Physiology Week 1 Flashcards
What are the three parts of the pharynx?
nasopharynx, oropharynx, and laryngopharynx
Describe how the nasopharynx blocks passage of food into the lungs
At the base of the nasopharynx there is a soft palate and penduluous uvula that block passage of food into the lungs
Describe how the oropharynx prevents large particles from entering the lung
The mucous layer of the oropharynx traps any large particles in the air that we breathe - instead of entering the lung, pass with the mucous into the stomach
What is the pharynx?
Wiki says: The pharynx (plural: pharynges) is the part of the throat that is behind the mouth and nasal cavity and above the esophagus and the larynx, or the tubes going down to the stomach and the lungs.
The laryngopharynx is a common pathway that allows both air as well as food to pass through the lungs and stomach. What happens when the air goes to the stomach? What about when food goes to the lungs?
air in stomach - burp
food in lungs - cough
Describe swallowing AKA deglutination
1) In buccal phase, the tongue presses against the hard palate, and the food bolus is forced into the oropharynx
2) In the pharyngeal-esophageal phase, the uvula and larynx rise to prevent food from entering the nasal cavity/trachea. The tongue blocks off the mouth.
- The upper esophageal sphincter relaxes and food enters the esophagus.
- during this phase, respiration is inhibited via reflex
3) The constrictor muscles of the pharynx contract, and food is forced down esophagus. The upper esophageal sphincter contracts after food enters.
4) Persistalsis moves food to the stomach.
5) The gastroesophageal sphincter surrounding the cardial oriface opens and food enters the stomach,
Which muscle is a major contributor to the upper esophageal sphincter high pressure zone?
cricopharyngeal muscle (skeletal)
Pharyngeal muscles contract to push food bolus into esophagus. What are the two muscular layers of the pharynx?
outer circular
inner longitudinal
Describe the three outer circle muscles of the pharynx and their function
Inferior, middle, superior constrictors
During swallowing, these muscles constrict to push food downwards.
Describe the three inner longitudinal muscles of the pharynx and their function
stylopharyngeus, salpingopharyngeus, palatopharyngeus
during swallowing, these shorten and widen the pharynx
True/False: All of the pharyngeal muscles are innervated by CNX.
False - all but the stylopharyngeus which is innervated by CNIX (glossopharyngeal)
True/False: The swallowing center is located in the medulla and each half controls the ipsilateral side
True
The major peripheral sensory inputs to the swallowing center are carried by which three nerves?
1) maxillary branch of TRIGEMINAL (V)
2) GLOSSOPHARYNGEAL (IX) on posterior 1/3 of tongue, tonsil, pharynx, middle ear
3) VAGUS (X) superior laryngeal branch
The motor output of the swallowing center is via the motor branches of which 5 nerves?
1) trigerminal (V)
2) facial (VII0
3) glyossopharyngeal (IX)
4) vagus (X)
5) hypoglossal (XII)
What is oropharyngeal dysphasia and what causes it (2 factors)?
Oropharyngeal dysphasia is the failure of the normal propulsion of the bolus from the mouth to the esophagus.
Caused by failure of the driving fore (propulsion) or an obstruction to flow
What occurs in oropharyngeal dysphasia when:
a) the muscles that move larynx are weakened
b) the muscles around the soft palate or the superior pharyngeal constrictors are weakened
a) aspiration [food enters larynx]
b) regurgitation into the nose
Describe four sources of failure of propulsion (driving force) that would lead to oropharyngeal dysphasia
brain, cranial nerve, myoneural junction, muscle
Describe two sources of obstructions that would lead to oropharyngeal dysphasia
mass effect, incomplete UES sphincter relaxation
Describe four diseases that cause muscle weakness leading to oropharyngeal dysplasia
CVA, poliomyelitis, myasthenia gravis, dermatomyositis
Describe two diseases that would lead to obstructions to flow
tumor or abscess
cricopharyngeal achalasia [failure of relaxation of muscle around UES]
Describe the cause and symptoms of dermatomyositis
dermatomyositis is a acquired muscle dz/inflamm myopathy.
Cause is UNK, thought to be viral
Sx: difficulty swallowing, muscle weakness, stiffness or soreness; purple or violet upper eyelids; purple-red skin rash, SOB
Describe the types of muscle found in the esophagus and the related diseases.
Cervical esophagus and top of thoracic includes the upper esophageal sphincter, skeletal muscle
dz: polymyositis, myasthenia gravis
Lower 2/3 includes thoracic and abdominal parts and contains the lower esophageal sphincter, smooth muscle
dz; scleroderma and achalasia
Describe primary peristalsis in the esophagus.
When do the sphincters open?
Primary peristalsis is triggered by swallowing.
The lower esophageal sphincter relaxes before the propagating contraction.
When a person swallows, tension receptors stimulation contraction in the pharynx which coincides with relaxation of UES and LES. They remain relaxed until the wave reaches them.
Describe the latency of esophageal contractions.
In normal persistalsis, there is an increasing latency period for each subsequent contraction.
The contractions are thought to be controlled by excitatory motor neurons, whereas the latency is thought to be controlled by activation of inhibitory motor neuron.