In this article, we are going to focus on the digestive system. So what is the digestive system in simple terms?

Digestion refers to the breakdown of food into smaller components that can be absorbed into the bloodstream. Think of your digestive system as a sophisticated machine that absorbs the food you eat and transforms it into nutrients which the body uses for energy, growth, and cell repair.

"I try to start every day with some sort of vegetable and fruit juice before I eat any kind of solid food. Because that really jump starts your body and digestive system with the high content of micronutrients that your body needs."

Jake Arrieta

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Why we Need a Digestive System

Much like how we can't live without air, nutrition is also essential to our survival. Everything I'll sell in our bodies requires nutrients that we can ingest from food and drink. However, as food is too big to get into ourselves so it needs to be broken down which is where our digestive system comes in.

A series of organs and glands break down the food into smaller molecules so it can be used as energy to help us function and survive. Once our digestive system has broken down the food small enough to enter the bloodstream, it is transformed into nutrients which the body uses for energy, growth, and cell repair.

The waste is then excreted when we go to the toilet.

Digestion is the process of how we digest and get nutrients from the food we consume. It involves a complicated series of organs and glands that break down the food.

Digestion System
Digestion is the process of how we break down and absorb nutrients from the food we consume. It involves a series of organs and glands that break down the food - Image by Clker-Free-Vector-Images from Pixabay

The Stages of Digestion

There are four main stages of digestion that you will need to be able to identify and define. They are as follows:

  1. Ingestion - this is the intake of food through the mouth
  2. Digestion - which is when the food is broken down into smaller molecules
  3. Absorption - is when the nutrients pass into the blood system
  4. Egestion - this part of the process involves the removal of undigested waste via the anus (it is important not to mix up egestion with excretion, Excretion is the removal of toxic materials, waste products of metabolism and excess substances from organisms, organs of excretion are the skin, kidneys and lungs.)

Not only are there are four stages of digestion, but there are also two types of digestion, physical digestion and chemical digestion.

Physical digestion is all the actual physical work the body those in order to digest the food:

  • Putting food in the net mouth.
  • Tearing, cutting and crushing of food by the teeth in the mouth.
  • Swallowing food, action made by the throat to push the food into the oesophagus
  • Peristalsis which is the muscular contractions of the oesophagus as it pushes food into the stomach.
  • The churning action that happens in the stomach while the food is being broken down
  • Small contractions which push food through the small and large intestine is fair absorbing nutrients.
  • Larger contractions which happen before food is egested through the anus.

Chemical digestion coincides with physical digestion through the different stages. It uses chemicals called enzymes to further break down food into usable molecules are nutrients by the body.

  • Saliva contains enzymes in the mouth which aid in dissolving food while the teeth are crushing in chewing.
  • In the stomach hydrochloric acid dissolves food and kills micro organisms, however, there is another chemical in the stomach, a type of mucous which stops the stomach from breaking down it's own walls.
  • Although bile is made in the liver, it is stored in the gallbladder and acts in the small intestine. There are two main functions of bile the first is to emulsify fats, which basically means break them down into tiny little fat droplets, which in turn detoxifies the body. Bile also contains a base which is needed to help neutralise stomach acid.
Diet
Maintaining a balanced diet can really aid in your overall wellbeing, by ensuring you eat nutrient-rich food you are looking after your general health - Image by RitaE from Pixabay

Foods - Types, Functions, and Common Sources.

Food is how the human body sources its nutrition.  Before we look at food groups, I want to get a quick mention of the importance of water and regular consumption.

Keeping the body hydrated is extremely important as it helps maintain a regular body temperature and allows cells to function normally. There are many other benefits of keeping hydrated but most importantly when you feel hydrated you feel refreshed and less tired. Of course, many people don't like to drink plain water but that's okay because water is the main ingredient in most drinks it can also be found in certain vegetables such as cucumbers or fruits like melon.

There are huge amounts of food groups, especially when it comes to vitamins and minerals, but there are some essential food groups which we can just not been without. Below is a list of those food groups their functions and common sources:

  • Carbohydrates - this food group can actually be broken down into three main parts:
    • Glucose (sugars) - most people don't assume sugars are part of carbohydrates however they are a fast supply of energy to the body and can be found in foods such as fruits, natural sweeteners such as honey and sugar but can also be found in a lot of processed sweets such as pastries and candy.
    • Starch - this carbohydrate provides the body with a much slower release of energy, meaning you can eat a small amount of it and it releases are gradually dread the day whereas with glucose the energy provided a short amount of time. Natural foods which are a source of data include potatoes and rice, man-made foods that are good sources include bread and pasta.
    • Fibre (older generations used to call this roughage) - prevent the body from getting constipated, it helps to push through waste and can be found in foods such as brown bread, whole-grain cereals and vegetables.
  • Proteins - protein is really important especially when it comes to developing muscles and enzymes but also keeping your nails and hair healthy. Foods that are a good source of protein include meets particularly red meat and chicken (of course this does not include skin or fat) fish, egg whites and different types of beans are also really good sources of protein.
  • Vitamins -  are they already mentioned there are a huge amount of vitamins, each with their own benefit however we are going to focus on two, the ones that support the immune system:
    • Vitamin C - helps promote the bodies natural regeneration and repair to tissue. It also protects against diseases such as gout and scurvy. Vitamin C can be found in fruit such as oranges, lemons, limes, strawberries and blackcurrants can also be found in vegetables such as peppers and broccoli.
    • Vitamin D - this vitamin is really important when it comes to maintaining well in me and function and when it comes to protecting your bones (prevents against rickets), muscles and the health of your heart. Foods that are good sources of vitamin D include mushrooms, red meats (liver, steak etc...), egg yolks, butter and oily fish (salmon, mackerel, tinned tuna and sardines).
  • Minerals -  again there is a huge range of minerals available, but we are going to focus on two of the main minerals we need to survive:
    • Iron - this mineral is needed by the body to promote growth and development. The body uses iron to make haemoglobin which is a protein in red blood cells that carries oxygen from the lungs to other parts of the body it also promotes myoglobin which is the protein that carries oxygen to the muscles Iron even helps the body to make some hormones. Some foods which are an excellent source of iron include: red meats (liver steak etc..), different kinds of beans, green vegetables (broccoli, spinach, cabbage, kale etc..)
    • Calcium - Your body needs calcium to build and maintain strong bones. Your heart, muscles and nerves also need calcium to function properly. Some foods which are an excellent source of calcium include: Cheese (most cheeses are excellent sources of calcium. Parmesan cheese has the most),  green vegetables (dark leafy greens like spinach, kale and cabbage)
  • Fats - Fat not only supplies the body with energy but also helps insulate the body, which helps regulate the body's temperature. Foods that are a source of good fats include Cheeses, Dark Chocolate, Eggs, Nuts and Seeds as well as Olive oil and oily fish.
digestion
Some foods contain nutrients from multiple food groups like how red meat is a source of iron, protein and vitamin D -  Image by free stock photos from www.picjumbo.com from Pixabay

For more information on other topics for Junior Cycle Biology such as human reproduction, evolution, ecology and genetics, make sure to check out the other articles in this series!

If you want to test your knowledge on the digestive system why not give the following google quiz a try.

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Maureen

Hey, I'm Maur/Mo, I'm a writer from Ireland. I've written a novel and a lot of poetry and fiction. Currently, I work as a content writer at superprof