Digestive System Flashcards
(98 cards)
1
Q
What kind of pH does the digestive system stabilize?
A
Plasma
2
Q
What is the ideal plasma pH?
A
7.4
3
Q
How many buffers are involved in stabilizing pH?
A
4
4
Q
4 Buffers that work to stabilize pH
A
- H2CO3 : HCO3- Pair
- Hemoglobin
- Proteins
- Phosphate
5
Q
How does the respiratory system maintain pH?
A
CO2 is an acid in water
6
Q
What is CO2 in water?
A
An acid
7
Q
What does the respiratory system maintain why CO2 increases?
A
pH
8
Q
How do kidneys maintain pH?
A
Secretion of H+, reabsorption of HCO3-
9
Q
How is plasma [H+] increased?
A
More HCO3- leaves
10
Q
Physical and chemical mediated breakdown of food
A
Digestion
11
Q
Macromolecules
A
Carbohydrates, lipids, proteins
12
Q
Carbohydrates, lipids, proteins
A
Macromolecules
13
Q
What is absorbed?
A
H2O and digestive products
14
Q
Transfer from lumen to extracellular fluid
A
Absorption
15
Q
Movement of material in GI tract utilizing smooth muscle
A
motility
16
Q
Movement of water, ions, and enzymes from extracellular fluid into GI tract
A
Secretion
17
Q
Three layers of GI tract in order
A
- Intermucosal Layer
- Submuscosa
- Muscularis Externa
18
Q
What is the intermucosal layer of GI tract composed of?
A
Epithelial cells
19
Q
What is the submucosa layer of GI Tract composed of?
A
Neural plexus, blood vessels, lymphatic vessels
20
Q
What is the muscularis externa layer of the GI Tract composed of?
A
Smooth Muscle
21
Q
What is the function of the muscularis externa layer of the GI Tract?
A
Motility
22
Q
What are the two layers of the muscularis externa layer?
A
Innercircular and outer longitudinal
23
Q
What type of muscles function for motility?
A
Smooth Muscle
24
Q
Near constant contraction that separates regions
A
Spincter
25
Progressive, ring-like contractions
Peristaltic contractions
26
What type of contraction is the migrating motor complex involved in?
Peristaltic contractions
27
Migrating Motor Complex range for organs
Stomach to colon
28
Migrating motor cortex duration
Every 90 minutes
29
What type of muscle is part of segmental contractions?
Longitudinal smooth muscle
30
This type of contraction functions in maximizing food exposure to GI products
Segmental contractions
31
Motility is neural mediated by this system
Enteric NS
32
What factors can cause reflexes in GI tract?
Stretch, hormones, pH, ect
33
What kind of connections do single unit smooth muscle cells have?
Gap Junctions
34
Do single unit smooth muscle cells have spontaneous depolarizations?
Yes
35
Do single unit smooth muscle cells have slow wave potentials?
Yes
36
How much GI fluid is secreted into the GI tract per day?
7 Liters
37
What is in the GI fluid?
Enzymes, H2O, HCO3-, Mucus
38
Where does the digestion of carbohydrates begin?
The mouth
39
What happens to carbohydrates in the mouth?
Broken down from polysaccharides to disaccharides
40
What starts carbohydrate digestion in the mouth? (2)
mastification and salvatory amylase
41
Does carbohydrate digestion continue in the stomach and why?
No, acidic environment destroys amylase activity
42
What is the pH of the stomach?
around 2, very acidic
43
Where is carbohydrate digestion resume?
duodenum
44
What resumes carbohydrate digestion in the duodenum?
Pancreatic amylase
45
What does pancreatic amylase do?
Finishes breaking carbohydrates down from polysaccharides to disaccharides
46
Where are brush borders located?
Epithelial cells in duodenum
47
What do brush borders contain?
Enzymes
48
Role of brush borders in carbohydrate digestion
Break disaccharides into monosaccharides
49
Simple sugars capable of absorption
Monosaccharides
50
What occurs in the mouth for protein digestion?
Mastification
51
What occurs in the stomach for protein digestion?
Initiation of digestion
52
Where are gastric pits located?
In the antral and pyloric regions of the stomach
53
What do mucus cells in the stomach produce?
Mucus
54
What macromolecules have digestion that involve the gastric pits of the stomach?
Protein
55
What role does mucus in the stomach play?
Protective barrier from acids
56
What do chief cells in the stomach produce?
Pepsinogen
57
What is pepsinogen?
Inactive enzyme in the stomach
58
What do the parietal cells in the stomach produce?
H+ and Cl-, produce HCl
59
What enzyme occurs when HCl acts on Pepsinogen?
Pepsin
60
What is pepsin?
Inactive enzyme
61
What does proteins become when pepsin acts on it?
Large peptide fragments
62
What do pancreatic peptides do to the large peptide fragments?
Breaks them into smaller peptide fragments
63
Where are large peptide fragments broken down?
Duodenum
64
What do aminopeptidases (Brush border) do to small peptide fragments?
Break them into individual amino acids that are absorbable
65
Roles of HCl (3)
1. Pepsinogen to pepsin
2. Low pH for antibacterial
3. Break down connective tissue of food
66
Where does lipid digestion began?
Duodenum
67
What enzyme starts lipid digestion?
Pancreatic lipase
68
Three pancreatic enzymes
1. Amylase
2. Peptidases
3. Lipase
69
What does triglycerides become when they interact with lipase?
Monoglycerides and free fatty acids
70
Product of the liver
Bile
71
Three bile salts
cholesterol, lecithin, bilirubin
72
Bilirubin function
Breakdown red blood cells
73
Where is bile stored?
Liver
74
Bile salts are
Amphipathic
75
What does amphipathic mean?
Hydrophobic and hydrophilic region
76
If something is hydrophobic, it is this regarding lipid
Lipophilic
77
Acts as a detergent to emulsify lipid droplets
Bile salts
78
Why does emulsification benefit lipid digestion? (3)
Breaks down big triG, increases surface area, and enhances digestion
79
How are lipids absorbed?
As monoglycerides plus FFA's
80
Where are TriG's reformed after absorption?
In epithelial cells
81
What do TriG's become part of after absorption?
Chylomicrons
82
What are chylomicrons a product of?
Golgi
83
Where do chylomicrons go to after formation?
Absorbed into lymphatic lacteal system
84
What is Gastrin? (role)
Hormone that stimulates gastric acid secretion
85
Where is gastrin produced?
G cells of stomach
86
What stimulates production of gastrin?
Proteins/peptides in stomach, distension
87
Role of cholecystokinin (CCK)
GI hormone that stimulates contraction of gall bladder, inhibits gastric emptying (metered movement of stomach contents into duodenum)
88
Where is Cholecystokinin (CCK) produced?
Duodenal epithelium
89
What stimulates the production of Cholecystokinin (CCK)?
Fatty acids and amino acids/peptides in duodenum
90
What is the role of secretin?
Inhibits gastric emptying, stimulates pancreatic bicarbonate release and pancreatic enzymes to neutralize stomach acid
91
Where is secretin released?
Small intestinal epithelial cells, esp duodenum
92
What stimulates secretin release?
decrease in small intestine pH
93
Role of Glucose-Dependent Insulinotropic Peptide (GIP)?
Stimulate release of insulin from endocrine pancreas to promote glucose uptake by cells
94
Where is Glucose-Dependent Insulinotropic Peptide (GIP) released from?
Small intestine epithelial cells
95
What stimulates the release of Glucose-Dependent Insulinotropic Peptide (GIP)?
Monosaccharides (glucose) in small intestine
96
What stimulates the release of motilin?
Lack of digestion or fasting
97
Where is motilin released from?
Small intestine epithelial cells
98
What is the role of motilin?
Stimulates migrating motor complex
