Bird Circulatory System: Function & Structure

Bird Circulatory System: Function & Structure
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  • 0:00 What Is the…
  • 0:38 Structure of the Bird…
  • 2:40 Size of Bird Hearts
  • 3:17 Capillaries in Birds
  • 4:05 Efficiency of Blood Pumping
  • 4:42 Lesson Summary
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Lesson Transcript
Instructor: Amanda Robb
In this lesson, we'll go over the important structures of the bird circulatory system and explain how they are different from those of other animals. We'll also learn the function for the structures of the circulatory system.

What Is the Circulatory System?

Picture yourself running on a cool fall day. The sun is shining and the leaves are changing color. You can probably feel the blood pumping through your body, powering you through the day's workout. While you're running, your heart is working hard to pump blood, which carries oxygen and nutrients all over your body for you to make energy. Your heart, blood, and the vessels that carry it are collectively referred to as the circulatory system. All animals have a circulatory system, and today we're going to look at the structure and function of bird circulatory systems, which are surprisingly like our human ones.

Structure of the Bird Circulatory System

To begin, let's start with the heart, which is like the boss of the circulatory system. The heart in birds and mammals is divided into four parts, called chambers. The job of the heart is to deliver oxygen and nutrients to the body through the blood. When the blood is in the body, the oxygen is used up to make energy.

The blood then flows back to the heart into the first chamber, or the right atrium, through blood vessels called veins, which bring all blood to the heart. From the right atrium, the deoxygenated blood goes to the right ventricle. The right ventricle is a larger chamber that pumps the blood to the lungs.

At the lungs, the blood picks up oxygen and is moved to the left atrium of the heart. The left atrium pumps blood to the left ventricle, the strongest chamber of the heart. The left ventricle's job is to pump blood through the arteries to the entire body, so it needs to have a thick wall of muscle to do such a big job. From there, the process repeats again with each heartbeat.

Only birds and mammals have four chambers to their heart. The purpose of this is to divide the oxygenated and deoxygenated blood efficiently. Other animals have two chambers, or no chambers in their heart, so all the blood mixes together. To be the most efficient at delivering oxygen, we want to keep the oxygenated blood moving towards the body and the deoxygenated blood coming back to the heart to get more oxygen.

Picture a street. The cars on the street are like the blood in our body. Our streets usually have two or more lanes. One you can imagine going into the city, and the other leads out to the country. With two lanes, the traffic can easily flow in two directions. However, if there were no lanes, all the traffic would be mixing together, going both directions. There would probably be a lot of accidents and people wouldn't get where they are going as efficiently. This is why a 4-chambered heart is helpful to an animal needing a lot of energy. Next, let's look at some other adaptations of the bird circulatory system.

Size of Bird Hearts

The bird's heart, although similar to mammals, is structured slightly differently for their lifestyle. Birds have proportionately larger hearts compared to mammals. A heart of a human is about 0.4% of our body weight, whereas a bird can have a heart weighing up to 4% of its body weight!

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