Gastrointestinal

Question 0

Factors that make the GI smooth muscle cell membrane more negative, making it less excitable.

Answer 0

Norepinephrine or epinephrine

Stimulation of sympathetic Nerves that secret mainly norepinephrine at their ending.

Question 1

Factors that depolarize the GI smooth muscle cell membrane, making it more excitable.

Answer 1

Stretching of the muscle, acetylcholine (parasympathetic nerves), specific gastrointestinal hormones

Question 2

Kinds os electrical waves in the GI system

Answer 2

Slow waves (caused by pacemakers - interstitial cells of Cajal) - do not cause the Ca++ to enter the cells, only Na - no contraction
Spikes - at peak of slow waves, Ca enter the fibers - contraction,
Tonic contractions - repetitive spike potentials, hormones or other factors

Question 3

Enteric nervous system

Answer 3

Myenteric plexus - Auerbach (between longitudinal and circular muscle layers)
Submucosa plexus - Meissner
Parasympathetic (vagus) - cranial - mouth, pharinge, esophagus, stomach, pancreas, -sacral - sigmoid and anus
Sympathetic - inhibit intestinal tract smooth muscle, excites mucosal muscle

Question 4

Stimuli to Gastrin secretion by G cells of the Antrum of stomach

Answer 4

Distention of stomach
Products of protein
Gastrin realizing peptide - released by nerves of mucosa during vagal stimulation.

Question 5

Actions of Gastrin

Answer 5

Stimulation of gastric acid secretion
Stimulation of growth of gastric mucosa
Vasodilatation
Promotes stomach emptying (enhance activity of pyloric pump

Question 6

Stimuli to secretion of cholecystokinin (CKK) by I cells in mucosa of duodenum and jejunum

Answer 6

Digestive products of fat, fatty acids and monoglycerides in the intestinal contents

Question 7

Actions of Cholecystokinin

Answer 7

Contracts gallbladder
Relaxation of sphincter of Oddi
Secretion of pancreatic digestive enzymes by acinar cells
Inhibits stomach contraction - give time for digestion of fat
Inhibits appetite - prevent over eating during meals - stimulate sensory nerves in duodenum
Vasodilatation

Question 8

Stimuli to secretin secretion by S cells in duodenum

Answer 8

Acid gastric juice emptying from pylorus

Question 9

Action of secretin

Answer 9

Mild effect on GI motility
Promote pancreatic secretion of bicarbonate - neutralize acid in small intestine
Stimulates liver ducktail secretion of watery solution of Na and HCO3
Vasodilatation

Question 10

Stimuli to secretion of Gastric inhibitory peptide by mucosa of upper small intestine

Answer 10

FA, AA and to a lesser extend, carbohydrates

Question 11

Action of Gastric inhibitory peptide (GIP)

Answer 11

Mild effect in decreasing motor activity of stomach when usurper small intestine is already overloaded
Stimulates insulin secretion ( glucose-dependent insulinotropuc peptide.

Question 12

Stimuli for secretion of motility by stomach and upper duodenum

Answer 12

Fasting

Question 13

Actions of motilin

Answer 13

Increase GI motility, released cyclically and stimulates waves of GI motility called interdigestive myoelectric complexes

Question 14

Where does the blood of portal vein comes from?

Answer 14

All the blood from gut, spleen and pancreas

Question 15

What comes with the blood from portal vein to the liver?

Answer 15

Bacteria - removed by reticuloendothelial cells before enters vena cava
Non-fat, water-soluble nutrients absorbed from gut (CH, ptn).

Question 16

Where do the fats absorbed fro GI tract go?

Answer 16

Absorbed into intestinal lymphatics and then conducted to systemic circulating blood by way of the thoracic duct, bypassing liver.

Question 17

Factors that cause vasodilatation in GI tract after a meal

Answer 17

Peptide hormones: CKK, vasoactive intestinal peptide, Gastrin, secretin
Kallidin and bradykinin secreted by GI glands
Decreases oxygen concentration - increase adenosine - potent vasodilator

Question 18

Factors that control small intestine peristalsis

Answer 18

Enhances: gastroenteric reflex (Myenteric plexus), Gastrin, CCK, insulin, motilin, serotonin
Inhibits: glucagon, secretin

Question 19

Anus sphincter

Answer 19

Internal-circular smooth muscle

External - striated voluntary muscle - pudendal nerve

Question 20

Autonomic reflexes that affect bowel activity

Answer 20

Excitatory: Gastrocolic, duodenocolic, gastroileal,
Inhibitory:enterogastric, peritoneointestinal, renointestinal, vesicointestinal

Question 21

Secretion of oxyntic gastric glands (body and fundus)

Answer 21

1-mucus neck cells - mucus
2-peptic or chief cells - pepsinogen
3-parietal or oxyntic cells - hydrochloric acid and intrinsic factor

Question 22

Actions of acetylcholine, Gastrin and histamine in gastric secretion

Answer 22

Acetylcholine - stimulates secretion of pepsinogen (chief cells), HCl (parietal cells) and mucus (neck cells)
Gastrin and histamine - stimulates secretion of HCl.

Question 23

Actions of pepsinogen

Answer 23

Activated to form pepsin when in contact with HCl

Pepsin - proteolytic enzyme when in highly acid medium ( digestion of colagen)

Question 24

Intrinsic factor

Answer 24

Produced by parietal cells Essential for absorption of vit B12 (maturation of red cells) in the ileum Absence of intrinsic factor = pernicious anemia

Question 25

Inhibit gastric secretion:

Answer 25

Reverse enterogastric reflex Secretin (mainly), gastric inhibitory peptide (glucose-dependent insulinotropic peptide), vasoactive intestinal polypeptide, somatostatin.

Question 26

Side effect of chronic use of proton pump inhibitor

Answer 26

Increase Gastrin secretion

Question 27

What occurs in the stomach between meals?

Answer 27

Increase of secretion of somatostatin by D cells

Question 28

The cephalic phase of HCl gastric secretion is mediated by:

Answer 28

Parasympathetic nervous activity

Question 29

Stimuli that causes pancreatic secretion

Answer 29

1) acetylcholine and cholecystokinin - secretion of pancreatic digestive enzymes 2) secretin - secretion of water solution of sodium bicarbonate

Question 30

Functions of bile salts and lecithin

Answer 30

Emulsification of fat particules - make the fat globules readily fragmentable by agitation with water Helps absorption of FA, monoglycerides, cholesterol and other lipids - transport medium to carry these particules to brush borders of intestinal epithelial cells

Question 31

Composition of bile

Answer 31

1) Bile salts - produced from cholesterol 2) Cholesterol 3) Bilirubin- end product of hemoglobin destruction 4) Lecithin - phospholipid 5) Electrolytes

Question 32

What are Brunner's glands?

Answer 32

Mucous glands at duodenum, between pylorus and papilla of Vater, that secrets mucus is response to: tactile or irritating stimuli, vagal stimulation and GI hormones (secretin)

Question 33

A 20 year old male develops severe diarrhea for 2 days. Will this condition alter his ventilation? If so, how?

Answer 33

Yes, increase minute ventilation

Question 34

A 20 year old male develops severe diarrhea for 2 days. Will this condition affect his acid-base status? If so, how?

Answer 34

Yes, metabolic acidosis.

Question 35

Jim had severe diarrhea for 2 days. What would be the best way to rehydrate his body?

Answer 35

drink isotonic salt solution containing sugar

Question 36

What is the dominant mechanism for entry of amino acids into the body?

Answer 36

Secondary active transport

Question 37

Na is actively transported through the intestinal membrane. What are the other substances that are dragged (co-transport) with it (secondary active absorption)?

Answer 37

1) glucose 2) amino acids 3) sodium-hydrogen exchanger

Question 38

How are chloride ions absorbed in the intestine?

Answer 38

1)By diffusion following electrical gradient created by Na absorption 2) in the ileum and large intestine by chloride-bicarbonate exchanger Obs: chloride excites cell on basolateral membrane through chloride channels

Question 39

How bicarbonate is absorbed in duodenum and jejunum?

Answer 39

1) hydrogen ions are secreted in exchange for Na 2) hydrogen ions combine with bicarbonate ions =>H2O+CO2 3) CO2 is absorbed into the blood and expired through lungs

Question 40

What is the importance of the bacterial activity in the colon?

Answer 40

To form vitamins K, B12, thiamine, riboflavin. Digestion of small amounts of cellulose. Form gases

Question 41

Which hormone stimulates strong smooth muscle contractions in the stomach?

Answer 41

Motilin - initiates migrating motor complex - sweeping of GI

Question 42

What are the consequences of loss os stomach secretions in gastric atrophy?

Answer 42

Achlohydria=>pepsin is nit activated | Pernicious anemia

Question 43

Most frequent sites os peptic ulcer

Answer 43

Within a few centimeters of the pylorus Lesser curvature o the antral end of the stomach More rarely in the lower end of the esophagus Marginal ulcer - wherever a surgical opening has been made between the stomach and the jejunum