🍔 4. Functional Types of Movements in the GI Tract

• What are the two types of movements in the gastrointestinal tract?

  Propulsive movements and mixing movements
• What is the purpose of propulsive movements in the gastrointestinal tract?

  To move food forward for digestion and absorption
• What is the role of mixing movements in the gastrointestinal tract?

  To keep intestinal contents thoroughly mixed
• What is the basic propulsive movement of the gastrointestinal tract called?

  Peristalsis
• How does peristalsis function in the gastrointestinal tract?

  A contractile ring moves forward, pushing material
• What analogy is used to describe the mechanism of peristalsis?

  Constricting fingers around a distended tube
• What stimulates intestinal peristalsis?

  Distenstion of the gut wall
• What happens when a large amount of food collects in the gut?

  The gut wall stretches, stimulating peristalsis
• What other stimuli can initiate peristalsis besides distention?

  Chemical or physical irritation of the gut lining
• How do strong parasympathetic signals affect peristalsis?

  They elicit strong peristalsis
• What is the function of the myenteric plexus in peristalsis?

  It is required for effective peristalsis
• What happens to peristalsis in the absence of the myenteric plexus?

  Peristalsis occurs weakly or not at all
• What effect does atropine have on peristalsis?

  It blocks peristalsis by paralyzing nerves
• Why is an active myenteric plexus essential for peristalsis?

  It facilitates the contraction of gut muscles
• What is the directional movement of peristaltic waves in the gut?

  Toward the anus
• What is the "Law of the Gut"?

  Peristalsis moves contents toward the anus
• Why does peristalsis die out in the orad direction?

  It is due to the myenteric plexus polarization
• How does the myenteric plexus influence peristalsis direction?

  It is polarized in the anal direction
• What initiates peristalsis in the intestinal tract?

  Distention of a segment of the intestinal tract
• How far does the contractile ring push contents during peristalsis?

  5 to 10 centimeters
• What is "receptive relaxation" in the gut?

  Relaxation downstream toward the anus
• What is the role of the myenteric plexus in peristalsis?

  It is essential for the peristaltic reflex
• What is the term for the reflex involving peristalsis?

  Myenteric reflex
• How do mixing movements differ in the alimentary tract?

  They vary in different parts of the tract
• What happens when peristaltic contractions are blocked by a sphincter?

  They churn the intestinal contents
• How long do local constrictive contractions last in the gut?

  5 to 30 seconds
• What is the effect of intermittent constrictive contractions in the gut?

  They chop and shear the contents
• What are the types of movements in the gastrointestinal tract?

  • Peristaltic movements: propel contents toward the anus
  • Mixing movements: churn and mix contents
  • Local constrictive contractions: chop and shear contents
• How are peristaltic and constrictive movements modified in the gastrointestinal tract?

  • They are adapted for proper propulsion
  • They vary in different parts of the tract
  • They ensure effective mixing and movement