Major Disorders of the Circulatory System

Instructor: Amanda Robb

Amanda holds a Masters in Science from Tufts Medical School in Cellular and Molecular Physiology. She has taught high school Biology and Physics for 8 years.

In this lesson we'll first review what the circulatory system is. Then we'll explore three major types of disorders in the circulatory system: heart attack, stroke, and atherosclerosis.

What is the Circulatory System?

Picture a highway bringing traffic in and out of a city. There are large, multi-lane highways that connect distant parts of the city, with roads branching from the exits. The smaller roads bring people and goods to every corner of the city. Although we're not filled with cars and concrete, the circulatory system has a similar function in our body.

The circulatory system is made of all your blood vessels, arteries and veins, and your heart. The job of the circulatory system is to pump blood all over your body, bringing oxygen to your cells and picking up waste for removal. Since oxygen is needed to make energy and keep our cells alive, people won't survive long without a functional circulatory system. Today we'll look at some common medical problems with the circulatory system, as well as their treatments.

Cardiac Arrest and Myocardial Infarction

As you stand outside your local emergency room, emergency technicians rush in an unconscious patient. Nurses shout 'Clear!' and try to shock the patient back to life. This person's heart has stopped during sudden cardiac arrest. Since the heart is an electrical organ, like our brain, sometimes the high voltage shocks from a defibrillator can start the heart again.

Sudden cardiac arrest occurs when the heart starts to beat irregularly. The main cause of this condition is a heart attack, or myocardial infarction, where blood stops flowing to the heart. During a myocardial infarction, the arteries that bring blood to the heart, called coronary arteries, get clogged with plaque. The heart can no longer deliver blood to itself and starts to die. The longer the heart goes without blood, the greater the damage will be.

A myocardial infarction occurs when blood flow to the heart is cut off
myocardial infarction

The immediate treatments for a heart attack all focus on getting oxygen to the heart and getting the clot out of the blood vessel. Aspirin, thrombolytic medications, which break up blood clots, and nitroglycerin, which increases the size of the blood vessels, are administered as soon as possible. People can be prescribed long term anti-clotting drugs to reduce the workload of the heart.

Diet and exercise can also prevent the clogging of arteries that leads to a heart attack. However, some people need a coronary artery bypass surgery. In this surgery, blood vessels are taken from another part of the body and grafted into the heart, connecting the heart to the main blood supply, working around the damaged coronary artery.


Similar to a heart attack, a stroke happens when blood flow to the brain is cut off due to a clogged artery. Like the heart, without oxygen your brain cells begin to die. The longer the brain lacks oxygen, the greater the damage will be.

A stroke occurs when the brain can no longer receive blood from the heart

If people start exhibiting symptoms of a stroke, like a sudden drooping face on one side, trouble seeing, confusion, numbness, or dizziness, call your emergency line immediately and note the time. Some medications only work in a certain window before they actually cause more damage, like the anti-clotting drug tissue plasminogen activator (TPA).

Other treatments for stroke include aspirin to thin the blood and insertion of a catheter into blood vessels in the groin, which can be navigated to the area of the clot in the brain, locally delivering medicine, called intra-arterial thrombolysis. That's right, a tube is inserted into the blood vessels in your upper thigh and is navigated all the way to your brain. It sounds gross and maybe a little scary, but if your brain is dying you do what you have to!

During intra-arterial thrombolysis a catheter is inserted through the groin to the site of blockage in the blood vessels
intra arterial thrombolysis

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