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Biology 12
DIGESTIVE SYSTEM ASSIGNMENT
Part I.
Vocabulary and Question Assignment
1.
Explain why digestion of food in humans is called an extracellular process?
Extracellular means outside the cell. Humans produce digestive enzymes inside cells but then secrete them into ducts or organs.
Therefore, digestion occurs outside the cells (unlike single celled organisms like amoebas that use phagocytosis to engulf their
food
2.
What are the functions of the digestive system?
To breakdown food, absorb nutrients and eliminate waste
Mouth.
3.
Distinguish between chemical and mechanical digestion. How is food mechanically digested in the mouth?
Mechanical breaks food into smaller pieces while chemical actually changes the chemical composition of the substrate.
Teeth…teeth mechanically break down food
4.
Why is salivary amylase classed as a hydrolytic enzyme?
It uses water to actually break apart the bonds and then OH- and H+ becomes part of the resulting products
5.
Once again, what is the role of water in the digestion of starch or any nutrient polymer? Be specific…think biomolecules
See above
Pharynx
6.
Identify the need for an epiglottis.
It prevents food from going down the trachea (air pipe)
Esophagus
7.
Explain the term peristalsis. Is it a voluntary process?
It is INvoluntary muscle contractions that pushes food down the esophagus
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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? Stomach (churning), small intestine, lg intestine, rctum
Slow process to allow for maximum nutrient absorption
9.
Describe the structure and operation of a sphincter. Name the sphincter separating the stomach and esophagus
Circular muscle will contract/ relax to allow food into the next part of the digestive system…cardiac sphincter
Stomach
10.
How is food mechanically digested in the stomach?
churning
11.
List 3 roles of HCl in the stomach.
#1 Denature/ unravel proteins into polypeptides
#2 Activate pepsinogen into pepsin
#3 Create a pH 1.52.5 which is ideal for pepsin to work (basically a different way of saying #2)
12.
What is meant by the term acid chyme?
This implies a certain composition of food. Starch has started to breakdown into maltose, protein has started to breakdown into
peptides and it would be acidic due to the HCl
13.
Name the sphincter that separates the stomach and small intestine.
pyloric
14.
What enzyme is present in the stomach? What is its inactive form called?
Pepsin…pepsinogen
Small Intestine
15.
16.
Would the emulsification of fat by bile salts be an example of chemical or physical (mechanical) digestion? Explain.
Physical…just creates smaller droplets of fat
What is the benefit of sodium bicarbonate (NaHCO3), being secreted by the pancreas into the small intestine?
It neutralizes the acid pH coming from the stomach. Creates optimal pH for enzymes that work in the small intestine
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17.
What is the role of pancreatic juice?
Water…transport of nutrients and to participate in hydrolysis
Sodium bicarbonate…see above
Trypsin, lipase, pancreatic amylase- all hydrolytic digestive enzymes
18.
Insulin is made by the pancreas and secreted into the blood, not the intestine. Explain its importance to the body.
Insulin will bind to liver protein receptors to cause glucose channels to open. Glucose enters liver and stores as glycogen. This
will lower the blood sugar
What is the general role of enzymes secreted from the duodenum?
Hydrolytic enzymes used to catalyze chemical reactions (digestion)
Why are ALL digestive enzymes described as hydrolytic?
They use water to breakdown their substrates
List 6 major roles of the liver.
BRSPUD
Bile production
Red blood cell breakdown
Blood sugar regulation
Blood protein production
Urea production
Detoxification of the blood
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20.
21.
Large Intestine
22.
23.
24.
25.
What are the functions of the colon (= large intestine)?
Conservation of water
Fiber can help prevent constipation, explain how.
Fibre holds onto water and prevents too much water being absorbed into the body
What is the value of bacteria found in the large intestine?
Breaks down indigestible material and releases vitamin K
Explain what would happen to cause a person to have diarrhea
Infection, food intolerance or stress can cause rapid contractions of the smooth muscle. This prevents water from being
absorbed into the blood and is instead eliminated
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Organ/Region
PH
Substrate
Enzyme
Origin of Enzyme
Product or Products
Mouth
Starch
Salivary amylase
Salivary glands
maltose
Stomach
Polypeptides
Pepsin
Stomach (gastric cells)
peptides
Small Intestine
Duodenum (lumen)
8.0
Lipid
(bile)
lipase
pancreas
fatty acids and glycerol
Small Intestine
(sodium bicarbonate)
8.0
peptides
Trypsin
pancreas
Smaller peptides
Small Intestine
8.0
Starch
Amylase
Pancreas
Maltose
Small Intestine
8.0
(Smaller) Peptides
Peptidase
Small Intestine
Amino Acids
Small Intestine
8.0
Sucrose
Sucrase
Small intestine
Fructose and Glucose
Small Intestine
8.0
Maltose
Maltase
Small intestine
glucose and glucose
Absorbed by villus
Small Intestine
8.0
Lactose
Lactase
Small Intestine
Galactose and glucose