You might think you know the ins and outs of how your body works from those books you read when you were younger (you know the ones!). But if you ever want to deepen your knowledge and learn more about the inner workings of your nervous system, digestive system, and everything in between, these courses about the human body are a great way to get started.

All from top universities, these classes will help deepen your understanding of your body, allowing you to fuel yourself better, exercise more effectively, and stay healthier. And the best part? While some will cost you, others are completely free. These are the best courses about the human body to start with.

The best courses about the human body from top universities

1. Vital Signs: Understanding What the Body Is Telling Us

School: University of Pennsylvania

Cost: Free

Your heart rate, temperature, blood pressure, and more—getting to know your vital signs can give you a better understanding of your overall health. This free course goes through how to measure them, what’s normal, and what they say about your physical well-being.

2. Cognitive Fitness

School: Harvard University

Cost: $30

In this class, you’ll learn how to keep your brain in good shape as you age. It goes into the best foods to eat for better brain power, how exercise and sleep can help keep your brain sharp, and more.

3. Science of Exercise

School: University of Colorado, Boulder

Cost: Free

If you’re curious about how your body responds to exercise on a physiological level, this class is for you. Not only does it go into your body’s needs when it comes to handling exercise in the first place, but it also helps you identify behaviors and choices that play a role in your training.

4. Intro to the Nervous System

Anyone who’s fascinated by the nervous system will enjoy taking this course. In it, you’ll learn the fundamentals of the nervous system and how it responds to stimuli, how you’re able to make decisions and interact with the world, and more.

School: Tufts University

Cost: $50

5. Introductory Human Physiology

School: Duke University

Cost: Free

In this course, you’ll dive deep into human physiology as the instructor teaches you all about the body’s nine organ systems and how they allow your body to function properly. One week you’ll be learning about the nervous system, and the next you’ll find out everything there is to know about your gut.

6. Introduction to Human Physiology

School: UC Berkeley Extension

Cost: $1,085

If you really want to know everything—and I mean everything—about human physiology, this course goes through the body’s cells, tissues, major organs, and systems. Even cooler, you get to attend it live every week with other students from all over the world.

7. Anatomy and Physiology

School: Stanford University

Cost: Free

This course goes into the structure and function of the human body, homeostasis, the levels of organization in the human body, and the integration of systems. Basically, by the time you’re finished, you’ll know more than you ever thought you would about your body and how to stay healthy.

8. How Does Your Body Digest Food?

School: Tufts University

Cost: $50

Sure, you know your body digests food after you eat it, but this course goes into the topic on a whole new level. You’ll find out exactly how nutrients are broken down, what happens when your digestive process isn’t running smoothly, and more.