Small and Large Do Now On the same side as last week in whichever box you left blank probably Monday List the 4 sphincters of the digestive system in order from first to last Most Digestion Occurs in the Small Intestine ID: 486205
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Slide1
Intestines
Small and LargeSlide2
Do Now
On the same side as last week, in whichever box you left blank (probably Monday):
List
the 4 sphincters of the digestive system in order from first to last.Slide3
Most Digestion Occurs in the Small Intestine
The small intestine consists of three segments:
Duodenum
: 10 in long
Jejunum
: 8 ft longIleum: 12 ft longMechanical and chemical digestion take place in the small intestine.The surface of the small intestine is lined with villi, which help maximize absorption.Microvilli: villi on the villiThe contact time in the small intestine is 3–10 hours, depending on the food eaten.
© 2014 Pearson Education, Inc.Slide4
© 2012 John Wiley & Sons, Inc. All rights reserved.
Small intestinesSlide5
Small intestine secretions
Pancreas
secretes
pancreatic juice
containing:
Bicarbonate neutralizes stomach acidPancreatic amylase: carbohydrates into sugarsPancreatic proteases: proteins into amino acidsPancreatic lipases: fats into fatty acidsLiver secretes bile which emulsifies fat (breaks up droplets) so lipases can access moleculesGall bladder stores
bile
© 2012 John Wiley & Sons, Inc. All rights reserved.
Slide6
How Are Digested Nutrients Absorbed?
Majority of absorption takes place in the
small
intestine
Nutrients are absorbed via…
Passive diffusion: Nutrients move from high concentration to low concentration; no energy is required.Facilitated diffusion: Nutrients move from high concentration to low concentration with the help of a carrier protein; no energy is required.Active transport: Nutrients move from low concentration to high concentration with the help of a carrier protein; energy is required.Endocytosis: Cell forms a vesicle to surround and engulf a nutrient.
© 2014 Pearson Education, Inc.Slide7
© 2014 Pearson Education, Inc.
Four Methods of Nutrient Absorption in the Small IntestineSlide8
© 2014 Pearson Education, Inc.
The Large Intestine Absorbs Water and Some Nutrients
Chyme
enters the large intestine through the
ileocecal
valve.Large intestine has three segments:Cecum
Colon
RectumSlide9Slide10
© 2014 Pearson Education, Inc.
Anatomy of the Large IntestineSlide11
Fluid Absorption Occurs in the Large Intestine
The majority of nutrients have been absorbed when
chyme
enters the large intestine.
Water and salt
are absorbed in the large intestine.The same mechanisms used in the small intestine are also used in the large intestine.Water — passive diffusionSodium — active transport
© 2014 Pearson Education, Inc.Slide12
The Large Intestine Absorbs Water and Some Nutrients (cont'd)
Bacteria
in the colon
ferment
some undigested and unabsorbed carbohydrates into simpler compounds,
methane gas, carbon dioxide, and hydrogen.Fermented fiber produces short-chain fatty acids.In the large intestine, 1 liter of fluid material is gradually reduced to 200 grams of brown fecal material.The intestinal matter passes through the large intestine in 12–70 hours, depending on the person's health, age, diet, and fiber intake.
© 2014 Pearson Education, Inc.Slide13
The Large Intestine Absorbs Water and Some Nutrients (cont'd)
Stool is propelled through the large intestine until it reaches the rectum, the 8-inch portion of the large intestine.
The
anal sphincter
is the opening of the rectum, or end of the GI tract.
The final stage of defecation is under voluntary control. It is also influenced by age, diet, prescription medications, health, and abdominal muscle tone.
© 2014 Pearson Education, Inc.Slide14
© 2014 Pearson Education, Inc.
Peristalsis and SegmentationSlide15Slide16
© 2014 Pearson Education, Inc.
Disorders of the Intestines
Flatulence
:
Intestinal gas, which needs to be released 10 to 20 times a day
Caused by: Foods high in fiber and starchEating quicklyDrinking carbonated beverages
Lack of exercise
SmokingSlide17
© 2014 Pearson Education, Inc.
Disorders of the Intestines (cont'd)
Diarrhea
:
The passage of watery, loose stools
more than three times a day Generally the result of bacterial, viral, or parasitic infections that cause food and fluids to
pass too quickly
through the colon
Chronic diarrhea may be the sign of a more serious problem.
Untreated diarrhea can lead to malnutrition.Diarrhea can lead to dehydration and potentially death, particularly in children and the elderly.Treated with fluid and electrolyte replacementSlide18
© 2014 Pearson Education, Inc.
Disorders of the Intestines (cont'd)
Constipation
:
Infrequent passage of dry, hardened stools
Often due to insufficient fiber or water intake Exercise, normal eating patterns, and proper rest can help resolve constipation.Laxatives should be used sparingly, as they can cause dehydration, salt imbalances, and laxative dependency.
Colon cleansing (enema) is not recommended as a treatment.Slide19
© 2014 Pearson Education, Inc.
Disorders of the Intestines (cont'd)
Hemorrhoids
:
Swelling of the veins of the rectum and anus
Can lead to bleeding, itching, and/or pain The cause is unknown. Contributing factors include straining to pass dry stools, pregnancy, constant constipation or diarrhea, and aging.
Treatment includes increased dietary fiber and fluid intake.
Some symptoms (itching and pain) can be relieved through use of creams, ice packs, and soaking in a warm bath.
Severe cases may require surgery.Slide20
© 2014 Pearson Education, Inc.
More Serious Intestinal Disorders
Irritable bowel syndrome (IBS)
:
Changes in colon rhythm
Those with IBS experience an overresponse to colon stimuli, resulting in alternating patterns of diarrhea, constipation, and abdominal pain.The exact cause is not known.Treatment includes increased dietary fiber, stress management, and prescription drugs.Slide21
© 2014 Pearson Education, Inc.
More Serious Intestinal Disorders (cont'd)
Ulcerative colitis
:
A chronic inflammation of the large intestine, resulting in ulcers in the lining of the colon
Tends to run in families Afflicts both men and women, beginning between the ages of 15 and 30There is no known cause or cure.
Treatment includes drug therapy and surgery.Slide22
© 2014 Pearson Education, Inc.
More Serious Intestinal Disorders (cont'd)
Colon cancer
The third-leading cause of cancer death
One of the most curable cancers if detected early
It begins with polyps on the lining of the colon that are often small, benign, and can be surgically removed.Polyps can develop into cancerous tumors if not detected early.Treatment includes radiation, chemotherapy, or surgery.
Survival rates vary depending on age, treatment response, and stage of cancer diagnosis.Slide23
© 2014 Pearson Education, Inc.
More Serious Intestinal Disorders (cont'd)
Crohn's disease
Similar to ulcerative colitis, but ulcers can occur throughout the GI tract
There is no known cause or cure.
Treatment includes drug therapy and possibly surgery.Celiac disease
A genetic disorder that causes damage to the small intestine when foods containing gluten are consumedSlide24
DOL-Answer on the empty day from last week (should be Monday)
Food
is moved through the GI tract by rhythmic muscular waves
called
segmentation
peristalsisbowel movementMasticationWhich of the following is true regarding the small intestine?it is shorter than the large intestineit is the major organ for digestion and absorptionit has access to the lymph tissue but not to the bloodstreamit is composed of the ileum, duodenum, and jejunum, in that order.What kind of digestion occurs in the small and large intestine?MechanicalChemicalMechanical and ChemicalNo digestion occurs