- dysphagia can be coughing, chocking if oropharyngeal - or regurg and food stuck if esophageal

Feb15 M1-Physiology - Esophagus Flashcards by Django E.

3 phases of deglutition

oral, pharyngeal, esophageal

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2 types of dysphagia

dysphagia can be coughing, chocking if oropharyngeal

- or regurg and food stuck if esophageal

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2 causes of dysphagia

mechanical obstruction (or structural abnormality) or neuromotor defect

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muscles in esophagus

proximal = SKM, then SKM and SM transition then SM (LES is SM)

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oral phase charact and 4 steps

only voluntary one

moistening
mastication
through formation (tongue moves food and holds liquid)
tongue mvmt posteriorly to move bolus to the back and trigger swallowing

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site of the voluntary center for swallowing

precentral gyrus (initiates swallow)

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precentral gyrus linked closely to what

deglutition centre in the medulla, responsible for involuntary coordination

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4 causes of anomalies in the oral phase of swallowing

neurom defect
congenital (cleft palate)
obstruction (ex. neoplasm)
trauma or inflammation

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3 prerequisites to the oral phase of swallowing

make pressure
prevent dissipation of that pressure
decrease resistance (for bolus passage)

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when swallowing becomes automatic

when bolus touches tonsils

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4 steps of pharyngeal phase to protect airways (nasal reflux)

raise soft palate.
raise base of the tongue
vocal cords come together (are below glottis)
tilting forward of epiglottis

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3 steps of pharyngeal phase to move from pharynx to esophagus

forward AND upward movement of the larynx + relaxation of esophagus
propagated contraction of pharyngeal constrictors
relaxation of UES

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what is needed for OPENING of UES

forward AND upward movement of the larynx + relaxation of esophagus
relaxation of UES (relaxation doesn’t mean opening)

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pharyngeal phase 7 steps: sensory afferents to the medulla (medullary swallowing center) travel in what cranialnerves

5, 9, 10 (10 is vagus)

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pharyngeal phase 7 steps: motor efferents from the medulla (medullary swallowing center) travel in what cranial nerves

5, 7, 9, 10 (vagus), 12

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other mechanism to protect airways by medullary deglutition center (or central pattern generator)

deglutition apnea (last a us): the deglutition centre inhibits the respiratory centre in the medulla

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3 types of things causing oropharyngeal dysphagia

obstruction or increased resistance (intra + extra luminal obstructions + xerostomia)
myogenic
nervous system

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other name for UES

cricopharyngeus muscle

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innervation of UES and consequence

vagus (PSS) impulse via a PRIMARY ORDER neuron. UES has nicotinic Ach receptor: MAKES THE MUSCLE CONTRACT

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how to make pharyngeal constrictors (muscles) (UES) relax

stop vagus Ach (N) input to the UES

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what are the ICCs (interstitial cells of Cajal)

cells of the myenteric plexus (Auerbach’s) located between inner circular and outer longitudinal

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2 plexuses of ENS

submucosal plexus (Meissner's) : PSS
myenteric plexus (Auerbach's): SS and PSS to muscles

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dual innervation of smooth muscle in the gut

vagus to Auerbach’s plexus: Ach (Nicotinir R)

neuron in Auerbach’s plexus to SM: Ach (muscarinic R on muscle (+) or inhibitory ntr like NO on muscle (-))

vago-vagal reflex present where

between deglutition centre and SKM upper esoph OR deglutition centre and SM and back to deglutition centre via vagus afferent

entero-enteric reflex is where

between Auerbach's plexus neurons and SM (distal esophagus and LOS)

forces involved in esophageal phase of deglutition

1. pharyngeal momentum 2. gravity 3. peristalsis

primary peristaltic wave def

wave of peristalsis when we swallow. 8-10 sec to propagate. part of deglutition reflex

2 high pressure zones in the esophagus

UES and LES

pressure changes in esophagus in response to primary peristalsis

causes propagation of a pressure complex (30-80 mmHg) that takes 10s

2 nuclei of the medulla giving the vagus

nucleus ambiguus and dorsal motor nucleus of the vagus

what generates peristalsis

central pattern generator (deglutition centre) of medulla relaxes downstream of bolus and contracts upstream of bolus

cutting vagus high in neck vs transthoracically consequence

high in neck: pharyngeal phase problem + no primary peristalsis transthoracically: if some fibers reach ENS, ENS can continue to propagate a normal peristalsis in SM

primary peristalsis: role of vagus and ENS

vagus: initiating in proximal esophagus ENS: continuation and propagation of primary peristalsis in distal esophagus

stimulus for primary peristalsis

pharyngeal receptors sense bolus: vago-vagal reflex

secondary peristalsis when and what

when local distension (bolus stuck or reflux) in esophagus: many waves until resolved

secondary peristalsis: innervation needed

vagus needed in upper esophagus but lower esophagus is fine with ENS

factors influencing esophageal transport (3)

1. viscosity of bolus 2. temperature of bolus 3. posture of the subject

why temp influences transport in esophagus

vago-vagal reflex where temperature sensing fibers cause inhibition of esophageal contractions if cold

LES what forms it

phrenoesophageal ligament, diaphragm, SM of the esophagus

UES vs LES closure

UES: neurogenic (vagus) LES: myogenic tone

UES vs LES relaxation

UES: central inhibition (Ach impulse STOPS) LES: local neurogenic (NANC (NO))

why LES differs from rest of GI tract + characteristics (6)

is hyperfunctioning and hypersensitive 1) more collagen 2) partially contracted at its RMP (resting membrane potention) : lower RMP 3) more resistant to stretch 4) sensitive to hypoxia 5) Ca dependent 6) more sensitive to hormones and ntrs

stuff that increases LES activity and important note

gastrin (IN PHARMA DOSES)

stuff that decreases LES activity and important note

secretin, CCK (IN PHARMA DOSES) + smoking, alcohol, morphine, fat, chocolate, carminatives (mechanisms with cAMP)

one thing that lowers LES pressure at endogenous dose

progesterone

pyrosis def

heartburn

GERD leads to what changes in esophagus

metaplastic changes in mucosa (Barrett's esophagus)

3 diseases related to GERD

1. esophagitis 2. Barrett's esophagus 3. hiatal hernia (as cause)

patients with GERD have what

defective secondary peristalsis + defective epithelial resistance in esophagus (damage)

3 esophageal studies

radiology, endoscopy, intraluminal pressure recording (manometry)

intraluminal pressure recording (manometry) explanation

use for dx + check dynamics of deglutition

causes of esophageal dysphagia + one to remember

achalasia**, stricture, cancer, eosinophilic esophagitis, spasm, ...

achalasia def

absent esophageal peristalsis (SM) and failure of LES to relax with swallowing

achalasia pathophgy + cause + consequence

kills inhibitory NO neurons. can't relax LES. dysphagia. cause is unkown

achalasia treatments

- SM relaxants - botox (blocks Ach and excitation locally) - peumatic balloon dilatation (break muscle) - surgical myotomy (break muscle)