THE QUICK AND DIRTY GUIDE TO CARDIOLOGY I
Next Unit: The Quick and Dirty Guide to Cardiology II
16 minute read
The General Idea
Cardiology is the study of the heart. You want to be great at this, so I want you to study this a little at a time, and do not move on to the next part until you have an excellent grasp of this one. The way these guides will work is that we will stack upon information learned in the last section. So, we will go from very general, to very specific, then back to general again as a way to help assimilate the information. There will be tests, videos, and more to make sure you have the correct information.
This isn't a guide you want to "finish." It's one you want to understand.
All of the parts of your body need oxygenated blood to survive. The two primary systems are the circulatory system and the respiratory system. The respiratory system is responsible for getting oxygen into the blood. The circulatory system is responsible for getting oxygenated blood to all the parts of your body and bringing the deoxygenated blood back to the lungs to get more oxygen.
Getting oxygenated blood to parts of your body is called perfusion. When you have enough oxygenated blood getting to the body part to make it function correctly, you have good perfusion. If you have inadequate oxygenation to the tissues of the body, you have poor perfusion.
Inadequate tissue perfusion can also be called hypo-perfusion, which we informally call "shock."
Example: "Hypovolemic shock" is inadequate tissue perfusion secondary to a lack of blood volume. Cardiogenic shock is just inadequate tissue perfusion caused by insufficient heart function.
The circulatory system is composed of vessels and a pump. The pump is the heart. Its a pouch of muscle that squeezes. Blood goes into the heart, and an electrical signal makes the heart contract, forcing the blood out of it and into your body. The heart is about the size of a fist and sits directly in the center of your chest, between your sternum and spine.
Right Right Lungs, Left Left Tissue
The heart is an organ with 4 pockets in it called chambers. Each chamber has a particular function. The RIGHT side of your heart's job is to pump blood to the pulmonary circulation for oxygen onloading. The LEFT side of your heart's job is to pump oxygenated blood to your tissue. Your body uses the oxygen in your blood for energy. After your body uses the oxygen in it, the "used" blood feeds into the right atrium. It flows from the right atrium through the tricuspid valve into the right ventricle. The right ventricle squeezes and shoots that blood through the pulmonic valve into the pulmonary artery and to the lungs. There, the blood is reoxygenated like oxygen kids jumping onto hemoglobin roller coaster cars. The ticket takers are the alveoli and they take co2 tickets and exchange them for a ride on the circulatory roller coaster ride that is our bloodstream. The oxygenated blood travels through the pulmonary veins into the left atrium. The blood goes through the "bicuspid" or "mitral" valve to the left ventricle. The left ventricle contracts and shoots that oxygenated blood out of the heart, over the aorta, and to the body to provide oxygen to tissues and organs!
The order that blood flows through the chambers is Right Atrium, Right Ventricle, Lungs, Left Atrium, Left Ventricle, Tissue. Right, right, lungs! Left, left, tissue! Right, right, lungs! Left, left, tissue! Train your brain!
Valves - This Place Beats All
The valves prevent blood from backing up and keep it all flowing in the right direction. That's the only purpose of valves. They work like the 1-way valves on a BVM. Take a look at it next time you have a BVM near you. If there is a problem with the valve, that means blood is able to flow the wrong direction. The valves are just named by their shape. The pulmonic semilunar valve is just called that because it is a half-moon in shape and it goes to the pulmonary system. The easy way to remember the bicuspid/tricuspid order is to remember that you ride a tricycle before you ride a bicycle. The tricuspid always comes first. It's on the right side and separates the right atrium from the right ventricle. The bicuspid separates the left atrium from the left ventricle. So, the order of the valves... Tricuspid Valve, Pulmonic valve, Bicuspid Valve, Aortic valve.
A way to remember the order of the valves. This Place Beats All or The Pig's Big Ass. TPBA = Tricuspid, Pulmonic, Bicuspid, Aortic.
Vessels moving deoxygenated blood toward the heart are called Veins. Vessels moving oxygenated blood away from the heart are called arteries. The big vessel that feeds "used" blood into your right atrium is called the vena cava. It's divided into 2 parts. The superior vena cava brings blood from your head and arms. The inferior vena cava brings blood back to the heart from your lower body. After that blood goes through the tricuspid valve and into the right ventricle, the right ventricle SQUEEZES and shoots the blood into the pulmonary artery which goes to the pulmonary circulation. It is there that oxygen is put back into the blood. After moving through the pulmonary circulation, the blood then goes through the pulmonary veins into the left atrium. The left atrium dumps the blood through the bicuspid valve into the left ventricle. The left ventricle SQUEEZES and shoots the blood up over the Aorta, which is the giant artery that feeds blood to the rest of the body.
So... lets review already... a drop of blood travels... chambers are in blue, major vessels in red, valves in green
Tissue - Vena Cava - Right Atrium - Tricuspid Valve - Right Ventricle - Pulmonic valve - Pulmonary Artery - Lungs -
Pulmonary Veins - Left Atrium - Bicuspid Valve - Left Ventricle - Aortic Valve - Aorta -Tissue
Here is a picture with all of these structures shown in approximate locations.
With your mind... imagine 1 drop of blood flowing and follow it mentally through each section of the heart