The GI Tract

Question 1

Alimentary canal is composed of

Answer 1

1.) esophagus
2.) stomach
3.) small intestine
4.) large intestine

(direct contact with food)

Question 2

The digestive accessory organs are:

Answer 2

1.) liver
2.) gallbladder
3.) pancreas

Question 3

All accessory digestive organs are derived embryologically as what?

Answer 3

“outgrowths” of the early alimentary canal

Question 4

5 functions of alimentary canal

Answer 4

1.) propulsion
2.) secretion (2 types = hormonal and fluid/mucous)
3.) digestion (2 types = chemical (enzymes/acisd) mechanical (movement)
4.) absorption (lumen –> bloodstream)
5.) immune function (microbe protection)

Question 5

Layers of the alimentary canal

Answer 5

1.) mucosa
2.) submucosa
3.) muscularis
4.) outer

Question 6

3 layers of the mucosa

Answer 6

Epithelium: A layer of cells that can absorb nutrients and provide a protective barrier.

Lamina propria: Connective tissue that supports the epithelium and contains blood vessels and lymphatic vessels.

Muscularis mucosae: A thin layer of smooth muscle that helps move the mucosa and aids in the absorption of nutrients.

Question 7

Where can large glands, large vessels, very large lymphs be found?

Answer 7

submucosa layer

Question 8

What is the plexus of neurons existing in the submucosa called? And what does it do?

Answer 8

Meissner’s plexus- regulates secretions and convey sensory info about what’s in the lumen

Question 9

What are the 2 layers of the muscularis layer?

Answer 9

1.) inner: circular surrounding lumen (squeezes lumen shut)
2.) outer: “longitudinal layer” – smooth muscle fibres run along the length of the canal (shortens the canal)

Sarah (serosa) goes on adventures (adventitia) outside (outer layer).

Question 10

What is the plexus that regulates the movements of the muscularis layer? Where is it found?

Answer 10

Auerbach’s (myenteric plexus), found between the two layers

Question 11

What are the 2 parts of the outer layer?

Answer 11

adventitia- anchors esophagus in the chest cavity

Serosa- LCT covered by simple squamous mesothelium

Question 12

What part of the outer layer of the alimentary canal secretes fluid that collects in the abdominal (peritoneal cavity)?

Answer 12

mesothelium of the serosa layer

Question 13

What is a source of peritoneal fluid?

Answer 13

mesothelium

Question 14

What part of the outer layer is continuous with the visceral perritoneal?

Answer 14

serosa

Question 15

What is the fluid filled gap between the wall of the abdomen and the organs contained within the abdomen

Answer 15

peritoneal cavity

Question 16

What are the 2 parts of the peritoneal cavity?

Answer 16

visceral : formed by the serosa and liver
parietal: inner lining of the ab. wall. (extremely sensitive to inflammation and other chemical irritants

Question 17

What does the esophagus connect? What are the 2 muscles?

Answer 17

pharynx –> stomach

upper esoph. sphinchter- pushes food
lower esoph. sphincter- limits stomach acid into esophagus. Relaxes to receive swallowed food

Question 18

What kind of lining?

Answer 18

stratified squamous epithelium (adventitia NOT serosa)

Question 19

What kind of cells does the stomach have? What do they do?

Answer 19

low columnar cells

Parietal cells – secrete acid and intrinsic factor
(IF is needed for absorption of B12)

Other cells secrete mucous to protect the lining or digestive enzymes specialized for digesting proteins

Question 20

What is the sphincter of the stomach?

Answer 20

pyloric- regulates amount of acid chyme that enters duodenum

Question 21

What’s the innermost muscularis layer of the 3 of the stomach?

Answer 21

oblique

Question 22

3 components of small intestine

Answer 22

Duodenum- receives chyme from stomach (That duo love to chum (chyme)
Jejunum- Immunity (Immunity is good in June, due to vitamin patches from the payers)
Ileum-longest, reabsorption of bile salts, micronutrients/ vitamins and water (If you are ill, you must reabsorb nutrients)

Don’t Judge Intestines

Question 23

Which part of the digestive system has highly folded epithelium (microvilli), mucosa (villi) and submucosal layers (circular folds) meant to optimize surface area?

Answer 23

Small intestine

(Columnar epithelium with many microvilli
interspersed with goblet cells and cells that secrete chemical messengers into the blood.
Messengers help regulate propulsion, overall metabolic function, secretions from the pancreas or liver)

Question 24

Main function of the large intestine?

Answer 24

absorb water from stool, store stool and housing microbes

Question 25

Does the LI have goblet cells? Microvili?

Answer 25

Yes plenty
Fewer than SI

Question 26

What’s unique about the muscular layer of the LI?

Answer 26

Continuous circular muscle layer

Longitudinal muscle layer is separated into bands that do not completely surround the canal

Question 27

How do accessory organs convey their secretions? Where to?

Answer 27

ducts, to the lumen and duodenum

Question 28

Liver rolesher

Answer 28

Roles of the liver:
Carbohydrate metabolism
Protein synthesis and degradation
Most proteins secreted into the bloodstream are from the liver
Lipid metabolism
Detoxification of molecules so that they can be secreted into the bile and defecated
Making hydrophobic molecules water soluble so that they can be eliminated by the kidney
Storage of vitamins and minerals
Synthesis of bile – essential for lipid digestion
Endocrine – secretion of IGF-1, important hormone regulating growth

Question 29

Where does the gall bladder release bile to upon contraction?

Answer 29

dupdenum

Question 30

What do pancreatic hormones and digestive enzymes impact?

Answer 30

glucose, protein and lipid metabolism (insulin, glucagon, somatostatin

Question 31

Diarrhea, gastroenteritis, inflammatory bowel disease, laxative use, gastrointestinal bleed
Or early bowel obstruction (often described as a high-pitched “tinkling” sound

Increased or decreased bowel sounds?

Answer 31

increased (hyperactive)

Question 32

Bowel obstruction, peritonitis, intestinal ischemia

Increased or decreased bowel sounds?

Answer 32

decreased

Question 33

Is hyper or hypoactive bowel more emergent?

Answer 33

hypo

Question 34

Abdominal pain in the six regions on the “sides” are often due to irritation of the ______ ______.

Answer 34

Parietal peritoneum

Question 35

Abdominal pain in the three areas in the “centre” can be visceral pain from the ____ or _____.

Answer 35

alimentary tract or accessory organs

Question 36

Large liver with firm, nontender edge?

Large liver that is firm and an irregular edge. May or may not be tender?

Answer 36

Hepatocellular carcinoma
Liver cirrhosis