1. Human digestion

2. Human digestive system (General plan)
Accessory digestive organs

3. Carbohydrate digestion Nucleic Acid digestion
Sites of digestion
Organ/s
Mechanical digestion
Carbohydrate digestion
Protein digestion
Nucleic Acid digestion
Lipid digestion
Oral cavity
Esophagus
Pharynx
Chewing
Peristalsis
Stomach
Churning
Mixing
Small intestine
Lumen
Epithelium
Polysaccharides
(starch, glycogen)
Disaccharides
(sucrose, lactose)
Salivary amylase
Smaller polysaccharides,
maltose
Pancreatic amylase
Maltose and other disaccharides
Disaccharidases
Monosaccharides
Proteins
Pepsin
Small polypeptides
Pancreatic trypsin and chymotrypsin
Smaller polypeptides
Small peptides
Dipeptidases, carboxypeptidase, aminopeptidase
Amino acids
DNA, RNA
Pancreatic
nucleases
Nucleotides
Nucleotidases
Nucleosides
Nucleosidases, phosphatases
Nitrogenous bases,
sugars, phosphates
Fat globules
Bile salts
Fat droplets
Pancreatic lipase
Glycerol, fatty
acids, glycerides

4. Composition of the adult human body

5. Digestion in the Mouth Salivary glands Teeth Produce saliva
Mostly water
Some enzymes
Salivary amylase
Lysozyme
Mucus or mucin
Teeth

6. Swallowing: from mouth to stomach

7. Digestion in the Stomach
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)
Vitamin B12 absorption by small intestine

8. Liver Gallbladder Secretes bile (stored in gall bladder)
Emulsifies fats
Gallbladder
Stores, concentrates, and releases bile into duodenum
Stimulated by the hormone cholecystokinin (CCK)

9. Pancreas Exocrine function Acinar cells secrete pancreatic juice
Amylase
Lipase
Trypsin
Chymotrypsin
Carboxypeptidase
Nuclease
NaHCO3-
Secretin and cholecystokinin (CCK) fr intestinal wall stimulates PJ production

11. Chemical digestion in the duodenum (con’t.)
anphys-fig jpg

12. Absorption in the small intestine
Chylomicron = cholesterol + fat globule+protein  lymph vessels  veins  heart
Capillaries  hepatic portal vessel (1 L/min)  liver  (regulation of blood sugar content)  heart

13. Reabsorption and elimination in the large intestine
Areas of the colon
Cecum
Rectum
Anus
Absorption of water and electrolytes
Concentration & elimination of solids
Home for bacteria that produce biotin, folic acid, vitamin K, several B-vitamins, gases

14. Hormones coordinate secretion of digestive juices
Name
Source
Stimulant
Target Organ
Function
Stomach Gastrin
Pyloric mucosa
Partially-digested food
Gastric glands
Secretion of gastric juice
Intestinal Gastrin
Intestinal mucosa
Stomach
Secretin
Acidity of chyme
Pancreas and liver
Secretion 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
Enterocrinin
Duodenum
Secretion of intestinal juice
Enterogastrone or Gastric Inhibitory Peptide (GIP)
Fats
Inhibits secretion of gastric juice and decreases gastric motility

15. Liver
Gall-
bladder
CCK
Entero-
gastrone
Gastrin
Stomach
Pancreas
Secretin
Duodenum
Key
Stimulation
Inhibition