Module 7.1 Overview of Digestion

Question 1

What is the primary function of the Digestive System?

Answer 1

The primary function of the digestive system is to transfer nutrients, water, and electrolytes to the blood for use by the cells.

Question 2

Unlike virtually all other body systems, the digestive system is not regulated based on the maintenance of _______\_

Answer 2

Unlike virtually all other body systems, the digestive system is not regulated based on the maintenance of homeostasis

Question 3

Instead of being regulated by homeostasis, the digestive system is regulated according to mechanisms that maximize the absorption of _____\_, _____\_, and _____\_, regardless of physiological need

Answer 3

Instead of being regulated by homeostasis, the digestive system is regulated according to mechanisms that maximize the absorption of nutrients, water, and electrolytes, regardless of physiological need

Question 4

What are the four processes of digestion?

Answer 4

1. motility,
2. secretion,
3. digestion, and
4. absorption

Question 5

Overview of the digestive system functions: The digestive system includes four processes: motility, secretion, digestion, and absorption.

_____ involves digestive tract muscular contractions that are responsible for mixing and moving the contents through the digestive tract

Answer 5

Motility involves digestive tract muscular contractions that are responsible for mixing and moving the contents through the digestive tract

Question 6

Secretions of the digestive system include

• digestive juices, which are secreted from the _____ glands and _____ the process of digestion, and
• digestive system hormones, which are secreted from the _____ cells and _____ digestive system function

Answer 6

Secretions of the digestive system include

• digestive juices, which are secreted from the exocrine glands and facilitate the process of digestion, and
• digestive system hormones, which are secreted from the endocrine cells and regulate digestive system function

Question 7

_____, the biochemical breakdown of food molecules by hydrolysis, is dependent on enzymes

Answer 7

Digestion, the biochemical breakdown of food molecules by hydrolysis, is dependent on enzymes

Question 8

_______\_ is the movement of digested nutrients, as well as water and electrolytes, from the digestive tract into the blood

Answer 8

Absorption is the movement of digested nutrients, as well as water and electrolytes, from the digestive tract into the blood

Question 9

The digestive system includes the

• ______ (______) _____\_ and the
• accessory organs, which include
  
  • the ______ _____\_,
  • _____\_,
  • _____\_, and
  • _____\_.

These structures are shown in the following diagram.

Answer 9

The digestive system includes the

• digestive (gastrointestinal) tract and the
• accessory organs, which include
  
  • the salivary glands,
  • pancreas,
  • liver, and
  • gallbladder.

These structures are shown in the following diagram.

Question 10

What is the digestive (gastrointestinal) tract?

Answer 10

The digestive tract is a long, hollow tube that extends from the mouth to the anus

Question 11

The digestive tract is continuous with the external environment and supports _____ that are specific to digestive processes and would not be appropriate for the internal environment of the body.

For example, the _____ contains higher concentrations of _____, _____, and ____\_-_____ compared to other compartments within the body

Answer 11

The digestive tract is continuous with the external environment and supports l_uminal conditions_ that are specific to digestive processes and would not be appropriate for the internal environment of the body.

For example, the lumen contains higher concentrations of acid, enzymes, and micro-organisms compared to other compartments within the body

Question 12

What are the four layers of the digestive tract wall?

Answer 12

1. the mucosa,
2. submucosa,
3. muscularis externa, and
4. serosa

Question 13

The mucosa is composed of

1. the _________\_,
2. the _________\_, and
3. the __________

Answer 13

The mucosa is composed of

1. the mucous membrane,
2. the lamina propria, and
3. the muscularis mucosae

Question 14

The mucous membrane is an ___\_cell layer consisting of ___\_ cells, ___\_cells, and ___\_ cells

Answer 14

The mucous membrane is an epithelial cell layer consisting of absorptive cells, exocrine cells, and endocrine cells

Question 15

The lamina propria is composed of ____\_and ____\_ tissue and also contains ____\_and ____\_ vessels and nerves.

Answer 15

The lamina propria is composed of connective and lymphoid tissue and also contains small blood and lymph vessels and nerves.

Question 16

The muscularis mucosae is composed of ________\_ cells

Answer 16

The muscularis mucosae is composed of smooth muscle cells

Question 17

The submucosa contains

• ________\_,
• large ____\_and ____\_ vessels, and
• the ________\_of the ________\_(ENS)

Answer 17

The submucosa contains

• connective tissue,
• large blood and lymphatic vessels, and
• the submucosal plexus of the enteric nervous system (ENS)

Question 18

The muscularis externa contains an

• ___ ___ ___ ___ layer
• ___ ___ ___ ___ layer
• ___ ___ of the enteric nervous system

Answer 18

The muscularis externa contains an

• inner circular smooth muscle layer
• outer longitudinal smooth muscle layer
• myenteric plexus of the enteric nervous system

Question 19

The serosa is composed of ____\______\_ and secretes ____\______\_, which is important for the lubrication of the digestive organs and surrounding viscera.

Answer 19

The serosa is composed of connective tissue and secretes serous fluid, which is important for the lubrication of the digestive organs and surrounding viscera.

Question 20

There are three energy-rich nutrient molecules that are consumed in the diet and must be processed by the digestive system:

1. ______,
2. ______, and
3. ______ .

Answer 20

There are three energy-rich nutrient molecules that are consumed in the diet and must be processed by the digestive system:

1. carbohydrates,
2. proteins, and
3. fats (lipids).

Question 21

Carbohydrates are consumed as _____\_or _____\_, such as sucrose, lactose, starch, glycogen, and cellulose.

These molecules must be digested into _____\_ in order to be absorbed

Answer 21

Carbohydrates are consumed as disaccharides or polysaccharides, such as sucrose, lactose, starch, glycogen, and cellulose.

These molecules must be digested into monosaccharides in order to be absorbed

Question 22

The enzymes responsible for the digestion of carbohydrates include ____\_, which are produced by the salivary glands and the pancreas, and ______\_, which are produced by the small intestine.

Answer 22

The enzymes responsible for the digestion of carbohydrates include amylases, which are produced by the salivary glands and the pancreas, and disaccharidases, which are produced by the small intestine.

Question 23

Amylase, produced by the _____\_and the _____\_ acts on _____\_to produce _____\_ and limit _____\_

Answer 23

Amylase, produced by the salivary glands and the pancreas acts on polysaccharides to produce disaccharides and limit dextrins

Question 24

Disaccharidases, produced by the ______\_act on ______\_ to produce ______\_

Answer 24

Disaccharidases, produced by the small intestine act on disaccharides to produce monosaccharides

Question 25

Proteins that are present in the digestive system originate from three potential sources:

Answer 25

Proteins that are present in the digestive system originate from three potential sources:

1. they can be ingested in the diet,
2. secreted as enzymes by exocrine cells, or
3. digested from sloughed-off cells of the digestive tract itself

Question 26

Proteins can be absorbed across the apical membrane as ____\_, ____\_, or ____\_, but can cross the basolateral membrane only as _____ ____\_

Answer 26

Proteins can be absorbed across the apical membrane as amino acids, dipeptides, or tripeptides, but can cross the basolateral membrane only as amino acids

Question 27

The enzymes that digest proteins are called ____\_and are secreted by the cells of the ____\_ and ____\_.

Answer 27

The enzymes that digest proteins are called proteases and are secreted by the cells of the stomach and pancreas.

Question 28

Fats are consumed primarily as _____\_

Answer 28

Fats are consumed primarily as triglycerides

Question 29

Unlike carbohydrates and proteins, fats are not _____\_and spontaneously aggregate in the aqueous ___\_ of the digestive tract

Answer 29

Unlike carbohydrates and proteins, fats are not water-soluble and spontaneously aggregate in the aqueous lumen of the digestive tract

Question 30

Fats are absorbed as ______\_and ______\_

Answer 30

Fats are absorbed as monoglycerides and fatty acids

Question 31

Monoglycerides and fatty acids are produced by the enzymatic actions of ____\_

Answer 31

monoglycerides and fatty acids are produced by the enzymatic actions of lipases

Question 32

Lipases are secreted by the ______\_, ____\_, and _______\_

Answer 32

Lipases are secreted by the salivary glands, stomach, and pancreas

Question 33

Along with ____\_and another pancreatic enzyme called ____\_, lipases break down each triglyceride into one ____\_and two ____\_ ____\_

Answer 33

Along with bile salts and another pancreatic enzyme called colipase, lipases break down each triglyceride into one monoglyceride and two fatty acids