Basics of the Circulatory System

Contributor: Hannah Brooks. Lesson ID: 12569

How do nutrients from your food get to those tiny cells in your body? What does blood do besides gross you out when you see it? Get to the heart of the matter in this lesson; you won't study in vein!

categories

Life Science

subject
Science
learning style
Visual
personality style
Lion
Grade Level
Middle School (6-8), High School (9-12)
Lesson Type
Dig Deeper

Lesson Plan - Get It!

Audio:

How are water parks and the circulatory system related?

Water parks have complex pump and pipe systems that move water throughout the park to water slides, rides, and different pools.

The circulatory system operates in a very similar way, pumping blood from a central location to all areas of the body. The circulatory system is comprised of your heart and blood vessels. Blood vessels include arteries, veins, and capillaries, that all serve specific purposes within the system.

circulatory system

The circulatory system depends on the heart, an organ, to pump blood throughout the body. The heart is an involuntary muscle, which means that it beats without direct instruction from the brain. Most people's heart beats between 60 and 100 times per minute. It is located between the lungs in the chest cavity.

human heart

The human heart is made up of thick muscle divided into four chambers.

heart anatomy

Notice the ventricle and atria components of the heart in the image above. The atria are located at the top of the heart, and are divided into the left atrium and right atrium. The bottom of the heart is divided into the left ventricle and right ventricle. The ventricles pump blood out of the heart, while the atria receive blood moving into the heart from the body.

The body's largest blood vessel is also found in the heart: the aorta. The aorta is an artery, a blood vessel that carries oxygenated blood away from the heart. This blood provides the oxygen and nutrients to the body that organs and tissues need to function. Arteries have really thick walls and branch into smaller arterioles farther away from the heart.

vein and artery

Veins move de-oxygenated blood back to the heart through a series of valves that prevent blood from flowing backwards. "De-oxygenated" means that the blood has already given the dissolved oxygen to organs and tissues throughout the body. Veins are less flexible and have a thinner smooth-muscle layer than arteries. The superior vena cava and inferior vena cava are the largest veins, and are located above and below the heart. Look back at the earlier image to review where they are located in the body.

capillary blood flow

Veins and arteries are connected by capillaries, the smallest type of blood vessel. These tiny structures allow veins and arteries to exchange water, carbon dioxide, nutrients, and a small amount of oxygen. They are also responsible for delivering oxygen and nutrients to cells, and for removing waste products from cells.

All of these components work together to move blood throughout the human body. The heart pumps large amounts of blood out to arms and legs, providing necessary oxygen to these areas. Arteries move blood away from the heart, while veins take blood back to the heart. Capillaries are important structures for providing oxygen and nutrients to cells and provide arteries and veins with a way to exchange blood.

Your heart is an amazing muscle, providing the nutrients and blood supply for your entire body. Arteries, veins, and capillaries act as pathways, moving the valuable fluid to tissues and organs.

  • Have you ever felt your pulse increase in your wrist or neck?
  • Why do you think your heart beats faster when you are excited or scared?
  • How can you help control the pace of your heart beat?

In the Got It? section, you will work through an online activity to complete a guide that will help you learn more about the structure of the heart and the way it pumps blood!

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