Esophageal motility

Objectives:

❖ Mastication and chewing reflex ❖ Swallowing process and its stages ❖ Types of esophageal ❖ Esophageal sphincter ❖ Function of lower esophageal sphincter ❖ Achalasia ❖ Incompetence of lower esophageal sphincter

Done by :

➔ Team leader: Rahaf AlShammari ➔ Team members: ◆ Majd AlBarrak, Shahad AlZahrani ◆ Khalid AlMutairi, Mohammed AlHassan Colour index: ◆ Abdullah AlSargani, Abdullah AlZaid ● Important ◆ Wejdan AlBadrani, Maha AlAmri ● Numbers ◆ Hadeel AlMukainzi, Shahad AlTayash ● Extra َ Norah AlKadi ◆ َوأن َّل ْي َ َس ِلْ ِْلن َسا ِنَ ِإََّلَ َما َس َع ىَ Mastication (Chewing) Functions: 1. To lubricate the bolus with salivary secretion.

2. To breakdown the bolus to small particles.

3. To begin of carbohydrate (by amylase). Teeth organization: ● Anterior teeth (incisors) for cutting. ● Posterior teeth (molars) for grinding. Chewing muscles are innervated by cranial nerve V (): ● Masseter ● Temporalis ● Pterygoid (lateral & medial)

Taste center (Hypothalamus + Brainstem) ➝ rhythmical chewing movements (Chewing reflex).

Chewing (stretch) reflex:

The presence of a bolus of food in the initiates reflex inhibition of the muscles of mastication ➝ the lower jaw drops ➝ stretch reflex of the jaw muscles & contraction ➝ jaw closure & compression of the bolus again against the linings of the mouth ➝ inhibits the jaw muscles once again, allowing the jaw to drop and rebound another time; this is repeated again and again. Food in mouth stimulates Oral & periodontal mechano- receptors

Jaw stretch reflex Jaw opening reflex

Stimulate jaw closure & muscle spindle stretch receptors 2

Very useful video Swallowing (Deglutition)

Swallowing is The ordered sequence of events that propel food from the mouth to the . ● Initiatarion is voluntary, thereafter it is entirely under reflex control. ● Inhibits respiration and prevents the entrance of food into the airway passages. ● The reflex portion of swallowing is controlled by the swallowing center in the medulla.

Stages of Swallowing

Oral Stage Pharyngeal Esophageal (voluntary) Stage Stage “Buccal stage” (involuntary) (involuntary)

I- The Oral Stage:

➢ This stage involves the voluntary rolling of the chewed food (bolus) posteriorly into the by the upward and backward pressure applied by the against the palate.

➢ The activation of somatosensory receptors in the pharynx initiates the involuntary swallowing reflex in the medulla. From here on, swallowing becomes entirely automatic and can not be stopped. 3 II- The Pharyngeal Stage:

1 2 3

The palatopharyngeal At the pharynx, the bolus The Is folds pull medially to stimulates epithelial pulled upward to close approximate and form a swallowing receptor the posterior nares sagittal slit through areas all around the which prevents the which food must pass pharynx opening and food from entering the into the posterior impulses pass to nasal cavities. pharynx. swallowing center and . accordingly initiate a Form a passage for the food. series of autonomic pharyngeal muscle contractions as follows:

4 5 6

The vocal cords are The upward Once the is raised strongly approximated movement of the and the and the larynx is pulled larynx pulls up and pharyngoesophageal upward and anteriorly enlarges the opening sphincter relaxes, the by the muscles. to the . entire muscular wall of These actions cause the The upper the pharynx contracts to swing esophageal sphincter propelling the food by backward over the relaxes and food peristalsis into the opening of the larynx. move into the upper esophagus. esophagus. Swallowing center inhibits عشان كذا لو تكلمنا واحنا ناكل .the ممكن نشرق

4 Summary of the Pharyngeal stage:

● The is closed. ● The esophagus is opened.“Sphincter relaxed” ● A fast peristaltic wave initiated by the nervous system of the pharynx forces the bolus of food into the upper esophagus . ● Time of process is < 2 second.

Nervous Initiation of the Pharyngeal Stage of Swallowing

Most Are located in a ring around the sensitive pharyngeal opening including the areas for its tonsillar pillars. initiating

Are received by the nucleus Sensory tractus solitarius via the medulla impulses oblongata through the 5th & 9th Pharyngeal . stage Swallowing Automatic successive stages of center swallowing initiated by neuronal initiates areas of the reticular substance of medulla & lower portion of .

Motor Are transmitted from the impulses to swallowing center by the 5th, 9th, pharynx 10th, and 12th cranial nerves and few of the superior cervical nerves.

5 III- The Esophageal Stage :

● The esophagus is a conduit to move food rapidly from the pharynx to the stomach. ● The esophageal stage is controlled partly by the swallowing reflex and partly by the (ENS). In case of vagotomy enteric nervous system takes over. Vagotomy: cutting of ● Physiologically, esophagus is divided into three functionally distinct regions: - Upper esophageal sphincter (UES) - Esophageal Body - Lower esophageal sphincter (UES)

The upper 1/3 of the Striated muscle (peristaltic waves are controlled by esophagus: impulses from IX and X nerves)

The lower 2/3 Smooth muscle (controlled by the X nerve through of the connections with esophageal myenteric nervous esophagus: system).

The swallowing A peristaltic wave begins just below UES when bolus reflex closes pass through it and traverse the entire esophagus. UES:

The lower esophageal Relaxes and the bolus enters the stomach. sphincter: “Receptive relaxation”

6 Esophageal peristalsis:

Types of Esophageal Peristalsis:

Primary Secondary

● A continuation of peristaltic wave that ● Bolus very big or sticky. begins in pharynx and spreads into esophagus ● Occurs in response to during the pharyngeal distention and continue stage of swallowing. until all the food is emptied ● This wave passes from into the stomach. the pharynx to the stomach in 8-10 sec. ● ENS and swallowing center ● Coordinated by are both involved swallowing center.

7 Types of Esophageal Peristalsis:

Primary

A bolus in esophagus

Push bolus towards Pressure receptors stomach Swallowing center

Vagus Esophageal phase of swallowing reflex Primary peristalsis

Secondary

A large sticky bolus in esophagus

Push bolus Pressure receptors towards stomach Lubricate Intrinsic Extrinsic nerves nerves

(Stronger) Salivation 8 Esophageal Sphincters

The Upper Esophageal Sphincter (UES)

It is formed of striated muscle but is not under voluntary Where control, located at the lower end of pharynx and guards the entrance into the esophagus.

● It prevents esophageal air insufflation during negative Function intrathoracic pressure events, as during inspiration. ● It prevents esophagopharyngeal/laryngeal reflux during esophageal peristalsis.

When Relax It relaxes during swallowing for about 1 second allowing the bolus to be forced through the relaxed UES

The lower Esophageal Sphincter (LES)

It is formed by circular smooth muscle located in an area Where Where of ~ 3 cm upward of the junction with the stomach.

In between swallowing, it normally remains tonically constricted to prevent reflux of gastric contents into esophagus. During swallowing, the peristaltic wave passes down the esophagus Function and causes a “receptive relaxation” of LES for 7-10 sec. (mediated by vagal impulses) to allow easy propulsion of the swallowed food into the stomach.

Pressure in the esophagus is mostly –ve (except for a short intra-abdominal segment). Why So that pressure in the stomach is always higher than the 9 esophagus. Causes of Competence and the antireflux functions of the LES 1 Its resting pressure (15- 30 mmHg).

2 The diaphragm wraps around the esophagus at the level of LES. Contraction of the diaphragm during inspiration helps to increase the pressure at the LES.

3 The flutter-valve closure of the lower esophagus by the increased intra-abdominal pressure prevents the high pressure in the stomach from forcing its contents into the esophagus.

4 Valve-like closure of the distal end of the esophagus. This involves a short portion of the esophagus that extends slightly into the stomach and caves the esophagus inward in response to increased intraabdominal P. “Caving of esophagus inside the stomach”

Doctor said: 3 mechanisms behind competency of LES: 1-Tonic contraction of smooth muscles. 2- Diaphragm contraction and wrapping. 3-Valve-like closure. Competence and the Antireflux Functions of the LES

Control of LES Function

Circular musculature of LES is regulated by nerves, (extrinsic & intrinsic), hormones and neuromodulators.

Contraction of LES Relaxation of LES

● Between swallows (tonic vagal ● During swallowing (efferent cholinergic impulses) vagal impulses).

● Stimulation of sympathetic ● The transmitter is NO or VIP. nerves . ● and 10 ● hormone. (CCK) Doctor said: Failure of sphincter to relax due to absence of Achalasia inhibitory neuron (vagus nerve)

It is due to of or The musculature of the lower absence of the myenteric esophagus instead remains plexus containing VIP & NO in contracted and the myenteric the lower third of esophagus plexus has lost the ability to (may be due to autoimmune transmit a signal to cause destruction of the nerves in relaxation of the LES (high esophageal wall). resting pressure).

Food becomes putridly infected Food transmission from the during the long periods of esophagus into the stomach is esophageal stasis causing impeded or prevented. As ulceration of the gets worse, the mucosa, severe substernal pain esophagus gradually enlarged or even rupture & death. as food collects within it.

11 Diagnosis:

I. Esophageal manometry. “Measure the pressure in the esophagus ” II. X-rays of upper digestive system (barium swallow). III. Upper endoscopy. Treatment:

Surgical Non-surgical

Myotomy Pneumatic dilation Injecting muscle Medication cutting the muscle at by balloon insertion relaxant (Botox) as muscle the lower end of the into the directly into the relaxants, esophageal esophageal esophageal nitroglycerin sphincter. sphincter. . sphincter. before .

Gastroesophageal Reflux Disease (GERD) Incompetence of the LES:

12 Contributing What is it Cause factors

Weight gain, fatty foods, caffeinated or It may result from a carbonated beverages, Incompetence of the generalized loss of intrinsic alcohol, tobacco lower esophageal sphincter tone or from smoking ,and drugs sphincter allows reflux recurrent inappropriate (anticholinergics, of gastric contents into transient relaxations antihistamines, calcium the esophagus. triggered by gastric channel blockers, secretions. progesterone and nitrates).

It can lead to Diagnosis Treatment

Reflux esophagitis, Is clinical, sometimes Involves lifestyle heartburn, esophageal with endoscopy, with or modification, acid stricture, ulcer, dysplastic without 24-h pH suppression using changes (cancerous) ,or testing. proton pump Barrett esophagus inhibitors, and (normal tissue lining the sometimes surgical esophagus resembles repair. tissue lining of the intestine).

13 Summary

Causes of Competence and the antireflux functions of the LES

1. Its resting pressure (15- 30 mmHg). 2. The diaphragm wraps around the esophagus at the level of LES 3. The flutter-valve closure of the lower esophagus by the increased intra-abdominal pressure. 4. Valve-like closure of the distal end of the esophagus.

the myenteric Food becomes plexus has lost putridly absence of the myenteric the ability to Food infected during plexus containing VIP & transmit a transmission the long NO in the lower third of signal to cause Is prevented periods of esophagus relaxation of esophageal the LES stasis

14 Questions

MCQs

1- Stages of swallowing: 5- One method to diagnose GERD is A) Oral, pharyngeal, esophageal. A) Endoscopy B) Mastication, oral, pharyngeal, B) Xray esophageal. C) Esophageal manometry C) Pharyngeal, esophageal. D) Pharyngeal, esophageal, gastric. 6- The esophageal stage is controlled by: 2- In the pharyngeal stage: A) Enteric nervous system A) palatopharyngeal folds pull B) Swallowing reflex medially to approximate and form C) Swallowing reflex+ENS a horizontal slit. B) The larynx is pulled upward and 7- The UES relaxes during swallowing anteriorly by the face muscles. for about: C) The soft palate is pulled downward A) 7-10 sec to close the posterior nares. B) 1 sec D) The epiglottis swings backwards C) 2 sec over the opening of the larynx. D) 5 sec

3-Enlargement of the esophagus due to 8- The surgical treatment for collection of food within it, is a Achalasia is: complication of: A) Injecting muscle relaxant A) Achalasia (Botox) B) GERD B) Pneumatic dilation by balloon C) H Pylori infection C) Nitroglycerin D) Heavy meal D) Myotomy

4- One of the UES functions is: 9- Which of these causes LES A) Prevention of the reflux of gastric contraction: contents into the esophagus A) Secretin B) Prevention of esophageal air B) CCK insufflation. C) Gastrin C) Prevention of the D) Nitroglycerin esophagopharyngeal/laryngeal reflux

D) (C+B)

D D C C

D

A A A D

B B

A

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