Module 2.1: Digestion: Food to Fuel

Question 1

Before food even enters the mouth, the nervous system and variety of hormones are set off by:

Answer 1

• cognition: thoughts about food can start the flow of saliva
• sound: hearing a description of the meal
• odor: smells stimulate a hunger response and influence its taste
• appearance: seeing the food
• taste: begins as the food enters your mouth and also how it feels

Question 2

What is Digestion?

Answer 2

Digestion is the process of transforming food into basic nutrients that can be absorbed and used by the body.

Question 3

Explain the mechanical process of digestion.

Answer 3

The mechanical process begins in the mouth with chewing. From there, involuntary muscle contractions are used to move food mixtures along the tract, a process referred to as peristalsis.

Question 3

What happens once the food enters the mouth?

Answer 3

It begins to breakdown into smaller units in both mechanical (chewing) and chemical (enzymes, acid, bile, and mucus) processes

Question 3

Explain the chemical process related to digestion.

Answer 3

Enzymes catalyze the chemical reactions required to break down food particles into smaller parts, which prepares the nutrients for absorption.

Question 4

Where does nutrient absorption occur?

Answer 4

Across the wall of the gastrointestinal (GI) tract—a long hollow tube consisting of several layers of tissue that begins with the mouth and ends at the anus.

Question 5

What is mucosa?

Answer 5

The mucosa (intestinal wall) is the inner-most layer, and it is made of absorptive cells and glands.

Question 6

What is circular and longitudinal muscles?

Answer 6

They comprise the outer layers, both of which function to mix and move food along the GI tract.

Question 7

What are the three processes the body can use to move nutrients from the GI tract into the blood/lymph system and eventually into the cells?

Answer 7

1. Passive diffusion: Substances move easily in and out of cells without the use of energy. Nutrients move from high to low concentrations.
2. Facilitated diffusion: No energy is required, but a special protein carrier is required to help substances cross in or out of the cell. Nutrients move from high to low concentrations.
3. Active transport: Energy is required to move substances in or out of the cell. Nutrients move from low to high concentrations.

Question 8

What is the difference between passive and active transport?

Answer 8

Passive transport does not require an input of energy to transport nutrients across the membrane. Facilitated diffusion needs a specialized carrier protein. In both cases, nutrients move from high concentration to low.

Active transport requires input of energy to move nutrients against the natural gradient, moving from areas of low to high concentration.

Question 9

What are the GI tract six main parts?

Answer 9

1 - mouth
2 - esophagus
3 - stomach
4 - small intestine
5 - large intestine
6 - rectum

Question 10

What are the four main organs that produce and secrete substances that aid in digestion, but are not part of the GI tract?

Answer 10

1 - salivary glands
2 - liver
3 - gallbladder
4 - pancreas

Question 11

What does the mouth do?

Answer 11

Alters the food particles and prepares them to be swallowed.
Both mechanical and chemical digestions take place in the mouth.

Question 12

What is saliva?

Answer 12

a watery fluid containing
(1) a lubricant (mucus) and
(2) enzymes to prepare food for the next step in the GI tract.

Question 13

How does mucus and enzymes aid in the break down of food?

Answer 13

Mucus mixes with food, lubricating the particles and making it easier to swallow.

Enzymes released in the mouth have specific functions:

• Salivary amylase breaks down starches.
• Lingual lipase breaks down fats.

Question 14

What are the five flavors that we tase?

Answer 14

1 – sweet
2 – salty
3 – sour
4 – bitter
5 – umami (a meaty flavor)

Question 15

What is the role of the esophagus?

Answer 15

It is the tube that connects the throat with the stomach. The role of the esophagus is to transport food to the stomach.

Question 16

During the swallowing process, food lands on a flap of tissue called _________.

Answer 16

epiglottis

Question 17

What does the epiglottis do?

Answer 17

The epiglottis folds down over the trachea, or wind pipe, during swallowing to prevent food from entering the trachea.

Question 18

What is the sphincter muscle?

Answer 18

The sphincter muscle is a circular muscle located at the end of the esophagus.

Once food passes through it on the way to the stomach, the muscle constricts (closes) and prevents the backflow of the stomach contents into the esophagus.

Question 19

What is the stomachs role?

Answer 19

The stomach’s role is to store, mix, dissolve, and continue the digestion of food.

Food particles in the stomach are mixed with gastric juice and enzymes. The acid in the gastric juice prepares proteins for digestion and activates enzymes.

Question 20

What are the two enzymes in the stomach?

Answer 20

1.Pepsin is an enzyme that breaks down proteins.
2.Gastric lipase is an enzyme that begins fat digestion.

Question 21

Define chyme, gastrin, and Intrinsic factor in the stomach.

Answer 21

Chyme is the resulting substance when food particles are mixed with stomach acids and enzymes.

Gastrin is the hormone responsible for controlling the concentration of acid in the stomach.

Intrinsic factor is a vital glycoprotein produced in the stomach.

Question 22

What is the small intestine?

Answer 22

Small intestine approximately twenty feet long and connects the stomach to the large intestine is lined with mucosa, and folded over many times.

Question 23

What is the pyloric sphincter?

Answer 23

The pyloric sphincter connects the stomach to the small intestines.
Its major role is to control the release of chyme into the small intestine.

Question 24

What are the 3 sections of the small intestine?

Answer 24

1. Duodenum: the first portion of the small intestine is wider than the remainder of the small intestine.
2. Jejunum: the middle section
3. Ileum: the final section that connects the small and large intestines

Question 25

What are the finger-like projections within the folds of the small intestine called?

Answer 25

Villi - they help trap food and necessary for the process of digestion and absorption.
Fat soluble nutrients go into the lymph system while other nutrients are absorbed into the bloodstream.

Question 26

What are organs are associated with the small intestine during digestion?

Answer 26

• The liver secretes bile, which is stored in the gallbladder.
• The gallbladder will store the bile until it receives a hormonal signal that fat has entered the small intestine.
  -The pancreas releases a mixture of water, bicarbonate, and enzymes called pancreatic juice that breaks down carbohydrates, protein, and fats.

Question 27

What are the hormones released by the pancreas that help with glucose regulation?

Answer 27

Glucagon and insulin

Question 28

What does the ileocecal sphincter do?

Answer 28

It prevent the contents of the large intestine from reentering the small intestine.

Question 29

What is the large intestine?

Answer 29

It is the last section of the digestive tract.
It is five feet long and known as the colon.

Question 30

Name the four sections that make up the large intestine.

Answer 30

(1) ascending colon (2) transverse colon (3) descending colon (4) sigmoid

Question 31

What is feces and where does it sit?

Answer 31

Feces is a semi-solid mass that passes through the large intestine.
It sits in the rectum- the end of the large intestine - until muscular contractions pushes in into the anus.

Question 32

What are the two bacterias important to our immune health?

Answer 32

Bifidobacterial and lactobacilli

Question 33

What are probiotics and prebiotics?

Answer 33

Probiotics are foods that contain these bacteria. Fermented milk and yogurt are examples of probiotics that can be marketed to improve your gut health and digestion.

Prebiotics refers to substances that stimulate bacterial growth in the large intestine.