Physiology Flashcards
(120 cards)
1
Q
Where are G cells located
A
Antrum of stomach, duodenum
2
Q
Which cells secrete gastrin
A
G cells
3
Q
Function of G cells
A
Increase:
- gastric H+ secretion
- growth of gastric mucosa
- increase gastric motility
4
Q
Increased vagal activity releasing gastrin-releasing peptide (GRP) stimulates which cells in the stomach
A
G cells to secrete gastrin
5
Q
What decreases gastrin release by G cells?
A
Decreased pH
6
Q
Increase in stomach distention or alkalinization will cause release of what regulatory substance
A
Gastrin from G cells
7
Q
Peptic ulcers with extremely high levels of gastrin even after administration of secretin indicates that you have what condition?
A
Zollinger-Ellison syndrome
8
Q
Conditions that increase gastrin levels
A
Chronic PPI use - alkalinizes stomach
Chronic atrophic gastritis - H. pylori infection
Zollinger-Ellison syndrome - gastrinoma
9
Q
Location of D cells in GI tract
A
Pancreatic islet and GI mucosa
10
Q
What do D cells secrete?
A
Somatostatin
11
Q
What is the function of somatostatin?
A
Decreases pretty much all types of secretions in stomach
12
Q
Somatostatin analog used to treat acromegaly, carcinoid syndrome and variceal bleeding
A
Ocreotide
13
Q
Stimulates D cells to secrete somatostatin
A
Acid
14
Q
Stops D cells from secreting somatostatin
A
Decreased vagal stimulation
15
Q
Secrete cholecystokinin
A
I cells
16
Q
Secrete somatostatin
A
D cells
17
Q
Secrete gastrin
A
G cells
18
Q
Location of I cells
A
Duodenum, jejunum
19
Q
Stimulates I cells to secrete cholecystokinin
A
Fatty acids and amino acids
20
Q
Causes pancreatic secretions, gallbladder contraction, decreases gastric emptying and increases relaxation of sphincter of Oddi
A
Cholecystokinin
21
Q
I cells secrete cholecystokinin and produce the following effects
A
Increased pancreatic secretions, gallbladder contraction, and relaxation of the sphincter of Oddi
Decrease gastric emptying
22
Q
Acts on neuronal muscarinic pathways to cause pancreatic secretions
A
Cholecystokinin
23
Q
Secrete secretin
A
S cells
24
Q
Location of S cells
A
Duodenum
25
Causes secretion of pancreatic HCO3- and bile and decreases gastric acid secretion
Secretin
26
S cells secret secretin and produce the following actions
Increase pancreatic bicarb and bile secretion
| Decrease gastric acid secretion
27
Allows pancreatic enzymes to function in the duodenum by neutralizing stomach acids
Bicarb secreted from pancreas
28
Type of cells found in the duodenum
S, I, K, G, M cells
29
What do K cells secrete?
Glucose-dependent insulinotropic peptide
30
Endocrine function of Glucose-dependent insulinotropic peptide
Increase insulin release
31
Exocrine function of Glucose-dependent insulinotropic peptide
Decrease gastric acid secretion
32
What increases Endocrine function of Glucose-dependent insulinotropic peptide secretion
Fatty acids, Amino acids, and Glucose (FAG)
33
Secrete Endocrine function of Glucose-dependent insulinotropic peptide
K cells
34
Where are K cells located
Duodenum, jejunum
35
Endocrine function of Glucose-dependent insulinotropic peptide is also known as what?
Gastric inhibitory peptide (GIP)
36
Produces migrating motor complexes
Motilin
37
Secretes motilin
Small intestine
38
Macrolide that is a motilin receptor agonist, used for stimulation of intestinal peristalsis
Erythromycin
39
What increases release of motilin
Fasting state
40
Secretes vasoactive intestinal polypeptide (VIP)
Parasympathetic ganglia in sphincters, gallbladder, small intestine
41
Causes increased intestinal water and electrolyte secretion and relaxation of intestinal smooth muscle and sphincters
VIP
42
Secretion of this peptide is increased by distention and vagal stimulation and decreased by adrenergic input
VIP
43
Patient presenting with watery diarrhea, hypokalemia and achlorhydria most likely has what?
VIPoma
44
Location of VIPoma
Non-alpha and non-beta islet cell tumor of the pancreas
45
What is typically the cause of achalasia
Increased LES tone from loss of NO
46
Function of NO in the GI tract
Increases smooth muscle relaxation including lower esophageal sphincter (LES)
47
What cells are located in the stomach?
Parietal cells, Chief cells, Mucosal cells, G cells
48
Hormone that acts on the stomach by increasing appetite
Ghrelin
49
What decreases secretion ghrelin?
Food
50
What increases secretion of ghrelin?
Fasting state
51
What heritable disease increases ghrelin
Prader-Willi syndrome
52
What elective procedure decreases ghrelin
Gastric bypass surgery
53
Required for B12 uptake in terminal ilium
Intrinsic factor
54
What cells secrete intrinsic factor?
Parietal cells
55
Where are parietal cells located?
Stomach
56
Consequence of autoimmune destruction of parietal cells
Chronic gastritis and pernicious anemia
57
Cells that secrete gastric acid in the stomach
Parietal cells
58
Function of gastric acid
Decrease pH and convert pepsinogen to pepsin
59
What increases gastric acid secretion by parietal cells?
Histamine, ACh, and gastrin
60
What decreases gastric acid secretion by parietal cells?
Somatostatin, GIP, prostaglandin, secretin
61
What drugs inhibit prostaglandin synthesis, increasing gastric acid secretion?
NSAIDs
62
Where are parietal cells located?
In the body of the stomach
63
Which cells secrete pepsin?
Chief cells
64
Where are Chief cells located?
In the body of the stomach
65
What is the function of pepsin
Protein digestion
66
What causes Chief cells to secrete pepsin?
Vagal stimulation and local acid
67
Secrete pepsin
Chief cells
68
Digests protein in stomach
Pepsin
69
Neutralizes acid
Bicarbonate
70
Secretes bicarbonate
Mucosal cells and Brunner glands
71
Where are mucosal cells found?
Stomach, duodenum, salivary glands, pancreas
72
Where are Brunner glands located?
Duodenum
73
What causes increased secretion of bicarbonate?
Secretin
74
Where is bicarbonate trapped in?
Mucus secreted by gastric epithelium
75
What is the function of mucus secreted by gastric epithelium?
Trap bicarbonate
76
What is the strongest regulator of gastric acid secretion
Histamine released by ECL cells via gastrin stimulation
77
In what section of the stomach are the majority of mucus cells found?
Antrum of the stomach
78
Responsible for starch digestion
Alpha amylase
79
Responsible for fat digestion
Lipases
80
Responsible for protein digestion
Proteases
81
Enzyme secreted in its active form
Alpha amylase
82
Brush border enzyme found on duodenal and jejunal mucosa that converts trypsinogen to its active form
Enterokinase/enteropeptidase
83
Function of Enterokinase/enteropeptidase
Convert trypsinogen to trypsin
84
Function of trypsin
Convert other zymogens to their active form
85
Proteases that digest protein
Trypsin, chymotrypsin, elastase, carboxypeptidases
86
Trypsin, chymotrypsin, elastase, carboxypeptidases are secreted as zymogens, inactive proenzymes and are converted to their active enzyme form by which enzyme
Trypsin
87
Trypsin converting trypsinogen to more trypsin is a type of what regulation
Positive feedback loop
88
What saccharides are absorbed by enterocytes?
Monosaccharides: glucose, galactose, fructose
89
Which sodium-glucose transport protein-1 (SGLT1) takes up which to monosaccharides?
Glucose and Galactose
90
Which transporter is responsible for the uptake of Fructose?
GLUT5
91
Which transporter is responsible for the uptake of all monosaccharides?
GLUT2
92
Which sodium-glucose transport protein has Na-dependent transport?
SGLT1
93
Which glucose transporter works via facilitated diffusion?
GLUT5
94
What form of iron is absorbed in the duodenum?
Fe2+ (oxidized)
95
What part of the small intestine absorbs iron?
Duodenum
96
What part of the GI tract absorbs folate?
Small bowel
97
Vitamin that requires intrinsic factor for absorption
B12
98
What part of the small intestine absorbs vitamin B12?
Terminal ileum
99
Part of the small intestine where bile and salts are absorbed
Terminal ileum
100
Patient with small bowel disease may be deficient in what nutrients?
Iron, B9 and B12
101
Unencapsulated lymphoid tissue found in lamina propria and submucosa of ileum
Peyer patches
102
Function of Peyer patches
Contain M cells that sample and present antigens to immune cells
103
Cells in Peyer patches that sample and present antigens to immune cells
M cells
104
Major type of immunoglobulin found in gut epithelium
IgA
105
B-cells in Peyer patches are stimulated and differentiate to secrete which type of immunoglobulin
IgA
106
Enzyme that is the rate-limiting step in bile acid synthesis
7alpha-hydroxylase
107
Responsible for digestion and absorption of lipids and fat-soluble vitamins
Bile
108
Responsible for cholesterol secretion and is the body's primary way of eliminating cholesterol
Bile
109
Provides antimicrobial activity in the GI tract via membrane disruption of pathogens
Bile
110
Functions of bile
1. Digestion and absorption of lipids and fat-soluble vitamins
2. Cholesterol excretion
3. Antimicrobial activity
111
What is bile composed of?
Bile salts, phospholipids, cholesterol, bilirubin, water, and ions
112
Enzyme that heme to biliverdin
Heme oxygenase
113
Protein that carries bilirubin to liver
Albumin
114
Bilirubin that is water insoluble
Indirect bilirubin
115
Function of UDP-glucuronosyl-transferase
Conjugate bilirubin to direct bilirubin
116
Bilirubin that is water soluble
Direct bilirubin
117
Form of bilirubin that is excreted in feces and gives stool its brown color
Stercobilin
118
What happens to the majority of bilirubin
Excreted in feces
119
Organ where bilirubin is conjugated
Liver
120
Form of bilirubin that is excreted in urine and gives it its yellow color
Urobilin
