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Biology 12
DIGESTIVE SYSTEM ASSIGNMENT
Learning Objectives: see LO’s I.
Reference: Chapter 14
Part I.
Vocabulary and Question Assignment
1.
Use a dictionary to help you explain why digestion of food in humans is called an
extracellular process?
2.
What are the functions of the digestive system?
Mouth.
3.
Distinguish between chemical and mechanical digestion. How is food
mechanically digested in the mouth?
4.
Why is salivary amylase classed as a hydrolytic enzyme?
5.
Once again, what is the role of water in the digestion of starch or any nutrient
polymer?
Pharynx
6.
Identify the need for an epiglottis.
.
Esophagus
7.
Define the term peristalsis.
8.
Where else does peristalsis occur in the digestive system? Why would peristalsis
be a rather slow-acting set of muscle contractions in other parts of the digestive
system?
9.
Describe the structure and operation of a sphincter. Name the sphincter
separating the esophagus and stomach.
Stomach
10.
How is food mechanically digested in the stomach (2 ways)?
11.
List 3 roles of HCl in the stomach.
12.
What is meant by the term acid chyme?
Biology 12/ruth
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13.
Name the sphincter that separates the stomach and small intestine. .
14.
What enzyme is present in the stomach? What is its inactive form called?
Small Intestine
15.
Would the emulsification of fat by bile salts be an example of chemical or
physical (mechanical) digestion? Explain.
16.
What are two benefits of sodium bicarbonate (NaHCO3), being secreted by the
pancreas into the small intestine?
17.
What is the role of pancreatic juice? Be specific and use your notes as a
reference.
18.
Insulin is made by the pancreas and secreted into the blood, not the intestine.
Explain its importance to the body.
19.
What is the general role of enzymes secreted from the duodenum and jejunum?
20.
Why are ALL digestive enzymes described as hydrolytic?
21.
List seven major roles of the liver.
Large Intestine
22.
What are the functions of the colon (= large intestine)?
23.
Fiber can reduce cholesterol in the blood and help prevent cancer. Explain how it
accomplishes both of these beneficial effects.
24
What is the value of bacteria found in the large intestine?
25.
Briefly describe why a human diet must contain carbohydrates, proteins, fats,
vitamins, minerals and water, that is, describe the contribution of each to our
metabolism. Give some specific examples.
Part II
Absorption of Products of Digestion
Structure of a Villus
1.
Draw an enlarged diagram of a villus (Fig. 12.6)
2.
Colour the blood vessel capillary bed and lymph vessel.
3.
Label all significant parts.
4.
Distinguish between villi and microvilli.
Biology 12/ruth
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Methods of Absorption (Ref. Ch. 4)
5.
Make brief notes for each of the following processes. Include a diagram where
requested.
a)
b)
c)
d)
e)
Diffusion
Osmosis
Facilitated transport (diagram)
Active Transport (diagram)
Endocytosis (diagram )
i.
pinocytosis Cell drinking
ii.
phagocytosis Cell eating
6.
The following nutrients are absorbed by the SI. List which process(es) listed above
ensure their absorption.
a)
glucose:
b)
amino acids:
c)
glycerol: fatty acids:
7.
Once absorbed the nutrients either enter a capillary or a lacteal. Indicate for each of the
nutrients which vessel it enters and the process by which it is absorbed.
a)
glucose:
b)
amino acids:
c)
lipids (reformed where?):
Biology 12/ruth
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Organ/Region
PH
Mouth
Substrate
Enzyme
Starch
Stomach
Product or Products
Salivary glands
Pepsin
Small Intestine
Duodenum (lumen)
8.2
Lumen
(sodium bicarbonate)
8.2
Trypsin
Lumen
8.2
Amylase
Microvilli
8.2
Microvilli
8.2
Microvilli
8.2
Microvilli
8.2
Biology 12/ruth
Origin of Enzyme
Lipid
(bile)
fatty acids and.....
Polypeptides
Dipeptides
Sucrase
glucose and glucose
Absorbed by villus
Lactose