Transcript The Digestive System and Nutrients

The Digestive System and Nutrients
Elli Kim, Vanessa Tam, Penny Ryu
Parts of the Digestive System
• Digestive tract organs
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Mouth
Pharynx
Esophagus
Stomach
Small intestine
Large intestine
Rectum
Anus
• Accessory organs
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Salivary glands
Liver
Gallbladder
Pancreas
Digestive Tract Organs
• Mouth – teeth chew food; tongue tastes and
pushes food for chewing and swallowing
• Pharynx – passageway where food is swallowed
• Esophagus – passageway where peristalsis pushes
food to stomach
• Stomach – secretes acid and digestive enzyme for
protein; churns, mixing food with secretions, and
sends chyme to small intestine
Pharynx
Digestive Tract Organs (Cont.)
• Small intestine – mixes
chyme with digestive
enzymes for final breakdown;
absorbs nutrient molecules
into body; secretes digestive
hormones into blood
• Large intestine – absorbs
water and salt to form feces
• Rectum – stores and
regulates elimination of feces
• Anus – you know what it is
Accessory Organs
• Salivary glands – secrete saliva; contains digestive
enzyme for carbohydrates
• Liver – major metabolic organ: processes and
stores nutrients; produces bile for emulsification of
fats
• Gallbladder – stores bile from liver; sends it to the
small intestine
• Pancreas – produces pancreatic juice: contains
digestive enzymes, and send it to the small
intestine; produces insulin and secretes it into the
blood after eating
When the food gets eaten…
The Process of Digestion
1. Mouth: breaks down food
① Teeth chew the food to break it down to smaller pieces
② Saliva is produced by the salivary glands
• Saliva contains an enzyme (salivary amylase) that begins
to digest the starch from food into smaller molecules
2. Pharynx: throat swallows food (voluntary)
3. Esophagus: squeezes the food down (involuntary)
① Layer of muscle enables walls to move
② Propels food and liquid through the system
③ Mix the contents
 Compare with squeezing mentos
④ Arrives at the Lower Esophageal Sphincter
The Process of Digestion
Lower Esophageal Sphincter: ring-like organ that closes the passage
between two organs
 As food approaches the sphincter, it relaxes so that the food can pass
through
Peristalsis: food moves from one organ to the next
4.Stomach: excretes stomach acid to break food down
 Thick mucus layer (pepsinogen): protects the interior stomach walls to
prevent stomach acid from dissolving stomach tissues (or else: peptic ulcer)
①Produces stomach acid (gastric juice: digestive enzymes + HCl; regulated
by gastrin) and a protein-digestive enzyme
②Stores food and liquid: upper stomach muscles relaxes and absorbs food
③Lower stomach mixes: mixes food, liquid, and digestive juice made by the
stomach to make chyme
④Push materials into small intestines through the pyloric sphincter
The Process of Digestion
5. Small Intestines: digest and absorb
① Duodenum: (1st 25 cm) digests starch (pancreatic amylase),
protein (proteolytic), fat (lipase) , nucleotides (phosphatases),
disaccharides (maltase, lactase)
- Mix digestive juice produced by:
• Pancreas: enzymes that break down carbohydrates, fats, and
proteins (trypsin, chymotrypsin, lipase, pancreatic amylase);
stimulated by secretin (produced by duodenim)
• Liver: bile (squeezed out from the gallbladder through bile ducts)
dissolves fat into liquid; stimulated by cholecystokinin (produced
by small intestines)
• Interior glands of the small intestines
② Jejunum (first part), Ileum (second part)
• Villi and Microvilli: large surface area allows better absorption
into capillaries
The Process of Digestion
6. Large Intestines (colon): absorbs water and
produce feces
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②
③
④
⑤
Cecum: appendix is attached at the end (tail-like)
Ascending colon: food going
Trasverse Colon: food is going horizontal
Descending colon: food going down
Sigmoid Colong
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Concentrates waste materials
Pushes the waste through rectum to anus
7. Anus: waste is excreted
Problem with the Stomach and the Intestine
Diarrhea:
contents of the intestines move too fast  isn't
enough time for water to be absorbed before the
feces are pushed out of the body
Constipation:
contents of the large intestines do not move along
fast enough  waste materials stay in the large
intestine so long  too much water is removed
and the feces become hard.
Nutrients
Protein-------amino acids
Starch------simple sugars
Fats------fatty acids & glycerol
Vitamins
Minerals
Proteins
Ex./ meat, eggs, beans
enzymes from the pancreatic juice and the lining of the
intestine carry out the breakdown of big molecules into small
molecules
absorbed from hollow of the small intestines into the blood
and into the rest of the body
Carbohydrates
-Ex./ bread, potatoes, pastries, rice, fruits, table sugar
(many of these contain both starch & fiber)
Digestible carbohydrates are broken down by enzymes in the saliva
Starch is digested in 2 steps…
1) enzyme in the saliva & pancreatic juice breaks the starch into
maltose then maltase splits the maltose into glucose molecules
2) glucose is carried to the liver
Fats
dissolved into watery content of the intestinal cavity
bile acids (produced by liver) are natural detergents to dissolve fat into
water, allowing the enzymes to break large fat molecules into smaller
molecules (fatty acids & cholesterol)
bile acids help fatty acids and cholesterol to move into mucosa
In mucosa, small molecules are formed back into big molecules 
theses molecules pass into lymphatic vessels near the intestine  these
vessels carry these fats to the veins blood carries these to different
parts of the body