GI Physiology

Question 1

The GI tract mainly has what type of innervation

Answer 1

single unit (muscle cells contract as a single unit)

Question 2

What is segmentation

Answer 2

Contractions of the intestine that mix chyme

Question 3

What is peristalsis

Answer 3

Contractions that are designed to propel chyme alone small intestine

Question 4

What type of contractions of smooth muscle occur behind the bolus

Answer 4

circular muscle contracts
longitudinal muscle relaxes

Question 5

What type of contractions of smooth muscle occur ahead of the bolus

Answer 5

circular muscle relaxes
longitudinal muscle contracts

Question 6

What are the 4 gastric secretions

Answer 6

HCL
Gastrin
instrinsic factor
pepsinogen

Question 7

What are the duodenal secretions

Answer 7

CCK
secretin
GIP

Question 8

What are the types of innervation of the GI tract?

Answer 8

SNS/PNS
auerbach’s plexuses
meissner’s plexuses
sensory fibers

Question 9

What are the pacesetter cells of the GI tract?

Answer 9

Cajal cells. They are found in the myenteric plexus.

Question 10

What types of electrical waves do pacesetter cells produce?

Answer 10

Cajal cells (pacesetter) produce slow waves of oscillating depolarization. (tonic contraction) only produce contractions in stomach

Question 11

What types of electrical waves do smooth muscles of the GI tract produce?

Answer 11

Spike potentials, linked via gap junctions. (phasic contractions).

Question 12

What stimulates spike potentials?

Answer 12

stretch
acetycholine
parasympathetics

Question 13

Where is intrinsic factor produce?

Answer 13

In the stomach by parietal cells

Question 14

What conditions lead to a gastric ulcer?

Answer 14

excessive acid or inadequate alkaline mucus

Question 15

How do H Pylori create ulcers?

Answer 15

Ureas converts urea to ammonia, leading to more alkaline environment to bacteria can grow.

Question 16

Function of GIP

Answer 16

inhibit Gastrin to indicate food has reached the duodenum.
Signal endocrine pancreas to release insulin

Question 17

What is VIP and where is it released from?

Answer 17

Vasoactive intestinal peptide, release from duodenum

Question 18

Function of VIP

Answer 18

Dilates intestinal capillaries to facilitate nutrient absorption

Question 19

What does secretin do?

Answer 19

stimulates release of pancreatic enzymes and bicarb

Question 20

Describe the cephalic phase of digestion?

Answer 20

Head drives hunger symptoms.
CNS stimulates vagus nerve to submucosal plexus of stomach.
Stimulates gastric cells to secrete their products.

Question 21

Describe the gastric phase of digestion?

Answer 21

Stretch receptors in stomach lining activate submucos and myenteric plexuses.
Stomach muscle mixes, gastric cells continue to secrete.

Question 22

Describe the intestinal phase of digestion?

Answer 22

As chyme is release into duodenum, stretch receptors of duodenum inhibit myenteric plexus.
CCK, GIP, secretin are released and inhibit gastric cells and stomach peristalsis.

Question 23

What is a physical difference of the duodenum wall compared to the jejeunum.

Answer 23

The duodenum has fewer plicae and smaller villi

Question 24

What triggers CCK release?

Answer 24

Lipids and carbohydrates arriving at duodenum

Question 25

What does CCK stimulate?

Answer 25

opening of sphincter of Oddi Gallbladder contraction

Question 26

What are the exocrine cells of the pancreas?

Answer 26

Acinar and centroacinar cells

Question 27

What do acinar cells produce in the pancreas?

Answer 27

zymogens

Question 28

What do centro-acinar cells produce in the pancreas?

Answer 28

bicarbonate

Question 29

What does the liver need to make clotting factor?

Answer 29

vitamin K

Question 30

What vitamins are lipid soluble?

Answer 30

Vitamin K, A, D, E

Question 31

What is conjugated bilirubin?

Answer 31

Bilirubin that is modified to be water soluble

Question 32

Where is bilirubin conjugated?

Answer 32

The liver

Question 33

What is direct bilirubin?

Answer 33

measuring directly the amount of conjugated bilirubin

Question 34

What is indirect bilirubin

Answer 34

Measuring total bilirubin and subtracting conjugated to calculate amount of unconjugated bilirubin

Question 35

Causes of portal hypertension?

Answer 35

cirrhosis hepatic fibrosis blockage of portal vein

Question 36

Consequences of portal hypertension?

Answer 36

Esophageal varices ascites (due to increased CHP, decreased BCOP) enlarged spleen cognitive dysfunction (hepatic encephalopathy)

Question 37

Carbohydrates are only absorbed in the intestines in what form?

Answer 37

monosaccharides

Question 38

How do carbohydrates enter enterocytes?

Answer 38

secondary active transport by Na/K ATPase

Question 39

How do carbohydrates exit enterocytes?

Answer 39

facilitated diffusion

Question 40

How do amino acids enter enterocytes?

Answer 40

sodium dependent co-transport

Question 41

How do amino acids exit enterocytes?

Answer 41

facilitated diffusion

Question 42

How do lipids enter enterocytes?

Answer 42

passive diffusion or facilitated transport

Question 43

How to lipids exit enterocytes

Answer 43

via lacteal lymph ducts to thoracic duct, then to blood stream