Why is the heart a double pump with four chambers
Circulatory System| How The Heart Functions as a Double pump
hey it's Michelle your CSC biology tutor
in this video on the circulatory system
I'm going to be paying special attention
to hold the heart functions as a double
pump so we know that in heart is a
muscular organ and it's responsible for
pumping blood and throughout the entire
body so you need to understand that the
heart is divided into the left side and
the right side which is separated by a
septum so it consists of four chambers
we have the left atrium and the left
ventricle and then the right atrium and
the right ventricle so I mentioned that
the heart functions as a double pump so
that simply means that the blood is
going to enter the heart twice so you
will realize that I have the left and
the right sides color-coded using red
and blue so let's take a look at the
diagram of the heart so as you can see
the right-hand side highlighted in blue
that simply represents the deoxygenated
blood that will be passing through that
side will be heart the left-hand side
highlighted in red represents oxygenated
blood that would pass through that side
so you can clearly see the septum will
separate these two sides of the heart to
prevent the blood from mixing so you
don't want the blood on the left side
mincing with the blood on the right side
so that septum is important in
separating the different set two sides
of the heart so let's pay attention to
why the heart is really separated into
two sides and why we have oxygenated
blood coming
through the left hand side and then
deoxygenated both coming through the
right hand side so you're going to show
you the blood flow through the heart
twice okay so like we're going to start
on the left hand side of the heart but
you need to understand that the blood is
going to be entering each side
simultaneously so as in heart is pumping
the blood will be entering the left hand
side carrying the oxygenated blood and
then it's going to be entering the right
hand side carrying deoxygenated blood is
going to be all happening at the same
time but for explanatory purposes I'm
going to start with one side and explain
what happens blood as it enters
the heart twice so let's start from the
left hand side so blood rich in oxygen
is going to be coming from the lungs so
this is the oxygenated blood rich in
oxygen coming from the lungs so you
remember the lungs is responsible for
taking in oxygen and breathing out
carbon dioxide so that blood coming from
the lungs is going to be rich in oxygen
hence why it is called oxygenated blood
so it's going to enter the left hand
side of the heart through the pulmonary
veins so that word pulmonary means
related to the lungs so the pulmonary
veins collects the oxygenated blood from
the lungs and takes it to the left
atrium so that's the first chamber the
upper chamber usually smaller so that
left atrium is going to receive the
oxygenated blood and when the left
atrium contracts remember the heart is
made of muscular tissue cardiac muscle
so in order for it to pump that cardiac
muscle needs to contract so the left
atrium is going to contract and force
the oxygenated blood
into the left ventricle now you're going
to notice that we have a pair of valves
here bicuspid valve also known as the
mitral valve so that bicuspid valve
along with all the other valves in the
heart our B spot is responsible for
preventing back flow we want the blood
going in one direction only so you don't
want that blood going back where it came
from so as the left atrium contracts it
squeezes and forces that blood past li
bicuspid valve and into the left
ventricle
now the left ventricle once it receives
the blood from the left atrium that in
turn is going to contract and force the
blood up past the aortic valve so we've
seen another valve here so that a are
tight valve separates the left ventricle
from the aorta so that blood is going to
be pumped up into the aorta passing the
aortic valve and that oxygenated blood
needs to be transported and circulated
to all the organs of the body so the
aorta is the largest artery in the body
so it's going to be connected to various
organs it's going to be responsible for
transporting blood rich in oxygen to all
the various organs so that's what you
see these various branches as
representing arteries are going to be
connected to the different organs of the
body so that blood ratio and oxygen once
it has offloaded its oxygen and the
various nutrients that it will be
carrying to the tissues in the organs it
then needs to return to the right hand
side of the heart so by know that blood
is going to be lacking oxygen so that's
why we refer to it as deoxygenated blood
so is laughing oxygen so it needs to
return to the heart in order for it to
collect the oxygen again
and lungs so this deoxygenated blood is
going to enter the vena cava and you
realize you have two branches of the
vena cava we have the superior vena cava
which would be brain blood from the
upper body and then the inferior vena
cava which should be brain body brain
blood from the lower body so these two
branches of the vena cava is going to be
brain in the deoxygenated blood into the
right side of the heart so that
deoxygenated blood enters the right
atrium the upper chamber and then once
our right atrium contracts it's going to
force the blood past the tricuspid valve
so you see in another valve here so that
tricuspid valve
remember the valves are responsible for
preventing back flow so the blood passes
the tricuspid valve and is forced into
the right ventricle now the right
ventricle when that contracts that is
when a 4c blood passed the pulmonic
valve also known as the pulmonary valve
so that separates the likely right
ventricle from the pulmonary artery
so that deoxygenated blood is going to
be carried through the pulmonary artery
towards the lungs why is it going to the
lungs typical oxygen because it's
lacking oxygen at this point so when
this deoxygenated blood enters the right
hand side of the heart the sole purpose
is to reach the lungs where it can
collect oxygen again so know that we
know that you should have an
understanding of how the blood enters
the heart twice let's just quickly
review all that I've discussed already
so the structure of the heart so
remember it's divided into the left side
and the right side and that is separated
by a septum so the heart consists of the
four chambers the left atrium and the
left
Trickle then the right atrium and right
ventricle
so in order to help you to remember
which side has which type of blood you
can use this acronym Lord
lor D so left oxygenated right
deoxygenated so that will definitely
help you to better understand which side
is carrying which type of blood and
another note here so if you look back to
the diagram you will notice that the
left ventricle
is actually thicker than the right
ventricle the reason for this is that
the blood that is forcing through the
left atrium to the left ventricle on
that that left side is responsible for
carrying blood throughout the entire
body so when the blood reaches the left
ventricle it is going to be under very
high pressure so that highly pressured
blood is going to be forced through the
aorta and taken to all the various parts
of the body so the reason that the
muscular walls of the left ventricle are
much thicker than the right ventricle is
because it has to withstand that greater
force that greater pressure of the blood
which has to be pumped up through the
aorta and taken to all the various parts
of the body with the right ventricle is
thinner because it's not going that far
the blood is not going that far it's
just being taken to the lungs which is
nearby so it doesn't have to withstand
as high pressure as the left ventricle
all right so let's let's review the
blood vessels that are connected to the
heart so on the left hand side you need
to remember remember the left side
bringing oxygenated blood taking out
that oxygenated blood to the entire body
so we have the pulmonary vein which
would take oxygenated blood to the heart
so that's taking the oxygenated blood
towards the left
atrium and the aorta is responsible for
taking the oxygenated blood to all the
organs of the body so remember that the
aorta is the largest artery in the body
so on the right side now we have the
vena cava and we have two branches in
superior and the inferior vena cava
remember that the superior vena cava
brings deoxygenated blood from the upper
part of the body while the inferior vena
cava brings the blood from the lower
part of the body so the vena cava is the
largest vein in the body so that is
taking deoxygenated blood towards the
heart
now the pulmonary artery would be
responsible for taking deoxygenated
blood to the lungs to pick up the oxygen
again so those are the important that
vessels that you have to remember now in
terms of the heart valves remember that
valves will prevent backflow of blood so
they keep the blood flowing in one
direction so we have the
atrioventricular valves which are
between the atria and the ventricles so
these including bicuspid valve or the
mitral valve on the left side and the
tricuspid valve on your right side now
the other set of valves are known as the
semilunar valves and these are found
between the ventricles and the arteries
so the aortic valve that would be phone
between the left ventricle and the aorta
well the pulmonary or the pulmonic valve
will be found between the right
ventricle and the pulmonary artery so
now we've examined the structure of the
heart and its associated blood vessels
let's take a look at the two types of
blood circulation so remember the heart
acts as a double pump brain blood into
the heart twice so basically this means
there are two different journeys that
blood will take before and after enters
the heart so the first journey or Luca
is a pulmonary circulation
on this journey deoxygenated blood from
the right side of the heart needs to be
taken to the lungs to receive oxygen
then once the blood has collected the
oxygen from the lungs it enters the left
side of the heart before it can go on
its journey around the body so they said
before a pulmonary means related to the
lungs so pulmonary circulation describes
the journey that the blood would take
from the heart to the lungs to pick up
oxygen and then from the lung city heart
to deliver that oxygen
now the second journey is a systemic
circulation the blood that is rich in
oxygen which enters the left side of the
heart needs to be now circulated from
the heart to all the body the body's
tissues and organs so that is why the
word systemic is used because it means
that the entire body is affected so
oxygen and the nutrients present in the
blood can be delivered to the entire
body so these are the two types of blood
circulation pulmonary circulation and
the systemic circulation so I hope you
now have a better understanding of how
the heart functions as a double pump
bring blood into the heart twice
