A friend of mine once told me
that one of the hardest moments of his life as a student...
...was when this...
...turned into this!
Ok, I know that it's a bit scary...
...but what if I told you that actually this alien has a logic way of functioning?
You just need to think positive!
So, let's meet the heart
our unknown and loud roommate that keeps us alive!
The heart is an organ
which is almost as big as your fist
...and it is located in the anterior and inferior mediastinum.
Around the heart there is a membrane called the "pericardium" which stabilizes its position in mediastinum...
...lubricates it, so unwanted friction with other organs is minimized during the heartbeat...
...and protects it from infections.
Imagine it like a bodyguard.
As we move deeper, we meet the "myocardium"
...which is the muscle part of the heart
...and its job is to allow electrical signals to pass, therefore making heartbeat possible.
Finally the interior part is called the "endocardium"
...and it is made from a layer of endothelial cells which cover the internal walls.
The heart has four chambers.
The two upper ones are called atria and they have thin walls...
...while the two lower ones are called ventricles and they have thicker walls.
The atria and the ventricles are separated by valves
...which function like small doors that open and close as the muscle contracts
....so the blood can move from the upper chambers towards the lower ones
The left ventricle is separated from the left atrium by the mitral valve...
...while the right ventricle is separated from the right atrium by the tricuspid valve.
Inside the two big vessels
–which are the aorta and the pulmonary artery–
...we can find the aortic and the pulmonary valve respectively.
The left part of the heart is responsible for transporting clean, oxygenated blood from the lungs towards the whole body.
The blood enters the left atrium using the pulmonary veins.
The left atrium contracts...
...and the mitral valve opens
...allowing the blood to enter the left ventricle.
Then the left ventricle contracts...
...and sends it to the aorta, so the aortic valve opens.
The blood is transported to the brain and the body.
When all the tissues are oxygenated
...it returns to the heart with all the CO2 that it has collected
...and it enters the right atrium from the inferior and superior vena cava.
The right atrium contracts...
...the tricuspid valve opens...
...and the blood enters the right ventricle.
The right ventricle also contracts...
...and sends it towards the pulmonary artery.
The pulmonary valve opens and the blood goes to the lungs...
...where it exchanges the CO2 with oxygen.
After that it enters the left atrium again.
So, if we combine all these movements we are going to have something like this.
Fun fact!
The sound of the common heartbeat that you know...
...has two parts...
...and it is produced when the valves close.
The first part is made by the mitral and the tricuspid valve...
...while the second part is made by the aortic and the pulmonary valve.
Easy huh?
I hope so!
Let's get trickier now.
How does the heart know how to move?
Why do the ventricles contract after the atria and not at the same time?
This happens because of some myocardial fibers
...which have the ability to send electrical impulses
...without any external source of stimulation.
The sinoatrial node is a group of such special muscle cells...
...and it is a pacemaker.
Imagine it like an electrical generator.
The sinoatrial nodule is situated in the right atrium...
...under the superior vena cava ...
...and it has a rate of 60-100 beats per minute.
The two atria are the first to receive the electrical signal...
...and for that reason they are the first to contract.
As the signal moves towards the ventricles...
...it meets one more group of special cells...
...called atrioventricular node...
which is practically a traffic light.
So, as the signal is speeding towards the ventricles, it slows it down...
...so they won't contract at the same time with the atria...
...and it is also a pacemaker with a rate of 40-60 beats per minute.
After that the signal continues its journey inside the bundle of His...
...which connects the atria to the ventricles.
The bundle of His is divided inside the septum in two bundle branches...
...the right one and the left one...
...for the right and the left ventricle respectively.
The left bundle branch is divided in the anterior and posterior fascicle.
It is quite normal that the left ventricle has a richer electrical system...
...because its walls are thicker and therefore it has a bigger surface to cover.
Finally, we have the Purkinje fibers...
...which extend to the whole myocardium of the ventricles...
and they are our third pacemaker with a rate 20-40 beats per minute.
The information about the electrical function of the heart is used by the electrocardiogram.
This is a method by which we collect data about the velocity of the signal and the way it propagates...
...and we interpret them.
But this is a story for another episode;
I think I gave you enough headaches for one day.
I hope that by the end of this video, most of the questions have been answered!
I remind you again that this video was made only for educational purposes...
...and it cannot be used for medical diagnosis in any way.
If you liked this subject press the like button and make a share for more videos by Human nature!
And as always stay tuned until the next episode!
For more infomation >> Hướng Dẫn Mod Map Liên Quân Giảm Lag - Map Bê Tông | SGaming - Duration: 3:17. 
For more infomation >> Thằng Điên - JusstaTee x Phương Ly | V HEARTBEAT LIVE NOVEMBER (30/11) - Duration: 3:54. 
For more infomation >> Kathanayakudu HD Telugu Movie Scene | Balakrishna | Vijayashanti | Suresh Prouctions - Duration: 4:09. 
For more infomation >> 【プリキュアづくし#12】モフルンづくし - Duration: 2:18. 
For more infomation >> Torrone goloso al pistacchio bimby per TM5 e TM31 - Duration: 7:33. 
Không có nhận xét nào:
Đăng nhận xét