Blood and Circulation Essentials

Think of blood as your body's ultimate transport system - it's actually a tissue made up of four key components working together. Plasma is the yellow liquid that does most of the heavy lifting, carrying everything from nutrients to waste products around your body.

Red blood cells are the real workhorses here. These biconcave discs (imagine a doughnut that's been squashed) have no nucleus because they're packed full of haemoglobin, the red protein that grabs onto oxygen and delivers it to your cells. Meanwhile, white blood cells act like your body's security team, fighting off infections and keeping you healthy.

The circulatory system is basically a massive network of tubes powered by your heart. Arteries carry blood away from your heart under high pressure (that's why cuts to arteries are dangerous), whilst veins bring blood back using special valves to prevent backflow. Capillaries are the tiny vessels where the real action happens - they're so thin that substances can easily diffuse in and out.

Quick Tip: Remember that coronary arteries supply your heart muscle itself with oxygen - when these get blocked, it causes heart attacks!

Your cells use aerobic respiration to turn glucose and oxygen into energy: Glucose + Oxygen → Carbon dioxide + Water. This is why you need that constant supply of oxygen and nutrients, and why you need to get rid of carbon dioxide waste.