Accessory digestive organs

Organs of the GI tract

Oral cavity,pharynx,esophagus

Carbohydrate digestion

Polysaccharides(starch, glycogen)

Disaccharides(sucrose, lactose)

Salivary amylase

Smaller polysaccharides,maltose

Stomach

Protein digestion Nucleic acid digestion Fat digestion

ProteinsPepsin

Small polypeptides

Lumen of small intes-tine

Polysaccharides

Pancreatic amylases

Maltose and otherdisaccharides

Epitheliumof smallintestine(brushborder)

Disaccharidases

Monosaccharides

Polypeptides

Pancreatic trypsin and chymotrypsin (These proteases cleave bonds adjacent to certain amino acids.)

Smallerpolypeptides

Pancreatic carboxypeptidase

Amino acids

Small peptides

Dipeptidases, carboxypeptidase, and aminopeptidase (These proteases split off one amino acid at a time, working from opposite ends of a polypeptide.)

Amino acids

DNA, RNA

Pancreaticnucleases

Nucleotides

Nucleotidases

NucleosidesNucleosidasesandphosphatases

Nitrogenous bases,sugars, phosphates

Fat globules (Insoluble inwater, fats aggregate asglobules.)

Bile salts

Fat droplets (A coating ofbile salts prevents small drop-lets from coalescing intolarger globules, increasingexposure to lipase.)

Pancreatic lipase

Glycerol, fattyacids, glycerides

Chewing, peristalsis

Churning, mixing

Peristalsis, mixing

Large intestine Resident bacteria in the colon digest material in chyme.

Vitamin-K and some B-complex vitamins are released by these bacteria.

Composition of the adult human body

Oral cavity,pharynx,esophagus

Carbohydrate digestion

Polysaccharides(starch, glycogen)

Disaccharides(sucrose, lactose)

Salivary amylase

Smaller polysaccharides,maltose

Stomach

Protein digestion Nucleic acid digestion Fat digestion

ProteinsPepsin

Small polypeptides

Lumen of small intes-tine

Polysaccharides

Pancreatic amylases

Maltose and otherdisaccharides

Epitheliumof smallintestine(brushborder)

Disaccharidases

Monosaccharides

Polypeptides

Pancreatic trypsin and chymotrypsin (These proteases cleave bonds adjacent to certain amino acids.)

Smallerpolypeptides

Pancreatic carboxypeptidase

Amino acids

Small peptides

Dipeptidases, carboxypeptidase, and aminopeptidase (These proteases split off one amino acid at a time, working from opposite ends of a polypeptide.)

Amino acids

DNA, RNA

Pancreaticnucleases

Nucleotides

Nucleotidases

NucleosidesNucleosidasesandphosphatases

Nitrogenous bases,sugars, phosphates

Fat globules (Insoluble inwater, fats aggregate asglobules.)

Bile salts

Fat droplets (A coating ofbile salts prevents small drop-lets from coalescing intolarger globules, increasingexposure to lipase.)

Pancreatic lipase

Glycerol, fattyacids, glycerides

Chewing, peristalsis

Churning, mixing

Peristalsis, mixing

Large intestine Resident bacteria in the colon digest material in chyme.

Vitamin-K and some B-complex vitamins are released by these bacteria.

Salivary glands◦ Produce saliva

Mostly water Some enzymes

Salivary amylase Lysozyme

Mucus or mucin

Teeth◦ Mechanical digestion◦ Different teeth

Different functions Fit omnivore diet

Tongue

Swallowing: from mouth to stomach

Oral cavity,pharynx,esophagus

Carbohydrate digestion

Polysaccharides(starch, glycogen)

Disaccharides(sucrose, lactose)

Salivary amylase

Smaller polysaccharides,maltose

Stomach

Protein digestion Nucleic acid digestion Fat digestion

ProteinsPepsin

Small polypeptides

Lumen of small intes-tine

Polysaccharides

Pancreatic amylases

Maltose and otherdisaccharides

Epitheliumof smallintestine(brushborder)

Disaccharidases

Monosaccharides

Polypeptides

Pancreatic trypsin and chymotrypsin (These proteases cleave bonds adjacent to certain amino acids.)

Smallerpolypeptides

Pancreatic carboxypeptidase

Amino acids

Small peptides

Dipeptidases, carboxypeptidase, and aminopeptidase (These proteases split off one amino acid at a time, working from opposite ends of a polypeptide.)

Amino acids

DNA, RNA

Pancreaticnucleases

Nucleotides

Nucleotidases

NucleosidesNucleosidasesandphosphatases

Nitrogenous bases,sugars, phosphates

Fat globules (Insoluble inwater, fats aggregate asglobules.)

Bile salts

Fat droplets (A coating ofbile salts prevents small drop-lets from coalescing intolarger globules, increasingexposure to lipase.)

Pancreatic lipase

Glycerol, fattyacids, glycerides

Chewing, peristalsis

Churning, mixing

Peristalsis, mixing

Large intestine Resident bacteria in the colon digest material in chyme.

Vitamin-K and some B-complex vitamins are released by these bacteria.

Muscular sac◦ Churns & mixes food

Gastric glands◦ Parietal cells HCl,

intrinsic factor◦ Goblet cells mucus◦ Chief cells

pepsinogen, weak gastric lipase

◦ Gastrin Hormone Controls gastric juices

Comes out as chyme (2-6 hours)

Pepsin (active enzyme)

HCl

Parietal cellChief cell

Stomach

Folds of epithelial tissue

Esophagus

Pyloric sphincter

Epithelium

Pepsinogen

3

2

1

Interior surface of stomach.- Highly folded - Dotted with pits

Gastric gland. -Secrete gastric juice-Three types of cells

Mucus cells

Chief cells- Pepsinogen

Parietal cells - Secrete HCl

1 Pepsinogen and HCI secreted into lumen

2 HCl convertspepsinogen to pepsin

3 Pepsin activatesmore pepsinogen

5 µ

m

Small intestine

Cardiac orifice

Liver Secretes bile (stored in gall bladder) Components: Bile

salts & bile pigments

Emulsifies fats

Gallbladder Stores, concentrates,

and releases bile into duodenum

Cystic duct + hepatic duct = common bile duct

Stimulated by the hormone cholecystokinin (CCK)

Exocrine function Acinar cells secrete

pancreatic juice◦ Amylase◦ Lipase◦ Trypsin◦ Chymotrypsin◦ Carboxypeptidase◦ Nuclease◦ NaHCO3

-

Secretin and cholecystokinin (CCK) fr intestinal wall stimulates PJ production

Oral cavity,pharynx,esophagus

Carbohydrate digestion

Polysaccharides(starch, glycogen)

Disaccharides(sucrose, lactose)

Salivary amylase

Smaller polysaccharides,maltose

Stomach

Protein digestion Nucleic acid digestion Fat digestion

ProteinsPepsin

Small polypeptides

Lumen of small intes-tine

Polysaccharides

Pancreatic amylases

Maltose and otherdisaccharides

Epitheliumof smallintestine(brushborder)

Disaccharidases

Monosaccharides

Polypeptides

Pancreatic trypsin and chymotrypsin (These proteases cleave bonds adjacent to certain amino acids.)

Smallerpolypeptides

Pancreatic carboxypeptidase

Amino acids

Small peptides

Dipeptidases, carboxypeptidase, and aminopeptidase (These proteases split off one amino acid at a time, working from opposite ends of a polypeptide.)

Amino acids

DNA, RNA

Pancreaticnucleases

Nucleotides

Nucleotidases

NucleosidesNucleosidasesandphosphatases

Nitrogenous bases,sugars, phosphates

Fat globules (Insoluble inwater, fats aggregate asglobules.)

Bile salts

Fat droplets (A coating ofbile salts prevents small drop-lets from coalescing intolarger globules, increasingexposure to lipase.)

Pancreatic lipase

Glycerol, fattyacids, glycerides

Chewing, peristalsis

Churning, mixing

Peristalsis, mixing

Large intestine Resident bacteria in the colon digest material in chyme.

Vitamin-K and some B-complex vitamins are released by these bacteria.

Enteropeptidase

Completes digestion of nutrients in chyme

Absorbs products of digestion

Receives enzymes from pancreas and gall bladder

Lumen, villi, lacteal, microvilli, intestinal glands

Watery fluid, digestive enzymes on microvilli: disaccharidase, dipeptidase, nucleotidases

25 cm

1-2 m

2 m

Liver

Bile

Acid chyme

Stomach

Pancreatic juice

Pancreas

Intestinaljuice

Duodenum of small intestine

Gall-bladder

Oral cavity,pharynx,esophagus

Carbohydrate digestion

Polysaccharides(starch, glycogen)

Disaccharides(sucrose, lactose)

Salivary amylase

Smaller polysaccharides,maltose

Stomach

Protein digestion Nucleic acid digestion Fat digestion

ProteinsPepsin

Small polypeptides

Lumen of small intes-tine

Polysaccharides

Pancreatic amylases

Maltose and otherdisaccharides

Epitheliumof smallintestine(brushborder)

Disaccharidases

Monosaccharides

Polypeptides

Pancreatic trypsin and chymotrypsin (These proteases cleave bonds adjacent to certain amino acids.)

Smallerpolypeptides

Pancreatic carboxypeptidase

Amino acids

Small peptides

Dipeptidases, carboxypeptidase, and aminopeptidase (These proteases split off one amino acid at a time, working from opposite ends of a polypeptide.)

Amino acids

DNA, RNA

Pancreaticnucleases

Nucleotides

Nucleotidases

NucleosidesNucleosidasesandphosphatases

Nitrogenous bases,sugars, phosphates

Fat globules (Insoluble inwater, fats aggregate asglobules.)

Bile salts

Fat droplets (A coating ofbile salts prevents small drop-lets from coalescing intolarger globules, increasingexposure to lipase.)

Pancreatic lipase

Glycerol, fattyacids, glycerides

Chewing, peristalsis

Churning, mixing

Peristalsis, mixing

Large intestine Resident bacteria in the colon digest material in chyme.

Vitamin-K and some B-complex vitamins are released by these bacteria.

Areas of Colon◦ Cecum ◦ Rectum ◦ Terminates at anus

Absorption of water and electrolytes

Concentration & elimination of solids

Home for bacteria that produce biotin, folic acid, vitamin K, several B-vitamins, gases

Name Source Stimulant Target Organ Function

Stomach GastrinPyloric mucosa

Partially-digested food

Gastric glandsSecretion of gastric juice

Intestinal Gastrin

Intestinal mucosa

Stomach

SecretinAcidity of

chymePancreas and

liverSecretion of PJ rich in

HCO3- and bile production

Cholecystokinin (CCK)

Fats or combination of acids and

fats

Pancreas and gallbladder

(Sphincter of Oddi in CBD)

Secretion of PJ, bile from gallbladder, opening of

SO

EnterocrininAcidity of

chymeDuodenum

Secretion of intestinal juice

Enterogastrone or Gastric Inhibitory

Peptide (GIP)

Fats StomachInhibits secretion of

gastric juice and decreases gastric motility

Liver

Gall-bladder

CCK

Entero-gastrone

Gastrin

Stomach

Pancreas

Secretin

CCK

Duodenum

Key

Stimulation

Inhibition