Gastrointesinal anatomy and physiology based on abdominal exam

Question 1

What is the alimentary canal?

Answer 1

Tubular structure makes direct contact with food & has a typical set of histological layers that surround a lumen.

Question 2

What is the alimentary canal composed of?

Answer 2

-Oral cavity and pharynx
-Esophagus
-Stomach
-Small intestine
-Large intestine

Question 3

Name the structures associated with the small intestine:

Answer 3

Duodenum, jejunum, ileum

Question 4

Name the structures associated with the large intestine:

Answer 4

Cecum, appendix, ascending, traverse, descending colon, rectum

Question 5

What are the accessory digestive organs?

Answer 5

-All of these organs are derived embryologically as “outgrowths” of the early alimentary canal

-All function as glands that secrete substances into the alimentary canal

-Salivary glands
-Liver & Gallbladder
-Pancreas

Question 6

Which two accessory organs have additional very important functions that impact the rest of the body?

Answer 6

Liver & Pancreas

Question 7

What, in general, does the alimentary canal do?

Answer 7

Propulsion: food is moved along the “tube” as it’s digested

Secretion(two types):
-Hormonal (impact digestion, secretion, and metabolism)
-Fluid or mucous (aid in propulsion & digestion)

Digestion:
-Chemical- enzymes and acid break chemical bonds in food material or substances facilitate enzymatic interactions

-Mechanical-movements of the canal mix food, break it apart, and increase the SA: volume ratio of food

Absorption (movement from lumen-> bloodstream):
-Water- we ingest over 1L of water per day & secrete 4-6L of water into the canal
-Macro-and micronutrients

Immune function:
-Protection from ingested microbes that are harmful
-Aiding microbes that are useful
-Educating the immune system about whether something that has been ingested is harmful or harmless

Question 8

What are the layers of the alimentary system?

Answer 8

Mucosa- Epithelial lining, lamina propria, muscularis mucosa

Question 9

Columnar w/ villi have what function the in the alimentary canal?

Answer 9

absorption/secretion

Question 10

Cuboidal or squamous has what function in the alimentary canal?

Answer 10

Protection from abrasion

Question 11

Goblet cells are usually located where? And what is their function?

Answer 11

Epithelial layer; mucous secretion

Question 12

Neuroendocrine cells are found where, and what is their function?

Answer 12

Cells are interspersed among the epithelium & release signals in response to different nutrients or chemical conditions in the lumen

Question 13

Lamina propria is the sight of:

Answer 13

-Blood and lymphatic vessels
-Immune tissue (resembles loosely-structured lymphatic nodules, known as MALT)

Question 14

Describe the muscular mucosa:

Answer 14

Alters the shape of the mucosa to optimize mixing and exposure of the epithelial cells to lumen contents

Question 15

Loose connective tissue w/ larger blood vessels and lymphatics

Answer 15

Submucosa

Question 16

What’s found in the submucosa?

Answer 16

-Larger glands
-Large lymph nodes
-A plexus of neurons

Question 17

What is the neuron plexus of the submucosa known as, and what does it regulate?

Answer 17

Meissner’s(submucosal) plexus: regulates secretions and convey sensory information about whats in the lumen

Question 18

Name the layer of the alimentary canal:
Usually just an inner and outer layer

Answer 18

Muscularis

Question 19

Inner layer of the muscularis:

Answer 19

“circular layer” smooth muscle fibers concentrically surround the lumen

Question 20

Outer layer of the muscularis:

Answer 20

“Longitudinal layer” smooth muscle fibers run along the length of the canal

(when this contracts: the canal shortens)

Question 21

What plexus regulates the movements of the Inner and Outer layer of the Muscularis layer of the alimentary canal?

Answer 21

Auerbach’s or myenteric plexus

(found between the inner and outer layers)

Question 22

What is the connective tissue that anchors the esophagus in the chest cavity, and what type of tissue is it?

Answer 22

Adventitia; connective tissue

Question 23

What is the loose connective tissue that is covered by a simple squamous mesothelium?

Answer 23

Serosa

Question 24

What does the mesothelium do?

Answer 24

Secretes fluid that collects in the abdominal (peritoneal) cavity

-Source of peritoneal fluid

(continuous with the visceral peritoneum)

Question 25

Fluid-filled gap between the wall of the abdomen and the organs contained within the abdomen

Answer 25

Peritoneal cavity

Question 26

The Visceral is formed by what?

Answer 26

Serosa of alimentary canal & the capsule of the liver.

Question 27

What is the inner lining of the abdominal wall?

Answer 27

Parietal peritoneum: extremely sensitive to inflammation & other chemical irritants

Question 28

Tube that extends from the pharynx to the stomach, only role is propulsion of food to the stomach.

Answer 28

Esophagus

Question 28

How long is the esophagus & where is located?

Answer 28

25cm; located retrosternally

Question 29

When this sphincter closes, it pushes food from the pharynx to the esophagus:

Answer 29

Upper esophageal sphincter

Question 30

This sphincter limits the movement of stomach acid into the esophagus-> relaxes to receive swallowed food

Answer 30

Lower esophageal sphincter

Question 31

A sack that can expand to receive and store ingested food

Answer 31

Stomach

Question 32

What movements accomplish mechanical digestion, and propulsion into the small intestine?

Answer 32

Muscular movements: Churning & breaking up food into acidic chyme

Question 33

What is the role of chemical digestion in the stomach?

Answer 33

-Denatures proteins and kills ingested bacteria -Secreted enzymes help to digest protein (collagen in particular)

Question 34

Stomach doesn't tell you when your full. (True/False)

Answer 34

False: this is a step of regulating food intake by the stomach

Question 35

Mucosa has low columnar cells that have a wide range of functions, what are they?

Answer 35

Parietal cells: Secrete acid and intrinsic factor (if needed to absorb B12) Other cells secrete mucous to protect the lining or digestive enzymes specialized for digesting proteins

Question 36

Muscularis has how many layers?

Answer 36

3: innermost layer is the oblique layer

Question 37

Regulates the amount of acidic chyme that enters the duodenum:

Answer 37

Pyloric sphincter

Question 38

What is the main digestive organ?

Answer 38

Small intestine (Largest surface area)

Question 39

The small intestine is the site of what?

Answer 39

Most chemical digestion, absorption, and secretion in the alimentary canal

Question 40

What are the three separate components of the small intestine?

Answer 40

Duodenum, Jejunum, and Ileum

Question 41

The short C-shaped tube that receives chyme from the stomach and overlies the head of the pancreas

Answer 41

Duodenum

Question 42

Both the duodenum and ________ have specialized immune tissue called________

Answer 42

Jejunum; Peyer's patches

Question 43

Longest portion of small intestine, main function is reabsorption of bile, salts, micronutrients/vitamins, and water

Answer 43

Ileum

Question 44

What type of epithelium is in the small intestine?

Answer 44

Highly folded (microvilli), mucosa (villi), and submucosal layers (circular folds) are meant to optimize surface area. -Columnar epithelium w/ 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 45

The main function of this organ is absorption of water from stool, storage of stool, and housing the majority of the microbes in the gut.

Answer 45

Large Intestine

Question 46

What type of epithelium make up the large intestine?

Answer 46

Low columnar cells with fewer microvilli, plenty of goblet cells

Question 47

What is the muscular layer of the large intestine?

Answer 47

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

Question 48

What organs have ducts that convey their secretions to the lumen of the duodenum?

Answer 48

Pancreas, Liver, Gallbladder, salivary glands

Question 49

What are the roles of the liver?

Answer 49

-Carbohydrate metabolism -Protein synthesis and degradation -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 50

Where do most of the proteins that are secreted into the bloodstream come from?

Answer 50

Liver

Question 51

Which accessory organ is in charge of the storage and modification of bile?

Answer 51

Contraction-> bile release into the duodenum

Question 52

What accessory organ has exocrine and endocrine functions?

Answer 52

Pancreas: Exocrine-secretes digestive enzymes that are crucial for carbohydrate, protein, and lipid chemical digestion Endocrine-secretes hormones that impact glucose, protein, and lipid metabolism into the bloodstream

Question 53

Where do the exocrine secretions from the pancreas go?

Answer 53

Pancreatic duct, which drains into the duodenum

Question 54

What are some of the hormones that are secreted through the pancreas?

Answer 54

Insulin, Glucagon, & Somatostatin

Question 55

What do hyperactive bowel sounds probably indicate?

Answer 55

Diarrhea, gastroenteritis, inflammatory bowel disease, laxative issues, gastrointestinal bleed or early bowel obstruction (often described as a high pitched tinkling sound)

Question 56

What do hypoactive bowel sounds typically indicate?

Answer 56

-Often suggests more emergent conditions -Bowel obstruction, peritonitis, intestinal ischemia

Question 57

How long do we listen before assuming absence of bowel sounds?

Answer 57

5 min

Question 58

Tenderness=

Answer 58

pain in the region where you palpate -Abdominal pain is present regardless of whether you palpate the abdomen (tender to light or deep palpation)

Question 59

"Deep" or visceral pain in the abdomen can come from what?

Answer 59

Stretching, ischemia, chemical irritation of a component of the alimentary tract or accessory organ (Sometimes pathologies in the thorax (heart attack, pneumonia) can also be present as abdominal pain.)

Question 60

A voluntary contraction of the abdominal musculature due to abdominal discomfort:

Answer 60

Guarding: -Can be exacerbated by anxiety -Serious pathology , but often less serious

Question 61

Involuntary contraction of the abdominal musculature , usually accompanied by severe pain.

Answer 61

Rigidity: -More serious pathology -Due to chemical irritation of the parietal peritoneum lining or "rubbing" of an inflamed organ against it: ex) -Bile (ruptured cholecystitis), infected material (ruptured or ischemic intestinal wall), Pancreatic secretions (Pancreatitis), gastric or duodenal contents (perforated peptic ulcer) -Inflamed structure rubbing against the parietal peritoneum-appendicitis, diverticulitis

Question 62

Abdominal pain in the three areas in the "center" can be:

Answer 62

Visceral pain from the alimentary tract or accessory organs (can also be due to irritation of the parietal peritoneum)

Question 63

Abdominal pain in the six regions on the "sides" are often due to what?

Answer 63

Irritation of the parietal peritoneum (Can also be due to visceral pain from non-GI organs)

Question 64

Abdominal pain FYI:

Answer 64

Good to know for the future

Question 65

What is hepatomegaly:

Answer 65

Enlarged Liver: -A palpable liver does not necessarily indicate hepatomegaly -Pathological changes in consistency could be noted-from the normal softness to an abnormally firm or hard liver (pathologies can also cause the liver size to increase)

Question 66

Liver Cirrhosis:

Answer 66

Large liver with firm, non-tender edge

Question 67

Hepatocellular carcinoma:

Answer 67

large liver that is firm and in irregular edge (may or may not be tender)