digestive system Flashcards
what is deglutination
swallowing
what is digestion
the mechanical and chemical process of breaking down food into smaller components to a form which can be used by the body
how lung is the digestive system
around 9 meters
what is involved in digestion
the mixing of food with digestive juices, movement through the digestive tract, breaking down large molecules into smaller ones
where does the digestive tract begin
the mouth
what is the role of saliva in digestion
lubrication and to start digestion as amylase begins starch digestion
swallowing is initiated by what
receptors in wall of pharynx when food or drink is near the back of the mouth
what happens when receptor detect food at the back of the mouth
afferent impulses are sent to swallowing centre in the brain stem, the brainstem the relays the signal to the coordinator of the process. interrupting breathing
what are the 3 layers of the oesophagus
skeletal muscle (upper third), smooth muscle (lower 2 thirds)
what are both ends of the oesophagus closed by
sphincters
what are sphincters
circular muscles that open and close to allow the passage of substances and fluids
how is food moved down the oesophagus
by peristatic waves - which occur every 9 seconds
secondary peristalsis is where multiple peristaltic waves occur to move food down the oesophagus
what does the epiglottis do during swallowing
it moves to cover the trachea to ensure food doesn’t go down the wrong passage causing choking
what is peristalsis
a series of mini contractions which occur in the oesophagus that push food down into the stomach
how does peristalsis
circular muscles contract behind the food pushing it a long, this follows by the contraction of longitudinal muscles ahead of the food mass, then further contraction in circular muscles forces food mass forward
