Gastrointestinal Physiology Quiz

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Questions and Answers

Which function of the digestive system is primarily responsible for moving food through the gastrointestinal tract?

Motility (correct)

Secretion

Absorption

Digestion

What is the main function of the submucosa layer in the gastrointestinal wall?

Muscle contraction for motility

Secretion and absorption

Protection from pathogens

Blood vessels and lymphatics (correct)

Which type of nervous regulation stimulates motility and secretion in the gastrointestinal tract?

Parasympathetic nervous regulation (correct)

Sympathetic nervous regulation

Extrinsic neural regulation

Intrinsic nerve plexus regulation

What is the primary role of the myenteric plexus within the gastrointestinal system?

Control motility Signup and view all the answers

What separates the longitudinal and circular muscle layers in the gastrointestinal tract wall?

Myenteric plexus Signup and view all the answers

Which neurotransmitter is important for enhancing motility in the gastrointestinal tract?

Acetylcholine Signup and view all the answers

Which function of the digestive system involves breaking down food into smaller components?

Digestion Signup and view all the answers

What role do intrinsic nerve plexuses play in regulating gastrointestinal functions?

They operate independently of extrinsic nerves Signup and view all the answers

What is the primary function of amylase found in saliva?

To initiate digestion of dietary starch Signup and view all the answers

Which stimulus is most likely to increase salivary secretion during severe stress?

Sympathetic activation Signup and view all the answers

Which type of cells in the gastric glands secrete hydrochloric acid (HCl)?

Parietal cells Signup and view all the answers

What inhibits gastric emptying when present in the duodenum?

Stretch Signup and view all the answers

What role does lysozyme play in saliva?

Protects against bacteria Signup and view all the answers

What is the order of gastric emptying speed for different food types?

Carbohydrate > Protein > Fat Signup and view all the answers

What hormone is secreted by G cells in the gastric glands?

Gastrin Signup and view all the answers

Which of the following is NOT a function of the stomach?

Digestion of starch Signup and view all the answers

What is the primary action of gastrin when secreted by G cells in the stomach?

Stimulates parietal cells to secrete HCl Signup and view all the answers

Which hormone is responsible for increasing the secretion of pancreatic bicarbonate?

Secretin Signup and view all the answers

What stimulates the release of Cholecystokinin (CCK)?

Lipid in the duodenum Signup and view all the answers

What is NOT a function of GIP (Gastric Inhibitory Peptide)?

Promotes gallbladder contraction Signup and view all the answers

Which type of gastrointestinal motility involves contraction behind a bolus and relaxation in front of it?

Peristalsis Signup and view all the answers

What effect does secretin have on gastric secretion?

Decreases gastric secretion Signup and view all the answers

Which of the following hormones is released in response to both lipid and acid in the duodenum?

CCK Signup and view all the answers

Which of the following is a main type of gastrointestinal motility that does not involve rhythmic contraction?

Tonic contractions Signup and view all the answers

What is the main function of the oral phase of swallowing?

Move bolus into the oropharynx Signup and view all the answers

During which phase does the swallowing reflex get triggered?

Oral phase Signup and view all the answers

Which statement correctly describes the involuntary phases of swallowing?

Respiration is inhibited in the pharyngeal phase Signup and view all the answers

What triggers the closure of the upper and lower esophageal sphincters?

Absence of swallowing Signup and view all the answers

Which of the following is true about secondary peristalsis?

It clears remains of bolus in the esophagus. Signup and view all the answers

What is the primary role of the lower esophageal sphincter?

Prevents gastric reflux into the esophagus Signup and view all the answers

What happens during the pharyngeal phase of swallowing?

Openings into the nose and trachea are closed Signup and view all the answers

Which of the following phases of swallowing is entirely voluntary?

Oral phase Signup and view all the answers

Study Notes

Gastrointestinal (GIT) Physiology

The digestive system is responsible for the breakdown of food into absorbable components.
The digestive system has four main functions: motility (movement of food), secretion (release of digestive juices), digestion (breakdown of food), and absorption (uptake of nutrients).
The digestive system includes organs like the mouth, pharynx, esophagus, stomach, small intestine, and large intestine. Accessory organs include the salivary glands, liver, gallbladder, and pancreas.

Parts of the Digestive System

Mouth: Mechanical digestion begins here by chewing, while saliva contains enzymes including amylase to initiate starch digestion.
Pharynx: The throat, a passageway for air and food.
Esophagus: Transports food from the pharynx to the stomach.
Stomach: Holds and mixes food with gastric juices (HCl, pepsin). Proteins are digested here.
Small Intestine: The primary site of digestion and absorption of nutrients.
Large Intestine: Absorbs water and electrolytes and forms feces.
Accessory organs: Salivary glands, liver, gallbladder, and pancreas contribute juices that aid digestion in the small intestine.

Digestive System Summary of Functions

Oral Cavity & Esophagus: Motility: swallowing and chewing. Secretion: saliva (amylase). Digestion: minimal carbohydrate and fat. Absorption: none.
Stomach: Motility: peristaltic mixing and propulsion. Secretion: HCI, pepsinogen, mucus, gastrin. Digestion: proteins, fats. Absorption: lipid-soluble substances.
Small Intestine: Motility: mixing (segmentation), propulsion. Secretion: enzymes (pancreas, liver, intestine), HCO3-. Digestion: carbohydrates, fats, protein, nucleic acids. Absorption: nutrients.
Large Intestine: Motility: segmental mixing, mass movement. Secretion: mucus. Digestion: limited (by bacteria). Absorption: water, mineral, vitamins.

Functional Anatomy of GIT Wall

Mucosa: Secretes, absorbs, protects.
Submucosa: Blood vessels and lymphatics, allows GIT wall stretch.
Muscularis: Motility is possible due to longitudinal and circular muscle layers.
Serosa: Attachment, lubrication; prevents friction.

Structure of GI

The GI tract has a layered structure with a lumen (central cavity) surrounded by mucosa, submucosa, muscularis externa, and serosa. These layers support secretion, absorption, and motility.
Specialized cells in each layer support these functions.

Stomach Functions

Motility: Storage and emptying of food, with emptying speed variable among food types.
Secretion: Secrete gastric juice with pepsin, HCI and other components.

The Stomach: Gastric Glands

The stomach contains gastric glands responsible for producing gastric juice.
Specialized cells in the gastric glands include parietal cells (HCl), chief cells (pepsin), mucous cells, enterochromaffin-like cells (histamine), and G cells (gastrin).

Secretion of Gastric Glands

Different cells in the gastric glands are stimulated by different factors to produce various components of gastric juice.

Control of Gastric Secretion

Gastric secretion is controlled by the cephalic (before food), gastric (during food), and intestinal (after food) phases, influenced by nerves, hormones, and other factors.

Gastric Acid Secretion

Parietal cells actively secrete HCI, playing a major role in protein digestion, killing bacteria and activation of pepsinogen.

Mechanism of Gastric Acid Secretion

Carbonic anhydrase catalyzes the reaction of CO2 and water to form carbonic acid, disassociating into hydrogen ions and bicarbonate ions, which are exchanged for chloride in the lumen.

Gastric Acid Protection

Strong acid in the stomach is contained due to the epithelial cells, tight junctions, and mucus lining. In addition, there is a high turnover rate to replace cells damaged by the acid.

Peptic Ulcer

Peptic ulcers are caused by injury to the stomach wall, most commonly from bacteria like Helicobacter pylori or drugs.

Drug Treatment of Peptic Ulcer

Drug treatments include H2-histamine receptor blockers, proton pump inhibitors, and antibiotics. These drugs aim to reduce acid secretion and treat infection.

Stomach Absorption

The stomach does not readily absorb much. Alcohol and aspirin, being relatively weak acids, can be absorbed in small quantities.

Pancreatic Juice and Bile

The pancreas has endocrine and exocrine functions. Endocrine secretions include hormones like insulin and glucagon while exocrine secretions are pancreatic juice rich in enzymes.
Pancreatic juice is rich in enzymes for digesting carbohydrates, proteins, fats, and nucleic acids. Pancreatic juice also contains bicarbonate, which neutralizes acidic chyme from the stomach.

Pancreatic Enzymes

The pancreas produces various enzymes, each specific for a different macromolecule, and must be activated in the duodenum by enterokinase or other specific enzymes.

Phases of Pancreatic Secretion

The pancreas' secretion is influenced by different phases (cephalic, gastric, and intestinal), triggered by factors like nerves and hormones in the duodenum. The intestinal phase is largely responsible for the secretion.

Hormonal Control of Pancreatic Juice

Two major hormones, Secretin and Cholecystokinin (CCK), regulate pancreatic secretion. Secretin stimulates bicarbonate production in the pancreatic duct cells. Cholecystokinin (CCK) stimulates enzyme secretion in the acinar cells.

Liver Functions

The liver secretes bile, processes nutrients, synthesizes proteins and clotting factors, filters blood, and excretes metabolites and drugs.

Bile

Bile is produced by the liver, stored in the gallbladder, and released into the duodenum to emulsify fats and enhance lipid digestion and absorption.

Control of Bile Secretion

Bile secretion is regulated by bile salts (enterohepatic circulation), secretin (acidic chyme), and vagal stimulation.

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Description

Test your knowledge on the functions of the digestive system and the anatomical structure of the gastrointestinal tract. This quiz covers topics such as the movement of food, nervous regulation, and the roles of various enzymes and muscle layers involved in digestion.