All You Need to Know About Veins and Arteries

Last updated: June 2021

Heart failure is heart disease, yet it also involves your vascular system. After all, your heart and blood vessels work together in what is often called your cardiovascular system. So, here’s all you need to know about your blood vessels.

Defining important terms

Vascular System

It’s a bodily system that carries lymph and blood through your body. It consists of lymphatic and blood vessels.1-2

Lymphatic (Lymph) vessels

These are very small vessels. They are microscopic and cannot be seen with the naked eye. They travel through all the tissues of your body. They carry lymph through your body. Lymph is a colorless fluid that contains white blood cells.

They also collect fluid that naturally seeps from blood vessels. Heart failure can overwhelm this system by causing an excessive amount of fluid to seep from blood vessels causing edema. Lymphatic vessels are one part of an extensive lymphatic system. I will keep it simple here and say this is all you need to know about this system for now.1,3

Blood vessels

They carry oxygen and other nutrients to your tissues and also carry waste products from your tissues back to your heart and lungs. They constrict (tense up) and dilate (relax). This is important for allowing your body to adjust to changes during the course of a day. 

They also play a role in inflammation which is important for fighting infections. Yet inflammation is also responsible for many of our chronic diseases, such as asthma, COPD, and rheumatoid arthritis.1,3-4

Types of blood vessels

There are three main types of blood vessels: arteries, veins, and capillaries.


These are blood vessels that carry freshly oxygenated blood from your lungs to all the tissues of your body.1


These are the smallest blood vessels. They are microscopic and unseen by the naked eye. They travel through all the tissues of your body connecting arterioles with venules. Capillaries from arterioles carry oxygenated blood to tissues. Capillaries returning from tissues carry unoxygenated blood to veins.1


These are blood vessels that carry unoxygenated blood from all the tissues of your body. Veins transport unoxygenated blood back to your heart and lungs to collect more oxygen. They tend to be located close to surfaces.

If you look at your hands, you may see bluish veins. They are blue because they do not contain oxygen. Their walls are less thick compared to arteries. This is mainly because the pressure required to move venous blood is low.

Gravity sometimes has an impact on the flow of blood through your veins. This has the greatest impact on your lower extremities. Heart failure can sometimes lead to foot (pedal) and ankle swelling and edema.1

More terms


These are the smallest arteries and connect to capillaries. When they constrict, this causes oxygenated blood to bypass capillaries. When dilated, blood flows easily to capillaries and tissues.1,5


These are small veins that connect veins and capillaries.1,5


This is the largest artery. It’s the artery that blood is pushed through after leaving your left ventricle. The walls are very thick because it is where your blood pressure is at its highest. From your aorta, arterial blood branches off to all the different parts of your body.1

Coronary arteries

These are a series of arteries that branch from your aorta to feed your heart. They make sure your heart receives a fresh supply of oxygen. Coronary Artery Disease can cause these arteries to become obstructed. This can lead to a loss of blood supply to your heart.

A surgery called a heart bypass can be used to fix this problem to improve blood flow and thereby prevent heart attacks.1

Superior and Inferior Vena Cava

These are large veins that collect all the venous blood in your body. They return venous blood to the right side of your heart. The right side of your heart then sends this blood to your lungs to pick up oxygen.1-2

Pulmonary capillaries

These are capillaries that wind through your lungs. They attach with small grape-like clusters inside your lungs called alveoli. Oxygen from the air you inhale enters these alveoli and then crosses the walls of alveoli into capillaries. These capillaries then carry freshly oxygenated blood to your arteries. These capillaries may be the link between COPD and heart failure.1

Pulmonary arteries

These vessels are the only arteries that are a part of your venous blood system. They carry unoxygenated blood from your heart to your lungs.1

Pulmonary veins

They carry freshly oxygenated blood from your lungs back to your heart.1

Cardiovascular system

This is the name of the bodily system that includes both your heart and your blood vessels. Together, all the blood vessels of your body form a complete loop throughout your body. Blood moves from your heart to your aorta and arteries, arterioles, capillaries, venules, veins, and back to your heart.

A second loop exists inside your lungs. Here, blood moves from your heart, through your pulmonary veins, through your pulmonary arterioles, capillaries, venules, pulmonary artery, and back to your heart.1-3

There you go. From time to time, we hear these terms from doctors and nurses so hopefully, you'll now feel more confident when you do!

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