2. physiology of deglutition
-
Upload
dr-krishna-koirala -
Category
Health & Medicine
-
view
82 -
download
0
Transcript of 2. physiology of deglutition
![Page 1: 2. physiology of deglutition](https://reader036.fdocuments.in/reader036/viewer/2022081520/587e2f5b1a28abb93e8b6b21/html5/thumbnails/1.jpg)
Physiology of Deglutition
Dr. Krishna Koirala
2016-12-05
![Page 2: 2. physiology of deglutition](https://reader036.fdocuments.in/reader036/viewer/2022081520/587e2f5b1a28abb93e8b6b21/html5/thumbnails/2.jpg)
• Mechanism which transmits liquids or solids from the mouth to the stomach via the pharynx and esophagus without entering the respiratory tract
• During swallowing, muscles are activated in an orderly sequence
– Controlled by complex neuromuscular interaction
– Triggered by volitional cortical drive or peripheral sensory input
– Sequential cascade does not alter after it starts
![Page 3: 2. physiology of deglutition](https://reader036.fdocuments.in/reader036/viewer/2022081520/587e2f5b1a28abb93e8b6b21/html5/thumbnails/3.jpg)
• Neural networks that are responsible for this automatic swallowing process are called central pattern generator
• Sites – Brainstem, nucleus tractus solitarius ,
nucleus ambiguus, reticular formation
![Page 4: 2. physiology of deglutition](https://reader036.fdocuments.in/reader036/viewer/2022081520/587e2f5b1a28abb93e8b6b21/html5/thumbnails/4.jpg)
![Page 5: 2. physiology of deglutition](https://reader036.fdocuments.in/reader036/viewer/2022081520/587e2f5b1a28abb93e8b6b21/html5/thumbnails/5.jpg)
Stages1. Oral stage (lasts for 1 second, voluntary)
–Preparatory phase
–Propulsive phase
2. Pharyngeal Stage (1 second, involuntary)
3. Esophageal Stage (8-20 sec, involuntary )
![Page 6: 2. physiology of deglutition](https://reader036.fdocuments.in/reader036/viewer/2022081520/587e2f5b1a28abb93e8b6b21/html5/thumbnails/6.jpg)
Oral preparatory stage
• Processing of the bolus to render it swallowable
• Solid food chewed, lubricated with saliva &
converted to a bolus
• Requires coordinated movement of lips, cheeks,
jaws and tongue against a closed oropharyngeal
isthmus
![Page 7: 2. physiology of deglutition](https://reader036.fdocuments.in/reader036/viewer/2022081520/587e2f5b1a28abb93e8b6b21/html5/thumbnails/7.jpg)
Nerves involved : V , VII, X, XII
Liquid - about 1 second, Solids - 5-
10 seconds
![Page 8: 2. physiology of deglutition](https://reader036.fdocuments.in/reader036/viewer/2022081520/587e2f5b1a28abb93e8b6b21/html5/thumbnails/8.jpg)
Oral propulsive stage• Propelling of food from the oral cavity into
the oropharynx
• Bolus propelled backwards by pressing of tongue against hard palate. Approximation of tongue against hard palate starts with tip of tongue and moves back
• Ends when food bolus crosses anterior
tonsillar pillars
![Page 9: 2. physiology of deglutition](https://reader036.fdocuments.in/reader036/viewer/2022081520/587e2f5b1a28abb93e8b6b21/html5/thumbnails/9.jpg)
Oral propulsive stage
![Page 10: 2. physiology of deglutition](https://reader036.fdocuments.in/reader036/viewer/2022081520/587e2f5b1a28abb93e8b6b21/html5/thumbnails/10.jpg)
Pharyngeal stage
1. Nasopharyngeal isthmus closed: soft palate touches Passavant’s ridge
2. Elevation of larynx negative pressure in hypopharyngeal lumen (suction pump)
3. Oropharyngeal isthmus closed: tongue base touches palate
![Page 11: 2. physiology of deglutition](https://reader036.fdocuments.in/reader036/viewer/2022081520/587e2f5b1a28abb93e8b6b21/html5/thumbnails/11.jpg)
![Page 12: 2. physiology of deglutition](https://reader036.fdocuments.in/reader036/viewer/2022081520/587e2f5b1a28abb93e8b6b21/html5/thumbnails/12.jpg)
4. Closure of larynx: (Laryngeal Tier Mechanism)
• Below upwards
– True vocal cords approximate
– False cords approximate
– Aryepiglottic folds approximate
• Temporary cessation of respiration
• Epiglottis falls back over laryngeal inlet due to laryngeal elevation and tongue pressure (lid effect)
![Page 13: 2. physiology of deglutition](https://reader036.fdocuments.in/reader036/viewer/2022081520/587e2f5b1a28abb93e8b6b21/html5/thumbnails/13.jpg)
Nasopharyngeal isthmus closed
![Page 14: 2. physiology of deglutition](https://reader036.fdocuments.in/reader036/viewer/2022081520/587e2f5b1a28abb93e8b6b21/html5/thumbnails/14.jpg)
Elevation & closure of Larynx
![Page 15: 2. physiology of deglutition](https://reader036.fdocuments.in/reader036/viewer/2022081520/587e2f5b1a28abb93e8b6b21/html5/thumbnails/15.jpg)
Oropharyngeal isthmus closed
![Page 16: 2. physiology of deglutition](https://reader036.fdocuments.in/reader036/viewer/2022081520/587e2f5b1a28abb93e8b6b21/html5/thumbnails/16.jpg)
5. Posterior retraction of tongue base ( tongue driving force)
6. Pharyngeal constrictors
contract
7. Elevation of pharynx
8. Opening of
cricopharyngeal sphincter
![Page 17: 2. physiology of deglutition](https://reader036.fdocuments.in/reader036/viewer/2022081520/587e2f5b1a28abb93e8b6b21/html5/thumbnails/17.jpg)
Opening of cricopharynx
![Page 18: 2. physiology of deglutition](https://reader036.fdocuments.in/reader036/viewer/2022081520/587e2f5b1a28abb93e8b6b21/html5/thumbnails/18.jpg)
Esophageal stage1. Closure of cricopharyngeal sphincter
2. Opening and descent of larynx
3. Primary peristalsis
– Large amplitude, propulsive, 8-9 seconds
4. Secondary peristalsis : arise locally in response to distension
– Small amplitude, propulsive, for food remnants
5. Tertiary Esophageal contractions6. Relaxation of lower esophageal sphincter
– Food bolus enters stomach
![Page 19: 2. physiology of deglutition](https://reader036.fdocuments.in/reader036/viewer/2022081520/587e2f5b1a28abb93e8b6b21/html5/thumbnails/19.jpg)
Closure of cricopharynx Opening & descent of larynx
![Page 20: 2. physiology of deglutition](https://reader036.fdocuments.in/reader036/viewer/2022081520/587e2f5b1a28abb93e8b6b21/html5/thumbnails/20.jpg)
Esophageal Peristalsis
![Page 21: 2. physiology of deglutition](https://reader036.fdocuments.in/reader036/viewer/2022081520/587e2f5b1a28abb93e8b6b21/html5/thumbnails/21.jpg)
Bolus enters stomach
![Page 22: 2. physiology of deglutition](https://reader036.fdocuments.in/reader036/viewer/2022081520/587e2f5b1a28abb93e8b6b21/html5/thumbnails/22.jpg)
Neural Mechanism• Afferents : V, IX & X cranial nerves
• Deglutition centre: Medulla oblongata
• Efferents
– X, XI & XII cranial nerves tongue, pharynx, larynx and esophageal muscles
• Cessation of respiration
– Connection between deglutition and respiration centres in medulla
![Page 23: 2. physiology of deglutition](https://reader036.fdocuments.in/reader036/viewer/2022081520/587e2f5b1a28abb93e8b6b21/html5/thumbnails/23.jpg)
• CN V : Chewing
• CN VII : Sensation to oropharynx & taste to anterior 2/3 of tongue
• CN IX : Taste to posterior 1/3rd of tongue, sensory and motor functions of the pharynx
• CN X : Taste to oropharynx, sensation and motor function to larynx and laryngopharynx . Airway protection
• CN XII : Contains motor fibers that primarily innervate the tongue
![Page 24: 2. physiology of deglutition](https://reader036.fdocuments.in/reader036/viewer/2022081520/587e2f5b1a28abb93e8b6b21/html5/thumbnails/24.jpg)
Factors preventing reflux• Anatomical– Lower esophageal sphincter contraction
– Pinch cock action of right crus of diaphragm– Lower esophageal mucosal folds (valvular)
– Oblique esophageal entry into stomach
– Oblique gastric muscle around lower esophagus
– Abdominal pressure > gastric pressure & intra-thoracic pressure
![Page 25: 2. physiology of deglutition](https://reader036.fdocuments.in/reader036/viewer/2022081520/587e2f5b1a28abb93e8b6b21/html5/thumbnails/25.jpg)
• Physiological
– Unidirectional esophageal
peristalsis
– Gastric emptying