Gastrointestinal Tract Physiology Quiz

A state where the membrane potential becomes more negative than the resting potential.

Norepinephrine and epinephrine, released by the sympathetic nervous system, can make the muscle membrane more negative, decreasing its excitability.

A type of continuous muscle contraction that can last for minutes or even hours.

One way tonic contraction can occur, where repeated action potentials lead to sustained contraction.

Another mechanism for tonic contraction, where hormones or other factors cause a persistent change in membrane potential without triggering full action potentials.

An independent nervous system within the walls of the digestive tract, regulating its functions.

The outer network of nerves in the enteric nervous system, located between muscle layers. Controls muscle contractions.

The inner network of nerves in the enteric nervous system, found in the submucosa. Controls secretion and absorption.

A nerve plexus located between the circular and longitudinal muscle layers of the GI tract, primarily regulating the motility of the gut.

A nerve plexus situated between the muscular and submucosal layers of the GI tract, primarily regulating the secretory functions of the gut.

Neurotransmitters released by the enteric nervous system that stimulate muscle contractions, enhancing the movement of food through the GI tract.

Examples of excitatory neurotransmitters include acetylcholine, which is also used in the central nervous system, and serotonin, a mood regulator.

Neurotransmitters released by the enteric nervous system that inhibit muscle contractions, slowing down the movement of food through the GI tract.

Examples of inhibitory neurotransmitters include vasoactive intestinal peptide (VIP), which is also used in the central nervous system, as well as neurotensin and encephalin.

The part of the nervous system that influences the enteric nervous system, including the sympathetic and parasympathetic branches.

Slow waves are rhythmic, electrical fluctuations in the membrane potential of smooth muscle cells in the gastrointestinal tract. They are not strong enough to cause muscle contraction on their own, but they influence the generation of spike potentials.

Interstitial cells of Cajal are specialized cells located within the walls of the gastrointestinal tract. They act as electrical pacemakers, generating slow waves that regulate the rhythmic contractions of the gut.

Spike potentials are true action potentials that occur in the smooth muscle of the gastrointestinal tract. They are triggered by the slow wave activity and directly cause muscle contraction.

The duration of spike potentials in the gastrointestinal smooth muscle is significantly longer than in nerve fibers. This is due to the presence of calcium-sodium channels that are slower to open and close.

Factors that depolarize the membrane of the gastrointestinal smooth muscle, making it more excitable, include stretching of the muscle, stimulation by acetylcholine released from the parasympathetic nerves, and stimulation by specific gastrointestinal hormones.

Acetylcholine is a neurotransmitter released from the endings of parasympathetic nerves. It plays a role in stimulating the gastrointestinal smooth muscle, thereby increasing its excitability and promoting contraction.

Several specific gastrointestinal hormones contribute to the regulation of gut motility. They influence the smooth muscle excitability and contraction, often in a specific way depending on their type and location.

Stretching of the gastrointestinal smooth muscle can depolarize the membrane, making it more excitable. This is a mechanism that helps regulate the gut's response to the presence of food.

Nerve fibers that originate in the spinal cord (T5 to L2) and travel to the celiac and mesenteric ganglia without synapsing. They release norepinephrine, which inhibits gut movements and secretions, and constricts sphincters.

Nerve fibers that originate in the brain stem (vagus nerve) and sacral spinal cord (S2-S4). They release acetylcholine, which stimulates gut movements and secretions.

Nerve fibers that carry sensory information from the gut to the central nervous system (brain and spinal cord).

These nerve fibers can be stimulated by various factors, including irritation or distension of the gut, or the presence of specific chemicals.

Signals generated by afferent nerve fibers can result in either excitation or inhibition of gut movements and secretions, helping to regulate digestion based on the situation.

Propelling food through the digestive system, similar to squeezing a tube to move its contents forward.

Keeping food mixed and thoroughly distributed within the digestive tract.

The primary way food is moved through the digestive system. It involves a ring-like contraction that travels down the tube.

Stretching of the gut wall triggered by food or other stimuli.

The enteric nervous system responds to gut distention by initiating a contraction behind the food.

Chemical or physical irritation of the gut lining can also initiate peristalsis.

The myenteric plexus is a network of nerves that plays a crucial role in peristalsis.

Mixing movements occur differently in various areas of the digestive tract.

A hormone produced in the stomach that stimulates gastric acid secretion and growth of the gastric mucosa.

It is secreted by I cells in the duodenum and jejunum in response to fats, fatty acids, and monoglycerides.

CCK strongly contracts the gallbladder, releasing bile into the small intestine to help digest fats.

Secretin is secreted by S cells in the duodenum in response to acidic gastric juice entering the small intestine.

Secretin promotes pancreatic bicarbonate secretion, which neutralizes acid in the small intestine.

Gastric Inhibitory Peptide (GIP) is secreted in the upper small intestine, primarily in response to fatty acids and amino acids.

GIP slows the emptying of the stomach to prevent overload in the small intestine.

Motilin is secreted by the upper duodenum during fasting. It stimulates interdigestive myoelectric complexes, waves of gastrointestinal motility.