the

Heart Valves - Atrioventricular Valves - Semilunar Valves - Tricuspid - Bicuspid

welcome to 5-minute school today's video

will be talking about the valves of the

heart I've included a diagram here which

shows the heart in a good amount of

detail and there are quite a few labels

on here as well but in today's video

we'll just be talking about the valves

which you can see on the left and right

side of the hearts on the left side here

on the right side here and we also

consider semilunar valves here now we

know already that the heart consists of

cardiac muscle and if you didn't know

cardiac muscle is basically consisting

of myocardial cells and between these

myocardial cells they are joined

together by intercalated disks but it's

not just cardiac muscle which makes up

the heart we have a fibrous skeleton in

place which helps to keep the structure

of the heart

now this fibrous skeleton is going to be

consisting of connective tissue so just

to make things a bit more clear the

atria and the ventricles they are

separated into two functional units by a

fibrous skeleton which is made up of

connective tissue and obviously we need

to enable blood to pass through this

fibrous skeleton so there are valves or

atrioventricular valves embedded within

this fibrous skeleton and this allows

the passage of blood to go through okay

so the atrial ventricular valve between

the right atrium remember this side is

the right side the right atrium and

ventricle is known as the tricuspid

valve and this has three flaps you can't

see it so well in this image but when

the valve is actually sure it is quite

clear that there are three components to

the valve on the left side between the

left atrium and ventricle we have the

bicuspid valve which is also known as

the mitral valve and this consists of

two flaps so the atrioventricular valves

allows blood to flow from the atria to

the ventricles but normally prevents the

backflow of blood and opening and

closing of the valves occurs due to

pressure differences between the atria

and ventricles remember when the atria

is filling with blood these valves are

closed if they were opened

then blood would just fill the atrium

straight away fall into the ventricles

so when the atria is filling with blood

these valves are closed when the

pressure in the atria gets very high

then it forces these valves to open and

then blood passes through from the atria

into the ventricles and then when the

pressure is building up in the

ventricles this pressure causes these

valves this snapshot okay and that's how

blood can pass on the next cycle from

the atria because the valves were

already shot from the previous closure

from the ventricles okay so what we need

to bear in mind is extremely high

pressures which are produced by the

ventricles could invert the atrial

ventricular flaps now what we need to

remember is we're just discussing the

basic physiology of the heart

there are various cases where we have

pathological processes going on and for

example if we have excessive pressure in

the ventricles because the heart is

trying to compensate for lack of oxygen

in different parts of the body so the

ventricle is pumping extremely high

pressures of blood then this pressure

could be so high that it could force

these flaps to push back open sorry to

invert into the atrium okay so this is a

pathological disease so high extremely

high pressures produced by the

ventricles could invert the

atrioventricular flaps and this is

prevented in some cases by a contraction

of papillary muscles within the

ventricles which are connected to the

atrial ventricular flaps by strong

tendinous cords called corded chordae

tendineae

okay you can see them from this image

here they're connected to the papillary

muscles of the heart and it's a fibrous

cord which is attached unto the valves

and it's see clearly this core called

here which is attached onto the valves

to prevent them from inverting and

that's sort of a a prevention but

remember in some cases

that could be damage to these cords as

well so we're just learning the

physiology for now but is important to

bear that in mind

lastly we're going to talk about the

semilunar valves and they are located at

the origin of the pulmonary artery in

aorta they open during ventricular

contraction and when the pressure in the

arteries is greater than the ventricles

they snap show okay so let's have a look

at them here you can see on from the

right side of the heart the ventricles

are here here we have the pulmonary

artery and we have the semilunar valve

here which obviously prevents backflow

of blood from the pulmonary artery back

into the ventricle so it's a similar

it's the exact same purpose as the

atrioventricular valve so the pressure

in the ventricles is going to get very

high in force these valves open and then

blood is going to go into the pulmonary

arteries but when the pressure here is

higher than the pressure in the

ventricles these valves are going to

snap shut okay so that's everything I'm

going to talk about in this video thank

you very much for watching