Digestive System Activites

Question 1

What are the goals of digestion?

Answer 1

-Extract nutrients from food and make energy (ATP) (Energy units are Calories : kcal)
-Obtain building blocks for growth and repair (less to be built by our body; saving on energy & some cannot be synthesized by the body; essential nutrients)

Question 2

Define essential nutrient + example

Answer 2

A nutrient that cannot be made by the body and must be provided by the diet (ex: vitamins, omega 3-6, 9/20 of the amino acids, minerals)

Question 3

What are the digestive activites?

Answer 3

1. Ingestion
2. Propulsion
3. Mechanical digestion
4. Chemical digestion
5. Absorption
6. Defecation

Question 4

What is ingestion and the organs involved?

Answer 4

-Entry of food through the mouth (mouth, teeth, tongue)
-Chewing, mixing with saliva and the first enzymes work together to form the bolus (chewed food & saliva)

Question 5

What is propulsion?

Answer 5

-Moving food forward through digestive tract
1. Deglutition or swallowing (voluntary)
2. Peristalsis (involuntary) (contraction waves of smooth muscles)

Question 6

What is mechanical digestion?

Answer 6

-It’s a physical process; makes smaller pieces out of big ones
1. Mascination (mouth)
2. Churning (stomach; bolus to chyme)
3. Segmentation (small intestine)
-Increases surface area and mobility of food

Question 7

What is chemical digestion?

Answer 7

-Enzymes (macromolecules are broken down and size of molecules matters for absorption)
-Starts in mouth and is completed in small intestine

Question 8

What is absorption?

Answer 8

-Nutrients exit the intestinal lumen and go through the intestinal wall to enter the body
1. Performed by the simple columnar epithelium of the small intestine
2. Nutrients go to bloodstream or lymphatic circulation

Question 9

What is defecation?

Answer 9

-Not all food can be digested and absorbed (chemically)
-Accumulation of feces in rectum