Gastrointestinal Tract Anatomy and Histology (Week 10) Flashcards
1
Q
The trunk is bound by the ____________ inferiorly
A
pelvic inlet
Note: this is kind of an imaginary line
2
Q
The trunk is bound by the ____________ superiorly
A
diaphragm
3
Q
The trunk is bound by _____________ posteriorly
A
vertebrae
4
Q
The trunk is bound by _____________ anterolaterally
A
musculo-aponeurotic walls
5
Q
The _______________ closes to ensure none of the acid from the stomach enters and damages the lining or muscle of the esophagus (which creates that heartburn feeling)
A
lower esophageal sphincter
6
Q
REVIEW: How many muscular layers does the stomach have?
A
3
7
Q
REVIEW: What part of the small intestine is closest to the stomach?
A
Duodenum
8
Q
True or False: Parts of the small intestine “dip” into the pelvic cavity
A
True
Recall: there is no real inferior physical boundary as the pelvic inlet marking the inferior border of the trunk is just an opening; this is what allows the small intestine to pass the border
9
Q
REVIEW: What makes up the small intestine?
A
- duodenum
- jejunum
- ileum
10
Q
REVIEW: What makes up the large intestine?
A
- cecum
- ascending colon
- transverse colon
- descending colon
- sigmoid colon
- rectum
11
Q
What are some of the accessory organs and other structures of the abdominal cavity?
A
- liver, gallbladder, pancreas, and their ducts
- spleen
- kidneys
- peritoneal folds
- vessels and nerves
12
Q
True or False: Like the small intestine, the large intestine also dips into the pelvic cavity
A
True
13
Q
What is the peritoneum?
A
A transparent, thin membrane that lines the abdominopelvic cavity and is continuous with the serosa of the abdominopelvic organs
Can be separated into the parietal peritoneum and the visceral peritoneum
14
Q
The ____________ peritoneum lines the interior of the body wall
A
parietal
15
Q
The ______________ peritoneum lines the visceral organs and is continuous with the serosa
A
visceral
16
Q
The ___________ peritoneum forms major folds known as mesenteries, omenta, and ligaments
A
visceral
17
Q
Pain is ____________ (well-localized/poorly localized) in the visceral peritoneum
A
poorly localized
18
Q
Pain is ______________ (well-localized/poorly localized) in the parietal peritoneum
A
well-localized [to the overlying dermatome]
19
Q
The ___________ peritoneum can sense pressure, cutting, heat, cold, laceration, and inflammatory irritation
A
parietal
20
Q
The ____________ peritoneum can sense ischemia, inflammation, stretch, and chemical irritation
A
visceral
21
Q
True or False: The visceral peritoneum and parietal peritoneum are both continuous with the serosa
A
False
Just the parietal peritoneum is continuous with the serosa
22
Q
A sharp pain would most likely be sensed in the parietal peritoneum or visceral peritoneum?
A
parietal peritoneum
23
Q
A dull pain would most likely be sensed in the parietal peritoneum or the visceral peritoneum?
A
visceral peritoneum
24
Q
What is the peritoneal cavity?
A
The cavity covered by the peritoneum; consists of the omentum and mesentery/mesocolon
25
The _____________ is a double-layered peritoneal membrane continuous with serosal surfaces, connected to the stomach
omentum
Note: there is a greater and lesser omenta
26
The ________ and _________ are double-layered peritoneal membranes that surround the small intestine and large intestine at particular sites of each, binding them to the posterior abdominal wall
mesentery (surrounds small intestine)
mesocolon (surrounds large intestine)
27
The mesentery lines the ______ and ________, binding them to the posterior abdominal wall
jejunum and ileum
Note: the mesentery helps keep the small intestine from being "tangled"
28
The mesocolon connects the ________ and __________, and binds them to the posterior abdominal wall
transverse colon and sigmoid colon
29
The ______________ (greater omentum/lesser omentum) is one of the largest folds and extends from the greater curvature of the stomach (inferior) to over the anterior aspect of the abdominal cavity, then folds back up to join with the transverse colon
greater omentum
30
True or False: The greater omentum stores a lot of visceral fat (fatty apron)
True
31
True or False: The greater omentum contains many lymph nodes
True
32
The _____________ divides the liver into right and left lobes, and attaches to the anterior abdominal wall (and thus attaching the liver to the anterior abdominal wall)
falciform ligament
33
True or False: Many structures are not fully surrounded by peritoneum
True
Either the entire surface does not really contact the peritoneum or the surface of the structure is not completely surrounded by the peritoneal lining
This is often called RETROPERITONEAL
34
What are some organs/structures that are considered retroperitoneal?
- most of the duodenum
- parts of the ascending and descending colon, and anal canal
- pancreas
- kidneys
- adrenal glands
- ureters
- aorta
- inferior vena cavae
35
There are sacs and bursa within the peritoneal cavity that are clinically and surgically relevant.
The omental bursa is behind what structures?
the stomach and the lesser omentum
36
The abdominal arterial vasculature is also known as the ____________
splanchnic circulation
37
What three arteries branch off of the abdominal aorta?
1) celiac trunk
2) superior mesenteric artery (SMA)
3) inferior mesenteric artery (IMA)
38
What does the celiac trunk give rise to?
- left gastric artery
- common hepatic artery
- splenic artery
39
What does the celiac trunk supply?
- pancreas
- liver
- gallbladder
- stomach
- duodenum
- spleen
- embryologic foregut
40
What does the superior mesenteric artery supply?
- pancreas
- stomach
- small intestine
- large intestine up until the transverse colon
- embryologic foregut and midgut
41
What does the inferior mesenteric artery supply?
the rest of the large intestine (after the transverse colon) and superior anus (embryologic hindgut)
42
True or False: The venous circulation of the abdomen is a portal circulation
True
Note: Portal circulation = capillary networks that are in series with each other
Portal circulation:
artery --> capillary --> portal vein --> capillary --> vein --> right atrium
Regular circulation:
artery --> capillary --> vein --> back to heart
43
What two veins join together to form the heptic portal vein?
superior mesenteric vein + splenic vein
44
True or False: The hepatic portal vein carries oxygen and nutrient-rich blood
False
It carries poorly oxygenated but nutrient rich blood. Most veins carry poorly oxygenated blood, but the blood is nutrient dense because it is coming from the stomach and intestines (where absorption of food is happening)
45
From the lumen to the outer wall of the GI tract in general, what is the order of the different histological layers?
mucosa --> submucosa --> muscularis --> serosa/adventitia
46
What histological layer of the GI tract is characterized by absorption, secretion, chemical digestion, many endocrine functions, and some immune functions?
mucosa
47
What histological layer of the GI tract is characterized by secretion, lots of blood vessels, a large plexus of neurons (submucosal or Meissner's plexus), and some immune functions?
submucosa
48
What histological layer of the GI tract is characterized by 2-3 layers of smooth muscle, main function is propulsion, and has a large neuronal plexus (muscular or Auerbach's plexus)?
muscularis
49
What histological layer of the GI tract is characterized by connective tissue that anchors the GI tract & allows mobility, and forms the peritoneum?
serosa/adventitia
50
The _____________ (mucosa/submucosa/muscularis/serosa) has a lot of circular folds
mucosa
51
What does the mucosa consist of?
- epithelial lining
- lamina propria
- muscularis mucosa
52
What does the epithelial lining of the mucosa consist of?
- epithelium (simple columnar w/apical microvilli in high absorption areas like the small intestine; stratified squamous or cuboidal in other areas; apical microvilli greatly increase surface area)
- goblet cells (secrete mucous, protecting/lubricating the GI tract + forms a water layer for diffusion of nutrients; helps "store" IgA)
- enteroendocrine cells
53
What does the lamina propria consist of?
- MALT (mucosa associated lymphoid tissue)
- blood and lymphatic vessels
- some glands
- loose connective tissue
Note: there are also a lot of mast cells present, which may or may not be associated with the MALT
54
What forms a border between the mucosa and submucosa?
muscularis mucosa
55
Enteroendocrine cells are part of the DNES. What does this stand for?
DNES = diffuse neuroendocrine system
(nervous system outside of the CNS)
Note from CGPT: "Neuroendocrine/[enteroendocrine] cells are structurally similar to neurons (nerve cells) and endocrine cells (hormone-secreting cells). They are capable of both receiving and transmitting neural signals and secreting hormones into the bloodstream."
56
True or False: Enteroendocrine cells are part of the epithelial lining, with lots being in the stomach and small intestine
True
57
Enteroendocrine cells can be open or closed. What does this mean?
OPEN = contacts the lumen and can sense luminal contents; as they become activated, they can secrete granules along the basal surface, towards the blood and other cells, thus having a paracrine (mostly) and endocrine function
CLOSED = do not contact the lumen, thus they are dependent on other sources of input to regulate secretion (e.g., hormones or nervous system input)
58
Where are G cells located?
What hormone do they secrete (and what stimulates its secretion)?
What is the main hormonal function?
Location: stomach
Hormone: gastrin (stimulated by amino acids in the stomach, vagal stimulation, and gastrin-releasing peptide)
Hormonal Function: increases secretion of stomach acid
59
Where are I cells located?
What hormone do they secrete (and what stimulates its secretion)?
What is the main hormonal function?
Location: small intestine
Hormone: CCK (stimulated by fats and proteins in the duodenum)
Hormonal Functions: pancreatic enzyme secretion, gallbladder contraction, satiety, INHIBITS gastric acid secretion
60
Where are Mo cells located?
What hormone do they secrete (and what stimulates its secretion)?
What is the main hormonal function?
Location: small intestine
Hormone: motilin (stimulated by fasting)
Hormonal Function: migrating motor complex (stimulates propulsion)
61
Where are S cells located?
What hormone do they secrete (and what stimulates its secretion)?
What is the main hormonal function?
Location: small intestine
Hormone: secretin (stimulated by acid in the small intestine, especially in the duodenum)
Hormonal Function: bicarbonate and water secretion from pancreas, INHIBITS gastric acid secretion and gastric emptying
62
True or False: 80% of the antibodies made in the body are in the GI tract
True
63
What are the two types of GALT (gut-associated lymphoid tissue)?
1) MALT (smaller nodules rich in macrophages and lymphocytes, found in the mucosa's lamina propria)
2) Peyer's patches (very large; found mostly throughout the distal small intestine (jejunum/ileum))
Note: in the epithelium overlying Peyer's patches are M cells (microfold cells); M cells selectively endocytose antigens and present them to dendritic cells and lymphocytes --> this is important in regulating the immune response to intraluminal antigens)
64
Most parts of the GI tract have their muscularis layer composed of an inner _______________ (circular/longitudinal) layer and an outer ______________ (circular/longitudinal) layer
inner circular layer
outer longitudinal layer
Note: the muscular nervous plexus (Auerbach's plexus) is found between these two layers and regulates muscular movements of the GI tract
65
The stomach's muscularis has an additional _________ layer, in addition to circular and longitudinal layers
oblique
66
The serosa forms the outer layer for most of the GI tract, composed of ________ (loose/dense) connective tissue covered by a simple squamous mesothelium that is continuous with the fluid-secreting peritoneum in the abdominal cavity
loose
Note: The esophagus has an adventitia (NO mesothelium, but dense connective tissue)
67
True or False: There are not many large blood and lymphatic vessels found within the serosa/mesentery
False
There are many large blood vessels and lymphatic vessels
68
True or False: Much of the activity in the GI tract is autonomous (functions independent of the CNS), however, input from the autonomic nervous system (parasympathetic & sympathetic) is also essential
True
The parasympathetic nervous system (PNS) especially is important (rest and digest) but we do have an enteric nervous system that can control propulsion, etc. on its own
69
REVIEW: Where is Auerbach's (myenteric) plexus located? What does it control?
Location = between circular and longitudinal muscle layers
Influences muscular movements
70
REVIEW: Where is Meissner's plexus located? What does it control?
Location = found diffusely throughout the submucosa
Influences secretions from glands in the mucosa and submucosa
71
True or False: The peritoneal membrane has a similar surface area as the total skin surface area (1.7m^2)
True
72
The entire surface of the peritoneal membrane is covered in secretory squamous mesothelium. How much peritoneal fluid is present?
only 50-75 mL (4-5 tbsp)
Note: this is due to the constant circulation and absorption of peritoneal fluid
73
__________ (small/large) particles are absorbed by venous pores and enter the portal circulation
Small
74
__________ (small/large) particles are absorbed by lymphatic capillaries and enter the thoracic duct
Large
75
What is excess accumulation of peritoneal fluid called?
ascites
76
What are the histological layers of the esophagus?
- mucosa
- submucosa
- muscularis
- adventitia (NOT serosa; does NOT secrete fluid)
77
What type of cells compose the mucosa's epithelium in the esophagus?
stratified squamous
(protects us when digesting foods)
78
What does the submucosa of the esophagus contain?
mucous-secreting glands
79
What type of muscle is found in the muscularis layer of the esophagus?
upper part = striated muscle
middle = transition between the two
lower part = smooth muscle
80
REVIEW: What are the histological layers of the stomach?
- mucosa
- submucosa
- muscularis
- serosa
81
What type of cells are in the epithelium of the stomach's mucosa layer?
simple columnar
Note: these are arranged into pits and glands that run deep into the lamina propria
82
Where are glands of the stomach located in relation to pits?
right below the pits
83
True or False: Glands can do various things (e.g., secrete acid or mucus) depending on which region of the stomach they are in
True
Note: in the fundus and body of the stomach, the function of the glands is acid secretion
84
What do mucous neck cells in the mucosa layer of the stomach do?
secrete alkaline mucous
(protects the stomach from acid secretion)
85
RECALL: The stomach's muscularis has an additional layer (three layers) instead of two. What is it called?
inner oblique layer
Note: (inner) oblique --> circular --> (outer) longitudinal
86
What is the stomach's serosa continuous with?
greater and lesser omentum
87
What are the histological layers of the small intestine?
- mucosa
- submucosa
- muscularis
- serosa
88
What are some characteristics of the mucosa layer of the small intestine?
- 3 levels of folding to optimize surface area (plicae circulares, villi, and microvilli on the surface of enterocytes)
- Peyer's patches (found mostly in the ileum, some in jejunum)
- crypts (depressions in between villi)
89
What are some characteristics of the submucosa layer of the small intestine?
- large Brunner glands (found in the duodenum; protects against stomach acid)
- Peyer's patches (in the ileum; extend from lamina propria all the way to the submucosa)
90
The muscularis layer of the small intestine has how many layers?
2
(circular and longitudinal)
91
What are the histological layers of the large intestine?
- mucosa
- submucosa
- muscularis
- serosa
92
The mucosa of the large intestine is arranged into _________________ that penetrate deep into the lamina propria
tubular intestinal glands
93
What are some characteristics of the mucosa layer of the large intestine?
- simple columnar epithelium (w/ fewer microvilli than the small intestine; we aren't absorbing as much)
- many goblet cells (secrete mucous)
- lots of MALT nodules in the lamina propria
94
What makes the muscularis layer of the large intestine unique?
While the circular layer is continuous like the other areas of the GI tract, the longitudinal layer is arranged into 3 separate bands known as TENIAE COLI (which is discontinuous, thus weak)
95
What condition is teniae coli associated with?
diverticulosis
