Lecture 7: The Digestive System Flashcards
The bacteriolytic enzyme in the saliva also does what?
protects your teeth
How do we control the secretion of saliva?
-A balance of sympathetic and parasympathetic activity
What happens if we shift the balance and get more parasympathetic activity?
We get more secretion of saliva
What would stimulate and increase salivation?
- placing food in your mouth
- active chewing
-looking & smelling at something you would like to eat
-nausea
Why does nausea increase salivation?
It is a protective mechanism.
What is the physiological way as to how nausea is a protective mechanism?
What follows nausea is vomiting and so that additional saliva dilutes the acid that you’re going to throw up a bit and that mucus helps to coat the esophagus because the esophagus doesn’t have much protection against acid.
Why is your teeth there in respect to digestive function?
They tear what you’re eating so you can take a bite OR they’re grinding and breaking it up to increase surface area
You have a patient who’s missing some or all of their teeth. What kind of effects might you see in their digestive system?
Patient may not want to eat at all. If they do eat, they’re not going to increase the surface area of their food effectively which causes a decrease in the effectiveness in their digestion.
What are the keys to the digestive system?
If you can’t digest it, you can’t absorb it.
Anything that decreases the effectiveness of your digestion is going to decrease how much nutrient you can absorb.
The fewer teeth you have, the …
the smaller the opportunity to increase the surface area of what you are eating.
The process of chewing your food is called__________.
Mastication
Where can you see mechanical digestion?
Mastication.
What is the function of Mastication?
Taking bigger things and breaking them into smaller pieces AND mixing what I ingested with the digestive secretions that are contributed by the glands in the oral cavity and the salivary glands.
In the digestive system, what are specifically focusing on in the pharynx.
In the digestive system, it is about oropharynx and laryngopharynx.
What is the function of the pharynx?
Gets food from the oral cavity to the esophagus.
What size is the esophagus?
About 25 cm long (10 inch)
Explain the structure of the Esophagus?
Connects the pharynx to the stomach and because the stomach is below the diaphragm, the esophagus has to pass through the diaphragm to connect to the stomach.
Since the esophagus has to pass through the diaphragm to connect to the stomach, there is a hole. What is that hole callled?
Esophageal Hiatus
When you are swallowing, what happens to the esophagus?
Esophagus is posterior to the trachea so it can expand into the trachea when swallowing
If not swallowing, what happens to the lumen of the esophagus?
It should be collapsed.
What helps us move stuff in the esophagus?
Peristalsis and Gravity
True or False.
The esophagus absorbs and digest.
FALSE
It’s about moving what you swallow to the stomach.
What is the esophagus lined with?
Stratified squamous epithelium
Why is stratified squamous epithelium important?
Protection against abrasions or sharp edges on food
(ex: tortilla chips)
As we move down the esophagus, what changes?
the muscle
The top 1/3rd of the esophagus consists of what kind of muscle?
Skeletal muscle
During that part of the swallowing is what?
voluntary
The middle 1/3rd of the esophagus consists of what kind of muscle?
A mixture of smooth muscle & skeletal muscle
Once you introduce smooth muscle, what happens?
It is now a reflex
The bottom 1/3rd of the esophagus consists of what kind of muscle?
is all smooth muscle
There is a sphincter muscle at the beginning of the esophagus and the esophagus connects to the stomach. What are they?
- Upper esophageal Sphincter (UES)
- Lower esophageal sphincter (LES)
The upper esophageal sphincter does what?
-Not a fuctional sphincter
-contracts to keep us from swallowing air when we breathe
The lower esophageal sphincter does what?
-star of the show
-a.k.a “Cardiac Sphincter”
-We need it there NOT TO control stuff going from esophagus to stomach, BUT TO keep stuff most of the time from going from the stomach back into the esophagus
“Heart Burn” is known as what?
GERD
( Gastroesophageal reflux disease)
What happens for GERD to occur?
Lower esophageal sphincter gets loose and as the stomach is mixing and churning stuff, low pH contexts of the stomach splash up into the esophagus and burn it.
Untreated or uncontrolled GERD can lead to what?
a major risk factor for esophageal cancer
Why do they call the lower esophageal sphincter the cardiac sphincter?
The pain you get when nothing is not working feels like it’s coming from the heart
When the cardiac sphincter is working properly at protecting the esophagus, that means what?
We can get very vigorous mixing of the stuff thats in the lumen of the stomach with the secretions of the stomach that are pretty nasty.
What would make the lower esophageal sphincter relax?
- ethanol
- caffeine
- chocolate
- mint
What is Deglutition?
Swallowing
What are the three stages of Deglutition?
- Oral Stage (Buccal phase)
2.Pharyngeal Stage
3.Esophageal Stage
What happens in the Oral Stage?
-Voluntary
-get food from oral cavity into oropharynx
-forming a bolus where tongue is pushing against the roof of the mouth and sweeping it back and moves the bolus. As bolus moves to oropharynx, the soft palate lifts it up and blocks off entrance to nasopharynx.
How does the bolus get prevented from moving into the oral cavity?
Because the tongue stays up while swallowing so the bolus can’t get back into the oral cavity.
What happens in the Pharyngeal Stage?
-Involuntary
-moves bolus from oropharynx into esophagus
-Epiglottis is flipped over to block the entrance to the larynx and the tongue is still up and blocking the entrance to the oropharynx and the soft palate is now held up by the tongue.
What happens in the Esophageal Phase?
-Involuntary
-moves from esophagus to the stomach
-About Peristalsis primarily and helped by gravity
When going through process of swallowing, we have waves of Peristalsis. Where?
In the esophagus
Waves of Peristalsis are triggered by what?
sensory stimulation in the oral cavity
At the dentist, when you numb the sensory nerves in the mouth, it becomes much harder to swallow. Why?
Because w/o that sensory signal in your mouth, you don’t get that peristalsis in the esophagus. Which is why when your mouth is still numb, you drool. You don’t get Peristalsis that lets me get that saliva.