GI Lecture 1

Question 1

List, in order, the major parts of the GI tract.

Answer 1

Mouth, Pharynx, Esophagus, Stomach, Small intestine, Large intestine

Question 2

How does the esophagus transfer food to the stomach?

Answer 2

Via peristaltic waves, from the upper esophagal sphincter to the lower esophagal sphincter

Question 3

What are the three sections of the stomach?

Answer 3

Fundus, body and antrum

Question 4

What is the sphincter at the end of the stomach called?

Answer 4

Pylorus

Question 5

What are the two regions of the stomach?

Answer 5

Orad (top), and caudad (bottom)

Question 6

What is the liquid contents delivered to the duodenum called?

Answer 6

Chyme

Question 7

What do cells in the stomach secrete?

Answer 7

mucous fluid, enzyme precursors, HCl, and hormones

Question 8

What are the parts of the small intestine?

Answer 8

Duodenum - a short section that recieves secretions from the pancreas and liver via the pancreatic and common bile ducts
Jejunum - roughly 40% of the small gut
Ileum - empties into the large intestine, about 60%

Question 9

What are the main structural differences between the jejunum and ilium?

Answer 9

The jejunum has a larger diameter, thicker wall, more prominent circular fold and a less fatty mesentery.

Question 10

What are the parts of the colon, in order?

Answer 10

(iileum) Cecum, Ascending colon, transverse colon, descending colon, sigmoid colon (rectum)

Question 11

What are the functions of the colon?

Answer 11

1. Re-absorbs water that was used in the digestion process and substances that were used in digestion.
2. Stores and concentrates feces before defecation

Question 12

What are the four main accessory organs to the digestive system?

Answer 12

Salivary glands, liver, gallbladder, and pancreas.

Question 13

What are acini?

Answer 13

The basic secretory units of salivary glands, which are composed of clusters of secretory cells.

Question 14

What are the three major salivary glands?

Answer 14

Sublingual, Submandibular, and Parotid

Question 15

What controls secretion of saliva?

Answer 15

The ANS (volume and type of saliva)

Question 16

What are the exocrine functions of the pancreas?

Answer 16

Secretion of digestive enzymes that break down nutrients and secretion of HCO3- which neutralizes chyme, both to the duodenum.

Question 17

What are the endocrine functions of the pancreas?

Answer 17

Insulin and glucagon secretion.

Question 18

What are two main functions of the liver?

Answer 18

1, Stores and releases nutients that have been absorbed by the digestive tract.
2. Produces and releases bile which is important in fat digestion.

Question 19

What are the two main functions of the gallbladder?

Answer 19

1. Stores and concentrates bile between meals

2. Releases bile to assist in the digestion of fat

Question 20

What is the submucosa?

Answer 20

The connective tissue, glands, blood vessels and nerve trunks in the GI tract wall

Question 21

What is the muscularis externa?

Answer 21

The outer region of the GI tract wall, which has two types of contractions:

1. Circular muscle contraction to induce a decrease in diameter of gut lumen
2. Longitudinal muscle contraction to induce shortening of a segment of the GI tract

Question 22

What is the muscularis mucosae?

Answer 22

The innermost muscle layer that allows mucosa to fold and form ridges.

Question 23

What are the myenteric and submucosal plexi?

Answer 23

Two layers of nerve cells in the GI tract wall that comprise the ENS.

Question 24

How do most molecules get absorbed?

Answer 24

The villus, which they diffuse through, into a capillary network inside the villus, and then get into systemic blood

Question 25

What does the central lacteal of the villus do?

Answer 25

Transport fats into the lymphatic vessel, to drain the fat from the intestine and rapidly flow into blood via the thoracic duct

Question 26

Describe blood flow (splanctic circulation)

Answer 26

Blood supply to the intestine carries water soluble nutrients.
Must first flow to the liver via the portal vein (to detoxify any bacteria)

Question 27

Which sphincters are smooth muscle and under involuntary control?

Answer 27

All but the external anal sphincter and upper esophagal sphincter, which are under the control of the CNS.

Question 28

Describe the resting pressure of sphincters

Answer 28

Positive

Question 29

Where is the illeocecal valve?

Answer 29

Between illeum and cecum.

Question 30

Where is the Sphincter of Oddi?

Answer 30

To gallbladder/pancreas from small gut