BIO 3.3 The Digestive System

Question 1

What is Digestion ? (Simplified)

Answer 1

The digestive system
takes in food, digests it,
absorbs nutrients and
excretes the remaining
waste.

The nutrients are used to build and repair tissue, and provide energy.

Question 2

4 Stages of Digestion

Answer 2

INGESTION: intake of food through the mouth

DIGESTION: transformation of complex molecules contained in food into simpler molecules

ABSORBTION: nutrients are absorbed to enter the circulatory and lymphatic systems through the blood and the lymph

ELIMINATION: getting rid of fecal matter that wasn’t absorbed

Question 3

Components (organs) of ingestion

Answer 3

Occurs in the MOUTH

Food moves down the esophagus assisted by peristalsis

Question 4

Components (organs) of digestion

Answer 4

MOUTH: teeth break down food, saliva (amalyse) chemically breaks down food

STOMACH: muscular contraction churns the food and gastric juices
(hydrochloric acid & enzymes) break down nutrients

SMALL INTESTINE: also breaks down fats with bile

Question 5

Components (organs) of absorption

Answer 5

SMALL INTESTINE: absorption of nutrients, smaller diameter

LARGE INTESTINE: absorption of water, larger diameter

Question 6

Components (organs) of elimination

Answer 6

RECTUM: stores fecal matter that has not been absorbed

ANUS: eliminated through the anus

Question 7

Accessory Organs

Answer 7

Aid in the digestion of food by supplying digestive enzymes and other fluids.

LIVER: Secretes bile needed for the digestion (emulsification) of lipids (fats)

GALLBLADDER: Stores bile produced in the liver

PANCREAS: Produces hormones (incl. insulin & glucagon) and pancreatic juices that pass to the small intestine to help break down
nutrients.

Question 8

Peristalsis

Answer 8

Circles of muscles lining the esophagus, coordinating contractions to push food down.

Question 9

Mechanical v.s Chemical Digestion

Answer 9

MECHANICAL: physically breaking down food (cutting up food with teeth)

CHEMICAL: chemical reactions that break down food (stomach acid breaking down food)

Question 10

Villi

Answer 10

Tiny, finger-like projections made up of cells that line the entire length of your small intestine

Increases surface area for nutrient absorption

Question 11

Bile

Answer 11

Enzymes secreted into the small intestine to digest lipids (fats)

Question 12

Amylase

Answer 12

Enzymes in saliva that break down sugars.