The Digestive System Nelli Astvatsatrian and Mia Stearn Period 5 AP Biology.
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Transcript of The Digestive System Nelli Astvatsatrian and Mia Stearn Period 5 AP Biology.
What is it?
The digestive system is a series of organs whose purpose it is to convert food into nutrients that are absorbed into the body and eliminate waste.
Organs of the Digestive System
● Mouth
● Throat
● Esophagus
● Stomach
● Small Intestine
● Colon (Large Intestine)
● Rectum
● Anus
https://www.brainpop.com/games/buildabodydigestivesystem/
From the Mouth to the Stomach● The digestive system begins with the mouth where the food
enters: 32 teeth grind up the food, three salivary glands produce saliva to soften food while the tongue(a muscle) also helps food to be swallowed.
● An enzyme called amylase in saliva begins to break down carbohydrates.
● The pharynx, or the throat, connects the mouth to the esophagus.
● The esophagus is a muscular tube that connects the throat to the upper gastrointestinal tract of stomach.
● Peristalses are muscle contractions in the esophagus that push food to the stomach.
● The food ends up in the cardiac sphincter, which closes the end of the esophagus so that the food enters the stomach to be stored.
● Food is stored in the stomach for proper digestion with hydrochloric acid.
The Small Intestine● After the food has been properly digested in the
stomach, it enters the lower gastrointestinal tract through the pyloric sphincter beginning with the small intestine.
● Chyme = acidic digested food● Chyme mixes with bile and pancreatic juice to
neutralize its acidity. ● The duodenum connects the stomach to the
jejunum. ● The middle of the small intestine is the jejunum,
which absorbs some essential nutrients through intestinal mucosa.
● Chyme enters the 10-foot long ilium to enter the cecum of the large intestine.
The Large Intestine● The small intestine connects to the large intestine through the
ileocecal sphincter.● The large intestine absorbs nutrients, water, and vitamins. ● Releases nutrients to blood stream● It is “larger: because it is thicker in diameter than the small
intestine.● It goes from across the abdomen across the abdominal cavity.● It is made up of four layers: mucosa, which lubricates the
innermost part of the large intestine for protection, then a structural support system of nerves, tissue, and blood vessels called submucosa, surrounded by the muscularis that contracts the large intestine, and outermost is the thin protective lubricant layer of serosa.
● Beneficial bacteria builds up to mix with the chyme that is passing through the cecum.
● These bacteria also digest components of the chyme that could not be digested otherwise.
● This is a process of fermentation that releases vitamins.
The Large Intestine (cont.)● ascending colon - carries feces to the transverse
colon
● transverse colon - largest portion that connects ascending and descending colons
● descending colon - leads to sigmoid
● sigmoid colon - last segment that leads to rectum
● rectum - stores feces
● anus - ejects feces
MAINTAINING HOMEOSTASIS…
homeostasis = the ability of an organism to maintain stability amidst changes
How pH Balance Helps Maintain Homeostasis
● A balance of pH in the digestive system is crucial- both acidic and basic pHs are needed
● Saliva in the mouth is mildly acidic for breaking down food
● The small intestine have to have a high pH (basic) because the enzymes used in digestion cannot work in an acidic environment
● The stomach must be highly acidic to start the breakdown process and defend the body against harmful bacteria, etc.
How Bacteria Helps Maintain Homeostasis
● the average human digestive track has around 500 species of helpful bacteria
● helpful bacteria are mostly in the large intestine
● help digestion by producing vitamins, forming feces, and shielding against potentially harmful bacteria
● When the bacteria population in a digestive tract is thrown off or decimated, the host will notice a change in the pace and quality of digestion
● There are many products to help digestion by promoting intestinal microflora's growth
How the Liver helps Maintain Homeostasis
● food is broken down to nutrient molecules absorbed by villi in small intestine.
● digestive tract and pancreas produce digestive enzymes
● produces bile, which digests fats● breaks down toxic substances like alcohol
and other drugs● produces urea● stores glucose as glycogen after eating● releases glucose in between eating so that
the blood glucose concentration remains constant
● destroys old blood cells and breaks down hemoglobin
Diseases of the Digestive System
● Gastroesophageal Reflux Disease (GERD) –Severe
“heartburn” (chest pain) caused by reflux of stomach acid
into the esophagus
● Jaundice – Yellowing of the skin and whites of the eyes
from a backup of bile metabolic by-products from the
blood into body tissues
● Diverticulosis – Small pouches on walls of the large
intestine causing discomfort
● Cirrhosis – degenerative disease of the liver that
develops in alcoholics
Diseases of the Digestive System (continued) Celiac disease- immune system reacts to gluten,
damages lining of small intestine, difficult for body to absorb nutrients from food
Inflammatory bowel diseaseCrohn’s Disease – a chronic inflammatory disease of the intestine, symptoms of abdominal pain, weight loss, diarrhea
Ulcerative colitis- similar to Crohn’s disease, but it affects only the colon (large intestine).
Irritable bowel syndrome- affects large/small intestine, makes food move through the colon too slowly/ quickly and can lead to diarrhea or constipation
Work Cited
"Body Systems and Homeostasis." Mader. N.p., n.d. Web. 23 May 2015.
<http://www.mhhe.com/biosci/genbio/maderbiology/supp/homeo.html>.
"Digestive System Diseases - Des Moines University." Des Moines University Digestive System Diseases Comments. N.p., n.d. Web. 23 May
2015. https://www.dmu.edu/medterms/digestive-system/digestive-system-diseases/
"For Optimal Print Results, Please Use Internet Explorer, Chrome or Safari. Digestive System Disorders." Digestive System Disorders -
AboutKidsHealth. N.p., n.d. Web. 23 May 2015. http://www.aboutkidshealth.ca/En/ResourceCentres/Nutrition/Digestive-system-conditions-
and-special-diets/Pages/Digestive-system-disorders.aspx
Zimmermann, By Kim Ann. "Digestive System: Facts, Function & Diseases." LiveScience. TechMedia Network, 22 Apr. 2015. Web. 24 May
2015. http://www.livescience.com/22367-digestive-system.html
"Large Intestine." InnerBody. N.p., n.d. Web. 24 May 2015. http://www.innerbody.com/anatomy/digestive/large-intestine#full-
description
"Large Intestine." WebMD. WebMD, n.d. Web. 24 May 2015. http://www.webmd.com/digestive-disorders/large-intestine
"What Is the Transverse Colon?" WiseGEEK. N.p., n.d. Web. 24 May 2015. http://www.wisegeekhealth.com/what-is-the-transverse-
colon.htm
"Rectum." Anatomy, Diagram & Function. N.p., n.d. Web. 26 May 2015. http://www.healthline.com/human-body-maps/rectum
Hall, Christina, and Lauren Fritsky. WiseGeek. Conjecture, n.d. Web. 26 May 2015. http://www.wisegeek.com/what-is-the-relationship-
between-the-digestive-system-and-homeostasis.htm
Carson, Nacie. "How Does the Digestive System Maintain Homeostasis?" EHow. Demand Media, 28 Oct. 2008. Web. 26 May 2015.
<http://www.ehow.com/how-does_4565570_digestive-system-maintain-homeostasis.html>.