Chapter 21: The Digestive System

Question 1

what are the folds in the small intestine called

Answer 1

Plicae

Question 2

What are the folds in the stomach called

Answer 2

Rugae

Question 3

What are the three layers of the inner lining of the gastrointestinal tract

Answer 3

mucosal epithelium, lamina propria, muscularis mucosae

Question 4

Why is intestinal epithelium considered leaky

Answer 4

because some water and some solutes can be absorbed between the cells.

Question 5

Where do nutrients enter the lymph and the blood

Answer 5

In the Lamina propria

Question 6

What does absorption mean

Answer 6

movement of substances from lumen of GI tract to extracellular fluid.

Question 7

What are the two meanings of the word secretion

Answer 7

1. movement if water and ions from ECF to digestive tract lumen.
2. The release of substances synthesized by GI epithelial cells into the lumen or the ECF

Question 8

What three challenges does the digestive system face

Answer 8

1. avoiding autodigestion: prevent the stomach from eating itself
2. mass balance:
3. defense: protection from foreign invaders

Question 9

Are gastrointestinal cells polarized

Answer 9

yes

Question 10

How are enzymes released

Answer 10

by exocytosis

Question 11

What is a Zymogen

Answer 11

an inactivated enzyme

Question 12

What are tonic contractions

Answer 12

sustained for minutes or hours. They occur in some smooth muscle sphincters and in the anterior portion of the stomach.

Question 12

What are tonic contractions

Answer 12

sustained for minutes or hours. They occur in some smooth muscle sphincters and in the anterior portion of the stomach.

Question 12

What are tonic contractions

Answer 12

sustained for minutes or hours. They occur in some smooth muscle sphincters and in the anterior portion of the stomach.

Question 13

What are phasic contractions

Answer 13

lasting only a few seconds, in posterior region of stomach and small intestine

Question 14

What are the interstitial cells of Cajal

Answer 14

act as an intermediary between neurons and smooth muscle. It functions as a pacemaker for slow wave activity in the GI tract

Question 15

What are the interstitial cells of Cajal

Answer 15

act as an intermediary between neurons and smooth muscle. It functions as a pacemaker for slow wave activity in the GI tract

Question 16

What happens when slow wave potential reach the threshold

Answer 16

voltage-gated Ca2+ channels in the muscle fiber open, CA2+ enters, and the cell fires one or more action potentials. Depolarization is due to the entry of Ca2+ into the cell. The entry also initiates muscle contracts

Question 17

What happens if the duration of the slow wave is longer?

Answer 17

the more action potentials fire, the greater the concentration force in the muscle.

Question 18

Contraction in the digestive system occur in 3 patterns. What are those patterns

Answer 18

1. Migrating motor complex(sweeps food and bacteria into the large intestine)
2. Peristalsis: moves bolus
3. segmental contractions: short segments of the intestine alternately contract and relax. circular muscles contract while the longitudinal muscles relax.

Question 19

What does the receptor GC-C used for, and what peptides activate it.

Answer 19

It is used to regulate fluid secretion in the intestine. It is activated by uroguaylin and guanylin

Question 20

What is the difference between absorption and secretion

Answer 20

Absorption moves material from the GI luman into the ECF. Secretion moves substances from the cells or the ECF into the lumen

Question 21

What are the 5 features the CNS shares with the ENS

Answer 21

1. Intrinsic neurons
2. neurotransmitters and neuromodulators
3. Glial support cells
4. Diffusion barrier
5. integrating center

Question 22

What are short reflexes

Answer 22

reflexes that originate within the enteric nerous system and are integrated there without outside input

Question 23

What are long reflexes

Answer 23

digestive reflexes integrated into the CNS

Question 24

What are the three families that gastric hormones divided into

Answer 24

Gastrin family, secretin family, gastric inhibitory pepside

Question 25

What hormones are associated with the gastrin family

Answer 25

gastrin and CCK. Gastrin and CCk can bind to the same CCKB receptor

Question 26

What hormones are associated with the secretin family

Answer 26

secretin, vasoactive intestinal peptide (VIP), a nonadrenergic-noncholonergic neurotransmitter, GIP, GLP-1

Question 27

What do GIp and GLP-1 do

Answer 27

They work together to create a feed-forward signal for insulin release.

Question 27

What does motilin do

Answer 27

increases in this secretion are associated with migrating motor complex

Question 28

Where do anticipatory stimuli and stimulus of food activate neurons

Answer 28

In the medulla oblongata. It then sends a signal to the enteric nervous system. Secretion is then produced in anticipation of food.

Question 29

Is saliva an exocrine or endocrine secretion

Answer 29

It is an exocrine secretion

Question 30

How is saliva produced

Answer 30

It is secreted by the acini cells and then dumped into the ducts. This NaCL is isotonic and as it makes its way though the ducts, the NaCl is reaborbed while K and HCO3- is dumped into the lumen

Question 31

How is the swallowing reflex activated

Answer 31

with the pressure of the bolus as the tongue pushes it against the soft pallet and the back of the mouth

Question 32

What are the phases of digestion

Answer 32

the cephalic phase, the gastric phase, and the intestinal phase

Question 33

What are the three functions of the stomach

Answer 33

It stores food and regulates its passage into the small intestine. The stomach chemically and mechanically digests food into chyme. It destroys bacteria that are swallowed

Question 34

What starts the cephalic phase

Answer 34

the vagal reflex

Question 35

What is receptive relaxation

Answer 35

When the stomach relaxes to hold increased volume. Helps the stomach regulate the amount of food entering it.

Question 36

What does the lower stomach do during digestion

Answer 36

peristaltic waves push food towards the pyloric, mixing it with acid and digestive enzymes. Chyme is squirted into the duodenum.

Question 37

What do G cells in the gastric glands do

Answer 37

They promote acid release bu acting on parietal cells and indirectly stimulating histamine release.

Question 38

How is gastrin release stimulated

Answer 38

By the presence of amino acids and peptides in the stomach. Also triggered by neural reflexes 670

Question 39

What is Gastrins role?

Answer 39

Gastric is released by G cells. Gastrin then activates parietal cells to create HCL. The accumulation of HCL activates the secretion of pepsinogen. Somoza ton is released in response to stop gastrin as a negative feedback response.

Question 40

What are the functions of gastric acid

Answer 40

inactivates salivary amylase,kills bacteria, denatures protiens to make pepsin digestion more accessable, triggers D cells to release somatostatin, releases and activates pepsin

Question 41

What is an alkaline tide

Answer 41

when the blood leaving the stomach is less acidic because of the buffer HCO3-

Question 42

What is the function of PPI

Answer 42

They reduce the amount of acid in the stomach

Question 43

Why does blood from the digestive tract go through the hepatic portal system first

Answer 43

It brings nutrients to the liver and picks up absorbed nutrients in the intestine.

Question 44

Where does the most amount of digestion occur

Answer 44

The small intestine

Question 45

How are protiens digested in the SI

Question 46

How are carbs digested

Question 47

How are lipids digested

Question 48

How do the pancreas, gallbladder and the liver function