Upper GI Structure & Function Flashcards
Why do we chew?
To prevent airway obstruction & to prolong our taste experience
What neuronal pathways are involved in chewing?
Reflex - the effect of pressure on mechanoreceptors inducing the action of jaw muscles
Somatic nerves - innervating the mouth and jaw
What are the components of saliva?
Water (99%) - solvent
Mucins - protein - water + mucin = mucus - lubrication
Alpha - amylase - breaksdown polysaccarides
Electrolytes - toncity and PH
Lysozymes - breakdown bacterial cell walls
What are three salivary ducts?
Parotid, submandibular and sub-lingual
What regions can be found in the salivary glands?
Mucous alveolus
Serous alveolus
Mixed Alveolus
What do the mucus alveolus, mixed alveolus and serous alveolus secrete?
Mucus alveolus - muscus
Mixed alveolus - mucus, alpha amylase and lysozyme
Serous alveolus - alpha amylase and lysozyme
What nerves control salivation and what division of the nervous system do they belong to?
Cranial nerve VII and glossopharyngeal XI - para
Sympathetic - alpha 1 - high mucus - beta 2 - high amylase
What are the layers of the oesophagus?
Mucosa (epithelium, lamina properia, muscularis mucousae), submucosa, muscularis externa & adventitia (because outside of the perioteal cavity)
The muscularis externa of the oesophagus is composed of what kind of muscle?
first 1/3 = skeletal
second 2/3 = smooth
What are the phases of swallowing?
The oral phase
The pharyangeal phase
The oesophageal phase
The preparation of the receptive stomach phase
What happens in then oral phase of swallowing? is this voluntary or involuntary?
Food is moved to the back of the mouth by the tongue. Voluntary.
What happens in the pharyngeal phase?
Food moves to the pharynx, where a set of reflexes start to move the food bolus down. The smooth palate moves up and back to ensure the nasopharynx is closed. The upper oesophageal spinchter opens. The epiglottis closes the trachea.
