Circulatory System:
The Blood’s Journey through the Body, a 6-Step Summary

The circulatory system is a network of organs and blood vessels that work together to move blood throughout an organism’s whole body.

Move blood throughout an organism’s whole body

20170427 circulatory system p1
(Click to Enlarge)

6 Step Summary of Blood’s Journey in the Body:

  1. Arriving at the lungs:
    The lungs gather a lot of oxygen through “breathing”.  When blood travels through the lungs, it drops off its carbon dioxide and pick up a lot of oxygen.  Therefore, the blood can drop off these oxygen as it travels throughout the body.
  2. Arriving at the left side of the heart:
    Blood, now rich in oxygen thanks to the lungs, arrives at the left side of the heart.
  3. Leaving the heart (heart’s left side):
    The left ventricle pumps blood out of the heart and sends blood on a long journey throughout the body.  This journey is called the systemic circulation.
  4. Visiting different body parts and doing gas exchange: 
    During the systemic circulation, blood drops off oxygen at different body parts while picking up their carbon dioxide.  In other words, gas exchange.  Note that blood drops by every part of the body EXCEPT the lungs because the lungs do not need help getting oxygen.
  5. Returning back to the heart (heart’s right side):
    Blood returns to the right atrium of the heart.  Now, the blood contains very low oxygen and very high amount of carbon dioxide.
  6. Leaving the heart (heart’s right side) and flowing towards the lungs:
    The right ventricle pumps blood out of the heart and into the lungs, where blood drops off its carbon dioxide and replenishes its oxygen.  (See step 1 for details.)


Next Generation Science Standards:

MS-LS1-3 Use argument supported by evidence for how the body is a system of interacting subsystems composed of groups of cells.

HS-LS1-2 Develop and use a model to illustrate the hierarchical organization of interacting systems that provide specific functions within multicellular organisms.

HS-LS1-3 Plan and conduct an investigation to provide evidence that feedback mechanisms maintain homeostasis.

What Science Does this Comic Teach?

Unit: Anatomy

⇒Chapter: Circulatory System

⇒Topic: Circulatory System

Additional Information


A ventricle is a chamber of the heart that is responsible for pushing blood out of the heart.  The human heart has two ventricles–1 right ventricle and 1 left ventricle.


An atrium is a chamber of the heart that is responsible for receiving blood into the heart.  The human heart has two atria (atria: plural form of atrium)–1 right atrium and 1 left atrium.

Cardiac Muscle

It is one of the 3 major types of muscles: cardiac, skeletal, and smooth.  Cardiac muscle is responsible for the transfer of blood, and it makes up the heart.

Oxygen (O2)

Oxygen is a gas required to most organisms, including humans.  Without oxygen, our tissues will die in a matter of minutes.  We breathe in oxygen.

Carbon Dioxide (CO2)

Carbon dioxide is a gas that is the waste product from metabolic activities.  It has to be removed from our tissues.  We breathe out carbon dioxide.


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