Chapter 26: Digestive System

Question 1

What are the two components of the digestive system and their general functions?

Answer 1

1.Gastrointestinal (GI) tract: continuous tube from oral cavity to anus
2. Accessory digestive organs: assist breakdown of food through the liver, pancreas, and gallbladder

Question 2

List the four tissue layers of the GI tract deep to superficial.

Answer 2

1. Mucosa
2. Submucosa
3. Muscularis
4. Serosa

Question 3

Name the tissue layer and tissue type of the mucosa.

Answer 3

1. Epithelium
   - simple columnar with microvilli
2. Lamina propia
   - areolar CT and capillaries (immune cells)
3. Muscularis mucosa
   - thin layer of smooth muscle

Question 4

Name the layers and tissue type of the submucosa.

Answer 4

Layers
1. Submucosal gland
2. Blood vessel
3. Submucosal nerve plexus
Tissue type: areolar or dense irregular CT

Question 5

Name the tissue layers of the muscularis.

Answer 5

1. Inner circular layer (smooth muscle)
2. Myenteric nerve plexus
3. Outer longitudinal layer (smooth muscle)

Question 6

What are the primary types of motility of the GI tract.

Answer 6

• Mixing
• Propulsion

Question 7

Name this most superficial layer and the tissue type.

Answer 7

Serosa
- areolar CT, collagen, elastic fibers

Question 8

What are the two oral cavity functions and what type of CT is present?

Answer 8

1. Ingestion
2. Digestion
   - mechanical (teeth and tongue)
   - chemical (saliva)
   Tissue type: nonkeratinized stratified squamous epithelium

Question 9

List the 5 functions of saliva from salivary glands.

Answer 9

1. moistens food = becomes bolus
2. begin chemical digestion of starch
3. food molecules dissolved for taste
4. cleanses oral cavity
5. help inhibits bacterial growth

Question 10

What are the three salivary glands?

Answer 10

• Parotid
• Submandibular
• Sublingual

Question 11

Identify this salivary gland and the amount of saliva it secretes.

Answer 11

Parotid salivary gland
- largest
- secretes 30% of saliva from parotid duct

Question 12

Identify these salivary glands and the amount of saliva they secrete.

Answer 12

Submandibular salivary gland (inferior to mandible)
- 65% of saliva from submandibular duct
Sublingual salivary gland (bottom of tongue)
- 5% of saliva from multiple submandibular ducts

Question 13

Describe the 3 phases of swallowing.

Answer 13

1. Chewing (voluntary)
   - bolus of food is pushed by tongue against hard palate
   - moves towards oropharynx
2. Pharyngeal (involuntary)
   - medulla oblongata controls swallowing reflex
   - epiglottis closes over laryngeal opening
3. Esophageal (involuntary)
   - muscles push bolus towards stomach

Question 14

The esophagus tube connects which structure to which organ?

Answer 14

Connects the laryngopharynx to stomach

Question 15

Is there digestion or absorption occurring in the esophagus?

Answer 15

no, propulsion only

Question 16

Which type tissue is located in the esophagus?

Answer 16

Non-keratinized stratified squamous
(Exception is the muscularis)

Question 17

List the 4 functions of the stomach.

Answer 17

• temporary storage
• bolus is chemically and mechanically digested
• protein digestion
• gastric folds (expansion)

Question 18

The liquid form of bolus in the stomach is called….

Answer 18

Chyme

Question 19

What are the 3 muscularis layers that churn food in the stomach?

Answer 19

• inner oblique layer
• middle circular layer
• outer longitudinal layer

Question 20

Explain the process of gastric mixing.

Answer 20

1. Contractions of smooth muscle in stomach wall mix bolus with gastric secretions to form chyme
2. Peristaltic waves move stomach contents toward pyloric region

Question 21

Explain the process of gastric emptying.

Answer 21

1. The pressure gradient from the peristaltic waves causes sphincter to open
2. Chyme enters duodenum
3. Pyloric sphincter closes and retropulsion occurs

Question 22

What are the two functions of the small intestine?

Answer 22

1. Absorb 90% of water and nutrients
2. Finish chemical digest (chyme)
3. Peristalsis

Question 23

What is the tissue type of the small intestine?

Answer 23

Simple columnar epithelium with microvilli

Question 24

What is the shortest portion of the small intestine? What constitutes it as being the anatomic blender?

Answer 24

Duodenum
- chyme from stomach
- bile from liver/gallbladder
- pancreatic juices

Question 25

Where does the most absorption and secretion occur in the small intestine?

Answer 25

Jejunum

Question 26

Which part of the small intestine completes absorption and connects to the ileocecal valve?

Answer 26

Ileum

Question 27

Identify this structure of the small intestine.

Answer 27

Circular folds

Question 28

Identify these structures of the small intestine.

Answer 28

1. Circular folds 2. Intestinal villi

Question 29

In intestinal villi, which two cells are present and what are their function?

Answer 29

1. Microvilli: absorbs nutrients 2. Goblet cells: produces mucin

Question 30

Why does the small intestine contain circular folds?

Answer 30

To increase surface area

Question 31

List the 3 functions of the large intestine.

Answer 31

1. Absorption of water from remaining chyme 2. Peristalsis 3. Defecation = feces

Question 32

What are the accessory digestive organs?

Answer 32

- liver - gallbladder - pancreas

Question 33

Identify this accessory digestive organ.

Answer 33

Liver

Question 34

What are the main functions of the liver?

Answer 34

1. Produce and secrete bile - bile emulsify fats - left and right hepatic duct 2. Detox - packed with smooth ER in cells

Question 35

Identify this accessory digestive organ.

Answer 35

Gallbladder

Question 36

What is the primary function of the gallbladder?

Answer 36

Concentrates and releases bile that is produced from the liver

Question 37

Describe the endocrine and exocrine functions of the pancreas.

Answer 37

Endocrine: produce and secrete insulin and glucagon Exocrine: produce pancreatic juices (mucin, bicarbonate, and digestive enzymes)

Question 38

Describe how all the accessory organs work together.

Answer 38

Question 39

Identify the following structures of the stomach.

Answer 39