GI System Flashcards
1
Q
What do bile salts do?
A
Emulsify fat
2
Q
What is blood detoxification?
A
Liver takes water insoluble compounds, adds chem groups to make them water soluble, allowing the kidneys to excrete them
3
Q
Microsomal enzymes/P450 system refers to
A
Liver enzymes
4
Q
What do microsomal enzymes do?
A
Inactivate compounds
5
Q
If a person has low levels of microsomal enzymes, what effects do drugs have on them?
A
Bigger effects
6
Q
If a person has higher levels of microsomal enzymes, what effects do drugs have on them?
A
Lower effects
7
Q
When does jaundice occur in adults?
A
If bile secretion is blocked or liver is nonfunctional
8
Q
What is hepatotoxicity
A
Liver disease
9
Q
What are the 3 phases of control
A
- cephalic phase
- gastric phase
- intestinal phase
10
Q
Cephalic phase
A
Vagus n. stimulates gastric secretion before food is swallowed.
11
Q
Gastric phase
A
Food stretches stomach activating myenteric & vagovagal reflexes.
Gastric secretion stimulated.
Histamine & gastrin also stimulate acid & enzyme secretion.
12
Q
Intestinal phase
A
Arriving of chyme into duodenum. Gastric function stopped due to inhibitory signals being sent.
13
Q
What are enterogastrones
A
Hormones that inhibit gastric motility
14
Q
Types of enterogastrones
A
- GIP (gastroinhibitory peptide)
- CCK (cholecystokinin)
- Secretin
15
Q
GIP
A
Stimulates pancreatic insulin production from islets; secreted by duodenum in response to carbs & lipids
16
Q
CCK
A
Secreted in response to fat & protein in chyme
Stimulates gallbladder contraction & release of pancreatic juice
17
Q
Secretin
A
In response to acidic intestinal pH
Stimulates bicarb from panreas
18
Q
What does the ENS control
A
Neurons & glia in gut
Interconnected by outer myenteric & inner submucosal
19
Q
What does the outer myenteric control
A
Motor activity
20
Q
What does the inner submucosal control
A
Secretion, absorption, local blood flow
21
Q
Sensory Neurons
A
Extrinsic afferents: travel outside of gut
Intrinsic afferents: localized
22
Q
Intestinal reflexes
A
Gastroileal reflex: increased motility of ileum
Ileogastric reflex: distension of ileum, decreased gastric motility
Intestino-intestinal reflex: overdistension of 1 segment - relaxation of rest of intestine
23
Q
What is in pancreatic juice
A
Bicarb- to help neutralize acid in stomach
Enzymes
24
Q
CCK
A
Secreted in response to protein & fat in duodenum
Stimulates release of pancreatic enzymes
25
What does secretin get produced in response to
Acid
26
Digestion beings in the
Mouth
27
Exocrine V. Endocrine secretion
Exocrine: secrete into duct; far reaching
Endocrine: secrete into bloodstream; work locally; hormones
28
What does digestion do?
Breaks food down into smaller subunits
29
Chemical breakdown
Breaking of CHEMICAL BONDS by small intestine
30
Mechanical breakdown
Chewing/ churning of stomach
31
What is absorption?
Going from lumen of digestive tract into bloodstream or lymph
32
What happens after absorption?
Delivered to tissue for energy storage
33
Lymph absorbs..
Fats
34
What is the problem with digestion?
Enzymes can digest tissue of digestive tract
35
Which get absorbed?
Fatty acids, monosaccharides, & amino acids
36
Peristalsis
Moves forward
37
Where does peristalsis occur
The esophagus, stomach, & intestines
38
Digestive system function
Motility, ingestion, secretion
39
Mastication
Chewing
40
Deglutition
Swallowing
41
What does digestion allow
Absorption
42
Where is food stored & why?
In stomach to get a continuous stream of nutrients entering blood, so that you don't need to eat continuously
43
Purpose of HCL
Provides a nonspecific immune defense against ingested pathogens
44
Peyers patches
Area of lymphoid tissue in intestinal tract; also protect against pathogens https://image.slidesharecdn.com/lymphaticsystemnotes-120330134955-phpapp01/95/lymphatic-system-notes-14-728.jpg?cb=1333115791
45
What protects immune function?
Tight junctions, Hcl, Peyers patches
46
Digestive tract refers to
Mouth --> anus
47
GI tract refers to
Stomach & intestines
48
Which layer is in contact with ingested food
Mucosa
49
Layers of the GI tract
Mucosa: innermost; lines lumen
Submucosa: below mucosa
Muscularis:
Serosa: outer connective
50
Goblet cell function
Produce mucus; helps things move along
51
Submucosal plexus
Regulates secretion; located in submucosa
52
Mucosa function
Absorption & secretion; lines lumen; simple columnar epithelium; has goblet cells
53
Submucosa function
Secretion; contains glands & nerve plexuses; vascular connective tissue layer
54
ENS function
Detects pH, detects food ingested, has sensory neurons (brain of the GI system)
55
How is food broken down?
Proteins --> amino acids
Fats --> fatty acids & glycerol
Carbs --> monomeric sugars
56
What is segmentation?
Mixing with digestive enzymes
57
Muscularis function & components
Segmentation & peristalsis; Inner circular & outer longitudinal layer; smooth muscle; myenteric plexus
58
Myenteric plexus innervation & location
Innervation: sympathetic & parasympathetic
Location: between 2 muscle layers
59
Myenteric plexus function
Major nerve supply to GI tract; movement contraction or relaxation of muscle layers
60
Esophagus connects
Pharynx --> stomach
61
Esophagus
Voluntary --> Involuntary; posterior to trachea; stratified squamous
62
Peristalsis of Bolus
Step 1: contraction of circular muscles behind food mass
Step 2: contraction of longitudinal muscles ahead of food mass
Step 3: contraction of circular muscle layer forces mass forward
63
Stomach empties into
Duodenum
64
Stomach function
Food storage & elimination, begin protein digestion, bactericidal (i.e hcl), chyme production
65
Purpose of layered muscles in stomach
Strength & support; for chyme production
66
Receptive relaxation reflex
Stomach relaxed when you swallow food allowing stomach to distend so you can eat more
67
What happens to chyme that doesn't make it to duodenum?
Turned back into stomach, churned more, a bit sent to intestines
68
What happens if too much chyme is sent at once?
Too much acidity; buffering capacity overwhelmed; pH of intestines will be acidic; enzymes won't work; possible ulcerations of duodenum
69
What if duodenum becomes overfilled?
Gastric motility inhibited
70
When does salivary amylase stop functioning?
When food gets to stomach b/c saliva has a neutral-basic pH & stomach has an acidic pH
71
T/F: The stomach does nutrient absorption
False; stomach does breakdown; mostly mechanical
72
What are rugae?
Inner surface folds (macroscopic)
73
Gastric pits
Openings of folds in gastric mucosa
74
Chief cells produce
Pepsinogen
75
Enterochromaffin cells secrete
Histamine & seratonin
76
G cells produce
Gastrin
77
D cells
Stomatostatin (inhibits digestive function)
78
Stem cells produce
New epithelium
79
Parietal cells
Hcl in stomach; intrinsic factor
80
Intrinsic factor
Secreted by parietal cells for B12 absorption
81
B12 is for
RBC production
82
What is pernicious anemia?
Not enough b12 for RBC production from not producing intrinsic factor
Tx: B12 injection NOT oral
83
What is gastric juice composed of?
Exocrine secretions, water, pepsin & hcl
84
How much gastric juice produced/day
2-4 L/day
85
What does the proton pump do?
Takes H ions --> stomach lumen in exchange for K; Bicarb --> blood; PUMPS PROTONS INTO STOMACH LUMEN
86
What are proton pump inhibitors?
Reduce acidity in stomach b/c H ions don't go out = no acid produced (i.e omeprazole)
87
What stimulated hcl production strongly?
Histamine
88
What stimulates adic production?
Gastrin, histamine, neurotransmitters, exercise, caffeine
89
Stomach acid funciton
Denature proteins; activates pepsinogen --> pepsin; provides optimal pH for pepsin; kills microbes
90
Most digestion & absorption occurs in the
S. intestine
91
Peptic ulcers
Erosion of stomach or duodenal mucosal membranes due to hyperacidity
92
Gastic ulcer cause
Depletion of mucous coat
93
Duodenal ulcer
Hyper-acidic conditions
94
Zollinger Ellison Syndrome
Gastrin secreted tumor (rare); produced by duodenal ulcers
95
H. Pylori
Cause of most gastric & duodenal ulcers; Tx: antibiotics & proton pump inhibitor
96
Small Intestinal Mucosa
Plicae circularis, villi, microvilli (brush border)
97
Enterokinase
For trypsin activation (brush border enzyme)
98
Segmentation
Muscular constrictions in lumen; churning
99
Intestinal microbiota function
Produce vitamin K & folic acid; ferment; outcompete pathogens; anti-inflammatory actions
100
If the stomach pumped it's contents all at once into the duodenum, how would this affect the activity of the enzymes within the s. intestine?
Activity would decrease; enzymes would go from neutral --> basic --> acidic; they don't work well under acidic conditions
101
NSAIDS result in stomach ulcerations by...
Inhibition of posteglandin synthesis ( is what stimulates mucous coat formation)
102
Defecation
Sphincters relax; rectal muscles contract
103
Liver function
Bile production & secretion --> fat emulsification; detoxification of compounds; largest internal organ
104
MMCs (migratory motor complexes)
| Hint: guy in commercial
occurs in between meals to prevent bacterial growth; stops when eating begins
105
Significance of increase S.A
For digestion & absorption to occur more effectively
106
Gastroesophageal junction
Where esophagus ends & stomach begins
107
Gastroesophageal sphincter
Thick circular muscle that prevents back flow from stomach; if doesn't close right: acid reflux --> ulcers; not fully functional in babies hence spit up after meals; not a true sphincter
108
LDL
Transports cholesterol to organs & vessels --> atherosclerosis
109
HDL
Returns cholesterol to liver aka good cholesterol
110
T/F: We want high ratio of LDL
False. HDL
111
What happens when LDL circles around the body?
Deposits cholesterol in sub-endothelial lining of vessels --> atherosclerotic plaque formation --> coronary artery disease
112
The higher the HDL is thought to be
Cardio protective against pulmonary artery disease & lower your risks of plaque deposit
113
VLDL converted into
LDL
114
If the liver needs cholesterol..
It will use LDL & convert them into bile salts
115
If the liver does not need cholesterol..
LDL will circulate around the body (not good)
116
Reverse cholesterol transport
HDL picks up some of LDL brings it back to liver; protective
117
Myenteric plexus regulates
Motility
118
Submucosal plexus regulates
Secretion
119
Smooth muscle is under what control
Involuntary
120
The parasympathetic innervation of the myenteric plexus stimulates what?
Motility
121
Swallowing is under what control?
Voluntary
122
Peristalsis is under what control?
Involuntary; by smooth muscle
123
Esophagus is found in areas subject to what?
Abrasion
124
Peristalsis moves what?
Bolus
125
What begins the digestion & absorption phase?
Salivary & gastric enzymes
126
What do tight junctions do?
Keep acid & pepsin within lumen
127
New stomach lining every ___ days
3
128
Why do people with hyper-acidic conditions present with duodenal ulcers instead of stomach ulcers?
Because the stomach is really well protected by mucous coat
129
Chronic use of NSAIDs does what
Corrodes mucous coat
130
What can h. pilori lead to?
Produces mucinase which degrades mucous coat --> stomach exposed --> stomach ulcers
131
Mucous production is stimulated by
Prostaglandins
132
T/F: ASA & NSAIDS inhibit prostaglandin synthesis
True
133
What are peptic ulcers?
Erosions of stomach or duodenal mucous membranes
134
Cause of a gastric ulcer
Depletion of mucous coat
135
Cause of a duodenal ulcer
Hyperacidity
136
What happens when more gastrin is produced than should
Stomach acid increases --> duodenal ulcer
137
Mucinase V . Urease
Mucinase erodes mucous lining of stomach, urease neutralizes gastric acid
138
Why is a proton pump inhibitor used to treat h. pylori?
To heal area & stop acid production
139
What is gastritis?
Inflammation of stomach mucosa caused by a breakdown of protective barriers
140
Gastritis: What is released due to inflammation?
Histamine --> acid production
141
Tx : gastritis
H2 blockers (i.e zantac)
142
What protects the duodenum?
Bicarb
143
What do mucosal cells & brunner's glands release?
Bicard
144
Pancreatic & bile secretions are..
Alkaline
145
Enterokinase is required for
Trypsin activation
146
Which intestine absorbs more water?
S. intestine
147
Causes of diarrhea
Enterotoxin & lactose intolerence
148
Why is enterotoxin a cause of diarrhea?
Keeps sodium & water in lumen
149
Causes of cirrhosis
chronic alcohol use, biliary obstruction, viral hepatitis, hepatotoxic chemicals
150
What gives feces its brown color & urine its amber color?
Bile pigments
151
What is the result of bile pigments accumulating due to a nonfunctioning liver?
Jaundice
152
What does the blue lamp do for babies with jaundice?
Converts bilirubin --> water soluble form
153
What shuts off acid production?
Negative feedback
