Week 4 Introduction to the GI Tract

Question 1

What organs are included in the GI tract?

Answer 1

The “tube” itself:

• Oesophagus
• Stomach
• Small intestine
• Large intestine (colon)
• Rectum
• Anus

Other organs of digestion also included:

• Liver
• Pancreas
• Galbladder

Question 2

Purpose of the mouth in the GIT?

Answer 2

• Mastication
• Begins digestion with amylase
• Some absorption

Question 3

Three stages of the pharynx?

Answer 3

• Nasopharynx
• Oralpharynx
• Laryngopharynx

Tip: Naso - nose
Oral - mouth
Laryngo - close to larynx

Question 4

Function of the pharynx in the GIT?

Answer 4

Swallowing of food form the buccal cavity to the oesophagus

Question 5

What is peristalsis?

Answer 5

The process of the involuntary contraction and relaxation of the muscles throughout the GI tract

Question 6

Muscles of the Oesophagus

Answer 6

• Upper third are striated (voluntary)
• Lower third smooth (involuntary)
• Middle mixed

Question 7

Sphincters of the oesophagus?

Answer 7

• Upper oesophageal sphincter - stops air getting into the GI
• Lower oesophageal sphincter - stops acid reflux

Question 8

What is a hiatal hernia?

Answer 8

A hiatal hernia occurs when the upper part of the stomach pushes up into the chest through a small opening in the diaphragm, the muscle that separates the abdomen from the chest.

Question 9

Sections of the stomach

Answer 9

• Cardia
• Fundus
• Body
• Antrum
• Pylorus (here is the pyloric sphincter after which is the small intestine)

Question 10

Parts of the gastric mucosa

Answer 10

• Glands: secrete mucous to protect gastic mucosa form acidic environment
• Chief cells: secrete enzymes
• Parietal cells: secrete hydrochoric acid and intrinsic factor
• Endocrine cells: secrete grelin and gastrin

Question 11

What do the gastric mucosa glands do?

Answer 11

Secrete mucous to protect the gastric mucosa

Question 12

What do the chief cells do?

Answer 12

Secrete enzymes (pepsinogen)

Question 13

What is the main enzyme in the stomach?

Answer 13

Pepsin

Question 14

What do the parietal cells do?

Answer 14

Secrete hydrochloric acid to break down foods and intrinsic factor for b12 absorption

Question 15

What do the endocrine cells of the gastric mucosa do?

Answer 15

Secrete grelin (hormone which promotes appetite) and gastrin (digestive hormone)

Question 16

What is grelin?

Answer 16

The hormone that promotes appetite

Question 17

What is gastrin?

Answer 17

The hormone that tells you body to digest - enhancing gastric mucosal growth, gastric motility (movement) and secretion of hydrochloric acid (HCl) into the stomach

Question 18

What is the hormone that promotes appetite?

Answer 18

Grelin

Question 19

What is the hormone that triggers digestion?

Answer 19

Gastrin

Question 20

Three sections of the small intestine?

Answer 20

1. Duodenum
2. Jejunum
3. Ileum

Hint: All end in “um” for “yum” and Ileum is the closest to the Ilium of the pelvis

Question 21

What are the villi?

Answer 21

These are the folded mucosa lining the small intestine

Folded to increase surfact area

Contains blood vessels for most nutrient absorption and lymph vessels for fatty (lipid) nutrient absorption. Lympth is part of the immune system but is also fatty

Also secretes mucus and enzymes

Millions of them and looks like carpet (gross, is this the bit of cow I ate in mexico?)

Question 22

Sections of the large intestine?

Answer 22

• Cecum
• Ascending colon
• Transverse colon
• Descending colon
• Sigmoid colon

Question 23

What is the rectum?

Answer 23

Last bit of the GI - a repository for stool

Question 24

What are crypts?

Answer 24

Like the villi but for the colon

Question 25

Functions of the large intestine vs the small intestine?

Answer 25

* Small intestine is responsible for some digestion as well as nutrient absorption * Large intestine releases no digestive enzymes. Absorbs water and electrolytes and eleminates faeces

Question 26

How are the muscles of the colon grouped?

Answer 26

They are grouped into dense strips and rings called taeniae coli, these form pouches

Question 27

What is the peritoneum?

Answer 27

A continous membrane that cover most abdominal organs

Question 28

Two layers of the peritoneum?

Answer 28

* Viseral - lines the organs * Parietal - lines the walls of the abdominal cavity

Question 29

Where is the gallbladder?

Answer 29

Below the liver

Question 30

What is the function oft he gallbladder?

Answer 30

Stores bile which is crucial for fat absorption When triggered by hormone CCK it empties

Question 31

Where is the pancreas?

Answer 31

Head lies within the curve of the duodenum. Tail touches the spleen.

Question 32

The exocrine pancreas

Answer 32

* Form majority of pancreatic tissue * Ductal collecting system that ends in the duodenum * Secrete pancreatic juice (digesting enzymes and sodium bicarbonate to neutralise stomach acid)

Question 33

The endocrine pancreas

Answer 33

* Consists of "islands" of endocrine cells called islets * Secretes hormones intot he capillaries * Most importantly insulin and glucagon

Question 34

What do the alpha and beta cells do in the pancreatic islets?

Answer 34

* Alpha makes glucogon * Beta makes insulin

Question 35

What do the peritoneum terms mean? * Intraperitoneal * Extraperitoneal * Retroperitoneal * Mesentry * Omentum

Answer 35

Question 36

Why do we need to know about the peritoneum

Answer 36

* Perforation * Peritonitis