2 - The Digestive System

Question 1

What is hydrolysis?

Answer 1

Breakdown of sucrose, starch, protein, fat etc., using water and specific digestive enzymes

Question 2

What are the products of hydrolysis of disaccharides e.g., sucrose, lactose, maltose?

Answer 2

Monosaccharides (glucose + fructose/galactose/glucose)

Question 3

What are the products of hydrolysis of polysaccharides e.g. starch, fiber?

Answer 3

Many monosaccharides

But fiber is not digestable in humans

Question 4

What are the products of hydrolysis of proteins?

Answer 4

Amino acids + small peptides

Question 5

What are the products of hydrolysis of fats e.g. triglycerides?

Answer 5

Mono-glyceride + 2 Fatty acid
or
Glycerol + 3 Fatty acid

Question 6

How does digestion and absorption of macro-nutrients happen in the mouth?

Answer 6

Mechanical crushing

Starch (broken down by amylase)
(Some fats broken down by lipase)

No absorption

Question 7

How does digestion and absorption of macro-nutrients happen in the stomach?

Answer 7

pH 2 gastric juice (activate pepsin, denature food proteins, destroy bacteria)

Protein (broken down by pepsin)

Glucose, amino acids, water and alcohol absorbed

Question 8

How does digestion and absorption of macro-nutrients happen in the small intestine?

Answer 8

Carbohydrates (digested by pancreatic amylase and intestinal enzymes)
Fat (emulsification by bile, digestion by pancreatic and intestinal lipase)
Protein (break down by trypsin)

Carbohydrates, fat, protein, water, and alcohol absorbed

Question 9

How does digestion and absorption of macro-nutrients happen in the large intestine?

Answer 9

Fiber (partly broken down by intestinal bacteria)

Water absorbed

Fat and undigested protein carried out as waste

Question 10

Where are carbohydrates digested?

Answer 10

Mouth

Small intestine

Question 11

Where are proteins digested?

Answer 11

Stomach

Small intestine

Question 12

Where are fats digested?

Answer 12

Small intestine

Question 13

Where are carbohydrates absorbed?

Answer 13

Stomach (glucose)

Small intestine

Question 14

Where are proteins absorbed?

Answer 14

Stomach (amino acids)

Small intestine

Question 15

Where are fats absorbed?

Answer 15

Small intestine

Question 16

Where is water absorbed?

Answer 16

Stomach
Small intestine
Large intestine

Question 17

Where is alcohol absorbed?

Answer 17

Stomach

Small intestine

Question 18

Is optimal absorption of micro-nutrients dependent on the chemical found it is found in food?

Answer 18

Yes. Iron from meat is better absorbed than iron from vegetables.

Question 19

What are some functions of water?

Answer 19

Maintain normal internal temperature
Medium for chemical reactions, transport of nutrients, enzyme action
Elimination of waste products (urine and stools)
Participates in energy formation

Question 20

Why do we need to replenish water?

Answer 20

To replace water lost in urine, perspiration, stools and exhaled air (maintain homeostasis e.g., pH fluctuations)

Water needs are affected by:
Activity
Weather
Illness
Specific diets
Specific foods

Question 21

What is the adequate intake of water?

Answer 21

Women - 11 cups/day

Men - 15 cups/day

Question 22

What can result from water deficiency?

Answer 22

Symptoms:
Nausea
Rapid heartbeat
Increased body temperature
Dizziness
Difficulty moving

Unresolved dehydration can lead to kidney failure or death
Ingestion of fluids generally produces quick recovery

Question 23

What can result from water toxicity?

Answer 23

Symptoms:
Confusion
Headache
Vomiting
Seizure
Coma
Death

Excess water intake can lead to low blood sodium
Drinking too much water too quickly e.g., marathon runners

Question 24

How many calories are there in alcohol?

Answer 24

7 Calories/gram

Alcohol is an energy dense, empty calorie food

Question 25

What are some of the ‘special privileges’ of alcohol in the body?

Answer 25

No digestion needed
Quick absorption in stomach and small intestine
In small intestine, alcohol absorption gets priority over other nutrients

Circulated to body tissues quickly and easily in the blood

Question 26

HOW is alcohol absorbed?

Answer 26

Broken down in the liver (broken down by alcohol dehydrogenase into acetaldehyde, which is broken down by acetaldehyde dehydrogenase into acetic acid/acetate)

It is absorbed more slowly with food, decreasing effects of alcohol and blood alcohol concentrations.

Question 27

What are the positives of consuming alcohol?

Answer 27

Moderate (men 2 drinks/day, women 1 drink/day) alcohol consumption has positive associations on health (heart disease, type 2 diabetes, hypertension, stroke, dementia).

Phytochemicals (especially red wine) act as antioxidants (heart protective, lowers inflammation)

Question 28

What are the negatives of consuming alcohol?

Answer 28

Heavy drinking - 5 or more drinks/day

Increased risk of high blood pressure, stroke, dementia, some cancers, nervous system disorders
Likely to have nutrient deficiencies
Alcohol dependency
Alcohol poisoning (mental confusion, vomiting, seizures, slow or irregular breathing, low body temperature)
Liver damage (steatohepatitis, i.e., fatty liver, may progress to cirrhosis)

Question 29

What are some other effects of alcohol? (not classified under positive or negative effects)

Answer 29

Intoxication (legal limit is 0.08%, body impaired at 0.13%, possible death at 0.35%)

Dehydration (increased urine output)

Hangover (dehydration and by-products of alcoholic fermentation)