AS Digestion

General information on human digestion

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DIGESTION
What is digestion?
Digestion is the process by which food is converted into substances
that can be absorbed and assimilated by the body.
This is accomplished by the mechanical and enzymatic breakdown of foods into
simpler chemical compounds.
The Stages of Digestion...
· Ingestion- taking large pieces of food into the body
· Digestion- breaking down the food by chemical and mechanical means
· Absorption- taking the soluble products of digestion to the body's cells
· Assimilation- the use of the absorbed nutrients
· Egestion- the removal of undigested material
*Excretion is the removal of substances from within body cells
The Alimentary Canal...
The alimentary canal is a long tube that runs from the mouth to the anus
· Mucosa- absorbs
the digested food
· Submucosa- loose
and elastic layer
that contains large blood vessels, nerves, glands and lymphatic tissues.
· Muscle Layer- made up of smooth muscles that allow the process of
peristalsis to occur
· Sucosa- layer of connective tissue that holds the gut together and attaches
it to the abdomen
Peristalsis

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Peristalsis is the process of wave like muscle contractions in the alimentary tract
that move food along
The Mouth
· Teeth- the chewing motion of the teeth breaks down the food (this
increase surface area) and forms a bolus/ ball.…read more

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The Small Intestine
The small intestine is 6.5 metres long and is divided into three sections...
the duodenum, the jejunum and the ileum.
The duodenum most of the digestion takes place here.
Pancreatic juice is secreted by the pancreas through the pancreatic duct. It contains
carbohydrase, protease and lipase enzymes to break down the chyme (food)
further.
Bile is secreted by the liver, stored in the gall bladder and released through the bile
duct.…read more

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