part 1 Physiology of GI Tract

Question 1

Name the 4 main functions performed by the digestive system.

Answer 1

ingestion
digestion (mechanical and chemical)
absorption
defecation

Question 2

What digestive system functions are carried out by the mouth?

Answer 2

ingestion and digestion

Question 3

Explain which digestive system functions are carried out by the stomach.

Answer 3

Mechanical and Chemical.

• Mechanical digestion continues as muscles churn and mix the food, breaking it into smaller pieces in the form of chyme, which is moved to the small intestine by peristalsis
• Chemical digestion continues as pepsin digests proteins.

Question 4

Explain which digestive system functions are carried out by the small intestine.

Answer 4

• chemical digestion continues as enzymes from the pancreatic juices break down starches and proteins, and begin digestion of fat.
• mechanical digestion continues as bile breaks down fat into small pieces.
• Absorption begins as digested food molecules, water and fat are absorbed into the bloodstream.

Question 5

Explain the two main hormones that are responsible for hunger and satiety.

Answer 5

Leptin and Ghrelin. Leptin is produced by adipose tissue (fat cells). The role of Leptin is to alert the brain to turn off the hunger center in the brain and activate the satiety center when consuming a meal. d
Ghrelin is produced by the stomach and has the opposite role. Ghrelin travels to the brain and stimulates the hunger center as it deactivates teh satiety center. Ideally, leptin and ghrelin work together to balance hunger and satiety.

Question 6

List the 5 biochemical materials needed by the body that are found in food.

Answer 6

Carbohydrates
Proteins
Lipids 
Vitamins 
Minerals

Question 7

What are the 2 classes of carbs and in what foods can each be found?

Answer 7

STARCHES - Wheat and vegetables (ex. potatoes)

SUGARS - Milk and fruits (ex. apples/peaches)

Question 8

what are the 3 classes of lipids?

Answer 8

Saturated fat
Unsaturated fat
Cholesterol

Question 9

what are the 2 classes of proteins and in what foods can each be found?

Answer 9

Complete Proteins: meat, poultry, eggs, milk or dairy products and soybeans

Incomplete Proteins: grains, legumes, seeds, nuts

Question 10

What is the definition of an essential amino acid, and how many essential amino acids are there for adults and where can they be found?

Answer 10

There are nine (9) amino acids called essential amino acids required in an adult human diet since the body is unable to make these amino acids. Complete proteins contain all nine essential amino acids.

Question 11

What are the 2 classes of vitamins? How is a vitamin different than a carbohydrate, lipid or protein? Why can ingetstion of excessive amounts of one type of vitamin be dangerous?

Answer 11

Water-soluable vitamins
Fat-soluable vitamins

Vitamins are organic compounds that are not consumed in metabolic reaction but help enzymes carry out the metabolic reactions which convert nutrients to materials needed by the body.
Fat-soluable vitamins are stored in body fat and the ingestion of excessive amounts can be problematic.

Question 12

List 2 ways in which minerals are different than carbohydrates, lipids and proteins. List the 7 minerals needed in the human diet and four foods which are good sources of these.

Answer 12

Minerals are INORGANIC compounds (not organic like carbohydrates, lipids and proteins) and are NOT used as fuel in metabolic reactions.
7 minerals: 
calcium
chloride
magnesium
phosphorous
potassium
sodium
sulfur

Milk, some meats, legumes, and vegetables are the best sources of minerals.