Download Unit 8: Digestion

Unit 8: Digestion
Mr. Nagel
Meade High School
Think…
• What organs are involved with digestion?
• Are there any foods that your body may be
incapable of processing?
• Are all foods broken down in the same
location?
– If yes, state which organ.
– If no, provide evidence.
• How long does the process of digestion
take in a human?
IB Syllabus Statements
• 6.1.1
– Explain why digestion of large food molecules is essential.
• 6.1.2
– Explain the need for enzymes in digestion.
• 6.1.3
– State the source, substrate, products and optimum pH conditions for
one amylase, one protease and one lipase.
• 6.1.4
– Draw and label a diagram of the digestive system.
• 6.1.5
– Outline the function of the stomach, small intestine and large intestine.
• 6.1.6
– Distinguish between absorption and assimilation.
• 6.1.7
– Explain how the structure of the villus is related to its role in absorption
and transport of the products of digestion.
• http://click4biology.info/c4b/6/hum6.1.htm
Enzymes
• Why do we need to break down food?
- Food consists of large molecules that are insoluble.
- In order to be absorbed into the blood, it must be broken
down!
• What would we use to accomplish this
task?
- Enzymes accelerate the chemical reactions (lower Ea)
necessary to perform hydrolysis in order to degrade
macromolecules into soluble sizes.
- [More energy = higher body temperature]
- Enzymes designed for this purpose work best at natural
body temperature.
Enzymes
• Enzymes that assist in digestion (in order of
appearance)
–
–
–
–
–
–
–
Salivary Amylase
Pepsin
Renin
Trypsin, Chymotrypsin, and other Peptidases
Pancreatic Amylase
Pancreatic Lipase
Lactase
• Enzymes are classified by task
– Amylases (break down starches into Sugar)
– Proteases (break down proteins into Amino Acids
– Lipases (break down fats into Fatty Acids and
Glycerol
– Nucleases (break down nucleic acids into
Nucleotides
Research: Enzymes
Amylase
Protease
Lipase
(1)Salivary Amylase
(3)Pepsin
(6)Pancreatic Lipase
(2)Pancreatic Amylase
(4)Trypsin
(5)Chymotrypsin
• For each enzyme identify its:
– Source
– Substrate
– Product
– Optimum pH
Enzymes
• Salivary Amylase
– Mouth; Starch; Smaller Sugars; 6.7-7.0
• Pancreatic Amylase
– Pancreas; Starch; Maltose; 6.9
• Pepsin
– Stomach; Polypetides; Peptides; 1.5-1.6
• Trypsin
– Pancreas; Polypetides; Peptides; 7.8-8.7
• Chymotrypsin
– Pancreas; Polypetides; Peptides; 7.9
• Pancreatic Lipase
– Pancreas; Triglyceride; Glycerol+FA Chains; 8.0
http://www.worthington-biochem.com/introbiochem/effectspH.html
Structure
Structure
Structure
http://www.enchantedlearning.com/subjects/anatomy/digestive/
Modeling the Digestive System
• Each group needs to construct one of the
following organs:
– (1)Stomach
– (2)Liver
– (3)Gallbladder
– (4)Pancreas
– (5)Small Intestine
– (6)Large Intestine
• Using the streamers and organs,
assemble the digestive system on the floor
as a class!
Function
•
•
•
•
Mouth
Esophagus
Stomach
Small Intestine
– Duodenum
– Jejunum
– Ilium
• Large Intestine
– Cecum
– Rectum
Food Types
• Follow the path of the following foods:
– Hamburger
– Salad
– Fruit
– Pizza
Absorption vs. Assimilation
• What does it mean to Absorb? Assimilate?
Absorption: Soluble products enter the blood stream by way of the epithelial
cells of the small intestine.
Assimilation: Soluble products are absorbed into cells and tissues via their
delivery by the circulatory system.
Surface Area is Key
• Villi and infolds of the small intestine increase
rate of absorption
–
–
–
–
(a) Folds increase SA:VOL by 3x’s
(b) Villi increase SA by 10x’s
(c) Microvilli increase SA by another 10x’s
Total: 300x’s the absorption power!!!
• Network of blood vessels carry nutrients
away
Assessment Questions
• What are the major organs involved in
human digestion?
– Which would you consider to be the ‘primary’
organ of digestion? Why?
• What are the major enzymes involved in
human digestion, and where are they
found?
– What foods do they break down?
• What purpose do the villi and folds of the
intestine serve in absorption?