Upper GI Tract structure and function Flashcards
Why Chew?
Prolong taste, help stop choking (keep resp system open
Control of chewing
Voluntary (somatic - skeletal muscles) and reflex (mecanoreceptors - contraction and relaxation based on pressure of food)
What are the 3 pairs of salivary gland?
Parotid, submadibular and sublingual
What is in saliva?
Water (99%)
Mucins (make mucus when mixed with water, lubricant)
Alpha amylase - breaks down polysaccharides into maltose and glucose
Electrolytes (Na/Cl/K, Na controls tonicity), pH through bicarbonates (stop teeth disintegrating!
Lysozyme - bacteriocidal - cleaves polysaccharide component of bact cell wall
What electrolytes are present in saliva and how is the pH controlled?
Na/Cl/K, Na controls tonicity), pH through bicarbonates (stop teeth disintegrating!
Biggest saliva gland, where?
Parotid, below and infront of ear
What type of glands are saliva?
Exocrine (secrete to outside of body)
exo vs endo crine glands
Exo = secrete to outside of body
Endo = secrete within the bloodstream
Serous vs mucous cells produce what?
Serous = watery fluid, lysozyme, alpha amylase etc
Mucus = mucins
NS innervation of salivary glands and secretion
Sypmathetic and parasympathetic
Symp = sticky, mucussy, amylasey saliva
Parasymp = watery secretion
Which nerves parasympathetic supply of salivary secretion
glossopharyngeal (IX) and facial (VII)
(NOT vagus)
Sympathetic vs parasympathetic salivary production
Symoathetic = viscous - mucus and amylase
Parasymp = watery
What receptors do we have that contribute to the reflex control of saliva production?
Chaemo/pressure receptors in the walls of the mouth/tongue
how long is the oesophagus?
around 25cm
What are the layers of the oespohagus?
-Mucosa (Stratified squamous epithelium (non keritizing - needs to be flexiable and move))
-Submucosa (including mucus glands for lubrication)
-Muscularis externa (superior 1/3 lined with skeletal muscle, inferior 2/3 = smooth muscle)
-adventitia
What epithelium are in the oesophagus?
stratified squamous - non-keritizing
re there glands in th epoesophagus?
Yes! In sub mucosa, produce mucous. Also glands in the stomach.
Control of the muscularis externa in hte oesophagus
Superior 1/3 = skeletal muscle
Inferior 2/3 = smooth muscle
Where are th esphincters in the oesophgus?
Inferior and superiorly
Inferior = prevents food from coming back up into the oesophagus from the stomach
Superior - prevents food from coming back up from the oesophagus (projectile vomiting
Wht cuases projectile vomitting in babies?
Under developed oesophagus sphincters… So nothing to stop the full regurgitation
What is the soft palate?
At the back of the mouth, forms a flap over th enose, stops food etc from going out of nose.
Where is the hard palate?
Front of mouth above the tongue, push food against it to help break down food and stimulates the salivary glands
Wht is the voluntay phase of swllowing?
The first (Oral) stage within the mouth. Controlled by skeletal muscle (tongue) and pushes Bolus to the back of the mouth.
What happens n the pharyngeal phse? How is it regul;ated?
Autonomic controlled by reflex contractions controlled by the swallowing center in the medulla (next to brething center)
Presence of food causes contraction of the pharyngeal muscles and the soft palate is pushed up to close off nasopharynx
