Flashcards in GI-Phys Deck (80)
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1
What is necessary for digesting fats?
Bile
2
What causes contraction of the GB?
CCK
3
What is an action of Secretin?
Stimulation of HCO3-
4
What causes Sphincter of Oddi to relax?
CCK
-->this allows bile and enzymes to flow to the duodenum
5
What determines the amount of bile salts the liver needs to produce?
Depends on the amount of bile salts reabsorbed
6
Where does carbohydrate digestion begin?
Mouth with salivary amylase
7
Where are disaccharides (sucrose, maltose, lactose, trehalose) digest?
Intestine
8
What are simple sugars?
-Glucose
-Galactose
-Fructose
9
Where are simple sugars absorbed?
Intestine by sodium cotransport (SGLT) and facilitated diffusion (Glut 2)
10
What is the action of Incretin?
Increases secretion of Insulin
11
Where does protein digestion begin?
Stomach with activation of GI proteases
12
What converts Pepsinogen?
-HCL (low pH)-->converts to Pepsin
13
What does Pepsin do?
-Breaks down proteins into amino acids and oligopeptides
14
What is the action of Enterokinase?
-Converts Trypsinogen to Trypsin in the small intestine
-Trypsin activates other proenzymes secreted from pancreas into ACTIVE form
15
Who does the bulk of protein digestion?
Active Pancreatic enzymes
16
What are the final products of protein digestion?
-Amino acids
-Dipeptides
-Tripeptides
17
How is protein absorbed?
-Na+-amino acid co-transport
-H+ di/tri-peptide co-transport
18
Where does fat digestion begin?
-Mouth with lingual lipase
19
Where are fats broken down?
Duodenum by digestive enzymes
20
What are the final products of lipids?
-Monoglyceride
-Cholesterol
-Lysolecithin
-Free fatty acids
21
Where are the final lipid products absorbed?
Jejunum via Michells and chylomicrons
22
What does B12 need to be absorbed in the intestine?
-Intrinsic factor
23
How are most water soluble vitamins absorbed?
Na+ co-transport
24
How is B6 absorbed?
Simple diffusion
25
What kind of contractions are present in the UES and LES?
Tonic
26
What is primarily responsible for increase tone of LES?
Loss of inhibitory enteric neurons--> achalasia
27
What is the progressive wave of muscle contractions that proceed along the esophagus, compressing the lumen and forcing food ahead called?
-Primary peristalsis
28
Nervous control of the GI tract would be impaired by damage to what?
Submucosa
29
Where does segmentation happen?
Intestine
30
Where does peristalsis happen?
-Esophagus
-Stomach
-Intestine
31
Where does haustration happen?
Colon
32
Define haustration
phasic contractions of long duration
33
Define mass movements
-Large infrequent peristaltic contractions, 1-3x/day
-Move contents over long distances, transverse colon-->sigmoid colon
34
Hirschsprungs dz
Decreases peristalsis- "megacolon"
35
When does migrating motility complex occur?
-Periods of fasting to move undigested material from stomach down to colon
-Every 90-120 minutes during fasting
36
Myogenic contractility
-Ability of the GI tract to contract even without nervous system input
37
What are the three layers of smooth muscle?
1. Outer longitudinal muscle
2. Inner circular muscle
3. Muscularis mucosa
38
What happens with longitudinal muscle contraction?
Decreased length
39
What happens with inner circular muscle contraction?
Decreased diameter
40
What stimulates enzyme secretion in the acing cells?
-CCK and ACh
41
What enzymes does the pancreas secrete?
-Lipase
-Amylase
-Trypsinogen
42
What do ductal cells sense?
-CCK
-ACh
-Secretin
*Begin alkaline secretion
43
What does Gastrin stimulate?
-ECL to release histamine-->histamine acts on parietal cells to release HCL
44
What is the primary event of the gastric phase process?
HCL release
45
What do peptides and amino acids in the food stimulate?
-G cells to release Gastrin
46
What does food block?
-Increases pH-->blocks stimulation of somatostatin secretion
47
what is the most important physiological antagonists of HCL secretion?
Somatostatin
-->Released when pH falls below 3 to inhibit acid secretion
48
What activates histamine?
-ACh
-Gastrin
49
What does Omeprazole do?
Inhibit H+-K+ ATPase pump so H+ ions can't be secreted into stomach
50
Where is intrinsic factor from?
Parietal cells
51
What happens as food moves into duodenum?
1. Enterogoastric Reflex-ACh release is inhibited (neural reflex) to STOP acid secretion
2. CCK and Secretin inhibit histamine release to further decrease acid secretion
52
are pancreas secretion isotonic or hypotonic?
Isotonic
53
What stimulates I cells?
Protein and fat in the duodenum
54
What do I cells release?
CCK
55
"Alkaline tide"
Increase pH of gastric venous blood after a meal (short lived)
56
Which phenomenon in salivary ducts explains why the final salivary secretion is hypotonic relative to the primary secretion of the acing cells?
-Absorption of more solute than water
57
What is the most important factor affecting salivary flow?
Hydration status
58
What gland contributes the most during stimulated salivary flow?
Parotid gland= very aqueous saliva
59
What gland contributes the most during unstimulated salivary flow?
Submandibular flow=more viscous
60
What carb must be digested before being absorbed by the small intestine?
Sucrose
61
Why do patients with diarrhea often have hypokalemia?
Faster chyme flow rate stimulates K+ secretion
62
How does V.Cholera cause diarrhea?
Increase cAMP levels
63
Resulting activation of cAMP or Ca2+ ?
Increased Cl- secretion
64
Hormones
Act @ locations far away from the source
-Gastrin, CCK, Secretin
65
Paracrines
Act locally
-Histamine, somatostatin
66
Neurocrines
Released from nerves and act locally @ short distance
-VIP, somatostatin, NO,
67
What does Sympathetic release of Norepinephrine cause?
-Decreased motility
-Decreased secretions
-Increased constriction of sphincters
68
What does Parasympathetics release of ACh cause?
-Increased motility
-Increased secretions
69
What does Parasympathetics release of vasoactive intestinal polypeptide (VIP) cause?
Decreased constriction of sphincters
70
What does Parasympathetics of Gastrin-Releasing Peptide (GRP) cause?
Increased Gastrin
71
What stimulates Secretin?
Acid entering duodenum
72
What is the action of secretin on stomach motility and secretions?
Inhibits
73
What is the action of Secretin at the Pancreas?
Stimulates HCO3-
74
What stimulates CCK?
-Fat and amino acids entering duodenum
-Inhibits stomach motility and secretions
75
Osmotic diarrhea
Ex: lactose intolerant
-Buildup of lactose in GI lumen holds water with it
76
Infectious/inflammatory diarrhea
-Salmonella, rotovirus
-Associated w/ widespread destruction of absorptive epithelium
77
Deranged motility causing diarrhea
Ex: hypermotility in some cases IBS
78
What is the major site of sodium absorption?
Jejunum
79
What is the net result of fecal fluid?
Alkalotic and high K+
80
