structure and function of the digestive system and nutrients

AS and A Level Physical Education (Sport & Coaching)

Macronutrients

Carbohydrates

Carbohydrates have three main purposes:

To provide the body with energy
To allow the body to store and transport energy
To aid in bodily needs e.g. immune system, fertilization, pathogenesis,

blood clotting, and development.

The structure of carbohydrates consist of three elements, these are carbon, hydrogen and Oxygen.

Carbohydrates can be broken down into two groups these are simple carbohydrates and complex carbohydrates.

Simple Carbohydrates are also known as simple sugars and these include substances such as Sucrose (a combination of Glucose and Fructose). Other examples may include Lactose (a combination of Glucose and Galactose). Simple sugars may also be broken down into the amount of bonds they have; monosaccharide’s consist of just one sugar, disaccharide consist of two sugars combined, and finally polysaccharides’ consist of many sugars, usually three or more. These carbohydrates all gain quick access to bloodstream providing a slow, prolonged release of energy.

Complex Carbohydrates come from starch and they are polymers made up of many monosaccharide’s’ joined together by glycosidic bonds. They are therefore very large, often branched, macromolecules. They tend to be solid, insoluble in water, and have no sweet taste. They go through the digestive system where they are broken down and transported to places in need of energy- it gives a steady release of energy over a prolonged period of time.

There are many common sources of carbohydrates, some of the sources for simple carbohydrates are:

Sweets
Cakes
Chocolate
Biscuits
Jam

Here are some examples of complex carbohydrates

Potatoes
Pasta
Spaghetti
Fruit
Whole Grain cereals e.g. Weetabix

Fats

Fats have three main purposes, these are:

To provide the body with warmth
To help in biological functions such as energy storage
To provide vitamins A, D, E, K

There are several different types of fats with different structure:

Monounsaturated – these do not raise blood cholesterol and encourages heart health
Polyunsaturated Fats - lowers blood cholesterol and encourages heart health
Omega-3 fats are a type of polyunsaturated fat found mainly in oily fish
Saturated Fats - raise blood cholesterol and promote heart disease
Trans Fats are the other type of fat that can raise your cholesterol level just like saturated fats