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8/13/2019 Biology Digestive System 1 Structures and Function
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It More Than Just a Gut Feeling
The Digestive System
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TAKS Objective 2The student will
demonstrate an understanding of
living systems and theenvironment.
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Explain What are the two main types of
digestion?
Physical/Mechanical: The physical
breakdown of food by non-enzyme
means.
Chemical: The use of enzymes tobreakdown food.
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List in Order the Pathways of Food
Through the Digestive System. The Mouth
Pharynx
Esophagus
Stomach
Small Intestine
Large Intestine Rectum
Anus
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Oral Cavity
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Oral Cavity (Mouth) What type of digestion occurs in the mouth? Both physical and chemical digestion takes place Tonguetaste
manipulates foodprepares food for swallowing by forminginto a ball (bolus)
Salivais secreted Moistens Protects mouth from abrasion Buffer against acids Kills some bacteria
What enzyme is secreted in saliva?
Salivary AmylaseEnzyme that begins digestion of carbohydrates
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Pharynx
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Pharynx Commonly call the throat
Intersection of GLOTTISand openingof the esophagus (gullet) is found here
EPIGLOTTISis a flap that closes theglottis when the act of swallowing
occurs (Closes the Trachea)
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Esophagus
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Stomach
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Stomach J Shaped organ that Stores and digests food.
GASTRIC JUICES - pH of 1-2
Enzyme: pepsin which acts on proteins.
HCl is needed to activate pepsin from its inactiveform pepsinogen.
GastrinHoromonesecreted to regulate gastricjuices.
Mucus covers the inner lining to prevent the acidfrom eating the tissue.
The PYLORIC SPHINCTER or pylorus connects thestomach to the small intestine and closes off thestomach at its posterior end.
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Small Intestine
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Small Intestine Most breaking down of macromolecules
occurs here.
6 meters in length Smaller diameter than the large intestine
Divided into 3 sections: Duodenum (first 25 cm) Jejunum
Ileum
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Digestion in Small Intestine Acid chyme enters duodenum
Intestinal wall releases a hormone
SECRETIN-signal pancreas to release a basicsolution to neutralize the acid.
CHOLECYSTOKININ (CCK)- released tosignal the gall bladder to release bile and the
pancreas to release digestive enzymes ENTEROGESTRONE-secreted to slow down
peristalsis
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Absorption and Distribution ofNutrients
VILLIsmall finger-like projections thatincrease the surface area
MICROVILLI
even smaller finger-likeprojections on the VILLI
LACTEALlarge lymph vessel found oneach villus (Absorbs FAT)
Capillariessmall blood vessels found oneach villus (Absorbs all nutrients EXCEPT Fat)
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Villi and Microvilli
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Accessory Organs
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Small Intestine AccessoryOrgans
Pancreas, Liver, and Gall Bladder
Add digestive enzymes, juices, and
hormones to the small intestine
These chemicals help break downprotein, fat and carbohydrates
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Liver, Pancreas, and GallBladder
Liver produces bile which is needed to helpdigest fat.
Gall bladder stores the bile.
Pancreas (Endocrine and Exocrine function)produces enzymes need to finish digesting the
main organic foods. It also produces insulin.
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Pancreas and Gall Bladder
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LIVER
Regulates the contents of the blood.
All blood contents enter the Liver via the
HEPATIC PORTAL VEIN.
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Large Intestine Alone
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Large Intestine (Colon)
Main function of the COLONis to reabsorb waterfrom the small intestinal material.
CECUM
T junction that connects the colon tothe small intestine
APPENDIXattached at the end of the cecum.
Stores solid waste in the area called the rectum. Bacteria (E. coli) live in this area of the body.
Produce odor, and Vitamin K
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Large Intestine w/Small