HANDOUT 1 GIT

Which physiological process is responsible for breaking down complex food molecules into simpler substances?

Which control system of GI functions involves the release of chemical messengers such as gastrin and secretin?

What is the main function of neural control in the GI tract?

In the context of GI physiology, what is the primary role of smooth muscle cells?

Which anatomical structure of the GI tract is primarily responsible for the absorption of nutrients?

What is the main function of blood flow control in the context of GI physiology?

Which hormone is released from the upper small intestinal specialized cells and is stimulated by fat and carbohydrates in chyme?

What stimulates the release of Secretin?

Which type of movement ensures the movement of chyme analward at an appropriate rate?

What is the function of migrating motor complex (MMC)?

What controls the rhythmic contractions of the longitudinal layer in the intestine?

Which hormone enhances intestinal motility?

How are peristaltic contractions initiated in the GI tract?

What initiates contractile ring 2-3 cm above the distended part and relaxation down to the distension of segment, which moves forward along the GI tract?

What is the role of the third thin layer of smooth muscle cells known as Muscularis mucosa?

What causes the appearance of slow waves in smooth muscle cells?

Which cells are believed to be the pacemaker cells of the gastrointestinal tract?

What is the role of interstitial cells of Cajal (ICCs) communication with smooth muscle cells?

How do smooth muscle cells respond to a wide range of stimuli caused by neurotransmitters or hormones?

What are the characteristics of Interstitial Cells of Cajal (ICCs)?

What is the source of Ca++ for contraction in smooth muscle cells?

What is the involuntary stage of deglutition subdivided into?

What is the function of the upper esophageal sphincter during deglutition?

Which nerve controls the lower third of the esophagus during deglutition?

What is the role of inhibitory neurons from the lower part of the esophagus?

What pathological condition may result from the failure of the lower esophageal sphincter to relax?

What is the function of receptive relaxation of the stomach?

What is responsible for determining the frequency of peristaltic constrictive waves in the stomach?

What structure prevents passage of food particles into the duodenum until they are well mixed with secretions?

What triggers hunger contractions in the stomach?

What hormone has a mild stimulatory effect on peristaltic activities of the stomach?

What initiates myenteric reflexes that cause an increase in pyloric pump activity?

What is the primary function of the enteric nervous system in the gastrointestinal tract?

Which division of the parasympathetic nervous system provides innervations to the esophagus, stomach, pancreas, and small intestine?

Which hormone is released from the upper small intestinal specialized cells and is stimulated by fat and carbohydrates in chyme?

What stimulates the release of VIP (Vasoactive Intestinal Peptide) in the enteric nervous system?

What is the function of motilin in the gastrointestinal tract?

Which anatomical structure of the GI tract is primarily responsible for the absorption of nutrients?

What initiates contractile ring 2-3 cm above the distended part and relaxation down to the distension of segment, which moves forward along the GI tract?

What is the main function of blood flow control in the context of GI physiology?

Which system causes a decrease in blood flow to the gut through vasoconstriction?

What is the main responsibility of the haustration contractions in the colon?

What initiates the intrinsic reflexes preceding the defecation act?

What is the role of mass contractions in the colon?

How do the propulsive movements (mass contractions) in the colon appear?

What is the effect of irritations like ulcerative colitis on the mass movements of the colon?

What causes feces to move into the rectum, initiating defecation reflex?

What is the role of intrinsic reflexes in defecation?

What represents the appearance of haustration contractions in the colon?

What is the effect of gastrocolic and duodenocolic reflexes on mass contractions?

What represents propulsive movements (mass contractions) in the colon?

How do intrinsic reflexes contribute to defecation?

What is responsible for increasing mass movements of the colon in cases like ulcerative colitis?

Is the primary function of the enteric nervous system in the gastrointestinal tract related to the release of chemical messengers such as gastrin and secretin?

Does the hormone Motilin have a role in enhancing intestinal motility?

Are interstitial cells of Cajal (ICCs) believed to be the pacemaker cells of the gastrointestinal tract?

Is neural control the main system responsible for determining the frequency of peristaltic constrictive waves in the stomach?

Does Vasoactive Intestinal Peptide (VIP) stimulate the release of Secretin in the enteric nervous system?

Is the effect of gastrocolic and duodenocolic reflexes on mass contractions a decrease in blood flow to the gut through vasoconstriction?

The myenteric plexus, also known as Auerbach’s plexus, controls gastrointestinal movements.

The submucosal plexus, also known as Meissner’s plexus, primarily controls gastrointestinal blood flow.

The parasympathetic nervous system provides innervations through vagus nerve to the distal half of the colon, sigmoidal, rectum, and anal region.

Sympathetic stimulation causes vasoconstriction, resulting in decreased blood flow to the gut.

Gastrin and Secretin release vasodilator substances after mucosal stimulation caused by meals.

The increase in absorption, secretion, and motor activities in the gut after a meal is accompanied by a decrease in blood flow.

Parasympathetic stimulation causes an increase in blood flow to the gut.

The initiation of chewing reflex is stimulated by smell and taste to cause chewing of food in the mouth.

The presence of food bolus in the mouth causes activation of the stretch reflex, leading to the initiation of chewing reflex.

Chewing results in grinding action on food to get smaller particles.

Mastication primarily occurs due to muscle stretching caused by the drop of the lower jaw.

Chewing reflex centers in hypothalamus and cerebral cortex are stimulated by muscle stretching caused by drop of the lower jaw.

The activity of muscularis mucosa is responsible for the shortening and elongating mucosal folds.

Haustration contractions of the colon are similar to segmentation contractions of the small intestine.

Mass contractions appear 1-3 times a day and last for 10-30 minutes each time.

Gastrocolic and duodenocolic reflexes facilitate mass contractions in the colon.

Defecation in normal people occurs as a voluntary act by relaxing the external sphincter.

Intrinsic reflexes preceding defecation act cause more contractions in ascending colon and rectum.

Extrinsic reflexes result in signals to the internal sphincter to cause relaxation during defecation.

All defecation reflexes are involuntary.

Muscularis mucosa is involved in causing haustral appearance in the colon.

The contractions caused by muscularis mucosa are affected by the activity of the enteric nervous system.

Proximal colonic content is mainly moved by haustration contractions.

Mass movements may be initiated by irritation of the colon, such as in ulcerative colitis.

Smooth muscle cells in the gastrointestinal tract are characterized by the presence of fast waves and spike potentials.

The release of Ca++ from sarcoplasmic reticulum in smooth muscle cells occurs by formation of IP3 resulting from signal transduction mechanisms.

Smooth muscle cells respond to a limited range of stimuli caused by neurotransmitters or hormones.

The 4 cells of Cajal play an insignificant role in the synchronization of smooth muscle cells activity.

Slow waves in smooth muscle cells are believed to be dependent on mechanical factors rather than metabolic factors.

The tonic contraction by smooth muscle cells is independent of the binding of ligands to their receptor.

The electrical activity of smooth muscle cells is solely controlled by the neurochemical system.

Interstitial Cells of Cajal (ICCs) are incapable of eliciting electrical activity as action potentials.

The entry of Ca++ from the interstitial fluid into smooth muscle cells occurs independently of any activation.

Smooth muscle cells do not form syncytium, and each cell functions independently.

The third thin layer of smooth muscle cells known as Muscularis mucosa is not involved in movements of mucosal folds or secretion from tubular glands.

The characteristic slow waves in smooth muscle cells represent undulating changes in membrane potential known as basic electrical rhythm (BER).

Decreased pH in the duodenum causes an increase in gastric emptying.

CCK (cholecystokinin) is released from the jejunum and its release is stimulated by fat in chyme.

GIP (Gastric Inhibitory Peptide) is released from upper small intestinal specialized cells and is stimulated by protein in chyme.

Peristaltic contractions move food along the GI tract and are caused by rhythmic shortening of the circular muscle layer.

The enteric nervous system has no role in controlling gastrointestinal functions, including movements and rate of chyme movements.

Hormones like secretin and glucagon enhance intestinal motility.

Circular smooth muscle cells provide mixing of food with GI secretions in the GI tract through segmentation contractions.

The maximum frequency of segmentation contractions is about 12/minute in the terminal ileum.

Migrating Motor Complex (MMC) primarily occurs during digestive periods.

The function of Migrating Motor Complex (MMC) is to propel chyme in the oralward direction.

Deglutition has three stages: voluntary, pharyngeal, and esophageal.

An effective peristaltic activity to cause a propulsive movement of chyme requires an intact and active enteric nervous system.

The primary peristaltic contractions in the esophagus continue the contractions initiated in the pharynx.

Parasympathetic nervous system modulates the peristaltic activities by changing the activity of neural network or by changing the activity of smooth muscle cells.

The lower esophageal sphincter relaxes to allow the bolus to move into the esophagus.

Achalasia occurs when the ability of myenteric plexus to cause relaxation of the sphincter has failed.

The pyloric sphincter constricts to impede emptying of chyme into the stomach.

The pyloric pump refers to the process that results in gastric emptying.

Pylorus is a large opening between the stomach and duodenum.

Hunger contractions in the stomach are rhythmical peristaltic contractions that appear when the stomach is full.

Gastrin has a mild stimulatory effect on the peristaltic activities of the stomach.

Filling of the stomach inhibits the tone of pyloric sphincter.

Interstitial cells of Cajal (ICCs) communicate with smooth muscle cells to initiate hunger contractions in the stomach.

Irritations like ulcerative colitis enhance mass contractions of the colon.