Download bio intestine paper

DONE BY SEAN PERSAUD AND SKY POUCHET
THE ALIMENTARY CANAL STRUCTURE +
FUNCTION
notes:
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alimentary cannal-long tube which runs from the mouth to the anus
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in certain places special muscles called SPHINCTER MUSCLES can close the
tubes in the alimentary canal e.g at the base of the stomach to prevent food from
entering the small intestine before it has been digested.
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the alimentary canal contains muscles which contract and relax to make food
move along.This movement is called peristalsis
1.
food enters the bouth where it is broken up my the
tongue,teeth and lips to create a larger surface area
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it is formed into a ball (bolus) by mixing it with mucus and the enzyme AMYLASE
(which breaks down starch to maltose).
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the bolus of food is taken down to the stomach via the oesophagus. a small
piece of cartilage called the EPIGLOTTIS covers the path to the lungs so that food does
not go down the wrong tube
2.
the stomach stores food and digests proteins
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it mixes the food with enzyme pepsin , rennin and hydrochloric acid which are
released in bits in the stomach walls (gastric pits).
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pepsin is a protease(break down proteins into polypeptides) it works best in
acidic condition hence HCL is secreated in the stomach.
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rennin is only produced in baby mammals to clot milk in order to form proteins
that the pepsin can digest.
after one or two hours the sphincter at the bottom of the stomach opens, allowing the
chyme to ender the small intestine
3.
the smalll intestine consists of the duodenum, the
jejunum
and the
ileum.
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pancreatic juice flows into the duodenum via the pancreatic duct
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pancreatic juice consists of the enzyme one is amylase, trypepsin (protease) and
lipase (which breaks down lipids/fats to fatty acids and glycerol)
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these do not work well in acidic environment so the pancreatic juice contains
sodium hydrogencarbonate which partially neutralises the acid.
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bile is made in the liver and stored in the gall bladder, it enters the duodenum
via the bile duct.
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bile contains no enzymes but helps to digest fats by breaking up the large fat
drops into smaller ones (emulsification). this is done by salts in the bile called bile salts.
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bile contains yellowish bile pigments made in the liver which are not needed and
are excreted in faeces.
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the small intestine is covered with millions of villi!!! each about 1mm long
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cells covering the villi make enzymes which stay close to the cell.
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Maltase + maltose= glucose
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sucrase + sucrose=glucose + fructose
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Lactase + lactose= glucose + galactose
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these broken up molecules of amino acids, simple sugars and fatty acids and
glycerol are now small enough to pass throgh the wall of the small intestine into the
bloood. this is called ABSORPTION.
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water mineral saltas and vitamins are also absorbed in the small intestine.
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The nutrients are taked by the hepatic portal vein to the
liver.
ON MY WAY TO THE ANUS
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undigested food travels travels out of the small intestine, through the caceum
past the appendix and into the colon.
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caecum and appendix have no function.
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in the colon (large intestine) more water and mineral salts are abosorbed.
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the rectim stores undigested food,(roughage bacteria and some dead cells from
the inside of the alimentary canal). this is called faeces.
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this faeces passes out through the anus in a process called egestion.
You can learn more about the alimentary canal by watchin this vedeo :)
https://www.youtube.com/watch?v=VSPdLCwfMu8
QUESTIONS!
1) The movement of muscles that move food down the alimentary canal?
2) What substances are secreted in the stomach of a baby mammal?
3) why does the stomach secrete hydrochloric acid?
4) Name in order the different sections of the small intestines?
5) What fluid enters the duodenum?
6) What substances are contained in this fluid?
7) What is the function of bile?
8) Where is the absorbed nutrients taken?
9) What is the name of the muscle that closes off sections of the alimentary canal to give
time for digestion e.g in the stomach?
10) What is the imprtance of villi in the alimentary canal?
HOPE EVERYONE FINDS THIS USEFULL :D