Lecture 19 Flashcards
Pharynx:
- Skeletal muscle lined by mucous membrane
- Deglutition or swallowing is facilitated by saliva and mucus
Deglutition or swallowing:
- bolus is pushed into the oropharynx
- sensory nerves send signals to deglutition center in brainstem
- soft palate is lifted to close nasopharynx
- larynx is lifted as epiglottis is bent to cover glottis
Esophagus:
- Collapsed muscular tube
- Pierces the diaphragm at hiatus
Histology of the Esophagus:
Mucosa
Submucosa
Muscularis
Adventitia
Mucosa =
stratified squamous
Submucosa =
large mucous glands
Muscularis =
upper 1/3 is skeletal, middle is mixed, lower 1/3 is smooth
Adventitia =
connective tissue blending with surrounding connective tissue–no peritoneum
Physiology of the Esophagus - Swallowing:
Voluntary phase
Involuntary phase
Voluntary phase—
tongue pushes food to back of oral cavity
Involuntary phase—-
pharyngeal stage:
- breathing stops & airways are closed
- soft palate & uvula are lifted to close off nasopharynx
- vocal cords close
- epiglottis is bent over airway as larynx is lifted
Swallowing:
- Upper sphincter relaxes when larynx is lifted
- Peristalsis pushes food down
- Lower sphincter relaxes as food approaches
Peristalsis in swallowing:
- circular fibers behind bolus
- longitudinal fibers in front of bolus
Swallowing Time:
Travel time is 4-8 seconds for solids and 1 sec for liquids
If lower sphincter fails to open
distension of esophagus feels like chest pain or heart attack