A common term for the digestive system.
If a medicine is swallowed it moves through the gut wall into the blood.
Once the medicine gets into your blood stream it is carried to every part of you within a very short time indeed. It will affect all of your body, not just the part that feels ill. It reaches your brain and all your other body organs. This is why it is so important that you only take medicine which has been prescribed or given to you, and that you take the right dose.