Respiration
What is Respiration ?
Respiration is how cells release energy from food.
It’s one of the most important processes in all living organisms — without it, your body wouldn’t have the energy it needs to move, grow, think, or even stay alive!
🚫 Respiration is NOT Breathing
Many people confuse respiration with breathing, but they’re not the same!
Breathing is the process of inhaling oxygen and exhaling carbon dioxide.
Respiration happens inside your cells. It’s the chemical process that breaks down glucose (a sugar from food) to release energy.
🔋 Why Do We Need Respiration?
Every cell in your body needs energy to do jobs like:
Building new cells
Repairing damage
Keeping your heart beating
Sending messages in your brain
Respiration provides this energy in a form called ATP (Adenosine Triphosphate).
Types of Respiration
There are two main types of respiration:
1. Aerobic Respiration
Needs oxygen
Happens in the mitochondria of cells
Releases a lot of energy
This is the type your body uses most of the time.
2. Anaerobic Respiration
Does NOT need oxygen
Happens when oxygen runs low — like during intense exercise
Releases less energy
🚶♂️In humans
Lactic acid builds up in muscles, causing cramps or fatigue.
Why Does Anaerobic Respiration Happen?
When you’re exercising hard and your muscles don’t get enough oxygen, your body switches to anaerobic respiration to keep producing energy. But it’s not ideal — it’s less efficient and causes muscle pain because of lactic acid.
Where Does It All Happen?
Aerobic respiration → Inside the mitochondria (the "powerhouse" of the cell)
Anaerobic respiration → In the cytoplasm (the jelly-like part of the cell)
Feature | Aerobic Respiration | Anaerobic Respiration |
Needs oxygen? | ✅ Yes | ❌ No |
Energy produced | 🔋 High | 🔋 Low |
Byproducts | CO₂ + H₂O | Lactic acid (humans), Ethanol + CO₂ (yeast) |
Location | Mitochondria | Cytoplasm |
🍞 In yeast (a type of fungus)
Glucose → Ethanol + Carbon dioxide + Energy
This process is called fermentation.
Fermentation in Real Life
Fermentation is a special kind of anaerobic respiration used in food and drink production.
Yeast fermentation is used to:
Make bread rise (carbon dioxide bubbles)
Produce alcohol in beer and wine (ethanol)
Top Tips
🟢 Respiration ≠ Breathing – respiration happens inside cells to release energy.
🟢 Glucose = Fuel – it's the sugar your body breaks down for energy.
🟢 Oxygen = Key for aerobic respiration — it helps release lots of energy.
🟢 Lactic acid = muscle pain! That’s anaerobic respiration in action.
🟢 Fermentation = how yeast produces alcohol and CO₂ without oxygen.
🟢 Aerobic = with oxygen, Anaerobic = without oxygen.
🟢 Mitochondria = where aerobic respiration happens — think of it as the cell’s battery!