Digestive System Ch. 14. Digestive System The digestive system has a simple job, gather nutrients....

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Digestive System Digestive System Ch. 14 Ch. 14

description

Gastrointestinal Tract A twisty, hollow tube that runs continuously from the mouth to the anus. A twisty, hollow tube that runs continuously from the mouth to the anus. It is divided into sections, each with a specific purpose. It is divided into sections, each with a specific purpose. Includes: Mouth, pharynx, esophagus, stomach, sm. Intestine, and lg. Intestine. Includes: Mouth, pharynx, esophagus, stomach, sm. Intestine, and lg. Intestine. The terminal opening is the anus. The terminal opening is the anus.

Transcript of Digestive System Ch. 14. Digestive System The digestive system has a simple job, gather nutrients....

Page 1: Digestive System Ch. 14. Digestive System The digestive system has a simple job, gather nutrients. The digestive system has a simple job, gather nutrients.

Digestive SystemDigestive SystemCh. 14Ch. 14

Page 2: Digestive System Ch. 14. Digestive System The digestive system has a simple job, gather nutrients. The digestive system has a simple job, gather nutrients.

Digestive SystemDigestive System The digestive system has a simple The digestive system has a simple

job, gather nutrients. job, gather nutrients. There are two divisions: There are two divisions:

Alimentary – Ingests, digests, absorbs, Alimentary – Ingests, digests, absorbs, defecates (stomach, intestine, etc) aka defecates (stomach, intestine, etc) aka gastrointestinal tractgastrointestinal tract

Accessory – helps the alimentary organs Accessory – helps the alimentary organs complete their goal. (teeth, pancreas, complete their goal. (teeth, pancreas, etc)etc)

Page 3: Digestive System Ch. 14. Digestive System The digestive system has a simple job, gather nutrients. The digestive system has a simple job, gather nutrients.

Gastrointestinal TractGastrointestinal Tract A twisty, hollow tube that runs A twisty, hollow tube that runs

continuously from the mouth to the continuously from the mouth to the anus. anus.

It is divided into sections, each with a It is divided into sections, each with a specific purpose. specific purpose.

Includes: Mouth, pharynx, esophagus, Includes: Mouth, pharynx, esophagus, stomach, sm. Intestine, and lg. stomach, sm. Intestine, and lg. Intestine. Intestine.

The terminal opening is the anus. The terminal opening is the anus.

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MouthMouth Lips protect anteriorLips protect anterior Cheeks form lateral Cheeks form lateral

wallswalls Hard and soft palate Hard and soft palate

form roofform roof Muscular tongue Muscular tongue

occupies the floor of occupies the floor of the oral cavity. the oral cavity.

Tongue attached to Tongue attached to the bottom of the the bottom of the mouth by the lingual mouth by the lingual frenulum. frenulum.

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MouthMouth The area between The area between

your cheeks/lips and your cheeks/lips and your teeth is called your teeth is called the vestibule. The the vestibule. The area behind your area behind your teeth is the oral teeth is the oral cavity proper. cavity proper.

Two sets of tonsils – Two sets of tonsils – palatine in the back, palatine in the back, lingual cover the lingual cover the back of the tongue back of the tongue just further along. just further along. When inflamed, it When inflamed, it hurts to swallow. hurts to swallow.

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MouthMouth Mastication – food in Mastication – food in

the mouth is chewed the mouth is chewed using teeth to break using teeth to break it down (give it more it down (give it more surface area)surface area)

Salivary glands Salivary glands produce saliva with produce saliva with amylase in it. The amylase in it. The tongue mixes the tongue mixes the food around like a food around like a washing machine. washing machine.

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TeethTeeth Teeth are used to Teeth are used to

rip and grind food rip and grind food into small bits. into small bits.

From birth – 2yr From birth – 2yr our milk teeth grow our milk teeth grow in, 20 total. in, 20 total.

From 7yr – 25yr our From 7yr – 25yr our second set second set (permanent) of (permanent) of teeth grow in. teeth grow in.

Full set is 32. This Full set is 32. This number changes number changes based on impaction based on impaction and wisdom teeth. and wisdom teeth.

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TeethTeeth Teeth are named Teeth are named

based on their based on their shape. shape.

Incisors for cuttingIncisors for cutting canines for canines for

piercing and piercing and rippingripping

premolars and premolars and molars for molars for grinding. grinding.

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ToothTooth Teeth have two Teeth have two

major areas, the major areas, the crown and the root. crown and the root.

The crown is covered The crown is covered in enamel – hardest in enamel – hardest substance in the substance in the body and heavily body and heavily mineralized with mineralized with calcium. calcium.

Gums or gingiva Gums or gingiva bridge the gap bridge the gap between teeth.between teeth.

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ToothTooth Below the gum line Below the gum line

is the root. Held in is the root. Held in place by the place by the periodontal periodontal membrane and the membrane and the cementum. cementum.

Internally, the tooth Internally, the tooth is made up of dentin, is made up of dentin, a bone like material a bone like material and the pulp. and the pulp.

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ToothTooth The pulp is a central The pulp is a central

cavity filled with cavity filled with connective tissue, connective tissue, blood vessels and blood vessels and nerve fibers. nerve fibers.

Cavities eat away Cavities eat away enamel, making the enamel, making the tooth weaker. If the tooth weaker. If the decomposition gets too decomposition gets too deep near the pulp, a deep near the pulp, a root canal is root canal is performed. performed.

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PharynxPharynx After the mouth, food enters the After the mouth, food enters the

“throat” or pharynx. “throat” or pharynx. The walls of the pharynx contain two The walls of the pharynx contain two

skeletal muscle layers which begin skeletal muscle layers which begin peristalsis (more later).peristalsis (more later).

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EsophagusEsophagus 10” tube that connects the throat to the 10” tube that connects the throat to the

stomachstomach Made of four layers (tunica)Made of four layers (tunica)

Mucosa – innermost, lines the lumen, surface Mucosa – innermost, lines the lumen, surface epithelium and smooth muscle. Friction-epithelium and smooth muscle. Friction-resisting. resisting.

Submucosa – soft connective tissue with blood Submucosa – soft connective tissue with blood vessesls, nerves, lymph vessels and nodes. vessesls, nerves, lymph vessels and nodes.

Muscularis Externa – Muscles for PeristalsisMuscularis Externa – Muscles for Peristalsis Serosa – serous fluid producing. Part of the Serosa – serous fluid producing. Part of the

continuous visceral peritoneum that lines the continuous visceral peritoneum that lines the abdominopelvic cavity, including mesentary. abdominopelvic cavity, including mesentary.

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StomachStomach On the left side of the abdominal cavity. On the left side of the abdominal cavity. Approximately 10” long, diameter Approximately 10” long, diameter

changes as food fills it. changes as food fills it. Can hold approximately 1 gallon of foodCan hold approximately 1 gallon of food Separated from the esophagus by the Separated from the esophagus by the

cardioesophageal sphincter and cardioesophageal sphincter and separated from the Sm. Intestine by the separated from the Sm. Intestine by the Pyloric Sphincter. Pyloric Sphincter.

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StomachStomach Stomach has three layers of muscles, Stomach has three layers of muscles,

running longitudinally, transversely, and running longitudinally, transversely, and obliquely. These three layers contract in obliquely. These three layers contract in rhythm to constantly churn and pummel rhythm to constantly churn and pummel the food. the food.

Proteins begin to be broken down here by Proteins begin to be broken down here by gastric juice. gastric juice.

Food stays here until it is the consistency Food stays here until it is the consistency of a heavy cream. Called chyme. of a heavy cream. Called chyme.

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Activity of the StomachActivity of the Stomach Produces Pepsin – enzyme that breaks Produces Pepsin – enzyme that breaks

down protein. down protein. Pepsin requires an acidic environment, Pepsin requires an acidic environment,

stomach also produces hydrochloric acid. stomach also produces hydrochloric acid. Stomach tissue is protected from this Stomach tissue is protected from this

acid by mucus. If no mucus, the stomach acid by mucus. If no mucus, the stomach could eat itself called an ulcer. could eat itself called an ulcer.

Stomach muscles constantly mix food Stomach muscles constantly mix food with acid. with acid.

Once liquefied, Chyme, food enters the Once liquefied, Chyme, food enters the sm. Intestine via the pyloric sphincter. sm. Intestine via the pyloric sphincter.

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Small IntestineSmall Intestine The major digestive The major digestive

organ.organ. 7 meters long7 meters long Can only process a Can only process a

small amount at a small amount at a time, kept in time, kept in stomach. stomach.

Three subdivisionsThree subdivisions DuodenumDuodenum JejunumJejunum IleumIleum

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DuodenumDuodenum The first and smallest section. Starts The first and smallest section. Starts

at the end of the stomach, turns down at the end of the stomach, turns down and then transverse. Makes a C and then transverse. Makes a C Shape. Shape.

Pancreatic duct empties here, Pancreatic duct empties here, releasing pancreatic digestive releasing pancreatic digestive enzymes. enzymes.

Bile duct from liver also empties into Bile duct from liver also empties into the duodenum. the duodenum.

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Activities of the Small Activities of the Small IntestineIntestine

The pancreas and gall bladder empty The pancreas and gall bladder empty their contents into the small intestine. their contents into the small intestine. This releases enzymes and neutralizes This releases enzymes and neutralizes the chyme back to about pH 8the chyme back to about pH 8

EnzymesEnzymes Pancreatic amylase, lactase, maltase and Pancreatic amylase, lactase, maltase and

sucrase finish the breakdown of carbs that sucrase finish the breakdown of carbs that was started in the mouthwas started in the mouth

Trypsin continues the breakdown of proteinsTrypsin continues the breakdown of proteins Bile and pancreatic lipase begin to Bile and pancreatic lipase begin to

breakdown fatsbreakdown fats

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Sm. IntestineSm. Intestine Nearly all food absorption occurs in Nearly all food absorption occurs in

the sm. Intestine. the sm. Intestine. A large amount of surface area is A large amount of surface area is

produced because the inside layer of produced because the inside layer of the sm. Intestine is highly folded the sm. Intestine is highly folded (circular folds). These folds have villi (circular folds). These folds have villi on them which are made up of cells on them which are made up of cells with microvilli. All of which make with microvilli. All of which make more surface area for absorption. more surface area for absorption.

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Activities of the Small Activities of the Small IntestineIntestine

As chyme is constantly digested by these As chyme is constantly digested by these various enzymes, nutrients are absorbed various enzymes, nutrients are absorbed by microvilli of the intestinal walls. by microvilli of the intestinal walls.

These nutrients are routed into the These nutrients are routed into the hepatatic portal vein. hepatatic portal vein.

They are taken to the liver for They are taken to the liver for detoxification before being emptied into detoxification before being emptied into the blood stream. the blood stream.

Chyme left in the small intestine is Chyme left in the small intestine is pushed through by peristalsis. pushed through by peristalsis.

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Large IntestineLarge Intestine Its name refers to its diameter, not its Its name refers to its diameter, not its

length (5ft)length (5ft) It extends from the ileocecal valve of It extends from the ileocecal valve of

the sm. Intestine to the anus. the sm. Intestine to the anus. Major function is to dry out the Major function is to dry out the

indigestible food residue by absorbing indigestible food residue by absorbing water and to eliminate the residue water and to eliminate the residue from the body as feces. from the body as feces.

Sections: cecum, appendix, colon, Sections: cecum, appendix, colon, rectum, and anal canal. rectum, and anal canal.

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Activities of the Large Activities of the Large IntestineIntestine

Chyme in the Lg. Intestine has very Chyme in the Lg. Intestine has very few nutrients. few nutrients.

Bacteria living in the lumen can Bacteria living in the lumen can breakdown the chyme releasing a breakdown the chyme releasing a few vitamins, but not much.few vitamins, but not much.

The liquid is absorbed by the lg. The liquid is absorbed by the lg. intestine, this makes the feces more intestine, this makes the feces more solid. solid.

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Accessory Digestive Accessory Digestive OrgansOrgans

Salivary Glands – make saliva – Salivary Glands – make saliva – mucus and serous fluids. Mucus mucus and serous fluids. Mucus moistens and binds the food into a moistens and binds the food into a mass called the bolus. mass called the bolus.

Serous fluid contains enzymes Serous fluid contains enzymes amylase to break down carbs. Also amylase to break down carbs. Also contains lysozyme and antibodies to contains lysozyme and antibodies to inhibit bacteria. inhibit bacteria.

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Accessory Digestive Accessory Digestive OrgansOrgans

TeethTeeth Pancreas – produces enzymes and Pancreas – produces enzymes and

alkaline fluid to break down food and alkaline fluid to break down food and neutralize acidic chyme.neutralize acidic chyme.

Liver – produces many enzymes, Liver – produces many enzymes, digestively, bile. Emulsifies fatsdigestively, bile. Emulsifies fats

Gallbladder – stores bile when Gallbladder – stores bile when digestion is not occuring. digestion is not occuring.

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Six Steps of DigestionSix Steps of Digestion IngestionIngestion PropulsionPropulsion Mechanical BreakdownMechanical Breakdown Chemical BreakdownChemical Breakdown AbsorptionAbsorption DefecationDefecation