>>Dr. Ketchum: Now we’re going to start
the immune system. And so what I want you
to think about first off is, “Well what
is immunity?” So humans demonstrate immunity
by possessing tissues that are capable of
recognizing and protecting them against non-self
invaders. Short and sweet—your immune system
is there to defend your body from foreign
invaders. Those foreign invaders come in all
shapes and sizes and varieties. So let’s
look at what the targets are for the immune
system. In other words, who are the foreign
invaders? Some of the targets are pathogens,
and these pathogens can be viral, bacterial,
like staphylococcus. They can be actual parasites,
like for example tapeworms, roundworms. The
targets may be fungi or even protozoa, which
some of you may be more familiar with protist.
Protist is a newer term that we’re using
these days.
Now there are also other targets for your
immune system. So worn out cells. As cells
in our body start to wear out and die, they
are now targets for the immune system. Because
when it’s wearing out and dying, it’s
more likely to start dysfunctioning and can
result in cancerous cells, can cause tumors,
and all sorts of things. So you want to kill
the worn out, dying cells. The other thing
that the immune system is going to target
are mutant cells. These are abnormal cells
in the body, and then also cellular debris.
So when you think about cellular debris, think
in terms of if you’re going to break down
a cell and the debris that’s associated
with that cell once it’s broken down. Okay,
so let’s take a look at some of these pathogens
here. So we have bacillus—this is a bacteria.
And these are just examples, so you do not
have to memorize these. Fasciola, these are
some flukes, these are flatworms that you
might inquire by eating undercooked fish for
example. This taenia solium, which is
a tapeworm, and specifically this is called
a pork tapeworm because you will become infected
with a pork tapeworm if you eat undercooked
pork; so it’s really important to cook your
meat thoroughly. There’s also a tapeworm
called the beef tapeworm. And the beef tapeworm
you get from eating undercooked beef. So for
those of you that eat your steak rare? Careful,
beef tapeworms can reside in your small intestine
for quite some time, and then when they die,
then the entire tapeworm can be released all
at once when they die. And they can be up
to eight, 10, 20 feet long, okay? So beef
tapeworms are really long.
Then there’s trichomonas vaginalis—trichomonas
vaginalis. So this is a protist, and based
on the name you would think that this pathogen
only affects females. That’s not true. Men
can actually get trichomonas vaginalis by
coming into contact with females. So during
sexual contact—so trichomonas vaginalis
is actually considered a sexually-transmitted
disease, an STD; so men can get trichomonas
vaginalis. Then there’s clostridium difficille.
Clostridium difficile is a bacteria that literally
reeks havoc in nursering homes, and what it
does to the elderly is it gives them profuse
diarrhea, and, and the diarrhea is so watery
that the elderly people tend to dehydrate
very quickly and sometimes they do succumb
to a clostridium difficile infection. Then
there’s giardia. Giardia is the cutest little
parasite on the planet. So when you look at
this little guy here, he looks like a happy
little thing. He looks like he’s smiling
and like he’s got big old glasses on like
Steve Erkle or something. This protozoa—and
this one wont kill you—but this is what
you call “Beaver Fever.” So if you drink
contaminated water that a beaver has pooped
in, the beaver pooped giardia into the water
and now you drink the water. So if you like
to go hiking and camping then it’s a really
good idea to filter your pond water.
All right, then there’s plasmodium. Plasmodium
is the protist that causes malaria, and I
know a lot of you have heard about malaria
and how many children that it kills every
minute of the day. And malaria is the number
one killer of children and adults in terms
of arthropod vector-born diseases.
So those are the examples of just various
targets for the immune system. We have
all of these cells, then, in our body that
have to amount an immune response. And here’s
the anatomy of the immune system. We’re
going to break this down into two components:
the leukocytes, those are white blood cells
that specialize in the immune function, and
then there are the lymphoid tissues. You have
different types of lymphoid tissues—the
central and peripheral. So these are both
what we call SDLs, and these are self-directed
learning. So you can imagine that as if this
information were in your workbook and you
were filling this in in your workbook. So for
example when we look at the phagocytes, I’ve
shown the phagocytes here for you. Neutrophils
function as phagocytes. These are types of
leukocytes. Monocytes are found in the blood,
and when they move into the tissue we change
their name, and now we call them a macrophage.
And then the cell in the middle is called
the dendritic cell. Look at it; it looks like
it’s got dendrites on it, right? So these
are all phagocytes. All of these will phagocytose
foreign material. So I’ve left you a question
here that says, “What are the four fixed
macrophages and where are they found?” I’m
going to give you one of them, the microglia,
just to give you a starter on that question.
Now the other cells that are very important
in mounting the immune response are the lymphocytes.
So again, these are also white blood cells,
and there’s various types of lymphocytes
that we’re going to discuss in detail later.
But to get you started on lymphocytes, I’ve
got a question here that says, “Most null
cells”—so you need to figure out what
a null cell is—“these are considered natural
killer cells.”
So we abbreviate natural killer cells NK and
then cells. Those
are very important in fighting certain kind
of infections. Are they bacterial or are they
viral? So I’ll let you finish filling out
that fill in the blank there.
Now the mast cells and dendritic cells
are also self-directed learning. So the question
there for you to answer is where are the mast
cells found—what do they secrete? What is
the function of a dendritic cell, and what
are the four types? Okay, then you have other
leukocytes that are important in secreting
chemicals. For example: eosinophils. So when
you think about eosinophils, these are white
blood cells that are really important in allergic
reactions, but they’re also very important
in that they secrete chemicals that will dissolve
or kill parasites. So from before when I mentioned
that you could have a tapeworm that's eight, 10,
12, 20 feet long, there’s no way for an eosinophil
to engulf a worm of that size. And so rather
than engulf it, eosinophils can actually secrete
these chemicals that dissolve them. Then there
are other leukocytes called basophils that
release some chemicals as well. Basophils
can release histamine, and histamine, if you
remember, is it a vasodialator or vasoconstrictor?
It’s a vasodialator, and basophils will
also secrete heparin. Heparin is an anticoagulant
or used as a blood thinner. So if you have
a blood clot, they would put you on heparin
treatment and what that would do is prevent
further clotting, and it would also help break
up that clot. Then we have the lymphoid
tissues the central lymphoid tissues and the
peripheral lymphoid tissues. So what I want
you to do is to make a list. What are the
central lymphoid tissues? And I’ll give
you an idea here—you should be listing two
of them. And then the peripheral lymphoid
tissues—you should be listing six of these.
And then what I want to know is what’s the
connection between these central lymphoid
tissues and the peripheral lymphoid tissues?
So in other words, when you have lymphocytes
in the central lymphoid tissue, do they always
stay there or do they migrate out? Then you
guys can complete these questions down below as well.
