Week 8: Digestive Flashcards
What is ingestion?
taking some food or some drink and putting it in your mouth
-adding complicated molecules
What is digestion?
taking those large complicated molecules that you ingested and breaking them down into smaller and simpler pieces (catabolism)
what is mechanical processing (aka motility)
Ingest this stuff from the point of ingestion, we have to be able to move it through digestive system so we can do all the things to it that we need to do
What do we also use motility for?
Physically break large molecules into smaller ones
Why would we want to break larger things into smaller things?
- if youre gonna have to break stuff down and use chemicals on it, you want as much surface area of ingested surface material as you can get
- So they can be used at the cellular level
what is secretion?
- Taking enzymes and juices from the various digestive organs and putting them in right place and time for coordination process of digestion
- Secreting right hormones at right time to get the right effect
What is absorption?
Moving something across an epithelium
Since the mouth and anus is open to the outside world, what does this mean for everything in the tube in the digestive tract?
it is also open to the outside world
How to get something inside body rather than open to the outside world?
it has to get absorbed through the epithelium and moved out of the tube that is connected to the outside world (absorption)
all of these tubes like every other surface in your body is lined with what?
epithelium
the only material that you can get out of your body is ?
stuff you haven’t absorbed yet
The inside of your esophagus, what is outside of the body?
the lumen
The lumen of your stomach is ___ your body but when you absorb through the ____, now its inside.
outside; epithelium
everything that we absorb but isn’t lipid, it will be absorbed by what and moved into?
an epithelial cell and moved into the blood
where are the lipids going?
into the lymphatic system
not just cholesterol and fats are going into the lymphatic system, what else goes?
fat soluble vitamins
which subclavian vein does it get delivered to?
left subclavian vein
what is elimination?
we cant absorb everything we digest and we cant digest everything we ingest, because there are some things we dont have the right enzymes to digest. because of that, we have material in the digestive system that is not gonna provide a fuel for your body that we need to get rid of so theres room for what we can digest.
what does elimination ultimately lead to?
defecation
What is regulation?
control of the first 6 previous processes
how is oral cavity important to digestive system?
mandatory part of the digestive system in a healthy person, the entrance.
how is esophagus important?
how we’re transporting what we have ingested to the stomach
what is the stomach involved in?
pretty serious digestion using chemicals and in physically breaking food into smaller parts
how is the rectum and anus important?
the exit end of digestive tract
when talking about digestive organs that are accessory, what are we talking about?
things that are contributing to the function of the digestive system but food doesn’t pass through them
what are the accessory structures?
- teeth
- tongue
- salivary glands
- liver
- gallbladder
- pancreas
how is the teeth important accessory structures?
the first thing that breaks food into smaller pieces to increase surface area and makes sure that pieces are small enough to swallow safely
how is the tongue important?
- important in actual process of swallowing,
- push against food you’ve ingested which will break it down
- taste
how do i know if this food is safe to swallow?
chemical analysis of what i put in my mouth
salivary glands
contribute saliva which will help digest and make the stuff we ingest more slippery so its easier to swallow
liver
has many functions, some are related to digestion and some are not
gallbladder
release bile into small intestine
pancreas
gives us not only hormones but most of the enzymes that are gonna be involved in digestion
2 layer connective membrane in abdominal cavity called?
peritoneum
difference sections of the peritoneum called?
reflections of the peritoneum
they have slightly different functions depending on which one we are talking about but what do they share?
they’re carrying the blood vessels going to and from different parts of digestive tract
what is the first reflection called?
lesser omentum
what is the lesser omentum attached to?
smaller curve of the stomach called lesser curvature
- hangs over the stomach to the edge of transverse colon
greater omentum covers?
hangs down and covers a little more of the small intestine and transverse colon
how long is the average small intestine of a human ?
20 ft long
The small intestine is a tube mostly made up of?
smooth muscle
what is the problem here?
a 20 ft tube that can tie itself in knots
These next reflection help the small intestine how?
by anchoring the small intestine to keep it from getting knotted
what shape is the mesentery?
fan shaped
what is the mesentery attached to?
posterior wall of the abdominal cavity on one side and the other edge attaches to the wall of the small intestine
why does it attach this way?
so that the small intestine can still move but it can’t get knotted around itself
what is the transverse mesecolon attache to?
also attaches to the posterior wall of the abdominal cavity
-free end attached to transverse colon and helps keep that in position and support the shape of large intestine
what is the sigmoid mesecolon
maintains the curve in large intestine
what does the curve do?
make it easier to get material from descending colon over to the rectum and anus
what is the alimentrary canal?
the whole tube that ingested food will travel to
where does it start and end?
start at oral cavity and end at anus
what does the GI tratc only include?
stomach and S/L intestine
why do you have 20 ft of small intestine?
surface area
what is the layer closest to the lumen called?
mucosa (mucosal lining)
deep to the mucosa is a layer called?
submucosa (submucosal layer)
The submucosa is connective tissue T/F
true
just outside the submucosa is a layer called?
muscularis (muscularis externa)
2 layers of smooth muscle
what is the layer closer to the submucosa?
circular smooth muscle
what is the layer further away from submucosa?
longitudinal smooth muscle
what is the outermost layer called?
serosa
the serosa is actually the ___, on a particular digestive organ
visceral peritoneum
The mucosa has 3 sublayers. what is the mucosal epithelium (mucous epithelium)
layer thats actually gonna touch what was ingested it?
what is deep to that and the second layer of the mucosa?
lamina propria
what is lamina propria?
-thin layer of areolar connective tissue
-there are mucus secreting glands in that area
what is the third layer of the mucosa?
muscularis mucosae
what is the muscularis mucosae?
thin layer of smooth muscle
- its there but the muscle thats gonna do the work is the muscularis externa
epithileum has a blood supply T/F
FALSE
the blood supply for the mucosa travels in the?
submucosa
what else do we have in the submucosa?
lymphatic vessels
There are 2 nerve plexus. the one in the submucosa sits right next to?
circular layer of smooth muscle called submucosal plexus (Meissner’s plexus)
What type of plexus is the submucosal plexus?
autonomic plexus
why would we need an autonomic plexus in the digestive system?
- glands
- smooth muscle
- no adipose
- no cardiac muscle
those four things are called?
autonomic effectors
if i have smooth muscle in my alimentary canal, it has to be controlled by?
autonomic nervous system
In the alimentary canal, I have smooth muscle in ?
blood vessels
- controlled by autonomic nervous system
The submucosal plexus and myenteric make up?
enteric nervous system bc is runs those smooth muscle in the alimentary canal
the parasympathetic system runs?
digestive system
the closest layer to the submucosal plexus is circular so that we can?
change diameter of alimentary canal
layer closest to serosa is longitudinal so we can?
to a certain extent, change the length of the muscle part
those two things working together will help us how?
break down stuff inside the tube and move material through the tube
in between the two layers of smooth muscle and muscularis externa is a second autonomic plexus called?
myenteric plexus (Auerbach’s plexus)
what do these two plexus run?
run smooth muscle and glands in the alimentary canal
smooth muscle has the main role in?
moving stuff through the alimentary canal
what are the two types of movement for digestive?
peristalsis and segmentation
what is peristalsis?
a reflex , to cause forward movement of what you have ingested
what is a bolus?
lump of food
what happens to the bolus when it moves?
it moves until it gets stuck and it stretches the smooth muscle in the tube and then as reflex, we/re gonna get contraction BEHIND the bolus and relaxation in front of it
- longitudinal muscle in the wall is going to contract and move back. what we wind up doing is pushing this bolus forward
next time it gets stuck, we have the same thing happen again
contract behind, relax in front of which gives us unidirectional movement in most situations.
what is segmentation?
mixing movement
- isn’t supposed to cause forward movement of bolus
What happens during segmentation?
we’re mixing what we’ve ingested with the secretions of whatever organ we’re in
if you only put digestive enzymes on the surface of something …
you can only digest at the surface
but if you mix
then you can be digesting from inside that bolus too
segmentation is also gonna be a way to break pieces physically into?
smaller chunks and increase surface area of what you’ve ingested
segmentation helps bring that stuff you’ve ingested into?
contact with the wall of the alimentary canal
why would that be important?
that is where the absorption is gonna take place, so the more stuff you can actually have touched the wall, the more that we can absorb
in any particular segment of the alimentary canal, you cant have?
peristalsis and segmentation going on at the same time
- they alternate
as you’re moving bolus down the tube…
its getting moved for a while and then its getting mixed and broken down and put in contact with the wall and then we’re gonna move it some more
you can have segmentation happening in one area but at the same time have peristalsis going on in?
a different area
What are the control of digestive functions?
local factors, neural mechanisms, and hormonal mechanisms
the pH of the ingested material that just got in small intestine is low , that is gonna trigger certain things to happen in small intestine such as?
- motility
- what gets secreted
- stretch of tube
peristalsis and segmentation are?
local factors
when you think of something to eat or drink and it cranks up your digestive system, that is an example of?
neural control
in paces where stretching tube leads to more motility, when you stretch the tube, you stretch the submucosa and myenteric plexuses which is the trigger for?
muscle to contract
the vagus nerve controls?
what our digestive function is by controlling what ‘s going on with the parasympathetic nervous system.
what is hormonal regulation?
control what gets secreted, when it gets secreted, how much is absorbed, etc..
- some structure somewhere puts chemical into the blood and it travels a distance and is bound by receptors in certain parts of the digestive system
what is are the functions of the mouth?
sensory analysis, mechanical processing, lubrication, limited digestion of carbohydrates & lipids
input from tastebuds form tongue which will help you make?
safety decision
- is it safe to swallow this
- does it taste strange
we have other receptors in the mouth like?
temperature receptors
- if temp of what you’ve just put in mouth is too hot, you might choose to spit it out so you wont burn your esophagus
the teeth and tongue are involved in?
mechanical processing (digesting)
what is an example of mechanical processing?
chewing
the tongue can also push food against?
hard palate
- breaks food into smaller pieces
saliva and mucus is produced by?
salivary glands
what is the oral cavity lined with?
stratified squamous epithelium
- some are keratinized and some isn’t
why are we using stratified squamous epitheliym here?
protection
-abrasion, and extreme temperature are gonna be an issue
places in the oral cavity that are more likely to be damaged and have a severe risk of abrasion are gonna have ?
keratinized stratified squamous epithelium
in the oral cavity, what has keratinized stratified squamous epithelium?
roof of mouth and areas on the gums
what has NON-keratinized stratified squamous epithelium?
inside of lips, area under the tongue, and cheeks
- not as likely to be damaged by abrasion
the epithelium on under side of the tongue isn’t keratinized making it just thin enough for?
certain hydrophobic medications to diffuse through
the tongue is covered with an epithelium but mostly its?
skeletal muscle
with respect to digestive function, what does the tongue do?
- push stuff against hard palate to help break it down
- involves shaping the bolus (makes shape that is approximately the shape of the lumen of esophagus making it easier to swallow)
what else does the tongue do that is no help whatsoever?
produces an enzyme called lingual lipase
how is this a problem?
of all the things we digest chemically, the nutrient that requires the most surface area for effective digestion is lipids, when talking about what the liver and gallbladder do, sizable portion of both those organs is about increasing surface area of lipids and maintaining that surface area so you can get effective efficient breakdown of lipids which we don’t have any of that in the mouth
- we don’t have enough surface area of lipid to have this lingual lipase to do us any good
- it gets mixed in with what we digest and gets swallowed with bolus and doesn’t digest anything.
- when it gets into the stomach, its an enzyme meaning its a protein, the lingual lipase is just gonna get digested
- gets recycled before we can even use it
why do we have this enzyme?
it may be that when we were much smaller organisms, that we actually did have enough surface area on the small amount of fat we were taking in bc we were smaller organisms that it did make a contribution
- doesn’t do anything now
what are the three pairs of salivary glands?
- parotid glands (largest), swells up when you get ??53:53
- sublingual, under the tongue
- submandibular,
they are all exocrine glands, so their secretions go in?
- a duct
- duct opens onto a surface,
- in case of the salivary glands, the surface is the surface of the mouth
what is the first function of saliva?
moistening up the food you’ve ingested
- mucus in saliva which coats what you will swallow so its slippery and easier to swallow and move through the esophagus
there is also an enzyme in saliva called?
salivary amylase
amylase is one of the families that breaks downs?
carbohydrates
since we don’t have that surface area problem we have with lingual lipase, salivary amylase does do some..
early carbohydrate digestion in the mouth and in the esophagus
the salivary amylase stops working once it gets into the?
stomach
why does it stop working in the stomach?
the pH is too low and the salivary amylase can’t maintain its shape that it need to function
Once salivary amylase goes in the stomach..
it becomes just another protein to digest because the pH is too low
where does the majority of the carbohydrate digestion take place?
small intestine
what is another thing that is important that we see in the saliva?
sodium bicarbonate
- bicarbonate is a buffer base
that little bit of bicarbonate in the saliva helps?
the pH in the mouth in the right range for salivary amylase to work
what other enzymes are in the saliva?
bacteriolytic enzymes
what do bacteriolytic enzymes do?
collection of enzymes that will kill bacteria that we do NOT want to get further into digestive system
if bacteria that normally exist in the mouth goes into the blood directly, they hang out in the?
cardiac valves
if you have a suppresses immune system and you get an abrasion from cleaning from dentist, normal bacteria in mouth will go into the cut and…
can go straight to the heart and destroy a valve
