Organisation and the Digestive System
Think of your body as perfectly organised levels, just like Russian dolls fitting inside each other. Specialised cells are the starting point - sperm cells have tails for swimming, nerve cells carry electrical impulses, and muscle cells contract and relax.
These similar cells group together to form tissues, which then combine to create organs like your heart or stomach. Finally, organs team up as organ systems - and that's where your digestive system becomes the star of the show.
Digestion is simply breaking large food molecules into small, soluble ones that your blood can transport around your body. Your digestive system includes everything from your mouth down to your anus, plus helper organs like the liver and pancreas.
Key Insight: The human digestive system works as a team - mouth chews and releases saliva, stomach churns food, liver makes bile, pancreas releases enzymes, small intestine does most digestion, and large intestine absorbs water.
Enzymes are your body's biological catalysts - they speed up reactions without being used up themselves. The lock and key theory explains how substrates fit perfectly into an enzyme's active site, react, then turn into products. These amazing molecules control your metabolism (all reactions in your cells) and work best at specific temperatures and pH levels - which is exactly why your body temperature stays at 37°C!