Physiology 2 - movements

Question 1

1. What are the 2 types of movements?

Answer 1

1. Propulsive - move towards the anus by Peristalsis

2. Mixing movement

Question 2

2. Describe Peristalsis

Answer 2

• main propulsive movement
• different parts alternate between contracting and relaxing states in a continuous way
• happens thanks to circular and longitudinal smooth muscles. quite streotyped
• unidirectional, except of pathological conditions (vomiting)
• require the contribution of the my enteric plexus
• stimulus is stretching of the wall by the food, drags can also start it,
  parasym contributes

Question 3

3. Describe mixing movements

Answer 3

• local intermittent constrictive contractions that occur every few cm in the gut wall
• usually lasts 5 to 30 seconds
• aimed to mixing the content
• facilitate digestion and absorption
• can be made by peristalsis if the peristaltic wave goes towards closed sphincter
• the movements are specific for each part of the tube according to their function, not so stereotypes along the GI
• GI movements are caused by a stimulus: mechanical (stretching) / chemicals physical / dependent on parasympathetic actuation

Question 4

4. What are the mouth’s function and movements?

Answer 4

Food ingestion and partial digestion of carbs

Chewing and swallowing

Question 5

5. Describe the mouth’s chewing movement

Answer 5

• automatic, nervous reflex: the stimulus is food inside the mouth then:
  i. food perceived to be in the mouth → mastication muscles relax (are inhibited) → drop the mandible (lower jaw) ->
  ii. stretch reflex is generated; muscles are perceived to be stretching → rebound contraction of these muscles (rising up the mandible) -> grinding action of teeth
• repeated as long as the food has to be doped
• important for:
• reduction of food particles for swallowing
• facilitating swallowing
• increase food surface for enzymes
• breaking cellulose
• make food enjoyable by stimulation of taste receptors
• increase saliva production (important for bolus formation and carbs digestion

Question 6

5. Describe the mouth’s swallowing movement

Answer 6

• passage of food from the oral cavity into esophagus
• strictly regulated
• 3 stages: voluntary, pharyngeal, esophageal

Question 7

6. What are the different stages of the swallowing?

Answer 7

1. Voluntary stage: when food is ready it’s squeezed posteriorly into the pharynx by the pressure made by the tongue upward and backward against the
   palate. after this stage only involuntary
2. Pharyngeal phase-initiation of peristaltic wave
   • facilitated by gravity
   - involves the brainstem (bolus entering pharynx stimulates epithelial swallowing receptor areas (like tonsillar pillars) and they impulse the brain stem
   I. soft palate pulled upwords and pharyngeal folds more medially
   ii vocal cords become strongly approximated, larynx is moved upward
   iii pharyngo esophageal sphincter relaxes
3. Esophageal stage
   i. Relaxation of gastroesophageal sphincter (normally closed to avoid reflex
   ii. Relaxation of muscles in the stomach
   • made by peristalsis