Digestion and Nutrition
Food, enzymes and digestive organs
What we will learn....
- Describe the organs of the human digestive system and explain their function
- Identify the constituents of a balanced diet and explain the function of various nutrients
- Explain where enzymes are produced, what they are and how they work
What does the digestive system do?
Ingestion - take food into the body (happens in the mouth)
Digestion - break the food up into tiny pieces
Egestion - remove the unwanted parts of the food from the body (happens at the Anus)
Human Cell
A real human cell
50-100 trillion cells!!
What are the organs of the digestive system?
But this is what is really looks like.....
The Main Nutrient Groups
Protein - growth and repair
Fat - protect the organs, store of energy, keep the body warm
Minerals - needed to keep everything healthy.For example IRON is needed to help red blood cells carry oxygen, and CALCIUM needed for healthy bones and teeth
Vitamins - needed to keep everything healthy. For example, vitamin A is needed for healthy eyesight, vitamin C is needed for healthy skin
Fibre - this is not digested but it is important as it cleans the intestines.
Healthy carbohydrates
Protein
Fats
Digestion
There are two types of digestion
- Mechanical - this is physically breaking food apart (think of teeth)
- Chemical - this is digestion using chemicals called enzymes
Mouth
Different shapes for different jobs
Incisors, canines and molars
Pre molars and molars are teeth at the back of the mouth which have a flat surface, this is to grind up food into small pieces.
Roots
Saliva also contains the enzyme AMYLASE which starts to break down starch (a really big carbohydrate).
The tongue shapes the food into a ball called a bolus so its easy to swallow.
Oesophagus
Does not produce enzymes, its job is take the bolus (ball of food) from the mouth to the stomach.
Contractions
Where is it?
What it REALLY looks like...
Stomach
Where is it?
Gastric juice
Protein
- Convert the food from a solid form into a liquid form. Every 20 seconds muscles in the stomach wall churn the food which helps to break it down.
- The stomach produces strong acid (hydrochloric acid) that kills most bacteria that is present in the food, this helps to prevent food poisoning.
- Pepsinogen (a protease enzyme) is made in the stomach that begins to digest protein.
After around 2-4 hours the food is squirted in small amounts into the first part of the small intestine.
Small intestine
The enzymes are not made by the small intestine, they are made by an organ called the pancreas.
The inside walls of the small intestine are covered in millions of microscopic structures called villi. When food has been digested it can be absorbed through the villi directly into the blood. Villi allow absorption to happen more quickly.
Absorption
Blood supply
Under the microscope...
What is an Enzyme?
They are used EVERYWHERE and all of the time, without them we could not survive because the normal chemical reactions in the body would not be quick enough.
Enzymes are used to digest the food we eat
Carbohydrase
Protease
Lipase
What happens AFTER digestion?
- SMALL INTESTINE
- ABSORPTION
- VILLI
make sure you know what they mean....
Large intestine
At this point there is still a lot of water in the food which needs to be reabsorbed back into the blood, this is the main job of the large intestine.
Fibre is important because it cleans the walls of the intestines and helps keep the digestive system working smoothly.
The right conditions
As temperature changes then enzymes begin to work slower until eventually they stop working completely.
This is why having a fever or being to cold is extremely dangerous, because it means your enzymes will stop working properly.
Which organs produce enzymes?
Stomach - contains a type of protease that begins the digestion of protein
Small intestine - this is the main organ for digestion. The pancreas produces all types of enzymes and squirts them into the small intestine.