DEGLUTITION REFLEX

DEGLUTITION REFLEX

Though the beginning of swallowing is a voluntary act, later it becomes involuntary and is carried out by a reflex action called deglutition reflex. It occurs during the pharyngeal and esophageal stages.

Stimulus

When the bolus enters the oropharyngeal region, the receptors present in this region are stimulated.

Afferent Fibers

Afferent impulses from the oropharyngeal receptors pass via the glossopharyngeal nerve fibers to the

deglutition center.

Center

Deglutition center is at the floor of the fourth ventricle in medulla oblongata of brain.

Efferent Fibers

Impulses from deglutition center travel through glossopharyngeal and vagus nerves (parasympathetic

motor fibers) and reach soft palate, pharynx and esophagus. The glossopharyngeal nerve is concerned

with pharyngeal stage of swallowing. The vagus nerve is concerned with esophageal stage.

Response

The reflex causes upward movement of soft palate, to close nasopharynx and upward movement of larynx, to close respiratory passage so that bolus enters the esophagus. Now the peristalsis occurs in esophagus, pushing the bolus into stomach.

1. Dysphagia

Dysphagia means difficulty in swallowing.

Causes of dysphagia

i. Mechanical obstruction of esophagus due to tumor, strictures, diverticular hernia (out pouching

of the wall), etc.

ii. Decreased movement of esophagus due to neurological disorders such as parkinsonism

iii. Muscular disorders leading to difficulty in swallowing during oral stage or esophageal stage.

2. Esophageal Achalasia or Achalasia Cardia

Esophageal achalasia or achalasia cardia is a neuromuscular disease, characterized by accumulation of

food substances in the esophagus preventing normal swallowing. It is due to the failure of lower esophageal (cardiac) sphincter to relax during swallowing. The accumu lated food substances cause dilatation of esophagus.

Features of esophageal achalasia

i. Dysphagia

ii. Chest pain

iii. Weight loss

iv. Cough.

3. Gastroesophageal Reflux Disease (GERD)

GERD is a disorder characterized by regurgitation of acidic gastric content through esophagus. The

regurgitated gastric content flows into pharynx or mouth. Regurgitation is due to the weakness or incompetence (failure to constrict) of lower esophageal sphincter.

Features of GERD

i. Heart burn or pyrosis (painful burning sensation in chest due to regurgitation of acidic gastric

content into esophagus)

ii. Esophagitis (inflammation of esophagus)

iii. Dysphagia

iv. Cough and change of voice

v. Esophageal ulcers or cancer (in chronic cases).

1. Gastric Dumping Syndrome

Gastric dumping syndrome or rapid gastric emptying is the condition characterized by series of upper abdominal symptoms. It is due to the rapid or quick dumping of undigested food from stomach into the jejunum. It occurs in patients following partial gastrectomy (removal of stomach) or gastroenterostomy (gastric bypass surgery). The rapid gastric emptying may begin immediately after taking meals (early dumping) or about few hours after taking meals (late dumping).

Causes

i. Gastric surgery.

ii. Zollinger-Ellison syndrome (rare disorder due to

severe peptic ulcer and gastrin-secreting tumor in pancreas).

Symptoms of early dumping

i. Nausea and vomiting

ii. Bloating (increase in abdominal volume with feeling of abdominal fullness and tightness)

iii. Diarrhea

iv. Sweating and weakness

v. Fatigue and dizziness

vi. Fainting and palpitations (sensation of heart beat).

Symptoms of late dumping

i. Hypoglycemia

ii. Sweating and weakness

iii. Dizziness.

2. Gastroparesis

Gastroparesis is a chronic disorder characterized by delayed gastric emptying. It usually occurs as a

secondary disorder, precipitated by a primary cause.

Causes

i. Diabetes mellitus

ii. Postsurgical complications

iii. Motility disorder

iv. Gastric infection

v. Metabolic and endocrine disorder

vi. Decrease in myenteric ganglia (rare).

Symptoms

i. Early satiety (feeling full with small quantity of food)

ii. Nausea

iii. Vomiting

iv. Bloating

v. Upper abdominal discomfort.

 

Post a Comment

0 Comments