Physiology is linked to Biology. It explains how life processes and structures work. Human Physiology is about how the different parts of the body work together, like the brain, heart and lungs. How does the heart pump blood, for example? That's physiology. What processes are at work when a human breathes in and out? That's physiology. We can study animal physiology too: how they grow and develop. When we study cells, that is also physiology: how they change and absorb or transmit chemicals. When we study plant physiology, we are looking at how they take in nutrients and sunlight, photosynthesis, and how they grow. All of these different life structures are called physiology.