Exam 4: Intro To GI And Swallowing

Question 1

What kind of movement does the esophagus have?
Stomach?
Small intestine?

Answer 1

Esophagus: peristalsis
Stomach: mixing
Small intestine: segmentation and peristalsis

Question 2

What controls the mid-esophagus to the internal anal sphincter?

Answer 2

ANS via visceral smooth muscle

Question 3

What are the layers of the GI tract from the serosal to luminal side?

Answer 3

Serosa, longitudinal muscle, myenteric plexus, circular muscle, submucosa, submucosal plexus, and mucosa

Question 4

What are the 3 components of the mucosa of the GI tract?

Answer 4

Muscularis mucosae, lamina propriety, and epithelium

Question 5

What two layers of the GI tract are part of the enteric NS?

Answer 5

Myenteric plexus (auerbachs) and submucosal plexus (Meissners)

Question 6

What is the advantage of parallel and series organization of splanchnic organization?

Answer 6

Parallel: allows for regulation of flow to individual organs
Series: liver is exposed to all absorbed substances

Question 7

Afferent signals to the plexuses of the ENS come from what?

Answer 7

Chemo and Mechanoreceptors

Question 8

What modulates the ENS?

Answer 8

The ANS, but the ENS does not require ANS input to carry out most functions

Question 9

What is the myenteric plexus responsible for?

Answer 9

Innervates longitudinal and circular smooth muscle layers and is primarily concerned with control of gut movements

Question 10

What does the submucosal plexus do?

Answer 10

Innervates the glandular epithelium, intestinal endocrine cells, and submucosal blood vessels, primarily concerned with control of intestinal secretion

Question 11

What does the SNS do in the GI system? Is it inhibitory or excitatory?

Answer 11

SNS releases NE in intramural plexuses and on vascular smooth muscle and secretory cells. This effect is usually inhibitory

Question 12

What innervates the salivary glands?

Answer 12

The cervical ganglia from the SNS and CN VII and IX from the PNS

Question 13

What innervates the distal colon?

Answer 13

The superior mesenteric ganglia from the SNS and the sacral and pelvic nerves from the PNS

Question 14

What innervates the rectum?

Answer 14

The inferior mesenteric ganglia from the SNS and the sacral and pelvic nerves from the PNS

Question 15

What kind of nerves have preganglionic nerves that synapse directly in the GI tract?

Answer 15

Parasympathetics

**sympathetics synapse prior to the GI tract, and the postganglionic nerve goes into the GI tract

Question 16

What is the largest endocrine organ in the body?

Answer 16

The GI tract

Question 17

What are the 3 things that GI peptides regulate?

Answer 17

• smooth muscle
• secretion of fluid and enzymes
• Growth of GI cells

Question 18

What are the 4 hormones of the GI tract?

Answer 18

Gastrin, cholecytokinin (CCK), secretin, and gastric inhibitory peptide

Question 19

What cells secrete gastrin?

Answer 19

G cells of the stomach

Question 20

What stimulates gastrin release?

Answer 20

• small peptides and amino acids
• distention of the stomach
• vagal stimulation

Question 21

What does gastrin do?

Answer 21

Increase gastric H+ secretion and stimulate growth of gastric mucosa

Question 22

What cells release CCK?

Answer 22

I cells of the duodenum and jejunum

Question 23

What stimulates CCK release?

Answer 23

Small peptides and amino acids

Fatty acids

Question 24

What is the effect of CCK?

Answer 24

• Increase pancreatic enzyme secretion
• increase pancreatic bicarb secretion
• stimulate contraction of the gallbladder and relaxation of the sphincter of oddi
• stimulates growth of the exocrine pancreas and gallbladder
• inhibits gastric emptying

Question 25

What cells secrete secretin?

Answer 25

S cells of the duodenum

Question 26

What stimulates secretin release?

Answer 26

H+ in the duodenum Fatty acids in the duodenum

Question 27

What is the effect of secretin?

Answer 27

- Increase pancreatic bicarbonate secretion - increase biliary bicarb secretion - decrease gastric H+ secretion - inhibits tropic effect of gastric on gastric mucosa

Question 28

What secretes GIP?

Answer 28

Duodenum and jejunum

Question 29

What stimulates GIP release?

Answer 29

fatty acids, amino acids, and oral glucose

Question 30

What are the effects of GIP?

Answer 30

- Inhibits gastric emptying - increase insulin secretion from pancreatic B cells - decrease gastric H+ secretion

Question 31

What are the two paracrines of the GI tract?

Answer 31

Somatostatin and histamine

Question 32

What are the 4 GI neurocrines?

Answer 32

- ACh - NE - Vasoactive intestinal peptide - Gastrin releasing peptide

Question 33

What does ACh do in the GI tract?

Answer 33

Increase secretions, relaxes sphincters, increases contraction of wall smooth muscle

Question 34

What does NE do in the GI tract?

Answer 34

Sphincter contraction, relaxation of wall smooth muscle

Question 35

What does Vasoactive intestinal peptide do in the GI tract?

Answer 35

Relaxation of smooth muscle, increase secretions

Question 36

What does gastrin releasing peptide do?

Answer 36

Increases gastrin secretion

Question 37

What neurons release ACH?

Answer 37

Cholinergic neurons

Question 38

What releases vasoactive intestinal peptide?

Answer 38

Neurons of the enteric nervous system

Question 39

What releases gastrin releasing peptide?

Answer 39

vagal neurons of gastric mucosa

Question 40

What are the two types of spontaneous oscillations of VSMC RMP?

Answer 40

Slow waves or basic electrical rhythm

Question 41

What causes the spontaneous oscillations in VSMC?

Answer 41

Variations of Ca and K conductances

Question 42

What initiates the Basic Electrical Rhythm (BER)?

Answer 42

Interstitial cells of Cajal, which are pacemakers cells that send long branched processes into the VSMC

Question 43

How does the ANS influence activity of the VSMC?

Answer 43

- ACh increases the BER amplitude, the number of spike potentials, and VSMC tension - NE as the reverse effect on these parameters - neither affects the BER frequency

Question 44

What are the 3 digestive phases?

Answer 44

Cephalexin Gastric Early and late intestinal

Question 45

What regulates migrating motor complex?

Answer 45

“Candidate” hormone motilin

Question 46

What is the migrating motor complex?

Answer 46

Cyclical pattern of motor activity designed to removed indigested material from the stomach

Question 47

What is the cephalexin phase of digestion?

Answer 47

The autonomic and endocrine reflexes that are triggered by anticipation of eating and the initial sensory contact with food. Serves to prepare the GI tract

Question 48

What is responsible for activation of the cephalexin phase? How?

Answer 48

PNS efferents are responsible for activation | -PNS activity increases secretion of saliva, gastric acid, gastrin, and pancreatic enzymes

Question 49

What is the site of formation of saliva?

Answer 49

Acinar glands

Question 50

What does alpha amylase do in saliva?

Answer 50

Starts starch digestion

Question 51

What does lingual lipase do in saliva?

Answer 51

Start fat digestion

Question 52

Saliva is hyper/hypotonic to water?

Answer 52

Hypotonic

Question 53

How do Na, Cl, K, and HCO3 levels in saliva compare to plasma?

Answer 53

- Na and Cl concentrations are less in the saliva than plasma - K and HCO3 levels are higher in saliva than plasma

Question 54

What is the salivary center in the medulla stimulated by?

Answer 54

Taste , smell, and tactile stimulation

Question 55

How do ACh and CIP from PNS nerve ending affect salivation?

Answer 55

- Increase saliva secretion - vasodilation - Salivary duct dilation - Secretion of amylase and mucous

Question 56

What mediates the relaxation of the LES?

Answer 56

VIP

Question 57

What is Achalasia?

Answer 57

When the LES fails to relax during swallowing so food accumulates in the esophagus dilating the organ

Question 58

What can cause achalasia?

Answer 58

Degeneration of the myenteric plexus, defective release of NO and VIP