Gastroduodenal Mucosal System Quiz

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary function of the alkaline mucus barrier in the gastroduodenal mucosal system?

It promotes the rapid turnover of epithelial cells.

It increases blood flow to the gastric mucosa.

It acts as a physical barrier to prevent bacteria from entering the GI tract.

It neutralizes gastric acid by secreting bicarbonate ions. (correct)

Which of the following mechanisms contributes to the maintenance of the epithelial cell barrier in the gastroduodenal mucosal system?

Neutralization of H+ ions in the extracellular fluid.

Rapid turnover of epithelial cells. (correct)

Increased blood flow to the gastric mucosa.

Secretion of mucus by surface mucus cells.

What is the main function of HCO3- in the gastroduodenal mucosal system?

It helps maintain the acidic environment of the stomach.

It promotes the absorption of nutrients from the gastrointestinal tract.

It neutralizes gastric acid, preventing damage to the epithelium. (correct)

It acts as a substrate for the production of gastric acid.

In what way does the high rate of mucosal blood flow contribute to the protection of the gastroduodenal mucosa?

It dilutes and neutralizes H+ ions that cross the tight junctions. (A) Signup and view all the answers

What is the approximate time frame for epithelial cell turnover in the gastroduodenal mucosa?

3-5 days (D) Signup and view all the answers

What type of cells are involved in restitution?

Columnar cells (D) Signup and view all the answers

Which of the following is NOT a result of prostaglandins generated by COX1 activity?

Pain perception (C) Signup and view all the answers

What is the immediate consequence of cell damage in the GI epithelium?

Activation of phospholipase A2 (A) Signup and view all the answers

What is the role of arachidonic acid in barrier regulation?

It is the precursor for prostaglandins (B) Signup and view all the answers

What is the effect of COX2 activity in the context of barrier regulation?

Increased pain perception (C) Signup and view all the answers

How does restitution differ from normal epithelial cell coverage?

Restitution involves squamous cells, while normal coverage uses columnar cells (D) Signup and view all the answers

Which of these events occurs in a sequential order starting with cell damage?

Arachidonic acid release, COX1 and COX2 activation, prostaglandin production (B) Signup and view all the answers

Which of these factors directly contribute to the inflammatory response in the GI tract?

Activation of COX2 (C) Signup and view all the answers

Which of the following gastrointestinal structures can send afferent signals to the Vomiting Center?

All of the above (D) Signup and view all the answers

What effect do non-specific NSAIDs have on the gastrointestinal tract?

They decrease blood flow to the stomach lining (B) Signup and view all the answers

What is the primary mechanism by which bloodborne toxins induce vomiting?

Activation of the chemoreceptor trigger zone (CTZ) (D) Signup and view all the answers

Which species are physiologically capable of vomiting?

Carnivores and Omnivores (D) Signup and view all the answers

What is the role of prestatcyclin in the cardiovascular system?

Vasodilation and inhibition of platelet aggregation (B) Signup and view all the answers

Which of the following is NOT a potential cause of vomiting?

Increased stomach acid production (C) Signup and view all the answers

What is the primary difference between COX-2-specific inhibitors and non-specific NSAIDs?

COX-2-specific inhibitors do not decrease protective prostaglandins (A) Signup and view all the answers

What is the physiological effect of thromboxane A2?

Vasoconstriction and platelet aggregation (D) Signup and view all the answers

Which of the following is NOT a source of circulating toxins that may trigger the chemoreceptor trigger zone (CTZ)?

Cerebral spinal fluid (D) Signup and view all the answers

What is the primary physiological function of the chemoreceptor trigger zone (CTZ)?

Detection and initiation of vomiting (C) Signup and view all the answers

During the retching stage of vomiting, which of the following occurs?

Increased intrathoracic pressure (B) Signup and view all the answers

Which of the following events is responsible for the characteristic forceful expulsion of vomit during the vomiting stage?

Sustained contraction of the abdominal muscles (B) Signup and view all the answers

Which of the following best describes the difference between vomiting and regurgitation?

Vomiting is primarily a protective mechanism, while regurgitation is a physiological process involved in rumination (C) Signup and view all the answers

Which of these is a potential metabolic consequence of protracted vomiting?

Hypokalemia (D) Signup and view all the answers

What is the role of the vagus nerve (VC) in the process of vomiting?

It sends signals to the brain to initiate the feeling of nausea (D) Signup and view all the answers

Which of the following is a characteristic of projectile vomiting?

It is characterized by a forceful expulsion of vomit (B) Signup and view all the answers

In the early stage of protracted vomiting, what is the primary cause of metabolic alkalosis?

Loss of gastric hydrochloric acid (HCl) with a strong alkaline tide. (B) Signup and view all the answers

What is the primary mechanism by which hypokalemia develops during the early stage of protracted vomiting?

Loss of potassium in vomitus and subsequent urinary excretion. (D) Signup and view all the answers

Which of the following is NOT a physiological system contributing to the gastroduodenal mucosal barrier?

Gastric acid secretion (A) Signup and view all the answers

Which of the following is NOT a stimulus to increase circulating aldosterone?

Hyperglycemia (A) Signup and view all the answers

Study Notes

Gastroduodenal Mucosal Barrier

The gastroduodenal mucosal barrier protects the epithelium from gastric acid
It is maintained by 3 physiological systems

Alkaline Mucus Barrier

Secretion of mucus from surface mucus cells
Secretion of bicarbonate from surface mucus cells into the mucus layer
Stomach: Chloride/bicarbonate exchange by surface epithelium
Duodenum: CFTR and Chloride/bicarbonate exchange

High Rate of Mucosal Blood Flow

Supports the metabolic rate of epithelial cells
Provides a source of bicarbonate
Removes hydrogen ions crossing tight junctions
The hydrogen ions are diluted and neutralized by the extracellular fluid.

Epithelial Cell Barrier, Restitution, and Turnover

Tight junctions restrict the exposed apical/luminal surface
Rapid cell turnover occurs every 3-5 days
Restitution after damage occurs within minutes

Role of Prostaglandins

Local damage to the GI epithelium (acid, abrasion) and submucosal elements (fibroblasts) release phospholipase A, which generates arachidonic acid.
Cells containing cyclooxygenase 1 and 2 (COX1 and COX2) generate prostaglandins from arachidonic acid.
COX1 activity stimulates all three physiological barriers
COX2 activity is important in pain perception

Ulcerogenic Action of Nonsteroidal Anti-inflammatory Drugs (NSAIDs)

Non-specific NSAIDs (aspirin, phenylbutazone, ibuprofen) inhibit both COX enzymes.
This leads to pain relief, but reduces alkaline mucus production, blood flow, and restitution.
COX-2 specific inhibitors (like Rimadyl for dogs) provide pain relief without impacting protective prostaglandins.

Pathophysiology of Vomiting

Species differences exist in the ability to vomit.
Carnivores and omnivores can vomit, while ruminants (physiological regurgitation of cud and pathological abomasal reflux) have different characteristics.
Horses, rabbits, and guinea pigs (other rodents) cannot vomit.

Vomiting Reflex

The vomiting center is located in the medulla's reticular formation.
It mediates nausea, retching, and vomiting.
Inputs to the vomiting center include: Vestibular apparatus, Visceral afferents, and Blood-born toxins (via the chemoreceptor trigger zone).

Process of Vomiting

Vomiting occurs in stages: nausea, retching, and vomiting.
Nausea includes experiences like salivation and proximal stomach relaxation.
Retching is a preparatory phase involving stomach relaxation and pylorus contraction.
Vomiting involves sustained abdominal muscle contraction and forced inspiratory movement.
The pressure gradient created helps expel the vomitus from the stomach to the esophagus.

Metabolic Consequences of Protracted Vomiting

Protracted vomiting leads to hypovolemia due to loss of isotonic, acidic fluid in vomitus.
Early stage results in metabolic alkalosis (loss of gastric HCl, increased blood pH), hypokalemia (K+ loss in vomitus and urine), and a shift of H+ ions into cells.
Late stage leads to metabolic acidosis due to hypovolemia, decreased tissue perfusion, and anaerobic glycolysis.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Test your knowledge on the gastroduodenal mucosal system, focusing on functions, protective mechanisms, and cell turnover. This quiz covers important aspects such as the roles of alkaline mucus, HCO3-, and the impact of blood flow on mucosal protection. Prepare to delve into cellular processes and the effects of different compounds in gastric health.