Human immune system - Human Health and Diseases, Biology, Class 12 Video Lecture

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no more fear from exam so now there we
have been talking about the immune
system let us discuss about the human
immune system so what are the different
parts of our body which forms the immune
system of our body now when we talk
about human immune system we spoke about
immunity we talked about the basic
concept of immunity what are the
different types of immunity how immunity
helps to fight infection so now let us
see what are the different parts of our
body which actually together comprise
the immune system the organs which
together fight infections and disease
causing organisms they fought together
joint hands to form the immune system of
our body so let us see what are the
different organs which form the immune
system so these organs will actually
recognize the antigen they will respond
to the antigen so how do how does the
immune system respond to antigen they
respond to antigen by producing
antibodies and those antibodies will
kill the antigens and then store them in
memory
now memory that is very important so
that when the same antigen attacks for
the second time a better fight or a
better response can be given so the
secondary response is always more
intense when compared to the primary
response so basically these are the
three tasks which are performed by the
organs which together form the immune
system and this is how the immune system
fight against infection so the various
organs which constitute the human immune
system are they are together known as
the lymphoid organs why are they called
lymphoid organs because we all know that
in the immune system immune system is
all about the immune response that is
how the immune system responds to the
antigens and the commune response is
given in the form of antibodies and who
produces antibodies the lymphocytes so
lymphocytes are the
leading role that means impose I impose
I play the most important role in the
human immune system so the organs where
these lymphocytes origin a to
differentiate proliferate and become
matured these organs are known as
lymphoid organs because these are the
organs where the lymphocytes will
originate they will be produced here so
they will take birth here they will grow
here they will differentiate here they
will become mature here so that is why
they are all called lymphoid organs now
what are the different lymphoid organs
bone marrow thymus split lymph nodes
tonsils and Pierce patches caught in
small intestines so these are some of
the lymphoid organs now out of these
organs bone marrow and thymus these two
are known as the primary lymphoid organs
whereas the other organs like spleen
lymph nodes tonsils and Pierce patches
they are known as the secondary lymphoid
organs now what is the difference
between primary and secondary lymphoid
organs now primary lymphoid organs are
those where the which play the most
important role in the development of
lymphocytes so these are the organs when
lymphocytes originate and differentiate
whereas secondary lymphoid organs are
those which provide sites for
interaction between the lymphocyte and
the antigen so here it is this part
where the origination differentiation
maturation of lymphocyte takes place so
the lymphocytes get ready in the primary
lymphoid organs now once the lymphocyte
is ready then it goes to the secondary
lymphoid organ and in this secondary
lymphoid organs there they provide the
site where the lymphocyte can attack the
antigen right so that is why they are
classified as primary and secondary
lymphoid organs other than this also
there are lymphoid tissues which also
form a part of the immune system the
lymphocytes which are like the hero of
the immune system because they do the
main job the B lymphocytes will produce
that is the plan
patience will produce them antibodies
the memory b-cells will remember or
recognize the antigen and the t-cells
will stimulate the B cells to produce
antibodies and find the antibodies which
I like
they are the chemicals which are
actually being produced by the
lymphocyte and they fight antigens so
this is all about the human immune
system so now what we are going to do is
we are going to talk about each of these
organs and we will see how they
participate in the process of immunity
so let us start with the primary
lymphoid organs so the first order that
we will talk about is bone marrow and
famous so these organs are involved in
the production development and
maturation of lymphocytes so that's what
I was telling that lymphocytes take
birth in the primary lymphoid organs
they become matured and they get ready
to fight the infection to fight the
antigens so they completely get ready
and in the primary lymphoid organs and
then they just go to the secondary
lymphoid organs to interact with the
antigens so bone marrow
what is bone marrow it is a flexible
tissue inside bone so where is the bone
marrow this structure which you see here
is the bone marrow so it is present
inside the bones and this is the place
where lymphocytes are produced so in
bone marrow at the sides of production
or the site of birth of lymphocytes
next is thymus
so where is thymus it is a by lobe the
gland which is located near heart it's
not here it's located near heart just
below the breastbone so this is thymus
so here you can clearly see them picture
huh it is a by loop structure so you can
see two loops like this and like this so
there are two loops present and this is
the site for development and maturation
of the lymphocytes so the lymphocytes
will be born in bone marrow and they
will develop and mature
and the timers and because of this they
have got the name t-lymphocytes
that is thymus lymphocytes the
lymphocytes which mature mature and
develop in the thymus gland that is why
they got the name T lymphocytes now
talking about the size of the timer so
here you can see an adult human being
and in that adult using the thymus gland
is extremely small however when a person
is born during birth the size of the
thymus gland is quite large and it
gradually tend to decrease in size by
the time puberty is 1/10 during
adolescence the thymus gland becomes
very small in size now let us talk about
the secondary lymphoid organs so the
first organ that we will talk about is
the spleen so what is clean it is a
being shaped organ located to the
upper-left part of abdomen so here this
organ is spleen so this acts as a filter
for blood and it is also a reservoir of
erythrocytes what already through sides
they are nothing but the red blood cells
so it helps in storage of red blood
cells and it also acts as printer for
blood so whenever blood comes to the
splint it actually filters out all the
unnecessary material from the blood so
it acts as a filter so the next
secondary lymphoid organ is the lymph
nodes now these are small organs which
are distributed widely throughout the
lymphatic system so they are like
present in many different parts of the
body so if you talk about the lymph
nodes so let us see where exactly do we
see lymph nodes so here you can see
these structures which are seen here
they are the lymph nodes and again the
lymph nodes are also present in this
region so this are your lymph nodes and
again you have lymph nodes around your
there are the area of your breast so
there also you have the lymph nodes you
again have lymph nodes
and your genital area so here also you
have lymph loans so they are distributed
throughout the body in different parts
of the body and what do they do they
trap antigens from the limbs now these
are the lymph nodes means the lymph
vessels it is a part of the lymphatic
system and they throughout the lymphatic
system the tissue fluid or the lymph is
flowing the lymph will contain antigens
and these lymph nodes will trap those
antigens now you understand why the
secondary lymphoid organs act as a site
of interaction between antigen and the
lymphocytes that's because if you look
at each secondary lymphoid organ whether
you talk about splint or you talk about
the lymph nodes all of them tries to
trap the antigens splint wraps and
regions from the blood lymph nodes trap
and regions from the lymph so they keep
the antigens with them and when the
lymphocytes come to their place that is
when the lymphocytes come to the spleen
or when the lymphocytes come to the
lymph nodes there is an interaction
between the lymphocytes and the antigen
so lymphocytes means they will produce
antibodies and their antibodies will
destroy the antigen so the secondary
organs are providing the site where the
antigen can interact or where the
lymphocyte can produce antibodies and
antibodies can interact with them and EJ
so now the next secondary lymphoid organ
is tonsil so what are tonsils these are
soft tissue lumps and this is present
somewhere here like near your throat
area so that is where you see tonsils
and they exist in pairs so there are two
tonsils which are present one on either
side at the back of the mouth now the
size of the tonsil values from person to
person some of them have quite small in
size for some it is little larger so how
do they help they help to trap germs
which might otherwise be inhaled by a
person so when the inhale that might
contain germs now some of them are
blocked by the nasal hair and whatever
gets in they are again trapped by the
tonsils so IB bodies are produced by the
immune cells
the tonsils and it does helps in
preventing any sort of throat infection
or gum infection because tonsils is
tonsils are a part of the respiratory
system in some way so it helps to trap
the jump so that the respiratory system
can be protected from any type of
infection
the last secondary organ is the Pierce
patches of small intestine now what are
these previous patches patches means the
small masses of tissues so these are
small masses of tissue which are present
in the small intestine so here here you
can see these are them tears patches of
small intestine now they are they are
present in the ileum region of small
intestine if you remember small
intestine has three parts
do genome helium and jejunum so these
tissues are present in the ileum region
and they prevent the growth of pathogens
in the small intestine that is their
purpose so now please have a look at
this please notice this that all the
secondary lymphoid organs they somehow
trap germs are either pathogens or some
or the other antigen and then they
provide that platform for the
lymphocytes to interact with the antigen
and then destroy the antigens so this is
how the human immune system words and
different organs of the immune system
function so with this I think we have
ended our discussion on immunity so we
saw what is immunity
what is human immune system and what are
the different types of immunity and a
please understand the concept of
immunity that is very important so after
this we are going to talk about some of
the very important diseases which are
very deadly as well thank you please
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