Download Digestion in Man

Human digestion
Human digestive system
(General plan)
Accessory
digestive organs
Sites of digestion
Organ/s
Mechanical
Oral cavity
Esophagus
Pharynx
Chewing
Peristalsis
digestion
Carbohydrate digestion
Polysaccharides
(starch, glycogen)
Protein
digestion
Nucleic Acid
digestion
Lipid
digestion
Disaccharides
(sucrose, lactose)
Salivary amylase
Smaller polysaccharides,
maltose
Stomach
Churning
Mixing
Peristalsis
Proteins
Pepsin
Small polypeptides
Small
intestine
Lumen
Peristalsis
Mixing
Polysaccharides
Pancreatic amylase
Pancreatic trypsin
and chymotrypsin
Smaller polypeptides
DNA, RNA
Fat globules
Pancreatic
nucleases
Bile salts
Nucleotides
Maltose and other
disaccharides
Small
intestine
Epithelium
Disaccharidases
Monosaccharides
Small peptides
Nucleotidases
Fat droplets
Pancreatic lipase
Glycerol, fatty
acids, glycerides
Nucleosides
Dipeptidases,
carboxypeptidase, Nucleosidases, phosphatases
aminopeptidase
Amino acids
Nitrogenous bases,
sugars, phosphates
Composition of the adult human body
Digestion in the
Mouth
• Salivary glands
– Produce saliva
• Mostly water
• Some enzymes
– Salivary amylase
– Lysozyme
• Mucus or mucin
• Teeth
Swallowing: from mouth to stomach
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)
Liver
 Secretes bile
(stored in gall bladder)
 Emulsifies fats
Gallbladder
 Stores, concentrates,
and releases bile into
duodenum
 Stimulated by the
hormone
cholecystokinin (CCK)
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
Chemical digestion in
the duodenum (con’t.)
Absorption in the small intestine
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
Hormones coordinate secretion of digestive
juices
Name
Stomach Gastrin
Source
Pyloric
mucosa
Intestinal Gastrin
Stimulant
Partiallydigested food
Target Organ
Function
Gastric glands
Secretion of gastric juice
Stomach
Secretin
Acidity of
chyme
Pancreas and
Secretion of PJ rich in
liver
HCO3- and bile production
Cholecystokinin
(CCK)
Fats or
combination
of acids and
fats
Pancreas and
gallbladder
Secretion of PJ, bile from
(Sphincter of gallbladder, opening of SO
Oddi in CBD)
Enterocrinin
Enterogastrone or
Gastric Inhibitory
Peptide (GIP)
Intestinal
mucosa
Acidity of
chyme
Fats
Duodenum
Secretion of intestinal
juice
Stomach
Inhibits secretion of
gastric juice and
decreases gastric motility
Liver
Enterogastrone
Gallbladder
Gastrin
CCK
Stomach
Pancreas
Secretin
Duodenum
CCK
Key
Stimulation
Inhibition