CPPS 303_Overview of GI system_Feb 24 & 26_2025 (1)

Question 1

What are the two main components of the digestive system?

Answer 1

• Luminal gastrointestinal tract
• Accessory components

• Luminal structures include mouth, pharynx, esophagus, stomach, small intestine, and large intestine.
• Accessory components include teeth, tongue, salivary glands, liver, gallbladder, and pancreas.

Question 2

What are the six general tasks performed by the gastrointestinal (GI) system?

Answer 2

• Ingestion
• Secretion
• Motility
• Digestion
• Absorption
• Defecation

Each task plays a critical role in processing food and eliminating waste.

Question 3

4 Anatomical Regions

Answer 3

• Mouth and Esophagus
• Stomach
• Small Intestine
• Large Intestine

Question 4

What is the function of the upper esophageal sphincter (UES)?

Answer 4

Controls deglutition (swallowing)

UES is composed of skeletal muscle.

Question 5

What does the lower esophageal sphincter (LES) prevent?

Answer 5

Prevents regurgitation of stomach contents

LES is composed of smooth muscle.

Question 6

What are the three sections of the small intestine?

Answer 6

• Duodenum
• Jejunum
• Ileum

Each section has specific roles in digestion and absorption.

Question 7

What is the role of the pyloric sphincter?

Answer 7

Controls stomach emptying into the duodenum

Prevents excessive acidic gastric content from entering the duodenum.

Question 8

Fill in the blank: The _______ connects the ileum to the cecum.

Answer 8

ileocecal sphincter

It prevents backflow of colonic contents.

Question 9

What are the four anatomical regions of the digestive system?

Answer 9

• Mouth and esophagus
• Stomach
• Small intestine
• Large intestine

Each region has unique functions and structures.

Question 10

What is the primary function of the stomach?

Answer 10

• Storage
• Digestion
• Protection

The stomach stores food, digests it into chyme, and protects against pathogens.

Question 11

What is the role of the sphincter of Oddi?

Answer 11

Controls the release of bile and pancreatic juice

Located between the duodenum and the outlet of the liver, gallbladder, and pancreas.

Question 12

What are the three phases of swallowing (deglutition)?

Answer 12

• Voluntary phase
• Pharyngeal phase
• Esophageal phase

Each phase has distinct mechanisms and controls for moving food from the mouth to the stomach.

Question 13

What is primary peristalsis?

Answer 13

Peristalsis initiated by swallowing

It helps move the bolus through the esophagus.

Question 14

What is the average duration for GI contents to remain in the stomach?

Answer 14

Approximately 1 liter can be stored

The stomach regulates passage into the small intestine.

Question 15

What substances are primarily absorbed in the stomach?

Answer 15

Lipid-soluble substances such as alcohol

The stomach mainly digests proteins and fats.

Question 16

What is the significance of gastric accommodation?

Answer 16

Allows the stomach to relax and expand to hold food

Closely associated with the vagovagal reflex.

Question 17

True or False: The esophagus is primarily a conduit for food passage.

Answer 17

True

It does not participate significantly in digestion or absorption.

Question 18

What is the role of the gastric juice in digestion?

Answer 18

Chemically and mechanically digest food

Contains HCl, pepsinogen, and gastric lipase.

Question 19

Fill in the blank: The _______ phase of swallowing is involuntary.

Answer 19

pharyngeal

This phase is triggered by pressure receptors in the oropharynx.

Question 20

What happens during the esophageal phase of swallowing?

Answer 20

Coordinated contractions and relaxations move the bolus to the stomach

This phase involves peristalsis of the esophagus.

Question 21

What are the components of the gastric juice?

Answer 21

• HCl
• Pepsinogen
• Gastric lipase
• Mucus
• Bicarbonate

Each component plays a role in digestion.

Question 22

What is retropulsion?

Answer 22

The process of mixing and size reduction in the stomach

Occurs at the gastroduodenal junction.

Question 23

What type of muscle is the upper third of the esophagus composed of?

Answer 23

Striated skeletal muscle

This composition allows for voluntary control during swallowing.

Question 24

What is the primary role of retropulsion in the stomach?

Answer 24

Mixing of gastric contents and size reduction

Retropulsion occurs when most of the gastric contents are propelled back into the main body of the stomach during contractions.

Question 25

What is the function of the gastroduodenal junction?

Answer 25

Emptying a small portion of gastric contents into the duodenum ## Footnote It is where gastric contents are first propelled toward before being emptied.

Question 26

What are the three regions of the small intestine?

Answer 26

* Duodenum * Jejunum * Ileum ## Footnote The duodenum is the shortest, and the ileum is the longest region.

Question 27

What are the major functions of the small intestine?

Answer 27

* Mix chyme with digestive enzymes * Bring food in contact with mucosa for absorption * Complete digestion of carbohydrates, proteins, and lipids * Begin and complete digestion of nucleic acids ## Footnote The small intestine absorbs about 90% of nutrients and water that pass through the GI tract.

Question 28

Fill in the blank: The small intestine absorbs about _______ of nutrients and water that pass through the GI tract.

Answer 28

90% ## Footnote This absorption is crucial for nutrient uptake.

Question 29

What types of substances does the small intestine absorb?

Answer 29

* Small peptides * Amino acids * Monosaccharides * Fatty acids * Monoglycerides * Cholesterol * Water * Electrolytes * Minerals * Vitamin B12 ## Footnote The ileum specifically absorbs vitamin B12.

Question 30

What is segmentation in the context of small intestine motility?

Answer 30

Alternate segments contract with little or no net forward movement ## Footnote It helps in mixing the chyme with digestive enzymes.

Question 31

What are the four major sections of the large intestine?

Answer 31

* Cecum * Colon * Rectum * Anal canal ## Footnote The cecum connects to the ascending colon and has the appendix attached.

Question 32

What are the major functions of the large intestine?

Answer 32

* Drive contents of colon into rectum * Produce B vitamins and vitamin K with gut flora * Convert some indigested food particles into absorbable constituents * Absorb water, ions, and vitamins * Defecation (emptying rectum) * Formation of feces ## Footnote Enzymatic activity in digestion is not associated with secretions of the colon.

Question 33

True or False: The large intestine is responsible for significant enzymatic activity in digestion.

Answer 33

False ## Footnote Enzymatic activity in digestion is primarily conducted by bacteria in the large intestine.

Question 34

What is the role of goblet cells in the large intestine?

Answer 34

Produce mucus ## Footnote This mucus is the major secretion product of the large intestine.

Question 35

What initiates the defecation reflex?

Answer 35

Distension of the rectal wall ## Footnote This reflex involves both local and parasympathetic reflexes.

Question 36

What are the two types of anal sphincters involved in defecation?

Answer 36

* Internal anal sphincter (smooth muscle, involuntary) * External anal sphincter (skeletal muscle, voluntary) ## Footnote The external sphincter is under conscious control to prevent fecal movement.

Question 37

What reflexes stimulate mass movements in the large intestine?

Answer 37

* Gastrocolic reflex * Duodenocolic reflex ## Footnote These reflexes are triggered by the extension of the stomach and duodenum.

Question 38

Fill in the blank: Peristaltic waves in the large intestine occur _______ times a day.

Answer 38

3-4 ## Footnote These contractions are important for the movement of chyme along the large intestine.