Digestive System. The organs that break down food to molecular size before it can be absorbed by the digestive system and used by the cells The organs

Digestive SystemDigestive System


The organs that break down food to The organs that break down food to molecular size before it can be molecular size before it can be absorbed by the digestive system absorbed by the digestive system and used by the cellsand used by the cells


Composed of the GI tract and Composed of the GI tract and accessory structuresaccessory structures


GI tract – a tube open at both ends GI tract – a tube open at both ends for the transit of food and wastes for the transit of food and wastes during processingduring processing


GI tract includesGI tract includes

1.1. MouthMouth

2.2. PharynxPharynx

3.3. EsophagusEsophagus

4.4. StomachStomach

5.5. Small intestineSmall intestine

6.6. Large intestineLarge intestine


Acessory structures contribute to Acessory structures contribute to food processingfood processing


Accessory structures includeAccessory structures include

1.1. TeethTeeth

2.2. TongueTongue

3.3. Salivary glandsSalivary glands

4.4. LiverLiver

5.5. GallbladderGallbladder

6.6. pancreaspancreas


Includes six basic processesIncludes six basic processes

Layers of GI TractLayers of GI Tract

1.1. MucosaMucosa

2.2. SubmucosaSubmucosa

3.3. MuscularisMuscularis

4.4. SerosaSerosa

MucosaMucosa

Consists of Consists of

1.1. EpitheliumEpithelium

2.2. Lamina propriaLamina propria

3.3. Muscularis mucosa Muscularis mucosa

EpitheliumEpithelium

Non-keratinized stratified squamous Non-keratinized stratified squamous epithelium in the esophagusepithelium in the esophagus

EpitheliumEpithelium

Simple columnar in the rest of the Simple columnar in the rest of the tracttract

Lamina propriaLamina propria

Contains loose connective tissueContains loose connective tissue

Lamina PropriaLamina Propria

Blood and lymph vesselsBlood and lymph vessels

Lamina PropriaLamina Propria

Nerves and sensorsNerves and sensors

Muscularis MucosaMuscularis Mucosa

Causes local folding of the mucosal Causes local folding of the mucosal layer to increase surface area for layer to increase surface area for digestion and absorptiondigestion and absorption

2. Submucosa2. Submucosa

Consists of areolar connective tissueConsists of areolar connective tissue

SubmucosaSubmucosa

Submucosal plexusSubmucosal plexus

SubmucosaSubmucosa

Glands and lymphatic tissueGlands and lymphatic tissue

3. Muscularis3. Muscularis

The mouth, pharynx, and superior The mouth, pharynx, and superior part of the esophagus contains part of the esophagus contains skeletal muscle that produces skeletal muscle that produces voluntary swallowingvoluntary swallowing

MuscularisMuscularis

Skeletal muscle forms the external Skeletal muscle forms the external (voluntary) anal sphincter(voluntary) anal sphincter


Consists of smooth muscle in an Consists of smooth muscle in an inner sheet of circular fibers and an inner sheet of circular fibers and an outer sheet of longitudinal fibersouter sheet of longitudinal fibers


Stomach contains an inner oblique Stomach contains an inner oblique layer alsolayer also

3. Serosa3. Serosa

Superficial layer of the GI tractSuperficial layer of the GI tract

SerosaSerosa

The esophagus is covered by an The esophagus is covered by an adventitia instead of serosaadventitia instead of serosa

SerosaSerosa

Inferior to the diaphragm also called Inferior to the diaphragm also called the visceral peritoneumthe visceral peritoneum

PeritoneumPeritoneum

Largest serous membrane of the Largest serous membrane of the bodybody


Two layersTwo layers


1.1. Parietal peritoneumParietal peritoneum

2.2. Visceral peritoneumVisceral peritoneum

Parietal PeritoneumParietal Peritoneum

Lines the wall of the abdominal Lines the wall of the abdominal cavitycavity

Visceral PeritoneumVisceral Peritoneum

Covers some of the organs Covers some of the organs

Peritoneal CavityPeritoneal Cavity

The space between the parietal and The space between the parietal and visceral portions that contains visceral portions that contains serous fluidserous fluid

MouthMouth

Oral cavityOral cavity

MouthMouth

Formed by the cheeks, hard and soft Formed by the cheeks, hard and soft palate, lips, and tonguepalate, lips, and tongue

MouthMouth

The space extends from the gums The space extends from the gums and teeth to the faucesand teeth to the fauces

MouthMouth

Fauces – opening between the oral Fauces – opening between the oral cavity and pharynxcavity and pharynx

Salivary GlandsSalivary Glands

Lie outside the mouth and pour their Lie outside the mouth and pour their contents into ducts that empty into contents into ducts that empty into the oral cavitythe oral cavity


Produce salivaProduce saliva


Three pairsThree pairs

1.1. ParotidParotid

2.2. SubmandibularSubmandibular

3.3. SublingualSublingual


Saliva lubricates and dissolves foodSaliva lubricates and dissolves food


Saliva start the chemical digestion of Saliva start the chemical digestion of carbscarbs


Parasympathetics stimulate Parasympathetics stimulate secretion of watery salivasecretion of watery saliva


Sympathetics stimulate the secretion Sympathetics stimulate the secretion of thick, tacky, salivaof thick, tacky, saliva

MumpsMumps

Inflammation and enlargement of Inflammation and enlargement of the parotid glandthe parotid gland

MumpsMumps

Symptoms include fever, pain, and Symptoms include fever, pain, and swelling of one or both glandsswelling of one or both glands

TongueTongue

Composed of skeletal muscle Composed of skeletal muscle covered with mucous membranecovered with mucous membrane

TongueTongue

The upper surface and sides are The upper surface and sides are covered with papillaecovered with papillae

TongueTongue

Some papillae contain taste budsSome papillae contain taste buds

TongueTongue

On the dorsum of the tongue are On the dorsum of the tongue are glands that secrete lingual lipaseglands that secrete lingual lipase

TeethTeeth

Adapted for mechanical digestionAdapted for mechanical digestion

TeethTeeth


1.1. CrownCrown

2.2. Neck Neck

3.3. Root Root

TeethTeeth

Teeth composed of dentinTeeth composed of dentin

TeethTeeth

Dentin – calcified connective tissue Dentin – calcified connective tissue that gives the tooth its basic shape that gives the tooth its basic shape and rigidityand rigidity

TeethTeeth

Dentin of the crown is covered by Dentin of the crown is covered by enamelenamel

TeethTeeth

The dentin of the root is covered by The dentin of the root is covered by cementumcementum

TeethTeeth

Cementum – attaches the root to the Cementum – attaches the root to the periodontal ligament periodontal ligament

TeethTeeth

The dentin encloses the pulp cavity The dentin encloses the pulp cavity in the crown and the root canals in in the crown and the root canals in the rootthe root

TeethTeeth

Two sets of teethTwo sets of teeth

1.1. Deciduous (primary)Deciduous (primary)

2.2. Pemanent (secondary)Pemanent (secondary)

TeethTeeth

Salivary amylase – converts Salivary amylase – converts polysaccharides (starches) to polysaccharides (starches) to disaccharides (maltose)disaccharides (maltose)

PharynxPharynx

Composed of skeletal muscle and Composed of skeletal muscle and lined by mucous membranelined by mucous membrane

PharynxPharynx


1.1. NasopharynxNasopharynx

2.2. OropharynxOropharynx

3.3. laryngopharynxlaryngopharynx

PharynxPharynx

Swallowing moves food from the Swallowing moves food from the mouth to the stomachmouth to the stomach

EsophagusEsophagus

Behind the tracheaBehind the trachea

Esophagus Esophagus

Connects the pharynx to the Connects the pharynx to the stomachstomach

EsophagusEsophagus

Serosa called the adventitiaSerosa called the adventitia

EsophagusEsophagus

Contains an upper and lower Contains an upper and lower esophageal sphinchteresophageal sphinchter

EsophagusEsophagus

Highly coordinated, propulsive Highly coordinated, propulsive contractions (peristalsis) of the contractions (peristalsis) of the muscularis push the bolus distallymuscularis push the bolus distally

StomachStomach

J-shapedJ-shaped

StomachStomach

Begins at the bottom of the Begins at the bottom of the esophagus and ends at the pyloric esophagus and ends at the pyloric sphinctersphincter

StomachStomach

Pyloric sphincter – separates the Pyloric sphincter – separates the stomach from the duodenum stomach from the duodenum

StomachStomach

Mixing and holding area for foodMixing and holding area for food

StomachStomach

Begins the digestion of foodBegins the digestion of food

StomachStomach

Water, HCL, and pepsin covert the Water, HCL, and pepsin covert the bolus of food to a clear liquid called bolus of food to a clear liquid called chymechyme

StomachStomach

Can absorb water, alcohol, and Can absorb water, alcohol, and apirinapirin

StomachStomach

Three regionsThree regions

1.1. CardiacCardiac

2.2. FundusFundus

3.3. BodyBody

4.4. Antrum Antrum

StomachStomach

When stomach is empty, the mucosa When stomach is empty, the mucosa lies in folds called rugaelies in folds called rugae

StomachStomach

Surface of the mucosa is a layer of Surface of the mucosa is a layer of simple columnar epithelium simple columnar epithelium

StomachStomach

Epithelial cells extend down into the Epithelial cells extend down into the lamina propria forming gastric pits lamina propria forming gastric pits and the narrower and deeper and the narrower and deeper continuations of the these, called continuations of the these, called gastric glandsgastric glands

StomachStomach

Gastric glands consist of 3 types of Gastric glands consist of 3 types of exocrine glandsexocrine glands

1.1. Mucous neck cellsMucous neck cells

2.2. Chief cellsChief cells

3.3. Parietal cellsParietal cells

StomachStomach

1. Mucous neck cells – secrete 1. Mucous neck cells – secrete mucousmucous

StomachStomach

Mucous rich in bicarbonate and Mucous rich in bicarbonate and prevents gastric acid from damaging prevents gastric acid from damaging the epitheliumthe epithelium

StomachStomach

2. Chief cells secrete pepsinogen 2. Chief cells secrete pepsinogen and gastric lipaseand gastric lipase

StomachStomach

Pepsinogen is activated by HCL into Pepsinogen is activated by HCL into pepsinpepsin

StomachStomach

Pepsin can also activate pepsinogenPepsin can also activate pepsinogen

StomachStomach

Pepsin digests proteinPepsin digests protein

StomachStomach

Gastric lipase splits certain Gastric lipase splits certain molecules in butterfat of milk into molecules in butterfat of milk into fatty acids and monoglycerides fatty acids and monoglycerides

StomachStomach

Gastric lipase has a VERY limited Gastric lipase has a VERY limited role in the adult stomachrole in the adult stomach

StomachStomach

3. Parietal cells secrete HCL and 3. Parietal cells secrete HCL and intrinsic factorintrinsic factor

StomachStomach

Intrinsic factor is important for Intrinsic factor is important for absorption of vitamin B-12absorption of vitamin B-12

StomachStomach

Parietal cells contain H2 receptors, Parietal cells contain H2 receptors, gastrin receptors, and Ach receptorsgastrin receptors, and Ach receptors

StomachStomach

H2 blockers such as Tagamet, H2 blockers such as Tagamet, Zantac , and Pepcid work hereZantac , and Pepcid work here

StomachStomach

Parietal cells also have receptors for Parietal cells also have receptors for somatostatin which decrease acid somatostatin which decrease acid secretionsecretion

StomachStomach

G cells in the antrum secrete the G cells in the antrum secrete the hormone Gastrin which increases hormone Gastrin which increases acid secretion and motilityacid secretion and motility

StomachStomach

Near parietal cells are Near parietal cells are mast cellsmast cells that releases histamine in responses that releases histamine in responses to gastrin or stimulation by the to gastrin or stimulation by the vagusvagus

StomachStomach

Ach is released by parasympathetic Ach is released by parasympathetic fibers fibers

StomachStomach

The serosa is a part of the visceral The serosa is a part of the visceral peritoneumperitoneum

StomachStomach

Above the lesser curvature, the Above the lesser curvature, the visceral peritoneum becomes the visceral peritoneum becomes the lesser omentumlesser omentum

StomachStomach

Below the greater curvature, the Below the greater curvature, the visceral peritoneum becomes the visceral peritoneum becomes the greater omentumgreater omentum

Regulation of Gastric Regulation of Gastric Secretion and MotilitySecretion and Motility

Gastric secretion is regulated by Gastric secretion is regulated by nervous and hormonal secretionsnervous and hormonal secretions

Regulation of Gastric Regulation of Gastric Secretion and MotilitySecretion and Motility

Stimulation occurs in three Stimulation occurs in three overlapping phasesoverlapping phases

1.1. CephalicCephalic

2.2. GastricGastric

3.3. IntestinalIntestinal

Cephalic PhaseCephalic Phase

Consists of reflexes initiated by Consists of reflexes initiated by sensory receptors in the head, such sensory receptors in the head, such as when you see, smell, or think as when you see, smell, or think about foodabout food

Cephalic PhaseCephalic Phase

Stimulates salivary flow, gastric Stimulates salivary flow, gastric secretion and motility secretion and motility

Gastric PhaseGastric Phase

Begins when food enters the Begins when food enters the stomachstomach


Distension of stomach and increase Distension of stomach and increase in pH stimulate gastric secretion via in pH stimulate gastric secretion via parasympathetic neuronsparasympathetic neurons


This results in increase in HCL This results in increase in HCL secretionsecretion


Protein, high pH, alcohol, and coffee Protein, high pH, alcohol, and coffee also stimulates gastrin secretionalso stimulates gastrin secretion


Histamine enhances the effects of Histamine enhances the effects of Ach and gastrinAch and gastrin


Gastrin secretion is limited by Gastrin secretion is limited by negative feedback negative feedback


Low pH under 2 decreases it Low pH under 2 decreases it secretionsecretion


Somatostatin from endocrine cells in Somatostatin from endocrine cells in the gastric wall inhibit the secretion the gastric wall inhibit the secretion of gastrin and histamineof gastrin and histamine


Somatostatin also inhibits acid Somatostatin also inhibits acid secretion in parietal cellssecretion in parietal cells

Intestinal phaseIntestinal phase

Stimulated by distension, low pH, Stimulated by distension, low pH, and increase in fatsand increase in fats

Intestinal PhaseIntestinal Phase

Long and short neural reflexes Long and short neural reflexes inhibit gastric acid secretioninhibit gastric acid secretion

Intestinal PhaseIntestinal Phase

Hormones released by the intestinal Hormones released by the intestinal tract such as Gastric inhibitory tract such as Gastric inhibitory peptide (GIP), secretin, and peptide (GIP), secretin, and cholecystokinin (CCK) inhibit gastric cholecystokinin (CCK) inhibit gastric acid secretionacid secretion

Regulation of Gastric Regulation of Gastric EmptyingEmptying

Gastric emptying – the periodic Gastric emptying – the periodic releases of chyme from the stomach releases of chyme from the stomach into the duodenuminto the duodenum


Stimulated by nerve impulses in Stimulated by nerve impulses in response to distention of the response to distention of the stomach and gastrinstomach and gastrin


Most food leaves the stomach 2-6 Most food leaves the stomach 2-6 hours after ingestionhours after ingestion


Carbs leave first, then proteins, then Carbs leave first, then proteins, then fatsfats


Gastric emptying is inhibited by CCK Gastric emptying is inhibited by CCK and GIP and short and long neural and GIP and short and long neural reflexesreflexes


GIP also promotes insulin secretion GIP also promotes insulin secretion in pancreasin pancreas

PancreasPancreas

It is connected to the duodenum via It is connected to the duodenum via the pancreatic duct and accessory the pancreatic duct and accessory ductduct

PancreasPancreas

The pancreatic duct fuses with the The pancreatic duct fuses with the common bile duct ate the ampulla of common bile duct ate the ampulla of VaterVater

PancreasPancreas

The pancreatic islets secrete The pancreatic islets secrete hormoneshormones

PancreasPancreas

Exocrine cells (acini) secrete a Exocrine cells (acini) secrete a mixture of fluid and digestive mixture of fluid and digestive enzymes called pancreatic juiceenzymes called pancreatic juice

PancreasPancreas

Pancreatic juice contains Pancreatic juice contains bicarbonate and enzymes that digest bicarbonate and enzymes that digest starch, proteins, fats, and nucleic starch, proteins, fats, and nucleic acidsacids

PancreasPancreas

Bicarbonate converts the acid Bicarbonate converts the acid stomach contents to a slightly stomach contents to a slightly alkaline pH (7.1-8.2)alkaline pH (7.1-8.2)

PancreasPancreas

This halts pepsin acitvity and This halts pepsin acitvity and promotes the activity of pancreatic promotes the activity of pancreatic enzymesenzymes

PancreasPancreas

Pancreatic amylase digests starchPancreatic amylase digests starch

PancreasPancreas

Trypsin, chymotrypsin, and Trypsin, chymotrypsin, and carboxypeptidase digest proteinscarboxypeptidase digest proteins

PancreasPancreas

Pancreatic lipase digest fatsPancreatic lipase digest fats

PancreasPancreas

Ribonuclease and deoxyribonuclease Ribonuclease and deoxyribonuclease digest nucleic acidsdigest nucleic acids

PancreasPancreas

These enzymes are secreted as These enzymes are secreted as inactive precursorsinactive precursors

PancreasPancreas

Trypsinogen is activated by Trypsinogen is activated by duodenal enterokinase, producing duodenal enterokinase, producing kinasekinase

PancreasPancreas

Trypsin then activates the other Trypsin then activates the other precursor enzymesprecursor enzymes

PancreasPancreas

CCK from the duodenum stimulates CCK from the duodenum stimulates the pancreas to secrete digestive the pancreas to secrete digestive enzymes and ejection of bile into the enzymes and ejection of bile into the duodenum via contraction of the gall duodenum via contraction of the gall bladderbladder

PancreasPancreas

Secretin stimulates the pancreas to Secretin stimulates the pancreas to secrete bicarbonatesecrete bicarbonate

Liver and GallbladderLiver and Gallbladder

Heaviest gland in the bodyHeaviest gland in the body


Second largest organ in the bodySecond largest organ in the body


The liver is divisible into left and The liver is divisible into left and right lobes, separated by the right lobes, separated by the falciform ligamentfalciform ligament


The gallbladder is a sac located in a The gallbladder is a sac located in a depression on the posterior surface depression on the posterior surface of the liverof the liver


The right and left hepatic duct The right and left hepatic duct combine to form the common combine to form the common hepatic duct which binds with the hepatic duct which binds with the cystic duct to form the common bile cystic duct to form the common bile ductduct


Functions of the gall bladder are to Functions of the gall bladder are to store and concentrate bile until it is store and concentrate bile until it is needed by the small intestine to help needed by the small intestine to help digest fatsdigest fats


The muscularis of the gallbladder The muscularis of the gallbladder ejects bile into the cystic ductejects bile into the cystic duct


The liver receives a double supply of The liver receives a double supply of blood from the hepatic artery and blood from the hepatic artery and the hepatic portal vein.the hepatic portal vein.


The hepatic portal vein receives The hepatic portal vein receives venous blood from the intestines.venous blood from the intestines.


All blood leaves the liver the liver via All blood leaves the liver the liver via the hepatic veins to the inferior vena the hepatic veins to the inferior vena cava.cava.


Hepatocytes produce bile that is Hepatocytes produce bile that is stored in the gallbladderstored in the gallbladder


Bile contains bilirubin, cholesterol, Bile contains bilirubin, cholesterol, and bile acidsand bile acids


Bile emulsifies triglyceridesBile emulsifies triglycerides

Functions of the LiverFunctions of the Liver

Carbohydrate, lipid, and protein Carbohydrate, lipid, and protein metabolismmetabolism


Removal of drugs and hormones Removal of drugs and hormones from the bloodfrom the blood


Excretion of bilirubinExcretion of bilirubin


Synthesis of bile saltsSynthesis of bile salts


Storage of vitamins and mineralsStorage of vitamins and minerals


PhagocytosisPhagocytosis


Activation of vitamin DActivation of vitamin D

Small IntestineSmall Intestine

Extends from the pyloric sphincter Extends from the pyloric sphincter to the ileocecal sphincterto the ileocecal sphincter


Divided into Divided into

1.1. DuodenumDuodenum

2.2. JejunumJejunum

3.3. ileumileum


The mucosa forms fingerlike The mucosa forms fingerlike villivilli


Lacteals – lymphatic capillaries Lacteals – lymphatic capillaries embedded in the villi for fat embedded in the villi for fat absorptionabsorption


Mucosal epithelium containsMucosal epithelium contains

1.1. Absorptive cellsAbsorptive cells

2.2. Goblet cellsGoblet cells

3.3. Enteroendocrine cellsEnteroendocrine cells

4.4. Paneth cellsPaneth cells


The free surface of absorptive cells The free surface of absorptive cells contains contains microvillimicrovilli


Crypts of Lieberkuhn – cavities lined Crypts of Lieberkuhn – cavities lined by glandular epithelium in the by glandular epithelium in the mucosamucosa


Duodenal glands – located in the Duodenal glands – located in the submucosa and secrete an alkaline submucosa and secrete an alkaline mucusmucus


Peyer’s patches – aggregated Peyer’s patches – aggregated lymphatic nodules in the submucosa lymphatic nodules in the submucosa of the ileumof the ileum


Brush border enzymes break down Brush border enzymes break down dipeptides and disaccharides on the dipeptides and disaccharides on the surface of microvillisurface of microvilli


Segmentation – localized contraction Segmentation – localized contraction in areas containing foodin areas containing food


Peristalsis – propels the chyme Peristalsis – propels the chyme onward through the intestinal tractonward through the intestinal tract

Chemical digestion in the Chemical digestion in the Small IntestineSmall Intestine

Pancreatic amylase breaks down Pancreatic amylase breaks down starches into maltosestarches into maltose


Maltase – breaks down maltose to 2 Maltase – breaks down maltose to 2 glucosesglucoses


Lactase – breaks down lactose to Lactase – breaks down lactose to glucose and galactoseglucose and galactose


Sucrase – breaks down sucrose to Sucrase – breaks down sucrose to glucose and fructoseglucose and fructose


Glucose, fructose, and galactose are Glucose, fructose, and galactose are absorbableabsorbable


Maltase, sucrase, and lactase are Maltase, sucrase, and lactase are brush border disaccharidasesbrush border disaccharidases


Trypsin and chymotrypsin break Trypsin and chymotrypsin break down proteins down proteins


Brush border enzymes split Brush border enzymes split dipeptides to amino acidsdipeptides to amino acids


Most dipeptides are split into amino Most dipeptides are split into amino acids inside epithelial cells.acids inside epithelial cells.


Bile salts break the globules of Bile salts break the globules of triglycerides into dropletstriglycerides into droplets


Pancreatic lipase hydrolyzes Pancreatic lipase hydrolyzes triglycerides into fatty acids and triglycerides into fatty acids and monoglyceridesmonoglycerides


Infants have low levels of pancreatic Infants have low levels of pancreatic lipaselipase


Infants have lipase mainly derived Infants have lipase mainly derived from chief cellsfrom chief cells


Breast milk also contains lipaseBreast milk also contains lipase

Large IntestineLarge Intestine

Extends from the ileocecal valve to Extends from the ileocecal valve to the anusthe anus


SubdivisionsSubdivisions

1.1. CecumCecum

2.2. ColonColon

3.3. RectumRectum

4.4. Anal canalAnal canal


Appendix – hangs inferior to the Appendix – hangs inferior to the cecumcecum


Colon divided intoColon divided into

1.1. AscendingAscending

2.2. TransverseTransverse

3.3. DescendingDescending

4.4. Sigmoid portionsSigmoid portions


The mucosa has no villiThe mucosa has no villi


The mucosa has simple columnar The mucosa has simple columnar epithelium with numerous goblet epithelium with numerous goblet cellscells


Taeniae colie – Three strips of Taeniae colie – Three strips of longitudinal muscles in the longitudinal muscles in the muscularismuscularis


The taeniae coli contract and gather The taeniae coli contract and gather the colon into a series of pouches the colon into a series of pouches called called haustrahaustra


The last stages of chemical digestion The last stages of chemical digestion occur in the large intestine through occur in the large intestine through bacterial action bacterial action


Some vitamins (K and folic acid) are Some vitamins (K and folic acid) are synthesized by bacterial action and synthesized by bacterial action and absorbed by the large intestineabsorbed by the large intestine


Absorbs water, electrolytes, and Absorbs water, electrolytes, and some vitaminssome vitamins


Feces consist of water, inorganic Feces consist of water, inorganic salts, sloughed-off epithelial cells, salts, sloughed-off epithelial cells, bacteria, products of bacterial bacteria, products of bacterial decomposition, and undigested parts decomposition, and undigested parts of foodof food


An important organ in maintaining An important organ in maintaining the body’s water balancethe body’s water balance

DefecationDefecation

Elimination of fecesElimination of feces


Aided by voluntary contractions of Aided by voluntary contractions of the diaphragm and abdominal the diaphragm and abdominal musclesmuscles


The external anal sphincter can be The external anal sphincter can be voluntarily controlled voluntarily controlled

DiarrheaDiarrhea

Frequent defecation of liquid feces Frequent defecation of liquid feces

DiarrheaDiarrhea

Caused by increased motility of the Caused by increased motility of the intestine and can lead to intestine and can lead to dehydration and electrolyte dehydration and electrolyte imbalancesimbalances

ConstipationConstipation

Refers to infrequent or difficult Refers to infrequent or difficult defecationdefecation


Causded by decreased motility of the Causded by decreased motility of the intestinesintestines


May be alleviated by increasing May be alleviated by increasing one’s intake of dietary fiber and one’s intake of dietary fiber and fluidsfluids

HepatitisHepatitis

Inflammation of the liverInflammation of the liver

HepatitisHepatitis

Caused by viruses, drugs, and Caused by viruses, drugs, and chemicals, including alcoholchemicals, including alcohol

Documents

Digestive System. The organs that break down food to molecular size before it can be absorbed by the digestive system and used by the cells The organs