there,
a lot of times they can out compete
any pathogens just entering.
Not allowing those pathogens to get a chance to even grow,
because there is way too much competition.
So with all this first line defenses,
we do have some more secondary, third,
and kind of beyond.
If we look at our non-specific defenses.
Phagocytic cells
Now, phagocytic cells are cells that are going to engulf,
a lot of times they'll say they'll eat other cells.
They'll eat foreign particles.
The idea is these cells are going
to destroy what they come into contact with,
if they don't recognize it.
So Neutrophils, Eosiniphils are two types
of white blood cells.
Macrophages, well they're made from a white blood cell.
All three of those cells are meant to destroy.
So this is how it works,
in Phagocytosis, the phagocytes will
basic capture a bacterium.
That kind of pinkish pill shaped thing is a bacterium.
Then it is going to actually
move the cell membranes around it.
as the cell membrane are moved around,
it'll completely surround and engulf.
That bacteria that has now been engulfed
will be inside a special vesicle.
This way it keeps it isolated.
It keeps it away from the rest of the cell.
While inside that vesicle,
there will be these lysosomes
that will then fuse releasing their digestive enzymes.
Those enzymes will break down bacteria,
eventually releasing the waste.
All the broken down particles
that were a bacteria at one point,
are now just individual building blocks.
They're harmless.
So, the cell will release those particles
back into your system for removal from the body.
So, it really looks like the cell is eating a bacteria,
digesting it, and then releasing it.
How about inflammation.
Now these phagocytic cells are going to go out and eat.
Inflammation, cannot really do anything.
It is just a swelling of an area.
When something gets swollen,
a lot of times it is also red.
It might be a little bit warm.
It might be painful to the touch.
It depends on what the injury was
and how severe it was.
But, inflammation can occur on various different levels.
Could be a cut, could be a bruise,
could be an impact, could be whatever.
Any damaged tissues can cause inflammation.
Now, all this is meant to help protect the area.
The redness, the warmth, the swelling, the pain,
it's all a protective measure.
So, here's how the inflammation response works.
First off, you have a site of injury.
From a simple splinter, to a paper cut,
to a knife laceration, to whatever.
Something injured the tissue.
The damaged cells release histamine.
Now you might have heard of histamines
as in you take anti-histamines.
Yeah, you might take anti-histamines for allergies.
Well the reason you take anti-histamines
are to try and stop this process from occurring.
When you have an allergic reaction,
you have your allergies, watery eyes, runny nose.
That's your body's way of responding
to an increase in a certain histamine.
Well if you have a site of injury,
you also produce histamine,
which causes swelling in that area.
It caused the blood vessels to dilate or open up.
By causing the blood vessels to dilate,
it makes them larger.
It makes them leaky.
Things just leak out of them.
As things are leaking out,
you get this complement protein that's leaking out.
It's meant to identify
and destroy the bacteria.
So, complement proteins are meant
to find bacteria and destroy them.
Or, if nothing else,
at least mark them for destruction.
As the blood vessel opens up even more,
it has even more leaks.
Then the phagocytic cells will come out.
Those phagocytic cells will look for the complement protein.
Wherever the complement protein is,
they will attract
and destroy wherever it's bound to.
So, while the inflammation might sound like it's backwards.
Sudden injury, you got cut, you want more blood?
well this is why I want more blood.
It is bringing particles in
to fight off potential infections.
It is bringing particles in to stop the bleeding.