Upper GI structure And Function Flashcards
How is chewing controlled?
Voluntary- somatic nerves of skeletal muscle in the jaw & mouth
Reflex- chewing puts pressure ongums and hard palate wich stimulates mechanoreceptors and inhibits jaw muscles which causes contraction of the oesophagus for swallowing.
What is saliva made up of?
99% fluid Mucins Electrolytes Lysosomes Alpha amylase
In saliva what is mucins?
Protein
Mucins + water = mucous
What is the function of lysosomes in saliva?
Cleaves polysaccharide from bacterial cell wall = bacteriocidal
What is the function of electrolytes in saliva?
They increase the PH and reduce osmolarity
What is the sympathetic control of the salivary secretion?
Stimulation of sympathetic creates small volume and high viscosity
High mucous content- alphaadrenoreceptor
High amylase - betadrenoreceptor
What is the parasympathetic stimulation of salivary secretion?
Facial VII and glossopharyngeal nerve XII
Stimulates high volume of watery secretion
What is the reflex control of salivary secretion?
Presence of food in the mouth activates chemoreceptors and pressure receptors which have the same effect of the parasympathetic system
What type of muscle is the muscularis externa in the oesophagus?
Skeletal in upper 1/3
Smooth in lower 2/3
During swallowing what is the function of the soft palate?
Reflexted backwards and upwards to block off the nasopharynx
What are the names of the 2 sphincters of the oesophagus?
Lower and upper oesophageal sphincters
What is the reason that the stomach is able sterilises its contents?
Gastric acid provides a microclimate below PH 2 which kills all bacteria
What lies within the stomachs mucosa?
Gastric pits which lead to gastric glands
Parietal and cheif cells
Mucous cells on its surface
