Chapter 41 - Organization of the Gastrointestinal System

Question 1

Is a tube that is specialized along its length for the sequential processing of food.

Answer 1

Gastrointestinal tube

Question 2

The GI tract consists of both the series of ________ stretching from the mouth to the anus and the several __________ that add secretions to these hollow organs.

Answer 2

Hollow organs

Accessory glands and organs

Question 3

The _______ and _______ are responsible for:

1. Chopping food into small pieces
2. Lubricating it
3. Initiating carbohydrate and fat digestion
4. Propelling the food into the esophagus.

Answer 3

Mouth and oropharynx

Question 4

The ________ acts as a conduit to the stomach.

Answer 4

Esophagus

Question 5

The ______ temporarily stores food and also initiates digestion by churning and by secreting proteases and acid.

Answer 5

Stomach

Question 6

The _________ continues the work of digestion and is the primary site for the absorption of nutrients.

Answer 6

Small intestine

Question 7

The ___________ reabsorbs fluids and electrolytes and also stores the fecal matter before expulsion from the body.

Answer 7

Large intestine

Question 8

The accessory glands and organs include the:

Answer 8

1. Salivary glands
2. Pancreas
3. Liver

Question 9

The __________ secretes digestive enzymes into the DUODENUM in addition to secreting HCO-3 to neutralize gastric acid.

Answer 9

Pancreas

Question 10

The liver secretes ______ which the gallbladder stores for future delivery to the duodenum during a meal.

Answer 10

Bile

Question 11

Bile contains ___________ which play a key role in the digestion of fats.

Answer 11

Bile acids

Question 12

The _______ consists of the EPITHELIAL LAYER, as well as an underlying layer of LOOSE CONNECTIVE TISSUE known as the __________ which contains CAPILLARIES, ENTERIC NEURONS and IMMUNE CELLS as well as a thin layer of SMOOTH MUSCLE known as ______________.

Answer 12

Mucosa

Lamina propria

Lamina muscularis mucosae (literally, the muscle layer of the mucosa).

Question 13

The layer of epithelial cells can be EVAGINATED to form ________ or INVAGINATED to form ________.

Answer 13

Villi

Crypts (or glands)

Question 14

Finally, on a larger scale the mucosa is organized into _________.

Answer 14

Large folds

Question 15

The __________ consists of LOOSE CONNECTIVE TISSUE and LARGE BLOOD VESSELS.

Answer 15

Submucosa

Question 16

The submucosa may also contain _______ that secrete material into the GI lumen.

Answer 16

Glands

Question 17

The muscle layer, the ___________ includes two layers of smooth muscle. _________ are present between these two muscle layers.

Answer 17

Muscularis externa

Enteric neurons

Question 18

The inner layer is ________.

Answer 18

Circular

Question 19

The outer layer is _________.

Answer 19

Longitudinal

Question 20

Assimilation of dietary food substances requires ________ as well as ________.

Answer 20

Digestion

Absorption

Question 21

The sedentary human body requires _____ body weight each day.

Answer 21

30 kcal/kg

Note: This nutrient requirement is normally acquired by the oral intake of multiple food substances that GI tract then assimilates.

Question 22

Absorb WATER and ELECTROLYTES.

Answer 22

Small and large intestine

Question 23

Absorbs lipids, carbohydrates and amino acids.

Answer 23

Small intestine

Question 24

Can provide sufficient calories to sustain adults and to support growth in premature infants.

Answer 24

Parenteral (i.e intravenous) alimentation

Question 25

Has been used successfully on a long-term basis in many clinical settings in which oral intake is impossible or undesirable.

Answer 25

Total parenteral nutrition

Question 26

Food substances are not necessarily - and often are - consumed in a __________ that the small intestine can directly absorb.

Answer 26

Chemical form

Question 27

To facilitate __________, the GI tract digests the food by both MECHANICAL and CHEMICAL PROCESSES.

Answer 27

Absorption

Question 28

_______ of ingested food begins in the mouth with CHEWING (MASTICATION).

Answer 28

Mechanical disruption

Question 29

The mechanical processes that alter food composition to facilitate absorption continue in the _______, both to initiate protein and lipid enzymatic digestion and to allow passage of gastric contents through the pylorus into the duodenum.

Answer 29

Stomach

Question 30

This change in the SIZE and CONSISTENCY of gastric contents is necessary because solids that are _______ in diameter do not pass through the pylorus.

Answer 30

> 2 mm

Question 31

Although most lipids are consumed in the form of triacylglycerols, it is ________ and _________, not triacylglycerols that are absorbed by the small intestine.

Answer 31

Fatty acids

Monoacylglycerols

Question 32

Thus, a complex series of _________ are required to convert dietary triacylglycerols to these smaller lipid forms.

Answer 32

Chemical reactions (lipid digestion)

Question 33

Similarly, amino acids are present in food as PROTEINS and LARGE PEPTIDES, but only amino acids and small peptides - primarly _________ and ________ are absorbed by the small intestine.

Answer 33

Dipeptides

Tripeptides

Question 34

Carbohydrates are present in the diet as:

Answer 34

1. Starch
2. Disaccharides
3. Monosaccharides

Question 35

However, because the small intestine absorbs all carbohydrates as __________.

Answer 35

Monosaccharides

Note: Most dietary carbohydrates require chemical digestion before their absorption.

Question 36

Digestion requires enzymes secreted in the:

Answer 36

“SPMS”

1. Stomach
2. Pancreas
3. Mouth
4. Small intestine

Question 37

_________ involves the conversion of dietary food nutrients to a form that the small intestine can absorb.

Answer 37

Digestion

Question 38

For carbohydrates and lipids, these digestive processes are initiated in the mouth by salivary and lingual enzymes: ________ for carbohydrates and ________ for lipids.

Answer 38

Amylase
Lipase

*Carbohydrate digestion does not involve any secreted gastric enzymes.

Question 39

___________ is initiated in the stomach by GASTRIC PROTEASES (i.e., pepsins), whereas additional lipid digestion in the stomach occurs primarily as a result of the lingual lipase that is swallowed, although some gastric lipase is also secreted.

Answer 39

Protein digestion

Question 40

Digestion is completed in the ____________ by the action of both pancreatic enzymes and enzymes at the brush border of the small intestine.

Answer 40

small intestine

Question 41

Pancreatic enzymes, which include ________, ________ and ________ are critical for the digestion of lipids, protein and carbohydrates, respectively.

Answer 41

lipase, chymotrypsin and amylase

Question 42

The enzymes on the luminal surface of the small intestine (e.g., brush border disaccharidases and dipeptidases) complete the digestion of ___________ and ___________.

Answer 42

carbohydrates and proteins

Question 43

Digestion by these brush border enzymes is referred to as ____________.

Answer 43

membrane digestion

Question 44

The load to the small intestine is also significantly ________ than that of the ingested material.

Answer 44

greater

Question 45

Dietary fluid intake is 1.5 to 2.5 L/day whereas the fluid load presented to the small intestine is __________.

Answer 45

8 to 9 L/day

Question 46

The necessary control is achieved by neural and hormonal processes that are initiated by _____________; the result is a coordinated series of motor and secretory responses.

Answer 46

dietary food substances