Chapter #15 Chapter #15

The Digestive SystemThe Digestive System

Chapter 15.1 Chapter 15.1

Digestion Digestion is the mechanical and chemical is the mechanical and chemical breakdown of foods and the absorption of breakdown of foods and the absorption of the resulting nutrients by cells.the resulting nutrients by cells.

The The digestive systemdigestive system consists of the consists of the alimentary canal, which extends about 9 alimentary canal, which extends about 9 meters (27 feet or 900 cm) from the mouth meters (27 feet or 900 cm) from the mouth to the anus.to the anus.

Alimentary CanalAlimentary Canal

MouthMouthPharynxPharynxEsophagusEsophagusStomachStomachSmall IntestineSmall IntestineLarge IntestineLarge IntestineRectumRectumAnusAnus

1.1. MouthMouth Mechanical breakdown of food; Mechanical breakdown of food; begins chemical digestion of begins chemical digestion of carbohydrates (bread).carbohydrates (bread).

Salivary glands secrete saliva, which Salivary glands secrete saliva, which contains enzymes that initiate breakdown contains enzymes that initiate breakdown of carbohydrates.of carbohydrates.

Pharynx connects mouth with Pharynx connects mouth with esophagus.esophagus.

2.2. EsophagusEsophagus peristalsis pushes food to peristalsis pushes food to stomach.stomach.

Peristalsis wavelike motion that propels Peristalsis wavelike motion that propels food.food.

3.3. StomachStomach secretes acid and enzymes. secretes acid and enzymes. Mixes food with secretions to begin Mixes food with secretions to begin enzymatic digestion of proteins.enzymatic digestion of proteins.

4.4. Small IntestineSmall Intestine mixes food with bile and mixes food with bile and pancreatic juice. Final enzymatic breakdown of pancreatic juice. Final enzymatic breakdown of food molecules: food molecules: main site of nutrient main site of nutrient absorption.absorption.

Liver Liver produces bile, which produces bile, which emulsifies fat.emulsifies fat. GallbladderGallbladder stores bile and introduces it into stores bile and introduces it into

small intestine.small intestine. Pancreas Pancreas produces and secretes pancreatic produces and secretes pancreatic

juice, containing digestive enzymes and juice, containing digestive enzymes and bicarbonate ions, into sm. Intestine.bicarbonate ions, into sm. Intestine.

Accessory organs are organs that are not a Accessory organs are organs that are not a direct route of the digestive system.direct route of the digestive system.

5.5. Large intestineLarge intestine absorbs water and absorbs water and electrolytes to form feces.electrolytes to form feces.

6.6. RectumRectum regulates elimination of feces. regulates elimination of feces.7.7. Anus Anus eliminates feces.eliminates feces. The digestive system is a tube, open at The digestive system is a tube, open at

both ends, that has a surface area of 186 both ends, that has a surface area of 186 square meters.square meters.

The main function is to supply body with The main function is to supply body with nutrients.nutrients.

15.2 General Characteristics15.2 General Characteristics

3 parts of the small intestine3 parts of the small intestine

1.1. DuodenumDuodenum

2.2. JejunumJejunum

3.3. IleumIleum

Alimentary CanalAlimentary Canal1.1. Mucosa or mucous membraneMucosa or mucous membrane the inner the inner

most layer. Contains glands that secrete most layer. Contains glands that secrete mucus and digestive enzymes. Carries mucus and digestive enzymes. Carries on secretion and absorption. Also, has on secretion and absorption. Also, has projections that increase the surface projections that increase the surface areaarea. Lumen=passageway.. Lumen=passageway.

2.2. SubmucosaSubmucosa contains loose connective contains loose connective tissue, glands, blood vessels, lymphatic tissue, glands, blood vessels, lymphatic vessels, and nerves. vessels, and nerves. Carry away Carry away absorbed materials.absorbed materials.

3.3. Muscular layerMuscular layer produces the movements. produces the movements.

4.4. Serosa or serous layerSerosa or serous layer the outer the outer covering of the digestive tube. Secretes covering of the digestive tube. Secretes fluid that lubricates the tube’s outer fluid that lubricates the tube’s outer surface so organs slide freely against surface so organs slide freely against one another.one another.

15.3 The Mouth15.3 The Mouth

The mouthThe mouth receives food and begins receives food and begins digestion by digestion by mechanically mechanically reducing the reducing the size of food and mixes them with saliva.size of food and mixes them with saliva.Oral cavityOral cavity includes the chamber between includes the chamber between the palate and tongue.the palate and tongue.PalatePalate forms the roof of the oral cavity and forms the roof of the oral cavity and is made of a hard palate (front) and Soft is made of a hard palate (front) and Soft palate (rear).palate (rear).Tongues function is to move food toward Tongues function is to move food toward the palate. Made out of skeletal muscle.the palate. Made out of skeletal muscle.

During swallowing, muscles draw the soft During swallowing, muscles draw the soft palate and uvula upward to separate the palate and uvula upward to separate the oral and nasal cavities.oral and nasal cavities.

Salvia Salvia cleanse the mouth and teeth, cleanse the mouth and teeth, dissolve chemicals necessary to tasting dissolve chemicals necessary to tasting food, and help in the formation of food food, and help in the formation of food bolus.bolus.

TonsilsTonsils

PalatinePalatine are lymphatic tissue in the back of are lymphatic tissue in the back of the mouth, on either side of the tongue the mouth, on either side of the tongue and closely associated with the palate. and closely associated with the palate. Help to fight infection. Help to fight infection. Pharyngeal or adenoidsPharyngeal or adenoids are on the are on the posterior wall of the pharynx. They can be posterior wall of the pharynx. They can be removed.removed.TonsillectomyTonsillectomy tonsil are surgically tonsil are surgically removed.removed.

TeethTeeth

Humans have 2 sets of teeth.Humans have 2 sets of teeth.

Primary teethPrimary teeth or deciduous usually erupt or deciduous usually erupt at 6months-4 years of age. at 6months-4 years of age. 20 primary20 primary teeth. 10 upper and 10 lower.teeth. 10 upper and 10 lower.

Secondary teethSecondary teeth or permanent consist of or permanent consist of 32 teeth32 teeth..

Good dental hygiene is essential because Good dental hygiene is essential because once damaged, enamel cannot be once damaged, enamel cannot be replaced.replaced.Enamel Enamel cover the crown. White and shiny.cover the crown. White and shiny.DentinDentin is found beneath the enamel. is found beneath the enamel. Dentin is a substance similar to bone.Dentin is a substance similar to bone.Pulp cavityPulp cavity contains blood vessels, contains blood vessels, nerves, and connective tissue.nerves, and connective tissue.Root canalsRoot canals contains the root. contains the root.

TeethTeeth

4 types of teeth4 types of teeth

1.1. Incisors (Front 4 teeth) bite off pieces of Incisors (Front 4 teeth) bite off pieces of food.food.

2.2. Cuspid grasp and tear food. Cuspid grasp and tear food.

3.3. Bicuspids or premolars grind food.Bicuspids or premolars grind food.

4.4. Molars grind food.Molars grind food.

15.4 Salivary Glands15.4 Salivary GlandsThe salivary glands secret saliva.The salivary glands secret saliva.Saliva moistens food particles, helps Saliva moistens food particles, helps them bind, and begins the them bind, and begins the chemical chemical digestions of carbohydrates.digestions of carbohydrates.Saliva dissolves food so that they can be Saliva dissolves food so that they can be tasted.tasted.2 types of secretions from the salivary 2 types of secretions from the salivary glands.glands.

1.1. Amylase Amylase digestive enzyme in mouth, digestive enzyme in mouth, stomach, pancreas.stomach, pancreas.

2.2. MucusMucus which binds with food particles to which binds with food particles to lubricate for swallowing.lubricate for swallowing.

Types of Salivary GlandsTypes of Salivary Glands

Parotid glandsParotid glands the largest. the largest.

Submandibular glandsSubmandibular glands located in the floor located in the floor of the mouth.of the mouth.

Sublingual glandsSublingual glands the smallest of the the smallest of the salivary glands, are on the floor of the salivary glands, are on the floor of the mouth.mouth.

15.5 Pharynx and Esophagus15.5 Pharynx and EsophagusPharynx connects the nasal and oral cavities Pharynx connects the nasal and oral cavities with the larynx and esophagus. with the larynx and esophagus. 3 parts3 parts

1.1. NasopharynxNasopharynx communicates with the nasal communicates with the nasal cavity and provides a passageway for air cavity and provides a passageway for air during breathing.during breathing.

2.2. OropharynxOropharynx is posterior to the soft palate and is posterior to the soft palate and inferior to the nasopharynx. It is the inferior to the nasopharynx. It is the passageway for food moving downward from passageway for food moving downward from the mouth and for air moving to and from the the mouth and for air moving to and from the nasal cavity.nasal cavity.

3.3. LaryngopharynxLaryngopharynx just inferior to the oropharynx, just inferior to the oropharynx, is a passageway to the esophagus.is a passageway to the esophagus.

EpiglottisEpiglottis closes off the top of the trachea closes off the top of the trachea (windpipe) so food is less likely to enter.(windpipe) so food is less likely to enter.

15.6 Stomach15.6 Stomach

The stomach is a J-shaped , pouchlike The stomach is a J-shaped , pouchlike organ that hangs inferior to the diaphragm organ that hangs inferior to the diaphragm in the upper left portion of the abdominal in the upper left portion of the abdominal cavity and has a capacity of about 1 liter.cavity and has a capacity of about 1 liter.

The stomach has thick folds of mucosal The stomach has thick folds of mucosal and submucosal layers and disappear and submucosal layers and disappear when the stomach wall is distended.when the stomach wall is distended.

StomachStomach

The stomach is divided into four regions.The stomach is divided into four regions.1.1. CardiacCardiac2.2. Fundic is the area that acts as a Fundic is the area that acts as a

temporary storage area for ingested temporary storage area for ingested food.food.

3.3. BodyBody4.4. PyloricPyloric Fatty food stay in the stomach the Fatty food stay in the stomach the

longestlongest..

Gastric SecretionsGastric Secretions

Gastric juiceGastric juice

1.1. Hydrochloric acidHydrochloric acid

2.2. Pepsin begins to digest proteinPepsin begins to digest protein Chyme is a semifluid paste of food Chyme is a semifluid paste of food

particles and gastric juice.particles and gastric juice.

Time Spent in organsTime Spent in organs

Mouth a few minutesMouth a few minutes

Esophagus a few minutesEsophagus a few minutes

Stomach 4 hoursStomach 4 hours

Small Intestine 12 hoursSmall Intestine 12 hours

Large Intestine 5 hoursLarge Intestine 5 hours

Total time in digestive system 21 hours.Total time in digestive system 21 hours.

15.7 Pancreas15.7 Pancreas

The pancreas make three different The pancreas make three different enzymes. One enzyme break down fats enzymes. One enzyme break down fats (pancreatic lipase), one enzyme break (pancreatic lipase), one enzyme break down protein (proteolytic), and the third down protein (proteolytic), and the third enzymes break down carbohydrates.enzymes break down carbohydrates.

15.8 Liver15.8 Liver

The The liverliver is the largest organ in the body it is the largest organ in the body it is the heaviest organ in the body at around is the heaviest organ in the body at around 3 pounds.3 pounds.It makes the chemical bile.It makes the chemical bile.BileBile is a green liquid that breaks large fat is a green liquid that breaks large fat droplets into small fat droplets.droplets into small fat droplets.GallbladderGallbladder is a small, baglike part located is a small, baglike part located under the liver. It stores bile until it is under the liver. It stores bile until it is needed by the small intestine.needed by the small intestine.

HepatitisHepatitis

Hepatitis is an inflammation of the liver.Hepatitis is an inflammation of the liver.

Types of HepatitisTypes of Hepatitis

1.1. Hepatitis AHepatitis A spreads by contact with food spreads by contact with food or objects contaminated with virus-or objects contaminated with virus-containing feces.containing feces.

2.2. Hepatitis BHepatitis B spreads by contact with virus- spreads by contact with virus-containing body fluids, such as blood, containing body fluids, such as blood, saliva, or semen.saliva, or semen.

3.3. Hepatitis CHepatitis C is believed to be responsible is believed to be responsible for about ½ the cases of hepatitis. for about ½ the cases of hepatitis. Transmitted in blood-by sharing razors or Transmitted in blood-by sharing razors or needles, from pregnant woman to fetus, needles, from pregnant woman to fetus, or in blood transfusions.or in blood transfusions.

4.4. Hepatitis DHepatitis D occurs in people already occurs in people already infected with hepatitis B. It is blood borne infected with hepatitis B. It is blood borne and associated with blood transfusions and associated with blood transfusions and intravenous drug use.and intravenous drug use.

5.5. Hepatitis EHepatitis E virus is usually transmitted in virus is usually transmitted in the water contaminated with feces.the water contaminated with feces.

6.6. Hepatitis FHepatitis F passes from feces and can passes from feces and can infect other primates.infect other primates.

7.7. Hepatitis GHepatitis G accounts for many cases of accounts for many cases of fulminant hepatitis.fulminant hepatitis.

15.9 Small Intestine15.9 Small Intestine

Small Intestine is a tubular organ that Small Intestine is a tubular organ that extends from the pyloric sphincter to the extends from the pyloric sphincter to the beginning of the large intestine. beginning of the large intestine. This is This is where most of the nutrients are absorbedwhere most of the nutrients are absorbed..

Receives secretions from the pancreas Receives secretions from the pancreas and liver. and liver.

Completes digestion, absorbs the products Completes digestion, absorbs the products of digestion, and transports the residues to of digestion, and transports the residues to the large intestines.the large intestines.

The small intestines constits of three portions.The small intestines constits of three portions.

1.1. Duodenum Duodenum

2.2. JejunumJejunum

3.3. IleumIleum Mesentery suspense the small intestine.Mesentery suspense the small intestine. Intestinal villiIntestinal villi is the inner wall of the small is the inner wall of the small

intestine appears velvety.intestine appears velvety. ¼ of feces is dead epithelial cells from the sm. ¼ of feces is dead epithelial cells from the sm.

Intestine.Intestine.

The The small intestinesmall intestine compared to the large compared to the large intestine is intestine is narrower and longernarrower and longer..

HeartburnHeartburn is caused by acid moving from the is caused by acid moving from the stomach into the esophagus. stomach into the esophagus.

Animals that do not have a digestive system Animals that do not have a digestive system absorb nutrients through their body covering. absorb nutrients through their body covering. Example Tapeworm.Example Tapeworm.

Plant eating animals Plant eating animals have have longer longer digestive digestive systemssystems because of the intake ofbecause of the intake of cellulose cellulose which which isis not absorbed not absorbed by the intestine.by the intestine.

Digestion is the breaking down of food into Digestion is the breaking down of food into small, usable small, usable moleculesmolecules usually usually glucose.glucose.

Digestive enzymesDigestive enzymesSalivary glandsSalivary glands make chemicals that make chemicals that digest only digest only carbohydrates.carbohydrates.

PancreasPancreas makes chemicals that digest makes chemicals that digest fat, fat, protein, and carbohydrates.protein, and carbohydrates.

LiverLiver makes chemicals that digest only makes chemicals that digest only fat.fat.

StomachStomach makes chemicals that digest only makes chemicals that digest only protein.protein.

Small intestineSmall intestine makes chemicals that makes chemicals that digest digest protein and carbohydratesprotein and carbohydrates..

Large intestineLarge intestine makes makes no chemicalsno chemicals to to digest food.digest food.

15.10 Large Intestine15.10 Large Intestine

Large intestine is so named because its Large intestine is so named because its diameter is greater than that of the small diameter is greater than that of the small intestine. Large intestine are about 1.5 intestine. Large intestine are about 1.5 meters long, and begins in the lower right meters long, and begins in the lower right side of the abdominal cavity.side of the abdominal cavity.

The large intestine The large intestine absorbs waterabsorbs water and and electrolytes.electrolytes.

The 4 parts of the large intestine:The 4 parts of the large intestine:

1.1. Cecum is the beginningCecum is the beginning

2.2. Colon is divided into 4 portions the ascending, Colon is divided into 4 portions the ascending, transverse, descending, and sigmoid colons. transverse, descending, and sigmoid colons. The colon is home to 100 trillion bacteria.The colon is home to 100 trillion bacteria.

3.3. Rectum extends about 5 cm below the tip of Rectum extends about 5 cm below the tip of the coccyx (tailbone).the coccyx (tailbone).

4.4. Anal canal the last 2.5 to 4 cm of the large Anal canal the last 2.5 to 4 cm of the large intestine.intestine.

Feces include materials that were not digested Feces include materials that were not digested or absorbed, water, electrolytes, mucus, or absorbed, water, electrolytes, mucus, intestinal cells, and bacteria. Feces is about intestinal cells, and bacteria. Feces is about 75% water. Feces pungent odor results from a 75% water. Feces pungent odor results from a variety of compounds that bacteria produce.variety of compounds that bacteria produce.

15.11 Nutrition and Nutrients15.11 Nutrition and Nutrients

NutritionNutrition is the study of nutrients and how is the study of nutrients and how the body utilizes.the body utilizes.Nutrients Nutrients all the chemicals that food is all the chemicals that food is made up of which inmade up of which in include include carbohydrates, lipids, proteins, vitamins, carbohydrates, lipids, proteins, vitamins, minerals, and water.minerals, and water.Nutrients that human cells cannot Nutrients that human cells cannot synthesize, such as certain amino acids, synthesize, such as certain amino acids, are called are called essential nutrients.essential nutrients.

CarbohydratesCarbohydratesAre organic compounds used primarily to Are organic compounds used primarily to supply energy for cellular processes.supply energy for cellular processes.Found in foods such as Found in foods such as starch and sugarstarch and sugarNot storedNot stored in large amounts in the body in large amounts in the bodyNeeded in Needed in greatest greatest amount each day.amount each day.CelluloseCellulose is a complex carbohydrate that is a complex carbohydrate that is abundant in food- it gives celery its is abundant in food- it gives celery its crunch. Humans cannot digest so crunch. Humans cannot digest so cellulose provides bulk (fiber or roughage) cellulose provides bulk (fiber or roughage) which facilitates food movement through which facilitates food movement through the digestive system.the digestive system.

LipidsLipids

Lipids are organic compounds that include Lipids are organic compounds that include fats, oilsfats, oils, and fatlike substances., and fatlike substances.

Found in foods such as Found in foods such as butter and oilbutter and oil

The food that is often The food that is often storedstored and used and used later as an later as an energy sourceenergy source..

The nutrient The nutrient stored under the skinstored under the skin and and around body organs.around body organs.

ProteinProtein

Proteins are polymers of amino acids with Proteins are polymers of amino acids with a wide variety of functions.a wide variety of functions.

Used to form muscle, bone, and skinUsed to form muscle, bone, and skin

Food rich in protein include meats, fish, Food rich in protein include meats, fish, poultry, cheese, nuts, milk, eggs, and poultry, cheese, nuts, milk, eggs, and cereals.cereals.

VitaminsVitaminsAre organic compounds that are required in Are organic compounds that are required in very small amountsvery small amounts for normal metabolic for normal metabolic processes. Not an energy source.processes. Not an energy source.

Riboflavin and niacinRiboflavin and niacin are examples are examples

Vitamins Vitamins allows cells to useallows cells to use carbohydrates carbohydrates and proteins.and proteins.

Vitamins are needed for Vitamins are needed for growth and tissue growth and tissue repair.repair.

Amount given as % RDA. Amount given as % RDA. Recommended Recommended Daily Allowance.Daily Allowance.

MineralsMinerals

Are elements other than carbon that are Are elements other than carbon that are essential in human metabolism.essential in human metabolism.Found on the Periodic Table. Calcium, Found on the Periodic Table. Calcium, iron, potassium, sodium, zinc, and iron, potassium, sodium, zinc, and magnesium are examples.magnesium are examples.Need in Need in very small amountsvery small amountsMay cause May cause anemia or muscle twitchinganemia or muscle twitching if if missing from diet.missing from diet.Amount Given as % RDAAmount Given as % RDA. . Not Not an energy source.an energy source.

WaterWater

Water is needed to cool the body, to Water is needed to cool the body, to chemical reactions in the body, and to chemical reactions in the body, and to carry away body waste.carry away body waste.

50% to 60% of the human body is water50% to 60% of the human body is water..

The average adult needs about 2 liters of The average adult needs about 2 liters of water a day.water a day.

DietsDiets

Balanced dietBalanced diet is a diet with the right is a diet with the right amount of each nutrient.amount of each nutrient.

Malnutrition Malnutrition if a persons diet lacks if a persons diet lacks essential nutrients or a person fails to use essential nutrients or a person fails to use available foods.available foods.