Gastrointestinal Motilities Overview
40 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the process called when food is broken down into smaller particles?

Mastication (chewing)

Chewing is a voluntary action, but it is mainly controlled by reflexes.

True

What is the role of the tongue in chewing and mixing?

The tongue helps mix food with saliva and move it around the mouth.

Which of the following is NOT a stage of deglutition (swallowing)?

<p>Peristaltic Stage</p> Signup and view all the answers

What is the role of the soft palate in deglutition?

<p>The soft palate moves upward to close the posterior nares (nostrils) to prevent food from entering the nasal cavity.</p> Signup and view all the answers

What is the role of the epiglottis in deglutition?

<p>It closes over the glottis (opening of the trachea) to prevent food from entering the airway.</p> Signup and view all the answers

What is the primary function of the stomach?

<p>Storage of food.</p> Signup and view all the answers

The stomach has a fixed size.

<p>False</p> Signup and view all the answers

What type of relaxation is initiated by the vagovagal reflex when food enters the stomach?

<p>Receptive relaxation</p> Signup and view all the answers

What is the name of the mixture of food and gastric secretions that is produced in the stomach?

<p>Chyme</p> Signup and view all the answers

What is the frequency of mixing waves in the stomach?

<p>Approximately three per minute (3/min).</p> Signup and view all the answers

The pyloric sphincter is always open, allowing chyme to freely pass into the duodenum.

<p>False</p> Signup and view all the answers

What is the name of the rhythmic contractions that occur in the stomach when it is empty?

<p>These contractions are associated with feelings of hunger and are linked to blood glucose levels.</p> Signup and view all the answers

Which hormone is secreted by the antral mucosa and stimulates gastric motility?

<p>Gastrin</p> Signup and view all the answers

What is the main function of the enterogastric reflexes?

<p>To inhibit gastric emptying.</p> Signup and view all the answers

What is the main role of the ENS (enteric nervous system)?

<p>The coordination of the gastrointestinal tract movements and processes.</p> Signup and view all the answers

What is the primary function of the parasympathetic nervous system with regards to GI motility?

<p>To modulate peristaltic activity.</p> Signup and view all the answers

Hormones like gastrin, CCK, and serotonin increase gastrointestinal motility.

<p>True</p> Signup and view all the answers

What is the term for the alternating contractions and relaxations of the circular smooth muscle in the small intestine?

<p>Segmentations</p> Signup and view all the answers

Which of the following is the main role of segmentations in the small intestine?

<p>Mixing chyme with secretions</p> Signup and view all the answers

What is another name for the peristaltic rush?

<p>Remove harmful agents</p> Signup and view all the answers

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

<p>Sweeping intestinal contents during the period between meals.</p> Signup and view all the answers

The muscularis mucosa layer influences the activity of the enteric nervous system.

<p>False</p> Signup and view all the answers

What are the two main types of movements in the colon?

<p>Haustration contractions and propulsive movements (mass contractions).</p> Signup and view all the answers

Haustration contractions are similar to segmentations in the small intestine.

<p>True</p> Signup and view all the answers

Haustration contractions primarily aid in water and electrolyte absorption.

<p>True</p> Signup and view all the answers

What is the main function of propulsive movements (mass contractions) in the colon?

<p>To move fecal material from the cecum to the transverse colon.</p> Signup and view all the answers

How often do mass contractions usually occur?

<p>One to three times per day.</p> Signup and view all the answers

Colon irritation can increase the frequency of mass contractions.

<p>True</p> Signup and view all the answers

What is the function of the internal anal sphincter?

<p>To prevent the involuntary release of feces from the rectum.</p> Signup and view all the answers

Defecation can occur solely through intrinsic reflexes.

<p>False</p> Signup and view all the answers

Increased abdominal pressure is achieved by contracting abdominal wall muscles and closing the glottis.

<p>True</p> Signup and view all the answers

The large intestine acts like a final station - its primary function is to regulate the movement of feces.

<p>True</p> Signup and view all the answers

The large intestine is the site of most digestion and absorption.

<p>False</p> Signup and view all the answers

Which of the following is NOT a function of haustration contractions?

<p>Propelling feces rapidly through the colon</p> Signup and view all the answers

Mass contractions often occur in the first hour after breakfast.

<p>True</p> Signup and view all the answers

What is the name of the reflex that is stimulated by food intake and leads to increased mass movements?

<p>Gastrocolic reflex</p> Signup and view all the answers

What is the involuntary action of the intestines that is triggered by irritation or distention?

<p>Propulsive rush</p> Signup and view all the answers

The migrating motor complex (MMC) occurs during meal times.

<p>False</p> Signup and view all the answers

What is the main role of the muscularis mucosa layer?

<p>To facilitate the absorptive process by the intestinal mucosa.</p> Signup and view all the answers

Study Notes

Gastrointestinal Motilities

  • Mastication (Chewing): Chewing breaks down food into smaller particles. This process is triggered by smell and taste, and is initially voluntary but progresses to a reflex. Jaw movement is stimulated by muscle stretching. Mixing of food with saliva occurs alongside the chewing action.

  • Deglutition (Swallowing): A two-stage process involving voluntary and involuntary actions. The voluntary stage involves the tongue pushing food upwards and backwards against the soft palate. The involuntary stage starts with the pharynx contracting (as food enters). Esophageal peristalsis occurs, moving the bolus along the esophagus. Swallowing receptors in the pharynx, and swallowing centers in the brain, are involved.

Pharyngeal Stage

  • Duration: Approximately 2 seconds.
  • Key Events: Respiration is halted, the soft palate closes the posterior nares, the larynx moves upward, the epiglottis closes, the upper esophageal sphincter relaxes, and the esophageal opening expands. These actions propel the bolus into the esophagus.

Esophageal Stage

  • Function: Conducts the bolus to the stomach.
  • Types of Contractions: Primary peristaltic contractions and secondary peristalsis. Primary contractions begin in the pharynx and continue through the esophagus (8-10 seconds). Secondary contractions are triggered by esophageal distension (retained food) or failure of the primary reflex.

Gastric Motilities

  • Primary Function: Food storage. The stomach can dilate from 50ml to 1000ml. Receptive relaxation reduces muscular tone to accommodate food entry.
  • Gastric Secretions and Mixing: Secretions and ingested food are mixed to form chyme. Peristaltic constrictive waves mix secretions with food and push chyme toward the duodenum. Waves occur at a frequency of 3/min in the mid-stomach moving toward the antrum.

Constrictive Rings

  • Description: As contractions approach the antrum they become more intense and form constrictive rings at the pylorus in the stomach. Retropulsion mixes food.

Gastric Emptying

  • Small Chyme Passage: Only small amounts of fluid-consistency chyme are passed.
  • Pyloric Pump: This process controls gastric emptying. The pylorus is a small opening and is guarded by a smooth muscle sphincter.

Neural and Hormonal Control of Gastric Emptying

  • Stimulation: Filling the stomach activates enteric reflexes, which increase pyloric pump activity and reduce sphincter tone. Gastrin stimulates peristaltic activity.
  • Inhibition: Entero-gastric reflexes are triggered by chyme entering the duodenum. This decreases pH and stimulates reflex responses. ENS; Prevertebral Ganglia; Vago-Vagal reflexes decrease antral propulsive contractions and increase sphincter tone. Hormonal feedback from the duodenum through cholecystokinin (CCK) and gastric inhibitory peptide (GIP) inhibit gastric emptying.

Intestinal Movements

  • Propulsive (Peristalsis) Movements: Chyme is propelled toward the anus at an appropriate rate.
  • Mixing (Segmentation) Movements: Food is mixed with gastrointestinal (GI) secretions to aid in digestion and absorption.

Neural Control of Peristalsis

  • Role of Enteric Nervous System: The ENS controls GI movements and chyme movement (the rate of movement). Excitatory neurons extend upward in the Orad Extension and inhibitory neurons extend downward in the Caudad Extension.
  • Mucosal Stimulation: Peristaltic contractions can also be triggered by mucosal stimulation.
  • Parasympathetic Nervous System: Modulates peristaltic activity by influencing neural networks and smooth muscle function.

Hormonal Control of GI Motility

  • Hormones Affecting Motility: Hormones affect intestinal motility during food processing: Gastrin, CCK, and Serotonin enhance motility. Secretin and Glucagon inhibit motility.

Mixing Movements

  • Mechanism of Mixing: Circular smooth muscle contractions create segmentations, mixing chyme and secretions.

Frequency of Segmentations

  • Determination: Determined by the Basic Electrical Rhythm (BER) or slow waves of smooth muscle cells. The maximum frequency is 12/minute in the upper intestine (duodenum and jejunum), and 8/minute in the terminal ileum.

Other Types of Intestinal Contractions

  • Peristaltic Rush: Powerful and rapid peristaltic contractions are triggered by mucosal irritation or intestinal distension.
  • Migrating Motor Complex (MMC): Sweep intestinal contents between meals. It starts in the distal stomach, continuing along the entire small intestine.

Movements Caused by Muscularis Mucosa

  • Function: Responsible for shortening and elongating the mucosal folds and aiding the absorptive process. The activity is influenced by the enteric nervous system

Movements of the Colon

  • **Description of Haustrations:**Similar to segmentation, this rhythmic contraction and relaxation of the circular layer of colonic smooth muscle spans 2.5 cm and lasts 30-60 seconds. Longitudinal muscle strips (teniae coli) cause the haustral appearance.
  • Haustral Functions Spread colonic contents over the mucosa to aid water and electrolyte absorption; and move fecal material slowly from the cecum and ascending colon to the transverse colon.
  • Propulsive Movements (Mass Contractions): A series of powerful contractions (1-3 times a day, lasting 10-30 minutes), typically occurring in the first hour after breakfast. Begins with constrictive rings at the transverse colon and moves approximately 20cm or more distally before relaxing for 2-3 minutes. Factors contributing to contractions are the gastrocolic and duodenocolic reflexes (autonomic nervous system influences); colon irritation can also promote mass movements

Reflexes Preceding Defecation

  • Intrinsic Reflexes: Triggered by rectal distension. Increased contractions of the descending colon, sigmoid, and rectum. Insufficient for defecation alone.
  • Extrinsic Reflexes (Parasympathetic): Rectal andsigmoid distension triggers increased signals, resulting in stronger contractions of these areas, relaxation of the internal anal sphincter; these are involuntary.

Studying That Suits You

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

Quiz Team

Related Documents

Gastro-intestinal Motilities PDF

Description

Explore the key processes involved in gastrointestinal motilities, including mastication and deglutition. Understand the roles of the tongue, pharynx, and esophagus in the swallowing process. This quiz covers the physiological actions critical to food movement through the digestive system.

More Like This

Use Quizgecko on...
Browser
Open
Browser
Browser