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Understanding the Immune System in One Video
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hi this is tom from zero to finals calm
this video is designed to give an
overview of immunology so that you
understand all the basic features of the
immune system it will also help you to
return to this video once you've already
learned the details so that you can
again fit those details back into the
bigger picture about how the immune
system works
the immune system can be categorized
into the innate immune system and the
specific immune system the innate immune
system consists of the components that
are already at the location of the
infection and respond immediately with a
generalized response the specific immune
system involves specialized T and B
cells that are waiting in places away
from the site of infection and then when
they're activated they launch a
specialized system that fights the
specific invading pathogen the specific
immune system takes a little while
longer to recognize the infection
particularly when a pathogen is invading
the body for the first time so in this
video we're going to cover both of these
systems and also talk about a system
called the complement system that works
alongside the innate and specific immune
systems
let's look at what happens when a
pathogen invades the body initially
there are physical barriers that need to
be broken before an infection can take
place the skin is an example of one of
these barriers most invaders will get
stuck at this barrier however
occasionally an invading pathogen will
get through such as when there's a cut
in the skin
as well as the skin there's other
physical barriers such as the mucosa of
the respiratory system the
gastrointestinal tract and the urinary
tract
there are also chemical barriers that
help destroy harmful pathogens before
they can cause any infection such as the
hydrochloric acid in the stomach
lysozyme in sweat and tears and lactic
acid in the vagina
let's look at the initial responses of
the immune system once an invading
pathogen has broken through the physical
and chemical barriers to infection three
things happen
number one macrophages recognize the
pathogen and activate the innate immune
system number 2 dendritic cells pick up
antigens from the pathogen and then head
off in the blood and lymphatic systems
to track down the relevant T and B cells
of the specific immune system and
activate them
number three the invading pathogen
activates the complement system directly
via the lectin pathway and the
alternative pathway and we'll talk a bit
more on those later
first let's look at how the innate
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