Digestive System Part 2 - Gastrointestinal Tract Flashcards
when we are done mechanically chewing our food, where does it go?
the oropharynx then into the laryngopharynx
at what point in food ingestion does the epiglottis drop?
at the laryngopharynx
what does the epiglottis do?
block the larynx to force food into the epiglottis
what is the esophagus?
a smooth muscle tube that has muscles that go into two different directions
what are the two types of muscles in the esophagus?
- circular smooth muscles
- longitudinal smooth muscles that run down the wall of the tube
where does the circular smooth muscles in the esophagus contract?
behind the bolus of food
what happens when a circular smooth muscle contracts in the esophagus?
they are going to squeeze and make the lumen of the esophagus smaller to push the bolus down
- longitudinal muscles work simultaneously
how does the longitudinal smooth muscles of the esophagus contract?
- in a wave-like motion to push the bolus down (sort of works with the circular muscles because the ‘pinch’ is in the same area)
how long does the circular and longitudinal smooth muscles of the esophagus contract and relax for?
all the way until we reach the opening of the stomach
what is a sphincter?
circular smooth muscle that when it contracts, it squeezes the tube shut
where is the lower esophageal spincter?
between the bottom of esophagus and the opening of the stomach
- sometimes called the cardiac sphincter because its not too far below the heart
what is the job of the low esophageal spincter?
- open when there is a bolus and let it into the stomach
- close behind the food (real job) because we don’t want the contents of the stomach going back up in the wrong direction
what is the top area of the stomach called?
the fundus
what is the entryway to the stomach called?
the cardia
what is the largest part of the stomach?
the body of the stomach
what are the two smaller, distal areas of the stomach?
- pyloric antrum
- pyloric canal
what happens when a bolus of food enters the stomach?
it spends quite some time in there going through mechanical and chemical breakdown
what are the two curvatures of the stomach?
- lesser curvature (superior side)
- greater curvature (inferior side)
how is mechanical breakdown of food done in the stomach?
squeezing and crushing and sloshing the bolus of food around
what is the difference between each of the 3 muscular layers of the stomach?
the fibres all go in different directions
what happens when all of the walls of smooth muscle in the stomach contract?
you get a lot of crushing of the food that is in the stomach and some sloshing
what does the inner wall of the stomach look like?
sort of lumpy like the brain
- called rugae
where do we find pits in the stomach called gastric glands?
in the rugae of the stomach
- all over inside the stomach
in the gastric glands, there is many types of cells in there. what are they all going to contribute to?
the digestive stuff in our stomach
- digestive enzymes
- mucous
what are the types of cells we can find in our gastric glands?
- surface mucous cell
- mucous neck cell
- parietal cell
- chief cell
- g cell
which gastric gland cells are the most superficial?
- surface mucous cell
- mucous neck cell
what do the superficial gastric gland cells produce?
mucous
why is fluid/mucous so important in the breakdown of food?
it allows us to chemically separate all the food and helps with the mechanical breakdown (makes it mushier)
what does the gastric gland parietal cell secrete?
- hydrochloric acid
- intrinsic factor
why is hydrochloric acid important in gastric glands?
because it is highly acidic (low pH), which will help us break down protein
- we cannot breakdown protein unless we have a very acidic environment
why is the only place in our body we see hydrochloric acid, is the stomach?
- other areas of the gastrointestinal tract, don’t have the lining in their walls to withstand that level of acid
when would we personally experience how acidic our stomach is?
- when we have vommitted
- if our lower esophageal sphincter for some reason as let stomach contents up into the esophagus and we get that burning sensation (heart burn)
what is gastroesophageal reflux?
an issue in some people when the lower esophageal sphincter does not close properly on a frequent basis
- can cause pain frequently in the esophagus (epithelial cells can be replenished, but still hurts)