T20 Digestive System Flashcards
1
Q
Which organs make up the alimentary canal?
A
mouth, pharynx, esophagus, stomach, small intestine, large intestine
2
Q
Which organs make up the accessory digestive structures?
A
teeth, tongue, salivary glands, pancreas, liver, and gallbladder
3
Q
What are the six digestive processes (in order)?
A
ingestion, propulsion, mechanical digestion, chemical digestion, absorption, defecation
4
Q
What is ingestion?
A
taking food into mouth
5
Q
What is propulsion?
A
swallowing and peristalsis moves food
6
Q
What is mechanical digestion?
A
chewing food in mouth, churning food in stomach, and segmentation of food in small intestine
7
Q
What is chemical digestion?
A
complex molecules (carbohydrates, proteins, and lipids) broken down to chemical components in the mouth, stomach, and small intestine
8
Q
What is absorption?
A
transport of digested nutrients from the lumen of the alimentary tract into the blood and lacteals
9
Q
What is defecation?
A
elimination of indigestible substances as feces
10
Q
What are the two steps of propulsion?
A
Peristalsis and Segmentation
11
Q
What is peristalsis?
A
－ the major means of propulsion. adjacent segments of the alimentary canal relax and contract which propels food forward.
－ rhythmic contractions of the longitudinal muscles in the gastrointestinal tract
12
Q
What is segmentation?
A
- nonadjacent segments of small intestine alternatively contract and relax, moving food forward and backward. food is mixed with digestive juices and slowly propelled
- contractions of the circular muscles in the digestive tract,
13
Q
What are the four abdominal quadrants?
A
right upper quadrant, left upper quadrant, right lower quadrant, left lower quadrant
14
Q
What are the two types of peritoneum?
A
visceral and parietal peritoneum
15
Q
What is visceral peritoneum?
A
serous membrane that surrounds digestive organs
16
Q
What is parietal peritoneum?
A
serous membrane that lines the body wall
17
Q
What is a mesentery?
A
double layer of peritoneum that attaches to abdominal wall (large int.)
18
Q
What do mesenteries do?
A
hold organs in place, sites of fat storage, provides route for blood vessels, lymphatic vessels, and nerves
19
Q
What is the intra peritoneal space?
A
located in the abdominal cavity and is surrounded by the peritoneum
20
Q
What are the four dorsal mesenteries?
A
greater omentum, mesentery proper, transverse mesocolon, sigmoid mesocolon
21
Q
What is the greater omentum?
A
layer of peritoneum that attaches to the greater curvature of the stomach
22
Q
What is the mesentery proper?
A
mesentery that supports the jejunum and ileum
23
Q
What is the transverse mesocolon?
A
mesentery that supports the transverse colon
24
Q
What is the sigmoid mesocolon?
A
mesentery that supports the sigmoid colon
25
What is the lesser omentum?
mesentery that attaches to the lesser curvature of the stomach, liver, and proximal part of duodenum
26
What is the falciform ligament?
binds anterior liver to anterior abdominal wall
27
What are the retroperitoneal organs?
organs that are behind the peritoneum and fuse directly to posterior abdominal wall
28
What are secondary retroperitoneal structures?
structures were initially suspended in mesentery and later migrated behind peritoneum during embryonic and fetal development
29
What are examples of secondary retroperitoneal structures?
head, neck, body of pancreas, duodenum, ascending/descending colon
30
What are the four layers of the alimentary tract from esophagus to anal canal (from inside to outside)?
mucosa, submucosa, muscularis externa, serosa layer (or adventitia layer in retroperitoneal organs)
31
What are the three layers of the mucosa?
epithelium, lamina propria, muscularis mucosae
32
What type of tissue is lamina propria made of?
loose areolar and/or reticular connective tissue
33
What type of muscle is muscularis mucosae made of?
smooth muscle
34
What is the function of lamina propria?
to nourish the epithelium and capillaries and to absorb digested nutrients
35
What is the function of muscularis mucosa?
produces local movements of the mucosa
36
What is the function of the submucosa layer?
enables alimentary canal to stretch and return to its shape as food pass through it
37
What type of tissue is submucosa made up of?
moderately dense connective tissue (intermediate between loose areolar and dense irregular)
38
What are the two layers of the muscularis externa?
circular muscularis and longitudinal muscularis
39
What is the circularis muscularis?
the inner layer of muscularis externa which orients around circumference of canal
40
What is the longitudinal muscualris?
the outer layer of the muscularis externa which orients around the length of the canal
41
What are the two layers of the muscularis externa responsible for?
peristalsis and segmentation (propulsion)
42
What epithelium is the serosa layer made of?
simple squamous epithelium underlain by a layer of areolar connective tissue
43
Which parts of the alimentary tract contain an adventitia?
parts of the alimentary tract which are not associated with the peritoneal cavity (e.g. esophagus and retroperitoneal organs)
44
Which two nerve plexuses innervate the alimentary tract?
myenteric and submucosal nerve plexuses
45
Where does the myenteric nerve plexus lie?
between the circular and longitudinal muscularis .
46
What does the myenteric nerve plexus control?
peristalsis
47
Where does the submucosal nerve plexus lie?
in the submucosa
48
What is the role of the submucosal nerve plexus?
to signal glands to secrete
49
How are adjacent muscle fibers connected?
with gap junctions
50
How does smooth muscle contract?
- dense bodies anchor thin filaments to sarcolemma, and through this anchoring attachment, the sliding myofilaments shorten the muscle cell by pulling on the cytoskeleton during muscle contraction.
- entry of Ca2+ into sarcoplasma stimulates smooth muscle to contract
51
How does Ca2+ enter the sarcoplasma?
through calveolae
52
What type of epithelium lines the oral cavity?
stratified squamous epithelium
53
What type of epithelium lines the pharynx?
stratified squamous epithelium
54
What type of epithelium lines the esophagus?
stratified squamous epithelium
55
What type of epithelium lines the stomach?
simple columnar epithelium
56
What type of epithelium lines the small intestine villi?
simple columnar epithelium
57
What type of epithelium lines the large intestine?
simple columnar epithelium
58
What type of epithelium lines the anal canal?
stratified squamous epithelium
59
What are deciduous teeth and how many are there?
"baby teeth" that start emerging at 6 months; there are 20
60
What are permanent teeth and how many are there?
start emerging by 6 years and are usually in by end of adolescence (except wisdom teeth) ; there are 32
61
How many incisors, canines, premolars, and molars are there?
8 incisors, 4 canines, 8 premolars, 12 molars
62
What are the three salivary glands?
parotid glands, submandibular glands, sublingual glands
63
Where are the parotid glands?
anterior to ear and is largest extrinsic gland; parallel to zygomatic arch
64
What can parotid glands be infected with?
mumps virus
65
Where does the submandibular gland lie?
along medial surface of mandibular body
66
Where does the sublingual gland lie?
lies in floor of oral cavity inferior to tongue
67
What types of cells does the parotid gland contain?
serous cells
68
What types of cells does the submandibular gland contain?
serous and mucous cells
69
What types of cells does the sublingual gland contain?
primarily mucous cells
70
What are the contents of saliva?
water, ions, mucus, bicarbonate buffer, and enzymes (e.g, amylase)
71
What does bicarbonate buffer in saliva do?
neutralizes acids produced by oral bacteria
72
What do the enzymes (amylase) in saliva do?
begin the digestion of complex carbohydrates
73
What type of epithelium lines oropharynx and laryngopharynx?
stratified squamous epithelium
74
What does the cardiac sphincter do?
closes to prevent stomach acid from entering the esophagus
75
What type of epithelium lines the esophagus?
stratified squamous epithelium
76
What happens to the mucosa and submucosa when bolus passes through esophagus?
the folds of mucosa and submucosa flatten out
77
What muscle makes up muscularis externa in superior 3rd of esophagus?
skeletal muscle
78
What muscle makes up the middle 3rd of esophagus?
mixed skeletal & smooth muscle
79
What muscle makes up the lower 3rd of esophagus?
smooth muscle
80
What are rugae?
longitudinal folds on internal surface of stomach that flatten when the stomach fills
81
What are the three layers of muscalris externa in the **stomach**?
circular, longitudinal, and oblique
82
What are gastric pits?
indentations in the stomach that are entrances to gastric glands
83
Which cells line the gastric glands?
mucous neck cells, enteroendocrine cells, parietal cells, chief cells
84
What do mucous neck cells in the stomach do?
secrete mucus
85
What do enteroendocrine cells in the stomach do?
secrete gastrin which signals parietal cells to produce HCl acid
86
What do parietal cells in the stomach in the stomach do?
secrete HCl acid and gastric intrinsic factor
87
What do chief cells in the stomach do?
secrete pepsinogen that is activated to pepsin when it encounters HCl acid in the gastric glands
88
What occurs when food enters the stomach?
- food is churned into chyme
- secretion of HCl acid creates acidic conditions
- pepsin begins protein digestion
- minor absorption can occur in stomach including water, electrolytes, and some drugs
89
What are two types of peptic ulcers?
gastric ulcers and duodenal ulcers
90
What causes peptic ulcers?
Helicobacter pylori
91
How does Helicobacter pylori cause ulcers?
it binds to gastric epithelium and induces over-secretion of acid and inflammation
92
Where do gastric ulcers occur?
in the pyloric region of stomach
93
Where do duodenal ulcers occur?
in the duodenum of small intestine
94
How long is the small intestine?
6 meters
95
How long is the large intestine?
1.5 meters
96
How long does it take food to move through segmentation and peristalsis (propulsion)?
3-6 hours
97
What are the three subdivisions of the small intestine?
duodenum, jejunum, and ileum
98
What is the innervation of the small intestine?
parasympathetic fibers from vagus nerve, sympathetic fibers from thoracic splanchnic nerves, and sensory nerves
99
What are the four digestive enzymes released into the duodenum?
proteases/peptidases, lipases, carbohydrates, nucleases
100
Where are the four digestive enzymes released into the duodenum produced?
pancreas
101
What do proteases and peptidases do?
split proteins into amino acids
102
What do lipases do?
split fat into fatty acids and glycerol
103
What do carbohydrases do?
split carbohydrates into simple sugars
104
What do nucleases do?
split nucleic acids into nucleotides
105
Where does the duodenum receive digestive enzymes from (specific ducts)?
main pancreatic duct and common bile duct
106
What does the pancreatic sphincter do?
controls entry of pancreatic juice enzymes
107
What does the bile sphincter do?
controls entry of bile
108
What does the hepatopancreatic ampulla contain?
pancreatic sphincter and bile sphincter
109
What opens the hepatopancreatic ampulla to the duodenal lumen?
major duodenal papilla
110
What cells does the small intestine wall contain?
enteroendocrine cells, goblet cells, absorptive cells, intestinal crypts (crypts of Lieberkuhn)
111
What do enteroendocrine cells in the duodenum do?
secrete hormones (ex. cholecytokinin) and other hormones that signal pancreas to secrete digestive enzymes and bicarbonate rich fluid
112
How is cholecytokinin hormone released in duodenum?
released in response to fatty chyme entering the duodenum
113
What does cholecytokinin do?
causes gallbladder's muscular wall to contract and ducts to relax and release bile into duodenum that emulsifies fats
114
What does alkaline bicarbonate mucus do in the duodenum?
help neutralize acidic chyme from stomach
115
What do the goblet cells of small intestine do?
secrete mucus that lubricates chyme and protects intestinal wall from enzymatic digestion
116
What do the intestinal crypts (crypts of Lieberkuhn) of the small intestine do?
renew mucosal epithelium by dividing rapidly and moving onto the villi w/ complete renewal of inner epithelium of the small intestine every 3-6 days
117
What do absorptive cells in the small intestine do?
uptake digested nutrients where carbohydrates and proteins are absorbed by blood capillaries and fat is absorbed by lacteal capillaries
118
What are the small intestine modifications to increase absorptive surface area?
circular folds, villi, microvilli
119
What cells are small intestine villi made up of?
absorptive cells
120
How many square meters of absorption does the villi/microvilli system provide?
200 square meters
121
What do brush border enzymes in microvilli do?
complete the final stages of digestion (breakdown) of nutrient molecules
122
What is the role of blood capillaries in villi lamina propria?
to absorb products of digestion of carbohydrates and protein
123
What is the role of lacteals (lymphatic capillaries) in villi lamina propria?
to absorb products of digestion of fat
124
What are chylomicrons?
lipid-protein complexes that enter the lacteal capillaries
125
What does the ileocecal valve do?
connects the ileum (end of small intestine) with the colon (beginning of large intestine)
126
Does the colon contain villi?
no
127
What is the role of colonocytes in the colon?
to take in water and electrolytes
128
What types of cells are present in the colon?
numerous goblet cells, absorptive cells (colonocytes), intestinal crypts
129
What is the role of the large intestine?
- small amount of digestion by bacteria in the colon; digested residue contains few nutrients
- mass peristaltic movements and haustral chumming moves feces towards the rectum
130
Where is the highest concentration of bacteria in the world found?
the colon of humans and other mammals
131
What is the teniae coli?
thickening of longitudinal muscularis with three longitudinal strips placed at equal intervals around colon and cecum
132
What is the haustra?
puckering sacs in large intestine created by teniae coli
133
What is haustral churning?
the sequential movements of contents from one haustra to the next
134
What are epiploic appendages?
fat-filled pouches of visceral peritoneum attached to intestine
135
How does the rectum generate strong contractions for defecation?
uses longitudinal muscle layer (no teniae coli)
136
What is the defecation reflex?
- as feces moves into the rectum, the walls distend, which stimulates sensory stretch receptors that send signals to spinal cord
- spinal reflex triggered--> parasympathetic efferent fibers stimulate contraction of smooth muscle in rectal walls and relaxation of internal anal sphincter
- if it is convenient to defecate, voluntary motor neurons are inhibited - allowing external anal sphincter to relax and allow feces out of anus
137
What is the portal triad of the liver composed of?
bile duct, portal venule, portal arteriole
138
What are Kupffer cells?
specialized macrophages which line the sinusoids and destroy bacteria
139
What is the path of blood through the liver?
blood from sinusoids flow into central vein of liver lobule which flows into interlobular veins which feed into the hepatic vein
140
What is the role of the left and right hepatic ducts of the liver?
to deliver bile made in the liver to the cystic duct of the gallbladder
141
What is the role of the cystic duct of the gallbladder?
to transport bile into the gallbladder
142
What is the role of the gallbladder?
to store and concentrate bile produced by liver cells
143
What is the role of bile?
to emulsify fats in the duodenum
144
How is bile expelled from gallbladder?
bile duct expels bile through bile sphincter into the duodenum
145
Which cells make up the exocrine function of the pancreas?
acinar cells and zymogen granules in acinar cells
146
What do acinar cells do?
make, store, and secrete pancreatic enzymes into duodenum
147
What is the role of zymogen granules in acinar cells?
to store enzymes in the inactive precursor form
148
Which cells make up the endocrine function of the pancreas?
alpha cells, beta cells, delta cells
149
What do alpha cells do?
secrete glucagon
150
What do beta cells do?
secrete insulin
151
What do delta cells do?
secrete somatostatin
152
What is the endocrine function of the pancreas?
to regulate blood sugar
