Transcript Digestive System - local

Digestive System
Yixuan He
Function
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Break up food into smaller pieces.
Transporting food to the GI tract (gastrointestinal)
Secreting digestive enzymes
Absorbing nutrients into the blood
Excreting solid waste products (waste)
Mouth
• The mouth is the beginning of the digestive tract
• Chewing breaks the food into small pieces
• Easily digested
Pharynx and Esophagus
• Pharynx
• The throat
• Receives the food from your mouth.
• Swallowing
• A voluntary reflex
• Esophagus
• Connects mouth to stomach
• A muscular tube extending from the pharynx and behind the
trachea to the stomach
• Food is pushed through the esophagus and into the stomach by
means of a series of contractions called peristalsis.
Stomach
• Storage bag for food
• Secretes acid and powerful enzymes that bread down the food
and change it to a consistency of liquid or paste.
• Flexible
• Expands when you eat
• Can hold up to 3 L of food
• If the stomach could not store food, you would have to eat
every twenty minutes or so instead of just three times a day.
Small Intestine
• folded into tiny fingerlike projections called villi
• Each villus contains blood vessels.
• surface area through which nutrients pass to the bloodstream is
greatly increased
• If the villi on the inner lining of the small intestine are flattened
out, they would cover about 4500 square meters.
• Where most of the nutrient is absorbed through the walls and
into the bloodstream
• Breaks down food
• Duodenum, Jejunum, and Ileum
• Duodenum is largely responsible for the continuing breakdown
process
• Jejunum and ileum being mainly responsible for absorption of
nutrients into the bloodstream.
Large Intestine (colon)
• five- to seven -foot -long muscular tube that connects the
small intestine to the rectum
• absorb water from the undigested food, hold the undigested
food for a while and then excrete it as feces.
• Consists of:
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cecum
ascending colon
transverse colon
descending colon
sigmoid colon
Rectum and Anus
• Rectum
• receives stool from the colon
• stores some feces and help with defecation
• Anus
• dispose of waste products out of the body
Accessory organs
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Salivary Glands
Liver
Pancreas
Gallbladder
Sphincters
Salivary Glands
• Saliva mixes with food to begin the process of breaking it
down.
• Fun fact: The smell of food triggers the salivary glands in your
mouth to secrete saliva, causing your mouth to water. When
you actually taste the food, saliva increases.
Liver and Pancreas
• Liver
• The largest organ inside the body
• It produces bile, a substance that helps in the digestion of fats.
• Process the blood coming from the small intestine.
• Purifies this blood of many impurities before traveling to the rest of
the body.
• Pancreas
• Produce pancreatic juice
• Pancreatic juice helps in neutralizing or weakening the acid in food
inside the stomach.
• Also contains different enzymes that are needed to further break
down starch, proteins and fats in the small intestine.
Gallbladder and Sphincters
• Gallbladder
• Small muscular sac
• Storage sac for excess bile.
• Sphincters
• Lower Esophagus Sphincter
• Located Just before the opening to the stomach
• Ring-shaped muscle
• This sphincter opens to let food pass into the stomach and closes to
keep it there.
• If your LES doesn't work properly, you may suffer from a condition
called GERD which causes heartburn and regurgitation
• anal sphincters (inner and exterior)
• control the exit of feces from the body
Physical digestion vs. Chemical
digestion
• Physical
• is the breakdown of food by physical means.
• Chemical
• molecules of water, vitamins, and minerals are small enough to
be absorbed through the intestinal wall and into the blood
stream
• proteins, carbohydrates, and fat molecules are too large and must
be broken down further by chemical means. This is chemical
digestion.
Physical digestion vs. Chemical
digestion
Chemical
Physical
• breakdown of food by
physical means
• Chewing and churning
• Digest food
and aid in
absorbing
nutrients.
• breakdown of food by
chemical means
• Acids and enzymes
Nutrients
• Carbohydrates:
• Saliva begins carbohydrate digestion with the enzyme salivary
amylase.
• The release of Pancreatic Amylase in the duodenum digests the
rest
• Protein
• Begins in the stomach with HCl and Pepsin.
• Inside the small intestine, the pancreatic enzymes trypsin and
chymotrypsin break down the polypeptides.
• Lipid
• The fat digesting enzyme lingual lipase starts breaking down fat
inside your mouth as you are chewing.
• Bile released from the gall bladder
Crohn’s Disease
• a chronic inflammatory condition of the gastrointestinal (GI)
tract.
• Symptoms:
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abdominal pain
diarrhea
weight loss
poor appetite
• Crohn’s disease may affect as many as 700,000 Americans.
• Crohn's is more prevalent among adolescents and young adults
between the ages of 15 and 35.
• Treatment:
• Medication
• Surgery
Irritable Bowel Syndrome
(IBS)
• Irritable bowel syndrome is a functional gastrointestinal (GI)
disorder, meaning it is a problem caused by changes in how
the GI tract works.
• Symptoms
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Diarrhea
Constipation
Passing mucus
Abdominal bloating
• Affects 3 to 20 percent of the population
• Treatment:
• Changes in eating, diet, and nutrition
• Medication
• Probiotics
Bibliography
• National Digestive Diseases Information Clearinghouse
(Division of NIDDK/NIH). American Medical Association.
• The Cleveland Clinic Foundation
• http://my.clevelandclinic.org/anatomy/digestive_system/hic_the
_structure_and_function_of_the_digestive_system.aspx
• Crohn's and Colitis Foundation of America
• National Digestive Diseases Information Clearinghouse
• http://digestive.niddk.nih.gov/ddiseases/pubs/ibs/
Bibliography (Cont.)
• Pictures:
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