The Heart. Seems like an appropriate place to begin. The centre of the anatomic universe.
Why is the heart so interesting? It's only a pump, yes, but the design is elegant.
A Bungalow Basement Walk-Out
Picture in your mind a house with only one floor (bungalow) that is built on the downslope of a hill. The basement of this house is a walk-out to a large backyard. Now picture the front yard about ten times as big as the backyard. Good so far?This house has two tenants, and is split down the middle. One tenant occupies the right side of the house and the other the left. Inside the house there are only four rooms, two on the main floor and two in the basement. Each tenant gets a main floor room and a basement room.
There are four exterior doors in this house - two front doors leading to each of the main floor rooms, and two basement doors leading out of those two rooms to the backyard.
Now, are these rooms connected inside the house somehow? Of course. Each tenant has a set of stairs between the main floor room and the basement room. There is no connection between the two tenants or their rooms. Not even shared laundry.
That seems like a lot of build up, but that my friends is essentially the anatomy of the heart. Let's fill in the blanks.
Atria, Ventricles, and Valves - Oh My
Still picturing the bungalow, we can now try to envision this house as a heart. We will make ourselves the "blood" that travels through the heart, but we are only allowed to do this in a very specific way according to the "house rules".
House Rule #1: We can only enter the house through the main floor doors. These doors lead to the main floor rooms, which represent the ATRIA of the heart (singular form of this word is Atrium).
House Rule #2: We can only enter the basement rooms by taking the stairs from the main floor. The basement rooms represent the VENTRICLES of the heart, and the connection between the main floor and the basement (stairs) are the first pair of VALVES we will encounter.
House Rule #3: The only way out of the house is through the basement doors. You can only exit through these doors and cannot re-enter. If you want back in the house, you have to go up to the main floor doors. These basement doors are the second pair of VALVES of the heart.
House Rule #4: If you leave the right side of the house, you can only play in the backyard, and can only re-enter through the left side of the house. If you leave the left side of the house, you can only play in the front yard, and can only re-enter through the right side of the house. This one is a bit complicated, but will make sense soon.
House Visitors - Blood Flow
You are a visitor to the house. You are a "blood" relative to the tenants and are looking for them. This is your pathway through the house looking for your cousin:
Starting in the front yard, you enter the house on the right side main floor. No sign of him there, so down the stairs to the basement room on the right. Nada. Out the door to the backyard you go, still wondering if he is there. After frolicking in the backyard for a spell, you travel back up to the main floor on the left side of the house now and reenter the upper room there. From this room, down the stairs you go to the basement, and then out the left lower door again. However, at this stage you are banished to the front yard from this door to continue your search. No cousin? Repeat the same process starting on the right side of the house.
This is how blood flows through the heart. Just like the house.
Blood enters the right atrium (main floor) of the heart and is pumped into the right ventricle (basement). The valve (stairs) separating these two chambers (rooms) is called the TRICUSPID valve. Blood from the right ventricle is then pumped out through another valve (door) called the PULMONARY valve towards the lungs (backyard). After circulating (frolicking) through the lungs, blood then re-enters the heart on the left side, ending up in the left atrium (main floor). It is pumped through a valve (stairs) called the MITRAL valve into the left ventricle (basement). From this ventricle, blood is pumped through the final valve (door) called the AORTIC valve back out to the body (front yard) to recirculate. Once returning from the body, blood begins the cycle again on the right side of the heart.
Bloody Easy
All of this may seem complicated, but if you can follow the rules and imagine yourself walking through the house and yards you should be fine. Failing that, just try to remember:
Body -> Right A -> Right V -> Lungs -> Left A -> Left V-> Body
Slosh. Circulate. Repeat.
The heart is a simple organ with an extraordinary purpose. We quickly cease to exist without this beautiful cycle of blood flow from right to left and back again. Every organ, every cell relies on this. Admiring its simplicity is the first step in appreciating its vital purpose.
Stay tuned for more heart talk in my next post....
Why is the heart so interesting? It's only a pump, yes, but the design is elegant.
A Bungalow Basement Walk-Out
Picture in your mind a house with only one floor (bungalow) that is built on the downslope of a hill. The basement of this house is a walk-out to a large backyard. Now picture the front yard about ten times as big as the backyard. Good so far?This house has two tenants, and is split down the middle. One tenant occupies the right side of the house and the other the left. Inside the house there are only four rooms, two on the main floor and two in the basement. Each tenant gets a main floor room and a basement room.
There are four exterior doors in this house - two front doors leading to each of the main floor rooms, and two basement doors leading out of those two rooms to the backyard.
Now, are these rooms connected inside the house somehow? Of course. Each tenant has a set of stairs between the main floor room and the basement room. There is no connection between the two tenants or their rooms. Not even shared laundry.
That seems like a lot of build up, but that my friends is essentially the anatomy of the heart. Let's fill in the blanks.
Atria, Ventricles, and Valves - Oh My
Still picturing the bungalow, we can now try to envision this house as a heart. We will make ourselves the "blood" that travels through the heart, but we are only allowed to do this in a very specific way according to the "house rules".
House Rule #1: We can only enter the house through the main floor doors. These doors lead to the main floor rooms, which represent the ATRIA of the heart (singular form of this word is Atrium).
House Rule #2: We can only enter the basement rooms by taking the stairs from the main floor. The basement rooms represent the VENTRICLES of the heart, and the connection between the main floor and the basement (stairs) are the first pair of VALVES we will encounter.
House Rule #3: The only way out of the house is through the basement doors. You can only exit through these doors and cannot re-enter. If you want back in the house, you have to go up to the main floor doors. These basement doors are the second pair of VALVES of the heart.
House Rule #4: If you leave the right side of the house, you can only play in the backyard, and can only re-enter through the left side of the house. If you leave the left side of the house, you can only play in the front yard, and can only re-enter through the right side of the house. This one is a bit complicated, but will make sense soon.
House Visitors - Blood Flow
You are a visitor to the house. You are a "blood" relative to the tenants and are looking for them. This is your pathway through the house looking for your cousin:
Starting in the front yard, you enter the house on the right side main floor. No sign of him there, so down the stairs to the basement room on the right. Nada. Out the door to the backyard you go, still wondering if he is there. After frolicking in the backyard for a spell, you travel back up to the main floor on the left side of the house now and reenter the upper room there. From this room, down the stairs you go to the basement, and then out the left lower door again. However, at this stage you are banished to the front yard from this door to continue your search. No cousin? Repeat the same process starting on the right side of the house.
This is how blood flows through the heart. Just like the house.
Blood enters the right atrium (main floor) of the heart and is pumped into the right ventricle (basement). The valve (stairs) separating these two chambers (rooms) is called the TRICUSPID valve. Blood from the right ventricle is then pumped out through another valve (door) called the PULMONARY valve towards the lungs (backyard). After circulating (frolicking) through the lungs, blood then re-enters the heart on the left side, ending up in the left atrium (main floor). It is pumped through a valve (stairs) called the MITRAL valve into the left ventricle (basement). From this ventricle, blood is pumped through the final valve (door) called the AORTIC valve back out to the body (front yard) to recirculate. Once returning from the body, blood begins the cycle again on the right side of the heart.
Bloody Easy
All of this may seem complicated, but if you can follow the rules and imagine yourself walking through the house and yards you should be fine. Failing that, just try to remember:
Body -> Right A -> Right V -> Lungs -> Left A -> Left V-> Body
Slosh. Circulate. Repeat.
The heart is a simple organ with an extraordinary purpose. We quickly cease to exist without this beautiful cycle of blood flow from right to left and back again. Every organ, every cell relies on this. Admiring its simplicity is the first step in appreciating its vital purpose.
Stay tuned for more heart talk in my next post....