Digestive system

food is essentialfor life= energy for activities=enables children to grow= repairs partof body as they wear out=fights diseas =provides insulation

protein

- found in meat fish and eggs

-needed in large amounts= body to grow and repair

- building blocks of the body

carbohydrates

- starches and sugars which provide energy and warmth

fats

- these keep you warm- but needed in smaller amounts

fibre

- found in fruits vegetables- mosy no digested= keeps digestine tract moving

Mineral salts

- in most foods of balanced diet- ensure body cells working properly- keep you healthy

water

- essential to keep the body cleansed and well hydrated

7 essential nutrients in a balanced diet

- protein

-carbohydrates

-fats

-fibre

-vitamins

-mineral salts

-water

-before food can do any jobs- changed into a form that the body can use

-task carried out by digestive system=also known as alimentary canal= a lon tube about 6m long

-alimantary canal= runs from mouth to anus

- as food moves along- broken down into smaller and simpler peices

- food absorbed by blood stream-used by body

- food not required becomes waste and is exspelled by the body

SIX MAIN PART INVOLVED IN DIGESTION

- mouth

- oesophagus

- stomach

- duodenum

- small intestine

- large intestine

mouth=

-large cavern bounded by the cheecks and lips, containing the tongue, teeth and salivary glands= essential in first part of digestion= breaking food into smaller digestable parts( teeth+tongue), moisten ( saliva) also allowing us to taste our food (only possible if taste buds coated with moistened substance

-once food soft and small enough to swallow= bolus= passes down the throat and into oesophagus

oesophagus

- swallowing = voluntary act

- once bolus reaches oesophagus= passes on by wave like  contractions called peristalsis = involuntary actnot governed by gravity- why you can eat/ drink upside down

- inside of oesophagus= covered in mucus lining- secrets mucus to ease the passage of the bolus 

stomach

- mucular bag situated on upper part of the abdomen

- when empty- volum=60ml

- full= stretch and hold 2 litres food

- at first just reservoir= but then stomach lining produces enzymes including hydrochloric acid- break down food to form pulp like soup= chyme

- can stay in stomach for up to 4 hours- some fatty foods stay longer

- once ready passed on- the pyloric sphincter relaxes=food passes into duodenum=first part of small intestines

duodenum

- partially digested, liquified food reaching duodenum contains much hydrochloric acid

- in duodenum= this acidity  is neutralised by an alkaline secretion  of the duodenum  itself

- by actions of bile- break dow fat -and pancreatic juice  which pour  which pour pour in from gall bladder and pancreas

small intestine

- rest of small intestine is where  the useful nutritional elements of food  are absorbed - leaving mainly water and food waste behind

- the absorption is done by many thousands of finger-like projections called villi

-villi= well supplied with capillaries which lead to veins

- the veins whick "collect" food do not go directly to heart  but via liver processing before it goes to rest of the body

large intestine

- 24 hours after being eaten  all that remains od meal is food that cannot be digested such as plant fibres or roughage and dead cells and certain amount of water

- in large intestine water is absorbed back into bloodstream and rest of matter passed out body

Liver

The liver lies under the diaphragm and near the stomach. It is the largest organ inside the body and one of the most important. Among the functions of the liver that are related to digestion are the following.

- It produces bile, a substance that helps in the digestion of fats.

Gall bladder

The gall bladder is a small muscular sac that is attached beneath the liver. Bile produced by the liver passes through a small tube and is stored in the gall bladder. From the gall bladder, bile is released to the small intestine digestion.

Pancreas

The pancreas is an organ that lies behind the stomach. Its function related to digestion is to produce pancreatic juice. Pancreatic juice helps in neutralizing or weakening the acid in food inside the stomach before it moves onto the small intestine. Pancreatic juice also contains different enzymes that are needed to further break down starch, proteins and fats in the small intestine.

APPENDIX

-no one really knows what appendix is for

- small wormed shape organ which lies where your small and large intestines meet