Without muscles, we wouldn't be able to do much of anything. This tutorial explores what muscle cells are and how they contract to let us move our bodies.
Circulatory_and_pulmonary_systems
As humans, we really like breathing oxygen. That's because the cells in our body will die if they don't get the oxygen they need to function. This tutorial describes how gases are exchanged between blood and the atmosphere in our lungs, and how oxygen is then pumped through the body by way of blood and the circulatory system.
How does you body defend itself against invaders, such as disease-causing bacteria and viruses? Learn more about your immune system, what cells make it up, and how it works in many different ways to protect you from harmful microbes (pathogens).
Neurons are specialized cells that allow our bodies to transmit signals from one part to another quickly. In this tutorial, we'll explore the anatomy of a neuron and the mechanism by which neurons transmit signals.
How do we get unwanted substances out of our blood? Through the kidney. This tutorial goes into detail about how the kidney works.
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