List the components of blood: red blood cells, white blood cells, platelets and plasma.

8.2 Transport in Humans 🚀

Blood – The Body’s Delivery System

Think of blood as a busy highway that transports everything the body needs – oxygen, nutrients, waste, and signals. It’s made up of four main components, each with a special job.

Components of Blood

• 🟥 Red Blood Cells (RBCs) – the oxygen‑carrying trucks.
• ⚪️ White Blood Cells (WBCs) – the body’s security guards.
• 🟠 Platelets – the emergency repair crew.
• 💧 Plasma – the highway’s fluid that carries everything else.

Analogy: Imagine a city where RBCs are delivery vans that bring oxygen to every house, WBCs are police officers keeping the city safe, platelets are firefighters stopping any bleeding, and plasma is the water that keeps the roads and buildings running smoothly.

How Oxygen Travels

Oxygen binds to hemoglobin inside RBCs. The reaction can be written as:

$$\text{Hb} + \text{O}_2 \rightleftharpoons \text{HbO}_2$$

When RBCs reach tissues, they release oxygen, turning back to the left side of the equation.

Exam Tip Box