GI Tract Flashcards
1
Q
_____ extends from oral cavity to anus
A
Alimentary canal
2
Q
What are the 5 phases of digestion?
A
Ingestion, fragmentation, digestion, absorption, and elimination
3
Q
____ occurs in the oral cavity and is accompanied by fragmentation
A
ingestion
4
Q
Ingestion occurs in the oral cavity and is accompanied by _______
A
fragmentation
5
Q
Stomach completes fragmentation and initiates _______
A
digestion
6
Q
Contractions of smooth muscle are called
A
peristalsis
7
Q
Peristalsis is under ____ control
A
autonomic control
8
Q
In duodenum, pancreatic & biliary secretions lead to ______
A
emulsification of fat
9
Q
In jejunum & ileum, 1’ function is ______
A
absorption of nutrients
10
Q
In colon, the primary function is _____ and ______
A
resorption of water & elimination of waste
11
Q
The GI tube is a muscular tube lined by ______
A
mucus membrane
12
Q
____ is scattered throughout the GI tract for lymphatic function
A
GALT
13
Q
What are the 4 distinct layers of the GI tract?
A
mucosa, submucosa, muscularis externa & adventitia
14
Q
the ____ layer of the GI tract functions in protection, secretion, and absorption
A
mucosa
15
Q
What are the 3 layers of the mucosa layer of the GI tract?
A
epithelium, lamina propria, and muscularis mucosae
16
Q
secretory & absorptive functions; different modifications at different levels of GI tract
A
epithelium
17
Q
Layer of mucosa of GI tract: underlying connective tissue; contains lymphoid nodules, glands, blood vessels & lymphatics
A
lamina propria
18
Q
Layer of mucosa of GI tract: thin layer of smooth Mm; boundary between mucosa & submucosa
A
muscularis mucosae
19
Q
Layer of loose to dense irregular connective tissue layer beneath muscularis mucosae
A
Submucosa
20
Q
Layer of GI tract: Supports mucosa, contains larger blood vessels, Nn, lymphatics
A
Submucosa
21
Q
Layer of GI tract: usually inner circular & outer longitudinal smooth Mm layers; Mm fibers oriented at right
A
Muscularis externa(= propria)
22
Q
local contractions => mixing of foodOccur both proximally & distally, in either direction
A
Segmentation
23
Q
Peristalsis propels food in what direction?
A
Distally (aborally)
24
Q
What kind of epithelium makes up the adventitia layer of the GI tract?
A
simple squamous epithelium
25
Layer of GI tract: outer loose connective tissue layer, contains major Nn, vessels, & adipose tissue•Within abdominal cavity, referred to as serosa(
Adventitia
26
Smooth Mm of gut controlled by ______ nervous sys
autonomic
27
parasympathetic stimulation of GI tract is (excitatory or inhibitory)
excitatory
28
sympathetic stimulation of GI tract is (excitatory or inhibitory)
inhibitory
29
Where are parasympathetic ganglia of gut located within wall of gut?
within submucosa and muscularis externa
30
Clusters of parasympathetic ganglia within submucosa; called _____
Meissner’s plexus
31
Larger clusters of parasympathetic ganglia located between inner circular & outer longitudinal Mm layers called ______
myenteric or Auerbach’s plexus
32
Short, muscular tube, lined by stratified squamous nonkeratinized epithelium
esophagus
33
In upper third of esophagus, muscularis externa composed of _____
voluntary skeletal Mm
34
In middle third of esophagus, muscularis externa composed of _____
skeletal and smooth muscle
35
In lower third of esophagus, muscularis externa composed of _____
smooth muscle only
36
Gastro-esophageal junction between esophagus & stomach contains ______
gastroesophageal sphincter
37
_____ is due to regurgitation of stomach acid into distal esophagus from cardia of stomach
Pyrosis—(aka “heartburn”)
38
surrounded by smooth Mm cardiac sphincter(= gastroesophageal sphincter) adjacent to esophagus; contains predominantly mucus-secreting glands
cardia
39
glandular portion of stomach; secretes acid, pepsin, & some mucus
fundus
40
contains 1’ mucus (& gastrin) secreting glandsSmooth Mm pyloric sphincter controls outflow from stomach into duodenum
pylorus
41
_____ controls outflow from stomach into duodenum
pyloric sphincter
42
_______ is loss of stomach/duodenal epithelium/ mucosa
Peptic/gastric ulcer
43
_______ is damage extends below level of basement membrane (=> bleeding)
Ulcer
44
_____ is partial loss of epithelium (no bleeding)
Erosion
45
How do you treat peptic ulcers and erosion?
antacids
46
Ulcers frequently associated with chronic infection with _____
Helicobacter pylori
47
Helicobacter pylori produces _____=> ↑ gastric pH => 2’ ↑ acid production
urease
48
How do you treat H. pylori from producing urease?
triple therapy”—2 long-term abx & proton pump inhibitor
49
Distensible organ used for food storage; Single chamber in most animals
stomach
50
Food undergoes mechanical breakdown via muscular activity & chemical breakdown via gastric secretions to form ______
chyme
51
In addition to inner circular & outer longitudinal Mm layers of stomach, also third _______ layer in muscularis externa
inner oblique
52
T/F: There is a lot of absorption that happens in the stomach
False
53
What is absorbed in the stomach?
water, alcohol, and some drugs
54
Stomach lining contains prominent longitudinal folds that increase surface area are called _____
rugae
55
In glandular bodyof stomach, mucosa contains prominent _______; Form entrance to gastric glands(straight, tubular glands), secrete ~2 liters watery gastric juice/ day
gastric pits
56
(straight, tubular glands), secrete ~2 liters watery gastric juice/ day
gastric glands
57
What are the things that gastric juice contains
HCl, pepsinogen, gastrin, rennin, & lipase
58
inactive precursor of pepsin, hydrolyzes protein)
pepsinogen
59
Pepsinogen converted to pepsin by action of ____
HCl
60
Mucosa itself protected by thick layer of _____
mucus
61
Cover luminal surface & upper third of pit; renewed q 3-5/ 4-7 days;
mucus secreting cells
62
secrete thick, insoluble mucus & bicarbonate ions; located on surface
surface mucus cells
63
secrete soluble mucus; located in upper third of pit, at neck of gastric gland
mucus neck cells
64
Secrete HCl& intrinsic factor(necessary for absorption of Vit B12 from ileum)•Most numerous in middle third of gland, stain pink to purple
acid secreting cells (parietal cells)
65
Secrete inactive pepsinogen•Located at base of gland (bottom third); stain purple due to large #’s of ribosomes
pepsin secreting cells (chief cells)
66
Parietal & chief cells controlled by _____ nervous system & hormones from endocrine cells in region of ______
autonomic; pylorus
67
Paracrine cells that Secrete variety of peptide hormones in response to local factors; control GI motility, gastric secretion
Enteroendocrine cells (APUD)
68
stimulates secretion of HCl & pepsin;
gastrin
69
Gastrin is secreted by ____ cells
G cells
70
Somatotropin is secreted by ____ cells
D cells
71
____ inhibits secretion of gastrin
Somatotropin
72
_____ inhibits gastric secretion & stimulates smooth Mm contraction
secretin
73
Secretin is secreted by ____ cells
S cells
74
_____ are mainly in neck of gland; Continuously divide to replace lost or damaged epithelial cells; As mature, migrate up or down gland
Undifferentiated stem cells
75
Where are the undifferentiated stem cells located in gastric gland?
neck of gland
76
_____ is the primary site of absorption
small intestine
77
Mucosa & submucosa throughout small intestine arranged in valve-like folds/ rings called ______ ; ↑surface area, contain submucosalcore
plica circulares(= valves of Kerkring)
78
Plica circulares are particularly prominent in what segment of small intestine?
jejunum
79
Mucuosal surface of small intestine made up of ____ which contain a core of ______
villi; lamina propria
80
____ are between villi
crypts of Leiberkuhn
81
Causes villus blunting & atrophy => malabsorption & weight loss
Coeliac disease(gluten enteropathy)
82
Epithelium of villi supported by ______, containing _____ and ______ for absorption of nutrients
connective tissue lamina propria; capillaries & lymphatics
83
Intestinal villi lined by _______ epithelium
simple columnar epithelium
84
Mucosal cells of the small intestine called ______, cover surface of villi
enterocytes
85
Apical/ luminal surface of villi highly folded, modified into ______ that ↑surface area for absorption;
microvilli(= striated or brush border)
86
Microvilli coated with protective ____ of disaccharides (site of membrane digestion)
glycocalyx
87
Interspersed among enterocytes are mucus secreting _____ cells ; Synthesize mucinogen
goblet cells
88
stored in membrane-bound granules; lubricates & protects epitheium
mucinogen(=> mucus)
89
Actively dividing ____ located at base of crypts of villi
stem cells
90
T/F: Cells migrate up villus, mature, & are shed
True
91
How often is the entire epithelial lining of small intestine replaced?
Every 3-5 days
92
_____ cells are found at base of crypts; contain large eosinophilic granules—produce antibacterial proteins called defensins, and enzymes, including lysozyme
Paneth cells
93
“S” cells secrete _____ (stimulate release of bicarbonate from pancreas)
secretin
94
I” cells secrete _____ (stimulates pancreatic secretion & contraction of gallbladder)
cholecystekinin, or CCK
95
stimulates pancreatic secretion & contraction of gallbladder
cholecystekinin, or CCK
96
“A” cells secrete _____ (↑ blood sugar)
glucagon
97
K” cells secrete
GIP (gastric inhibitory peptide)
98
_____ located in lamina propria & submucosa of small intestine•Contains plasma cells, sec IgA
MALT
99
Epithelium contains enlarged _______ —squamoid enterocytes modified for Ag sampling, uptake of macromolecules
“M” cells(microfold)
100
dome-shaped areas grossly visible on surface of mucosa, project into lumen
Peyer’s patches
101
Characterized by presence of Brunner’s glands in submucosa
duodenum
102
Large #’s of highly convoluted, branched, tubuloalveolar submucosal glands; Secrete mucus & zymogens; unique to duodenum
Brunner’s glands
103
Main function of ______—neutralize gastric acid & pepsin, assisted by pancreas & gallbladder
duodenum
104
_____ and _____ empty into duodenum at major duodenal papilla
Pancreatic duct & bile duct
105
Chyme from stomach stimulates release of 2 hormones from APUD cells—____ and ____; Both promote section of exocrine pancreas
secretin & CCK
106
Pancreatic secretions highly ______, due to ______ which neutralize stomach acid
alkaline; bicarbonate
107
____ also stimulates contraction of gallbladder & release of bile acids
CCK
108
_____ act as emulsifying agents for digestion of lipids, form micelles
bile acids
109
Pancreatic secretions also contain proteolytic enzymes ____ and ____ for digestion of proteins
trypsin & chymotrypsin
110
In addition to trypsin & chymotrypsin, pancreatic secretions also contain ___ and _____ (proteolytic enzymes for digestion of proteins)
amylase and lipase
111
trypsin & chymotrypsin are secreted as ______
inactive precursors or zymogens
112
trypsin activated by ____
enterokinase
113
trypsin then activates ______
chymotrypsin
114
What are the 2 steps of digestion?
luminal digestion and membrane digestion
115
____ digestion involves mixing of chyme with pancreatic enzymes => molecular breakdown
luminal digestion—
116
____ digestion involves enzymes of glycocalyx on plasma membrane of enterocytes
membrane digestion—
117
______ synthesize various enzymes, (peptidases, peptide hydrolases, disaccharidases) &produce various carrier proteins for absorption of carbohydrates & AA’s
Enterocytes
118
What enzymes do enterocytes synthesize?
peptidases, peptide hydrolases, disaccharidases
119
____ initially denatured by HCl from parietal cells, then hydrolyzed by pepsin into polypeptide fragments•Continued by pancreatic enzymes—trypsin, chymotrypsin, elastase, & carboxypeptidase => formation of small peptide fragments, AA’s; absorbed by enterocytes via active transport by carrier proteins
Proteins
120
______ and ______ hydrolyze starch to disaccharides (sucrose, lactose,maltose, & isomaltose); Further broken down into monosaccharides (glucose, galactose, & fructose), absorbed by facilitated diffusion
Salivary & pancreatic amylase
121
AA’s & monosaccharides absorbed by ______ lining villi, transported across epithelium, enter capillaries within lamina propria => portal V to liver for storage
enterocytes
122
1’ starches; poly-, oligo-, & disaccharides
Carbohydrates
123
_____ 1’ triglycerides from diet, emulsified by action of bile acids
Lipids
124
Lipids are Further broken down into monoglycerides & FA’s by _____, form extracellular micelles•
pancreatic lipase
125
Micelles are absorbed by enterocytes, then re-synthesized into triglycerides within enterocytes & coated with proteins & phospholipids to form ______
intracellular chylomicrons
126
Intracellular chylomicrons are transported across enterocytes to _____, blind-ended lymph vessels within lamina propria of villi
lacteals
127
_____ includes cecum, apppendix; ascending, transverse, descending, & sigmoid colon, & rectum; lacks villi & plicae circulares
Large intestine
128
small, blind-ended sac, 2-13 cm in length distal to ileo-cecal junction; Vestigial cecum; used for bacterial digestion in herbivores; Contains large amounts of submucosal MALT, active in children
Appendix
129
1’ function, H2O & electrolyte resorption; also produces mucus for elimination of undigested food & waste; (large #’s of goblet cellsin epithelium & colonic glandsin submucosa—but no Brunner’s glands)
Colon
130
No villi for nutrient absorption•No plicae circulares; mucosal folds contain core of lamina propria•Mucosal epithelium similar to small intestine, but Paneth cells generally absent in adults
Colon
131
T/F: In the colon, MALT in large intestine form domed Peyer’s patches
False: does not form
132
T/F: In the colon, No lacteals present in lamina propria
True
133
Epithelial cell replacement of colon every ____ days from stem cells located at base of glandular crypts
5 days
134
Outer longitudinal M layer in muscularis externa is reduced or incomplete—forms 3 longitudinal strips,______ Responsible for formation of haustra,
taenia coli
135
sacculations of large intestine
haustra,
136
T/F: Large #’s of commensal bacteria (“coliforms”) present in large intestine
True
137
Any mass arising from the wall of the colon that protrudes into the lumen•Generally asymptomatic; most common sign, rectal bleeding•Tx: Sx removal
Polyps—adenoma
138
↑ roughage & fiber in diet ↓ colon cancer by ↓ transit Fme & ↑ GI motility•Tx: Surgical removal; if extensive, may require resection of portion of colon•New test kits for early detection; detect tumor Ab; also colonoscopy screening over 50
Colon cancer—adenocarcinoma
139
Short, dilated, terminal portion of large intestine•Contains transverse rectal folds and large #’s of mucus glands•Transition of mucosa from simple columnar epithelium to stratified squamous epithelium at anal canal
Rectum
140
Anal canal contains longitudinal folds called ______
anal columns(= columns of Morgani)
141
Within anal canal, _____ extend into submucosa & muscularis externa (branched, straight, tubular glands—secrete mucus)
anal glands
142
Surrounding Mm forms ______ (external—voluntary, skeletal Mm; internal—involuntary, smooth Mm)
internal & external anal sphincters
143
Anal sphincter that is voluntary and made up of skeletal muscle
external anal sphincter
144
Anal sphincter that is involuntary and made up of smooth muscle
internal anal sphincter
145
Occasional enlargement & irritation of submucosal Vv~ anal canal =>_____ (like varicose Vv)
hemorrhoids
146
external opening; exit of GI tract
Anus
