The document discusses the human digestive system. It describes the organs and structures involved in digestion, including the mouth, esophagus, stomach, small intestine, large intestine, liver, gallbladder and pancreas. It explains the roles of these organs and structures in breaking down nutrients like carbohydrates, proteins and fats into smaller molecules that can be absorbed and used by the body. Key enzymes produced in different organs that aid in digestion are also identified.

1. Digestive
System
Mrs. Stein

2. Nutrients
 Supply the body with materials for energy, growth,
and maintenance
 Carbohydrates - major energy source
 Simple (fruit, sugar) and complex (starch, grain)
 Fats (lipids) - found in cell membranes
 Fatty acids and glycerol
 Proteins play a variety of roles; growth, repair
 Amino acids
 Meat, beans, dairy
 Vitamins help regulate processes
 Minerals are inorganic compounds needed in small
amounts
 Calcium in bones, iron in hemoglobin

3. Digestive System
Pharynx
Salivary
Glands
Stomach
Esophagus
Mouth
Large Intestine
Gallbladder
(behind the liver)
Liver
Pancreas
(behind stomach)
Rectum
Small
Intestine

4. Digestion
 Break down large
molecules into smaller
molecules which can be
used by cells
 Physical and chemical
 Alimentary Canal – one
way tube which food
passes through the body
 Accessory structures
do not carry food, but aid
in digestion
Pharynx
Salivary
Glands
Stomach
Esophagus
Mouth
Large Intestine
Gallbladder
(behind the liver)
Liver
Pancreas
(behind stomach)
Rectum
Small
Intestine

5. Accessory Structures
 Liver produces bile which emulsifies fat
 Gallbladder stores bile
 Pancreas produces enzymes

6. Mouth
 Mechanical digestion
 Teeth crush food
 Saliva moistens food and
contains salivary amylase
 Starch into simpler sugar
 Chemical digestion

7. Esophagus
 Muscular tube connects
pharynx & stomach
 Peristalsis
 Waves of muscle contractions
 Bolus enters the stomach
thru a sphincter
 Acid may back up into the
esophagus
 Heartburn, reflux

8. Stomach
 Chemical digestion
 HCl kills bacteria, lowers pH to activate pepsin
 Proteins break down
 Peptic ulcer – hole in stomach wall
 Caused by bacteria
 Muscular sac lined with
mucus
 Protection, lubrication
 Mechanical digestion
 Smooth muscles churn
food

9. Small Intestine
 Duodenum - 1st
part of the small intestine
Enzymes & fluids enter here
 Carbohydrates, lipids, and proteins
digested here
 Nutrients absorbed
Pharynx
Salivary
Glands
Stomach
Esophagus
Mouth
Large Intestine
Gallbladder
(behind the liver)
Liver Pancreas
(behind stomach)
Rectum
Small
Intestine

10. Small Intestine
 Lined with finger-like projections called villi
Increase surface area for absorption
 Carbs and proteins
enter capillaries
 Fats enter the
lymph vessels
 Water, cellulose,
and indigestibles
remain

11. Large Intestine
 Absorbs water from
undigested material
 Bacteria synthesize
vitamin K
 Feces is stored in the
rectum, excreted by the
anus

12. Enzymes
 Stomach
 Pepsin – proteins  smaller peptide chains
 Rennin – curdles milk proteins
 Pancreas produces 3 enzymes which are
secreted into the duodenum
 Pancreatic amylase – starch  maltose
 Trypsin – proteins  amino acids
 Lipase – fats  fatty acids and glycerol

13. Enzymes of the Small Intestine
 Enzymes break disaccharides into
monosaccharides
 Maltase: maltose  2 glucose molecules
 Lactase: lactose  glucose and galactose
 Sucrase: sucrose  glucose and fructose
 Peptidase – breaks down small polypeptides
into amino acids

14. Enzyme or
Digestive
Fluid
Where it is
manufactured
Where it acts
What
molecule it
acts on
What results
from its
action
Salivary Amylase Mouth Maltose
Gastric Glands Stomach Proteins
Bile Duodenum
Pancreas Duodenum Starch
Trypsin Duodenum
Pancreas Duodenum Lipids
Maltase Duodenum Maltose
Duodenum Duodenum
Glucose and
Fructose
Lactase Duodenum Duodenum
Duodenum Duodenum Amino Acid
Pepsin
Salivary Gland
Liver
Polypeptides
Starch
Smaller Lipids
Pancreatic Amylase
Lipids
Pancreas Smaller PeptidesPolypeptides
Maltose
Lipase
Sucrase
Duodenum
Fatty Acids &
Glycerol
Sucrose
Glucose
Glucose & GalactoseLactose
PeptidesPeptidase

15. Accessory Structures