16.3 Pharynx and Esophagus Flashcards
What is the common name for the glottis?
Vocal cords
What is the pharynx?
It is the cavity at the rear of the throat
What is the function of the pharynx?
It acts as a common passageway for both the digestive system and the respiratory system.This necessitates mechanisms to guide food and air into the proper passageways beyond the pharynx.
What is the function of the pharynx in the digestive system?
It serves as the link between the mouth and the esophagus for food
What is the function of the pharynx in the respiratory system?
It provides access between the nasal passages and trachea for air
What two things does the pharynx house in its walls?
The tonsils and lymphoid tissue
What is the function of the tonsils and lymphoid tissue in the pharynx?
They fight off pathogens that enter the body through the mouth and nose.
What is the motility associated with the pharynx and esophagus?
Swallowing
What is swallowing?
The entire process of moving food from the mouth through the esophagus into the stomach
Swallowing is a sequentially programmed…………………reflex
all-or-none
What initiates swallowing?
When a bolus is voluntarily forced by the tongue to the rear of the mouth and into the pharynx
What is a bolus?
Ball of chewed or liquid food
Explain the whole first step process of swallowing
After the bolus is pushed into the pharynx, the pressure of the bolus stimulates pharyngeal pressure receptors. This sends afferent impulses to the swallowing center in the medulla of the brain stem. The swallowing center then reflexly activates in the appropriate sequence of the muscles involved in swallowing.
What is the most complex reflex in the body?
Swallowing
Explain the oropharyngeal stage of swallowing(2)
This stage involves moving the bolus from the mouth, through the pharynx and into the esophagus.
What 7 properties prevent the bolus from entering the respiratory airways and direct it into the esophagus?
- Swallowing temporarily inhibits the respiratory center, closing off the airways meaning you cannot breath
- The uvula is elevated and lodges against the back of the throat, sealing off the nasal passage from the pharynx, and preventing food from entering the nose.
- The tongue’s position against the hard palate keeps food from reentering the mouth during swallowing.
- Food is prevented from entering the trachea primarily by the elevation of the larynx and the tight closure of the glottis across the laryngeal opening.
- The epiglottis folds backwards down over the closed glottis for additional protection.
- Pharyngoesophageal sphincter
- Peristalsis
What causes the sealing of the glottis?
Contraction of laryngeal muscles aligns the vocal folds tightly to seal the glottis.
What is the epiglottis?
A flap of cartilagenous tissue anterior to the glottis
With the glottis closed pharyngeal muscles to force the _______________ into the esophagus
bolus
What is the function of the pharyngoesophageal sphincter?
It prevents air from entering the digestive tract since it remains closed during breathing. (closed most of the time) only open during swallowing
What is the esophagus?
A fairly straight muscular tube that extends between the pharynx and the stomach.
Where is the esophagus mostly situated?
The thoracic cavity, it penetrates the diaphragm and joins the stomach in the abdominal cavity a few cms between the diaphragm
what is a sphincter
It is a ring-like muscular structure that when closed, prevents passage through the tube it guards.
What is the actualy same of the upper esophageal sphincter?
pharyngoesophageal sphincter
What is the actually name of the lower esophageal sphincter?
gastroesophageal sphincter
When is the pharyngoesophageal sphincter opened and closed?
open: during swallowing to allow bolus to pass into the esophagus
closed: Once the bolus has entered the esophagus (during breathing which is most of the time)
What waves push food through the esophagus to the stomach
Peristaltic waves
peristaltic waves are controlled by the __________________which undergoes innervation by means of the _________
swallowing center, vagus nerve
Define peristalsis
It is the ring-like contraction of the circular smooth muscle that move progressively forward, pushing the bolus into a relaxed area ahead of the contraction
When do secondary peristaltic waves come into action?
When we swallow a large or sticky bolus, the bolus distends the esophagus which activates the stretch receptors. In response, the intrinsic nerve plexus at the point of distension initiates additional waves to clear the lodged bolus. Distension of the esophagus also increases salivary secretion to lubricate it to prevent friction.
the gastroesophageal sphincter prevents ____________of gastric contents
Reflux
What keeps the smooth muscle gastroesophageal sphincter tonically contracted?
Myogenic activity
Inspiration causes ………….
Subatmospheric intrapleural pressure
What is the purpose of the contraction of the gastroesophageal sphincter increasing during inspiration?
To reduce the chance of reflux of acidic gastric contents into the esophageal when subatmospheric intrapleural pressure would favour backward movement of gastric contents.
What is heartburn?
When gastric contents in the stomach flow backwards into the esophagus. This irritates the esophagus and causes discomfort due to the acidity.
When is the gastroesophageal sphincter open and closed?
open: As the bolus is going down the esophagus by peristaltic waves
closed: After the bolus has entered the stomach.
What is the only esophageal secretion and what is its function?
It is mucus which serves to lubricate the passage of food to lessen the possible damage to the esophageal by any sharp edges of food. Moreover, it protects the esophagus against damage caused by acid and enzymes in gastric juice should gastric reflux occur.
True or false: The protective mucus of the esophageal is secreted throughout the length of the digestive tract?
True
Does any digestion or absorption occur during swallowing?
No! the process is too short.
