Natural selection and adaptation | Mechanisms of evolution | High school biology | Khan Academy

The circulatory system is a vital network consisting of the heart, blood vessels, and blood that moves nutrients, oxygen, and waste through the body. It acts as the body's transport system, keeping all cells alive and healthy. #biology #anatomy #edit #viral #fyp

Cancer doesn't start as a lump. It starts with a single line of DNA going off script. 🔬 Cancer is what happens when abnormal cells grow out of control, and it begins deep inside the cell. Your DNA holds the genes that code for everything a cell does, including two critical instructions: when to divide, and when to undergo apoptosis (controlled, programmed cell death). Normally these are tightly regulated. But when certain genes mutate, that order breaks down and cells start dividing unchecked.