Lecture 7: The Digestive System Flashcards
(122 cards)
1
Q
The bacteriolytic enzyme in the saliva also does what?
A
protects your teeth
2
Q
How do we control the secretion of saliva?
A
-A balance of sympathetic and parasympathetic activity
3
Q
What happens if we shift the balance and get more parasympathetic activity?
A
We get more secretion of saliva
4
Q
What would stimulate and increase salivation?
A
- placing food in your mouth
- active chewing
-looking & smelling at something you would like to eat
-nausea
5
Q
Why does nausea increase salivation?
A
It is a protective mechanism.
6
Q
What is the physiological way as to how nausea is a protective mechanism?
A
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.
7
Q
Why is your teeth there in respect to digestive function?
A
They tear what you’re eating so you can take a bite OR they’re grinding and breaking it up to increase surface area
8
Q
You have a patient who’s missing some or all of their teeth. What kind of effects might you see in their digestive system?
A
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.
9
Q
What are the keys to the digestive system?
A
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.
10
Q
The fewer teeth you have, the …
A
the smaller the opportunity to increase the surface area of what you are eating.
11
Q
The process of chewing your food is called__________.
A
Mastication
12
Q
Where can you see mechanical digestion?
A
Mastication.
13
Q
What is the function of Mastication?
A
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.
14
Q
In the digestive system, what are specifically focusing on in the pharynx.
A
In the digestive system, it is about oropharynx and laryngopharynx.
15
Q
What is the function of the pharynx?
A
Gets food from the oral cavity to the esophagus.
16
Q
What size is the esophagus?
A
About 25 cm long (10 inch)
17
Q
Explain the structure of the Esophagus?
A
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.
18
Q
Since the esophagus has to pass through the diaphragm to connect to the stomach, there is a hole. What is that hole callled?
A
Esophageal Hiatus
19
Q
When you are swallowing, what happens to the esophagus?
A
Esophagus is posterior to the trachea so it can expand into the trachea when swallowing
20
Q
If not swallowing, what happens to the lumen of the esophagus?
A
It should be collapsed.
21
Q
What helps us move stuff in the esophagus?
A
Peristalsis and Gravity
22
Q
True or False.
The esophagus absorbs and digest.
A
FALSE
It’s about moving what you swallow to the stomach.
23
Q
What is the esophagus lined with?
A
Stratified squamous epithelium
24
Q
Why is stratified squamous epithelium important?
A
Protection against abrasions or sharp edges on food
(ex: tortilla chips)
25
As we move down the esophagus, what changes?
the muscle
26
The top 1/3rd of the esophagus consists of what kind of muscle?
Skeletal muscle
27
During that part of the swallowing is what?
voluntary
28
The middle 1/3rd of the esophagus consists of what kind of muscle?
A mixture of smooth muscle & skeletal muscle
29
Once you introduce smooth muscle, what happens?
It is now a reflex
30
The bottom 1/3rd of the esophagus consists of what kind of muscle?
is all smooth muscle
31
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)
32
The upper esophageal sphincter does what?
-Not a fuctional sphincter
-contracts to keep us from swallowing air when we breathe
33
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
34
"Heart Burn" is known as what?
GERD
( Gastroesophageal reflux disease)
35
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.
36
Untreated or uncontrolled GERD can lead to what?
a major risk factor for esophageal cancer
37
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
38
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.
39
What would make the lower esophageal sphincter relax?
1. ethanol
2. caffeine
3. chocolate
4. mint
40
What is Deglutition?
Swallowing
41
What are the three stages of Deglutition?
1. Oral Stage (Buccal phase)
2.Pharyngeal Stage
3.Esophageal Stage
42
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.
43
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.
44
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.
45
What happens in the Esophageal Phase?
-Involuntary
-moves from esophagus to the stomach
-About Peristalsis primarily and helped by gravity
46
When going through process of swallowing, we have waves of Peristalsis. Where?
In the esophagus
47
Waves of Peristalsis are triggered by what?
sensory stimulation in the oral cavity
48
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.
49
The process from Oral stage through delivering bolus to the stomach takes how long?
1-3 seconds and it blocks respiration.
50
What are the seven functions of the stomach?
1. Stomach acts a food reservoir
2. Secrete gastric juice (fluid + digestive enzymes made my exocrine glands to go in lumen of stomach)
3. Stomach a muscular bag to churn and mix the stuff you swallowed with gastric juices
4. Secrete intrinsic factor (chemical binds Vit.12 so that it can't get digested in the stomach, but to be absorbed in the small intestine)
5. Stomach performs a little bit of absorption- some drugs, some water, ethanol, short chain fatty acids found in butter & milk fat
6. Stomach hormones produces gastrin & ghrelin (stomach puts these hormones into the blood)
7. Helps the body deal with pathogenic bacteria that was swallowed by food OR carried in mucus that was swallowed from the respiratory tract
51
Juices go into __________, the hormones go into the________.
lumen , blood
52
The size of the stomach is going to vary. Why?
It depends if it's empty, if you had a cracker, or a full meal.
53
The position of the stomach is also going to vary. Why?
It depends on how much stuff is pushing up on it.
54
When the stomach is empty, it is collapsed. What shape would this be?
J shaped bag
55
The stomach connects to what?
the beginning section of the small intestine called duodenum.
56
The average adult stomach can hold between...
1 - 1.5 L
57
What does this tell you?
This tells us that it is liquid. By the time the stuff is ready to leave the stomach, it's going to be liquid or semi-solid.
58
5/6th to the stomach is where?
To the left of midline
59
What happens to the stomach when you breathe?
When you breathe in, the diaphragm pushes down and moves your stomach down. When you breathe out, the diaphragm moves back up and stomach goes back up before the last breath.
60
After you eat a lot, it gets hard to breathe. Why?
Your stomach is so full that there is not enough room to move it very much and you cannot breathe very deeply. The diaphragm can't move down because the stomach won't get out of the way.
61
What are the regions of the stomach?
lesser and greater curvature
62
What is the lesser curvature?
medial surface, Smaller curve
63
What is the greater curvature?
the lateral surface
64
The _____________ _____________ is attached to the lesser curvature.
lesser omentum
65
The _____________ _____________ is attached to the greater curvature.
greater omentum
66
What are the 4 main areas of the stomach?
-Cardia
-Fundus
-Body
-Pylorus
67
Where is the Cardia?
Where the esophagus connects to the stomach
68
Where is the Fundus?
left & above esophagus
69
Where is the Body?
Central part of stomach
70
Where is the Pylorus?
part that connects to the small intestine
71
There is a sphincter muscle that is at the entrance of the stomach and the exit of the stomach. What are they called?
Lower Esophageal Sphincter (cardiac sphincter) is at the entrance of the stomach.
The one between the exit of the stomach and the first section of the small intestine (duodenum) is called pyloric sphincter.
72
Why do we need the sphincter at either end of the stomach?
So we can prevent stuff from moving backwards in most situations so we don't damage the esophagus and we prevent material from moving forward until it's been digested.
73
The stomach has a modification in the mucosa. What is that modification?
We have a folds in the mucosa and the upward projections of these folds are called rugae.
74
What is the spaces between these folds called?
gastric pits
75
Why would you want folding here? (why is rugae important?)
-to increase surface area for secretions of the components of gastric juice
-if i ignore signals from my body to stop eating, I'm going to stretch my stomach. It will give me the ability to stretch the lining w/o it tearing.
76
At the bottom of these gastric pits, we have what?
Gastric glands
77
In gastric glands, there are different types of cells.
Up in the gastric pit, we have cells called mucus neck cells (a.k.a goblet cells). They secrete mucus.
78
What are the 3 major types of secretory cells?
Chief Cells, Parietal cells, and Endocrine cells.
79
What do Chief cells do?
Chief cells secrete inactive precursor to enzymes that are involved in protein digestion in the stomach.
The enzyme, once activated that come from those chief cells, digest protein
80
Further down in the glands, we have parietal cells. What do they do?
Parietal cells secrete intrinsic factor and hydrochloric acid into gastric juice.
81
The inactive precursor that we're gonna get from chief cells is called...
Pepsinogen
82
Pepsinogen is converted to what by what?
Pepsin by Hydrochloric Acid
83
Pepsinogen can't get activated inside the cell. So it can't digest the protein in the chief cell. Where should it be to be activated?
It has to be in the lumen of the stomach to be activated because that's where the HCl acid is going to be.
84
Endocrine Cells
It goes out into the interstitial fluid and gets picked up by blood vessels.
85
There are 3 hormones to deal with. What are they?
-Ghrelin
-Gastrin
-Somatostatin
86
What does Ghrelin do? (P/D1 cells)
-makes you hungry
-is released by the stomach goes into the blood and travels into the hypothalamus
-hormone that says "idc what it is, imma eat it :0 '
87
Most cells that release Ghrelin are going to be where?
In gastric glands in pyloric section of the stomach
88
What does Gastrin do? (G cells)
-stimulate gastric secretion
-stimulate parietal cells (primarily chief cells to a certain extent), to produce their secretions and dump them in the gastric glands so they wind up in the stomach
-increases gastric motility
89
What does Somatostatin do? (D cells)
-Growth Hormone inhibiting hormone
-controls hormone release by inhibiting it
-inhibits gastrin and ghrelin release
90
What commonly overrides the Somatostatin?
Activity of the vegus nerve. The vegus nerve gets us more gastric secretion and gets us more gastric motility.
91
In the muscularis, there are three layers in the stomach. What are they?
Oblique, Circular, and Longitudinal Layer
92
What is the oblique layer?
The layer closest to lumen.
93
What is over the oblique layer?
Circular layer
94
What over the circular layer?
Longitudinal layer
95
Why do we get 3 layers of smooth muscle instead of two?
-More direction of contraction which means more direction I can apply force to break down the stuff that's in my stomach.
-Gives more powerful mechanical digestion.
-Contract and churn physically break things and make it smaller
96
HCl acid and the low pH does what?
-denature protein that we put in the stomach
97
When stomach has done what it needs to do, the material that is in there is liquid or mostly liquid. What is that called?
Chyme
98
Pyloric Sphincter opens about 20 seconds. What happens during those 20 seconds?
In that 20 seconds, we get that small quantity of chyme squirted from the stomach into the duodenim.
99
The types of motility that we see in the stomach. If wave of motility is moving stuff in the duodenim, what is it called?
Propulsion: moving forward in the next section.
100
What must happen for Propulsion to occur?
1. Pyloric Sphincter has to be open
2. Wave of motility has to be pointed at the pyloric sphincter
3. Stuff that arrives at pyloric sphincter when it's open has to be small enough to fit through
101
If wave of motility isn't directed at the pyloric sphincter, but it's directed at this spot in the body, what happens?
The chyme doesn't go into the small intestine. Chyme is going to throw stuff at the wall and it bounces off broken into smaller pieces.
102
If there are things in the chyme that are too big to get through the pyloric sphincter what happens?
They will hit the edges of the pyloric sphincter and bounce off and go broken into smaller pieces.
103
This is a way for what?
To make the chyme more liquid and increase the surface area for various chemicals in the gastric juice to do more work.
104
We don't talk about Peristalsis and Segmentation in the stomach. Why?
We don't have a tube to that we're just stretching to trigger things.
105
This motility is triggered by what?
Vegus nerve and by gastrin.
106
Why should we not overwhelm the duodenum ?
Everything about controlling gastric motility, intestinal motility, what hormones get secreted, is all about NOT overwhelming duodenum.
107
Duodenim is how long?
1 inch wide and 9 inches long.
108
Since the duodenim can't hold much, what do we do?
We release over time.
109
What two things help controll chyme moving forward in a way that the duodenim doesn't get overwhelmed?
1. Enterogastric reflex: reflex connection between duodenim and the stomach.
2. Gastric Inhibitory Peptide: a hormone produced by doudenim. It inhibits the stomach.
110
If duodenim gets stretched and you stretch the myenteric and submucosal plexuses, what happens?
It sends a signal through the parasympathetic nervous system that ultimately going to turn down gastric motility and gastric secretion
111
If I turn down gastric motility and gastric secretions, what happens?
I just turn down digestion in the stomach. Stuff is not going to be ready to leave the stomach as quickly.
112
What triggers the release of Gastric Inhibitory Peptide?
-stretch in duodenim
-acid in duodenim
-Carbohydrates in the duodenim
113
Gastric Inhibitory Peptide is released when...
there are carbs in the duodenim because the GIP goes to pancreas and stimulates insulin release.
114
Why is GIP important for blood glucose levels?
GIP is an early carbohydrate warning system so we can have the insulin ready b4 blood glucose levels get too high.
115
Why do we not need to overwhelm the doudenim?
-the volume of chyme it can handle is so much smaller than the volume of chyme the stomach can hold
-what's going to happen in the rest of the small intestine, what's motility looks like, what type of intestinal juice we get determines by what the duodenim sees in that chyme. Depends on the duodenim getting enough time to analyze it.
116
If we get so much chyme in the duodenim that it stretches, what happens?
We increase motility in the small intestine and the duodenim doesn't get enough time to look at that stuff. Meaning not enough time to digest and absorb it.
117
Depending on what you ate, it can take anywhere from ....
2-6 hours for your stomach to completely empty.
118
The stuff that leaves the earliest is...
fluid
119
The next thing that leaves is...
Protein & carbs
120
The stuff that stays in the stomach the longest is...
lipids
121
No matter what it is that we're trying to complete digestion of in the small intestine or absorption of in the small intestine, what is your body's first response?
To slow down the stomach. Because if it goes through the doudenim too fast, it'l go through the whole small intestine too fast.
122
What happens if it goes through the small intestine too fast?
Not effectively digest it and not going to be able to absorb it.
