1. Mouth – Where Digestion Begins #

Your mouth is like the entrance to a busy food factory. When you take a bite of food, three important things happen at the same time.

Ingestion – Getting Food Into Your Body:
This simply means putting food into your mouth and eating it. Your lips, tongue, and teeth all work together to get food inside. Your tongue helps move food around so your teeth can do their job properly.

Physical (mechanical) Digestion – Breaking Food Apart:
Your teeth act like little tools in a workshop. You have different types of teeth for different jobs. Your front teeth (incisors) cut food like scissors. Your pointed teeth (canines) tear food apart. Your back teeth (molars) crush and grind food into smaller pieces. This makes food easier to swallow and gives enzymes more surface area to work on.

Chemical Digestion – Starting the Chemical Breakdown:
While you’re chewing, your mouth makes saliva (spit). This isn’t just water – it contains a special enzyme called amylase. This enzyme is like a tiny worker that starts breaking down starchy foods like bread, rice, and potatoes. It turns the big starch molecules into smaller sugar molecules that your body can use later.

2. Salivary Glands – The Saliva Makers #

You have six small organs called salivary glands in your head – three pairs on each side of your face. Think of them as little factories that work all day making saliva for your mouth.

What They Do:
These glands make about 1.5 liters of saliva every single day – that’s like three bottles of water! The saliva isn’t just water though. It’s a special mixture that contains the enzyme amylase, which helps break down starchy foods.

How They Work:
When you see, smell, or even think about food, your brain sends signals to these glands telling them to start making more saliva. This is why your mouth “waters” when you smell something delicious cooking. The saliva gets released through small tubes that empty into your mouth.

Why Saliva is Important:
Saliva does more than just help with digestion. It keeps your mouth moist so you can speak clearly, it helps you taste food properly, and it even helps protect your teeth from harmful bacteria.

3. Stomach – The Powerful Food Mixer #

Your stomach is like a strong, muscular bag that sits just below your ribcage. It’s about the size of your fist when empty, but it can stretch to hold up to 1.5 liters of food and liquid – that’s like a big bottle of soda!

Physical (mechanical) Digestion in the Stomach:
The walls of your stomach are made of powerful muscles. These muscles squeeze and churn the food around for about 2-4 hours. Imagine putting food in a bag and squeezing and shaking it over and over – that’s what your stomach does. This mixing action breaks food into even smaller pieces and creates a thick, soupy mixture called chyme.

Chemical Digestion with Enzymes:
Your stomach makes enzymes called proteases. These are special chemicals that break down proteins from foods like meat, eggs, and cheese. The proteases cut the long protein chains into smaller pieces that your body can use to build muscles and repair tissues.

The Role of Stomach Acid:
Your stomach also makes hydrochloric acid – this is very strong acid that could actually burn through metal! But don’t worry, your stomach has a thick, slimy layer called mucus that protects it from the acid. This acid helps kill harmful bacteria in food and also helps the protease enzymes work better.

4. Small Intestine – The Main Digestion Center #

The small intestine is the longest part of your digestive system – about 6 meters long! That’s longer than a giraffe is tall. It’s called “small” because it’s narrow (about 3 cm wide), not because it’s short.

The Two Parts of the Small Intestine:

Duodenum – The First Part:
This is where most of the chemical digestion happens. It’s only about 25 cm long, but it’s very busy! When the acidic chyme comes from your stomach, the duodenum receives help from two important organs – the liver and pancreas. They send digestive juices here to break down all types of food molecules.

Ileum – The Second Part:
This is much longer (about 3.5 meters) and its main job is absorption. The walls have millions of tiny finger-like bumps called villi that grab nutrients from the digested food and send them into your bloodstream.

Chemical Digestion Jobs in the Small Intestine:
Four different enzymes work here like a team of specialists. Amylase continues breaking down any remaining starch into maltose. Then maltase takes over and breaks the maltose into glucose (simple sugar that gives you energy). Protease enzymes finish breaking down proteins into amino acids (the building blocks your body uses to make new proteins). Finally, lipase enzymes break down fats and oils into fatty acids and glycerol so your body can absorb them.

5. Liver – Your Body’s Chemical Factory #

Your liver is the largest internal organ in your body – about the size of a football! It sits on the right side of your body, just under your ribs. The liver is like a busy factory that does over 500 different jobs, but for digestion, it has two main tasks.

Making Bile:
The liver makes a green-yellow liquid called bile every day. Bile isn’t an enzyme, but it’s very important for digesting fats. Think of bile like dish soap – just as soap helps break up greasy dishes, bile breaks up fat droplets in your food into tiny pieces. This makes it much easier for lipase enzymes to work on the fats. Without bile, you would have trouble digesting butter, oil, cheese, and other fatty foods.

Storing Glycogen:
When you eat foods with sugar or starch, your liver converts the extra glucose into a storage form called glycogen. It’s like your liver is a warehouse that stores energy for later. When your body needs energy between meals or while you sleep, your liver converts the glycogen back into glucose and releases it into your bloodstream. This keeps your energy levels steady throughout the day.

Other Amazing Liver Jobs:
Your liver also filters toxins from your blood, makes important proteins, and helps control your body temperature. It’s so important that you cannot live without it!

6. Gall Bladder – The Bile Storage Tank #

Your gall bladder is a small, pear-shaped organ that sits right next to your liver. It’s only about 8 cm long and 4 cm wide – about the size of a small lime. Even though it’s small, it has a very important job in digestion.

What the Gall Bladder Does:
The gall bladder acts like a storage tank for bile. Your liver makes bile all the time, but you don’t always need it. So the gall bladder stores the bile and concentrates it, making it stronger and more effective. It can hold about 30-50 ml of bile – that’s like a small medicine cup full.

How It Knows When to Work:
When you eat fatty foods like pizza, fried chicken, or ice cream, your body sends a chemical signal to your gall bladder. This signal tells the gall bladder to squeeze and push bile through a small tube into the duodenum (first part of the small intestine). The bile then helps break down the fats in your meal.

Why Timing Matters:
The gall bladder is smart – it only releases bile when you actually need it. This is much more efficient than having bile flowing all the time. It’s like having a garden sprinkler that only turns on when your plants are thirsty.

7. Pancreas – The Enzyme Powerhouse #

Your pancreas is about 15 cm long and sits behind your stomach. It’s shaped a bit like a fish and has two very important jobs in your body – helping with digestion and controlling blood sugar. For digestion, it’s like a super-factory that makes the most important digestive juices.

Making Pancreatic Juice:
Every day, your pancreas makes about 1.5 liters of a special liquid called pancreatic juice. This juice contains three of the most important digestive enzymes your body needs. Think of the pancreas as a pharmacy that makes exactly the right medicines (enzymes) to break down different types of food.

The Three Super Enzymes:
First, it makes amylase to break down starches like bread, pasta, and potatoes. Second, it makes protease to break down proteins from meat, fish, eggs, and beans. Third, it makes lipase to break down fats and oils from foods like butter, nuts, and fried foods. Having all three enzymes means the pancreas can help digest every major type of food molecule.

Why Pancreatic Juice is Alkaline:
The pancreatic juice is alkaline (the opposite of acidic). This is very important because when food comes from your stomach, it’s very acidic from all the stomach acid. The alkaline pancreatic juice neutralizes this acid, making the environment just right for the enzymes to work properly. It’s like adding baking soda to lemon juice to make it less sour.

8. Large Intestine (Colon) – The Water Recycler #

After food has been digested and most nutrients absorbed in the small intestine, what’s left moves into the large intestine (also called the colon). Even though it’s called “large,” it’s actually much shorter than the small intestine – only about 1.5 meters long. It’s called large because it’s much wider – about 6 cm across.

The Main Job – Water Absorption:
When the leftover food material enters the large intestine, it’s still quite watery and soupy. The main job of the large intestine is to absorb most of this water back into your body. This is very important because your body needs to conserve water. If the large intestine didn’t do this job, you would lose several liters of water every day and become very dehydrated.

How It Works:
The walls of the large intestine are specially designed to soak up water like a sponge. As the watery waste moves slowly through the colon (this takes about 12-24 hours), more and more water gets absorbed. Gradually, the liquid waste becomes more solid and forms what we call feces or poop.

Other Important Jobs:
The large intestine also absorbs some vitamins that are made by helpful bacteria living there. These bacteria are actually good for you – they help make vitamin K, which your body needs for blood clotting. The large intestine also absorbs any remaining minerals like sodium that might be useful.

9. Rectum and Anus – The Final Exit #

The rectum and anus are the final parts of your digestive system. They work together to complete the process called egestion – getting rid of waste that your body cannot digest or use.

The Rectum – Temporary Storage:
The rectum is the last 15-20 cm of the large intestine. It acts like a storage room for solid waste (feces) until your body is ready to get rid of it. The rectum has special sensors that can detect when it’s getting full. When enough waste builds up, these sensors send signals to your brain letting you know it’s time to go to the toilet.

The Anus – The Exit Door:
The anus is the opening at the very end of the digestive system. It has two sets of muscles called sphincters that work like doors. One set works automatically (you can’t control it), and the other set you can control. This means you can decide when it’s a good time to go to the bathroom.

The Process of Egestion:
When you’re ready to go to the toilet, the muscles in your rectum contract and push the waste toward the anus. At the same time, you relax the sphincter muscles you can control, and the waste leaves your body. This process removes all the parts of food that your body couldn’t break down or absorb – things like fiber, dead bacteria, and other indigestible materials.

Why This is Important:
Getting rid of waste is crucial for staying healthy. If waste stayed in your body too long, harmful bacteria could multiply and toxins could build up. The egestion process keeps your digestive system clean and working properly.