1
Q
What does the disassembly pipeline depend on?
A
Motility - peristalsis and segmentation Secretion - enzymes, ions, etc. in mouth, stomach and small intestine Absorption - nutrients, bile salts, etc. Regulation of GI function - neural and hormonal
2
Q
What does post-prandial mean?
A
After a meal
3
Q
What is the brain of the gut?
A
The enteric nervous system
4
Q
Generally, the vagus nerve is part of the ________________________ nervous system and will cause _____________ motility and _____________ secretions.
A
parasympathetic, increased, increased
5
Q
Generally, the sympathetic nervous system will cause ___________ motility and _______________ secretions.
A
decreased, decreased
6
Q
Vitamin B12 is bound to _____________ in food and must be released before digestion. This process begins in the ______________ when freed vitamin B12 binds to _________________, a protein that protects the vitamin from stomach acidity. Much more vitamin B12 is then freed in the _____________________ due to the ___________________ and the freed vitamin B12 molecules bind to ______________________. The remaining _______________ is then removed in the ____________ by digestive enzymes and absorption of the _________________ complex occurs primarily in the ______________________.
A
proteins, mouth when food and saliva mix, haptocorrin, stomach, acidity, intrinsic factor, haptocorrin, duodenum, B12-intrinsic factor, ileum
7
Q
What are the functions of saliva?
A
Digestion - amylase digests carbs Protection - remineralization Lubrication Immune function ALSO contains haptocorrin which binds VitB12
8
Q
Digestion begins in the _____________________________:
A
Mouth with teeth and saliva Salivary enzyme breaks down carbohydrates
9
Q
What is the master gland of metabolism?
A
The liver
10
Q
Protein matrix is first disrupted in the ______________ with ________________ Protein digestion starts in the ________________ by being broken down by _________________, an enzyme that is derived from _______________ secreted by _________________ cells. Protein -> polypeptide Then, proteins are further broken down by ____________________ secreted by _________________ cells.
A
Mouth, mastication, Stomach, pepsin, pepsinogen, chief cells, polypeptide -> AAs, tri- and di-peptides
11
Q
What part of the GI tract produces intrinsic factor (IF) and what does it do?
A
Stomach - parietal cells Binds to VitB12 to allow uptake of it
12
Q
What enzymes do pancreatic acinar cells secrete?
A
Peptidase (proteins), lipase (fats/fat soluble vitamins), amylase (carbs)
13
Q
The large intestine doesn’t do much, however, it does remove water and does some absorption as well as arguably its most important function:
A
Housing the gut microbiome
14
Q
What movement is associated with the mouth?
A
Chewing
15
Q
What movement is associated with the esophagus?
A
Peristalsis
16
Q
What movement is associated with the stomach?
A
Upper stomach relaxes to let food enter Lower stomach mixes food with digestive juice
17
Q
What movement is associated with the small intestine?
A
Peristalsis
18
Q
What movement is associated with the pancreas?
A
None
19
Q
What movement is associated with the large intestine?
A
Peristalsis
20
Q
What are the types of contractions?
A
Tonic and phasic contractions
21
Q
What is tonic contraction?
A
Sustained, occurs in smooth muscle sphincters
22
Q
What are phasic contractions?
A
Last a few seconds
23
Q
What are the two actions possible in the GI tract based on the nature of the smooth muscle arrangement in the walls?
A
Peristalsis: moves forward Segmentation: mixes
24
Q
What is the enteric nervous system?
A
Vast, mesh-like network of neurons and glia embedded in the bowel wall along the length of the GI tract Master regulator of GI: motility, sensation and secretion
25
What does the ENS consist of?
Motor and sensory neurons that innervate muscular layers, secretory glands, and lymphatic vascular system Organized into Meissner's plexus and Auerbach's plexus
26
What circuit does the ENS form?
Sensory-motor reflex circuit composed of: -Intrinsic primary afferent neurons (IPANs) -Interneurons -Motor neurons
27
Aside from motility, what are the roles of the ENS?
Gut-barrier function Sensing of luminal contents Interaction with gut microbiota & constituent organisms
28
The ENS communicates with the CNS via _________________ of sympathetic innervation and _________________________ for parasympathetic innervation.
Pre-vertebral ganglia, vagus nerve
29
The ENS can act autonomously, responding to ___________________________________. However, the CNS can also affect the ENS by responding to ____________________ to cause ______________________ or _______________________ motility and secretions.
Local stimuli, external stimuli, a speeding up, delaying
30
What local stimuli does the ENS sense?
pH Stretch Osmolarity Products of digestion
31
What external stimuli does the CNS respond to that affects the ENS?
Sight, smell, etc.
32
Short reflexes involve __________________ while long reflexes involve _____________.
the ENS, both the ENS and CNS
33
What is an example of a long reflex?
Vomiting
34
What is an example of a short reflex?
Gastrocolic reflex (tension/stretch in stomach increases peristalsis in colon)
35
What is IBS?
Irritable bowel syndrome Reflex dysregulation Presents as "cobblestone" buccal mucosa, mucosal tags, and gingival erythema
36
What are the digestion phases?
Cephalic Gastric Intestinal
37
What are the stimulations in the cephalic phase of digestion?
Sight/thought of food or taste/smell travels via vagus nerve to stomach
38
What are the stimulations in the gastric phase of digestion?
Stomach distention activating stretch receptors travels to CNS (vagus n.) and in local reflexes Food chemicals and rising pH chemoreceptors cause gastrin release
39
What are the stimulations in the intestinal phase of digestion?
low pH and partially digested foods causes gastrin release
40
What could mess up the cephalic phase of digestion and what would that lead to?
Loss of appetite or depression, inhibits stomach secretory activity
41
What could mess up the gastric phase of digestion and what could that lead to?
Excessive acidity -> decreased gastrin -> less stomach activity Emotional distress -> sympathetic overrides parasympathetic -> less stomach activity
42
What could mess up the intestinal phase of digestion and what could that lead to?
Distention in duodenum or presence of fatty, acidic, hypertonic chyme, or irritants -> entero-gastric reflex Same stimuli can also cause release of intestinal hormones
43
What is deglutition?
Swallowing
44
What is the oral phase?
The tongue forms a food bolus and pushes it into the laryngopharynx
45
What is the pharyngeal phase?
Begins as bolus reaches tonsils Elevation of soft palate, larynx and hyoid, as well as retroflexion of epiglottis and closure of vocal folds Respiration briefly halted
46
What is the esophageal phase?
Peristalsis through esophagus to stomach
47
What cells in the pyloric antrum are specific to that part of the stomach and what do they secrete?
Gastrin cells (EECs): gastrin D cells: somatostatin
48
What protects the stomach from self-digestion?
Alkaline mucus barrier -physical barrier -bicarbonate ion neutralizes H+ TJs in epithelium Stem cells - completely replace surface epithelium every 3-6 days
49
What stimulates parietal cells?
ACh, gastrin, and histamine
50
What do EECs do?
release array of peptides that orchestrate appetite, energy intake, and blood glucose
51
In the fasting state, _______________ is released from ____________ cells in the _________________ to cause ____________________.
ghrelin, Gastric Gr-cells (EECs), stomach, hunger
52
What does ghrelin do?
Makes you hungry: Hypothalamus: increases food intake, lipid sensing Stomach: increases motility, acid secretion Intestine: increases motility
53
After you eat, what initially causes your appetite to decrease? What other pathway causes modulates hunger?
Distention activating mechanoreceptors on vagal afferents Chyme in duodenum triggers hormone release from EECs which can affect receptors on vagal afferents, or travel through the blood
54
What hormones do EECs release in response to meal ingestion?
Cholecystokinin (CCK) Glucose-Dependent Insulinotropic Peptide (GIP) Glucagon-Like Peptide 1 (GLP-1) Peptide YY (PYY)
55
What does GLP-1 do?
Decreases food intake and gastric emptying Increases insulin (beta cells) Decreases glucagon (alpha cells) Increases somatostatin (delta cells)
56
What does GIP do?
Increases insulin (beta cells) Increases somatostatin (delta cells)
57
What does CCK do?
Bile production in liver and release in gallbladder Increases digestive enzyme release from pancreatic acinar cells Decreases food intake and gastric emptying
58
What does PYY do?
Satiates appetite Decreases gastric motility & emptying Stimulates pancreatic secretions
59
What is Leptin?
WAT adipocyte hormone Regulates appetite Loss of fat -> decreased circulating leptin -> increased hunger
60
What are examples of a GLP-1 agonists and what do they do?
Wegovy and ozempic (semaglutide) Help people lose weight- Feel full quicker & don't crave sweets Have potential side effects - nausea, vomiting, etc. Increasing evidence suggests more serious side effects: -gastroparesis -pancreatitis -bowel obstruction
61
The amount of time food spends in the stomach is dependent on the macronutrient composition of the meal. What is the order from longest to shortest time that food spends in the stomach?
High fat meal >> high protein meal > carbohydrates
62
What is the pH of the stomach and why is it so low?
pH of 2-4 Kills most microorganisms, denatures dietary proteins, activates pepsinogen
63
What is Orlistat?
Lipase inhibitor Used to manage obesity Also decreases fat-soluble vitamin uptake
64
When does chyme neutralize?
In the duodenum with the secretion of bicarbonate from the pancreas
65
What are zymogens?
Inactive enzymes, activated by cleavage
66
The pancreas secretes __________________ which are then activated in the _______________________ by _________________ secreted by ______________________.
zymogens, duodenum, enterokinase, enterocytes
67
What activates alpha cells to secrete glucagon?
Low blood glucose *GIP can also stimulate in T2D
68
What are incretins?
Hormones released to increase insulin and decrease glucagon after a meal GLP-1 and GIP
69
If you have a patient taking GLP-1 agonists, what should you consider when they come to receive dental treatment?
ASA recommends withholding GLP-1 agonists before elective procedures due to risk of regurgitation and aspiration during sedation
70
What is resistin?
WAT hormone that increases insulin resistance Associated with impaired glucose tolerance test (GTT)
71
Carbohydrates are first digested in the __________________________ by _________________ found in _______________________. Carbohydrates are then further digested in the ______________________ by _________________ secreted by ______________________.
Mouth, amylase, saliva small intestine, amylase and brush border enzymes, pancreatic acinar cells and enterocytes
72
Dietary fat is first digested in the _____________________ by _________________ secreted by _______________________. This process is dependent on the emulsification of dietary fat by ___________________ secreted by __________________. Dietary fats are then absorbed in the ____________________ by ________________ cells and enter ___________________:
duodenum, lipase, pancreatic acinar cells, bile salts, the liver and gallbladder Jejunum and ileum (more ileum), enterocytes, lacteals
73
What are the enteroendocrine "sensors" that detect chemical, bacterial, and mechanical signals in the GI tract and where do they send their signal?
Intestinal neuropod cells (type of EEC) -distinguish chemical properties of chyme -provide vagal feedback to modulate GI function Synapse with vagus nerve
74
The vagal nerve stimulation by sugars and sweeteners occurs in the
Small intestine
75
In relation to neural pathways, how are artificial sweeteners different from real sugar?
Artificial sweeteners = purinergic neurotransmission (NT=ATP) Sugar = glutamatergic neurotransmission (NT=glutamate)
76
What are the components of the mucosal barrier in the GI tract?
Physical elements: mucus layer, epithelium, commensal microbiota Immunological defenses: AMPs, WBCs
77
Intestinal homeostasis is maintained by intact _____________ in the epithelium:
Tight junctions
78
What does ROS do to the intestinal epithelium?
Disrupts TJs = leaky gut syndrome = chronic inflammation
79
What are enterochromaffin (EC) cells?
Type of EEC Secrete Serotonin (5-HT)
80
How much of the body's serotonin is present in the GI tract?
95%
81
How do EECs modulate the microbiota species, glucose and lipid metabolism? Find duplicate
Serotonin (5-HT) released from enterochromaffin cells
82
What does 5-HT released from ECs do to the body?
Activates vagal afferent fibers to induce intestinal motility and gastric emptying Stimulates glucose and lipid metabolism and immune responses in blood
83
The endocannabinoid system plays an important role in modulating ___________________________________ and can change the synthesis of ________________________________________
Intestinal permeability, tight junction proteins
84
What is the CFTR?
Cystic fibrosis transmembrane conductance regulator Gene that codes for ion channel protein that allows for CHLORIDE ions (Cl-) Dysregulation can affect pH homeostasis, immunity, chronic inflammation
85
Enzymes released in the small intestine that are not from the digestive glands are called _____________________________
Brush border enzymes
86
Humans cannot produce enzymes to breakdown most fibrous polysaccharides, however they are still valuable in such that they _____________________________
Provide dietary fiber (propels food to prevent constipation)
87
What are the brush border enzymes involved in carbohydrate digestion?
- Lactase Sucrase Maltase
88
Glucose is absorbed in the _______________ by the _______________________ on the apical surface of _________________ cells and exit via the _________________ on the basal surface Fructose is absorbed in the _______________ by the ____________________ on the apical surface of ________________ cells and exit via the _________________ on the basal surface
Small intestine, SGLT symporter, enterocytes, GLUT2 Small intestine, GLUT5, enterocytes, GLUT2
89
Di- and tri-peptides are absorbed in the __________________ by ______________________ Amino acids are absorbed in the ___________________ by _____________________ Small peptides are absorbed in the _________________ by ____________________
small intestine, cotransport with H+ small intestine, cotransport with Na+ small intestine, transcytosis
90
What is secretin and what does it do?
Hormone released by EECs in response to acidic chyme -Stimulates pancreatic duct cells to secrete bicarbonate and fluid -Inhibits parietal cells in stomach
91
What is enterohepatic circulation?
Recycling of bile salts from small intestine back to liver via the hepatic portal vein 95% recycled
92
What do some drugs do to the enterohepatic circulation?
Some antibiotics kill susceptible intestinal flora and reduce levels of deconjugating enzymes
93
What are the endocrine functions of the liver?
Secretes IGF-1 in response to GH Forms T3 from T4 Activates VitD Secretes angiotensinogen Metabolizes hormones Secretes cytokines involved in immune defenses
94
What is the main way to get rid of excess cholesterol?
Bile
95
What is the P450 system?
Family of enzymes - CYPs - that break down most drugs, medications, xenobiotics and other toxic substances in the liver - metabolize thousands of endo- and exogenous compounds
96
While most drugs are ________________ by CYPs, some drugs are _________________ by them
detoxified, activated
97
CYPs can sometimes be inhibited by ______________________ which is why you are not supposed to ingest it while taking some medications. CYP activity can also decrease by _________________________________
Grapefruit juice, smoking or poor nutrition
98
What is NAFLD?
| non-alcoholic fatty liver disease
Non-alcoholic fatty liver disease Accumulation of lipids in hepatocytes - called steatosis
99
What causes NAFLD?
| non-alcoholic fatty liver disease
Obesity and systematic insulin resistance Results from dysfunction adipocytes releasing adipokines and resistin
100
Adipokines are involved in modulating insulin resistance which is at the heart of many obesity-related digestive diseases. What are these diseases?
- Gastroesophageal reflux disease (GERD) Barrett's esophagus Esophageal cancer Colon polyps and cancer Non-alcoholic fatty liver disease (NAFLD) Hepatitis Cholelithiasis Gallbladder cancer Cholangiocarcinoma Pancreatic cancer Diabetes
101
What is the Gut-Brain axis?
Bi-directional neurohormonal communication system CNS & ENS as well as neural, endocrine, immune and metabolic pathways particularly the HPA axis Also includes microbiome
102
Interaction between the human body and microbiota form a complex, distinct, and harmonized _________________that defines the relationship as _________________, ___________________ or ___________________
bionetwork, commensal, symbiotic, pathogenic
103
What host factors affect the human microbiota?
Age, genes, hormonal changes, nutrition, predisposing disease, lifestyle, geography, drugs, etc. Host immunity may play a role
104
What does a disruption to the microbiota do?
Called dysbiosis Contributes to life-threatening diseases
105
What is the gut microbiome?
Trillions of bacteria, fungi, and viruses living in the gut
106
Periodontal disease occurs because of dysbiosis, most often in patients with genetic that ___________________________________________________________________, leading to ____________________________________________________________ in these susceptible individuals
Mount an exaggerated immune response to microbes, an exaggerated inflammatory reaction
107
What is the gut-liver axis?
Bi-directional reciprocal relationship facilitated by the portal venous system Microbial products transported to liver Liver reacts via bile acid pathway and intestinal Ab production
108
What regulates the composition of the gut microbiome?
The liver
109
There has been research linking missing teeth with ____________________________ and _____________________________.
CV diseases, diabetes
110
People with tooth loss or other swallowing problems can lead to _________________________ and affect _____________________ Therefore, ________________________________ is essential to healthy gut ecosystem
Nutritional deficiencies, gut motility Proper chewing
111
Bacterial colonization starts ___________________. Therefore, __________________, _____________________________, and _______________________________ have an increased risk for gut microbiota dysbiosis
At birth, preterm infants, infants taking antibiotics, infants born by C-section
112
What are prebiotics?
Molecules indigestible to humans, but can be metabolized by the microbiota
113
What are probiotics?
Live strains of strictly selected microorganisms which confer a health benefit on the host
114
What are synbiotics?
Prebiotics and probiotics used in combination
115
What are postbiotics?
Metabolites of the probiotic bacteria
116
How do postbiotics affect the metabolic homeostasis?
Metabolites they produce affect GI hormone secretions
117
What do SCFA do in the gut?
| short chain fatty acids
Short chain fatty acids Stimulate EECs to release GLP-1 and PYY -> activates adipose to release leptin -> decreased hunger SCFAs also enhance insulin sensitivity and mitochondrial functions in muscle cells and promotes insulin secretion from beta cells
118
The gut microbiota can produce a range of neuroactive molecules including: _________________________. All of these are essential for regulating ____________________________ in the gut
- ACh, catecholamines, GABA, histamine, melatonin, and seratonin Peristalsis and sensation
119
Differences in _______________________________________ have emerged as factors to account for variation in immunization outcome
the composition of the intestinal microbiome
120
In a healthy state, what is the function of the gut microbiome?
Control nutrient metabolism Defend against pathogens Deliver signals to immune cells to promote physiology and immunity
121
When is communication between the gut microbiota and the host CNS programmed and how long does it last?
First three years of life Remains stable throughout life (unless drugs given)
122
What are the two critical barriers that the bi-direction communication between the gut microbiota and the host CNS?
Intestinal epithelial and blood-brain barrier
123
Stool softeners and emollients drugs, stimulant laxatives, and osmotic laxative has been positively associated with __________________________________. However, ______________________________ were not associated with these diseases.
Dementia, Alzheimer's, and vascular dementia risk Bulk forming laxatives
124
What is the only probiotic that is designed for oral-care?
ProBiora
125
What did the University of Lincoln-Nebraska researchers develop in relation to the gut microbiome?
Bifidobacterium adolescentis IVS-1 Stays in gut longer, improves gut barrier function (supports TJs)
126
What is the oral-gut-brain axis?
Interactions between mouth, gut and brain that are linked through microbiota
127
Periodontitis can lead to ___________________ if bacteria translocate and recolonize in the GI tract. Two subdivisions of this disease are _________________ and _________________
Inflammatory bowel disorder (IBD), Crohn's disease, ulcerative colitis
128
What are the two methods by which oral bacteria may recolonize in the gut?
Hematogenous route: bloodstream due to mechanical disruption Via swallowing - PPIs and antibiotics
129
What are the two types of oral presentations for someone with Crohn's disease?
Lip and oral swelling with 'cobblestoning' of oral mucosa Mucogingival ulcers - secondary manifestations due to nutritional deficiencies
130
What are the symptoms of celiac disease?
Chronic diarrhea, bloating, and abdominal pain Essential Nutrient deficiencies (osteoporosis, etc.) Dental enamel defects (DEDs) in all 4 quadrants - this can be the only symptom of CeD, so patients should be screened
131
The microbiota-gut-brain axis plays an essential role in our overall health, including _______________________ and _________________________________
Mental well-being, cognitive health
132
What is ProbioBrain?
Probiotic solution aimed at treating mental wellness
D1 Fall - Physiology
flashcards
Decks in class (24)
# Cards
-
Exam 1 - Intro to Physiology15
-
Exam 1 - Cell Membrane Dynamics32
-
Exam 1 - Skeletal Muscle Physiology101
-
Exam 2 - Neurophysiology76
-
Exam 2 - Bone Mineralization (some histology crossover)24
-
Exam 2 - Bone Homeostasis and Repair (some histology crossover)86
-
Exam 2 - Endocrine (Andrew's Cards)133
-
Exam 2 - Reproductive (Andrew's Cards)45
-
Exam 3 - Smooth Muscle Phys (Andrew's)49
-
Exam 3 - Gas Exchange (Andrew's)77
-
Exam 3 - Mechanisms of Breathing (Andrew's)95
-
Exam 3 - Cardiac Muscle Phys (Andrew's)26
-
Exam 3 - Rhythmic Excitation (Andrew's)62
-
Exam 3 - Cardiac Cycle (Andrew's)31
-
Exam 3 - Stroke Volume and Cardiac Output (Andrew's)33
-
Exam 3 - Blood Flow and BP (Andrew's)80
-
Exam 4 - Digestive Phys132
-
Exam 4 - Renal282
-
Exam 4 - Wound Healing65
-
Exam 4 - Digestive Phys from notebook LM74
-
Exam 4 - Renal from notebook LM69
-
Exam 4 - Wound Healing (hard)70
-
Exam 4 - Digestive Phys (hard)87
-
Exam 4 - Renal (hard)80
