Gastrointestinal Tract Flashcards
(169 cards)
1
Q
What lines the oral cavity and oropharynx
A
Stratified squamous non-keratinising epithelium
- protective layer
2
Q
Oral cancer
A
Squamous cell carcinoma
Can excise them operatively
Responsive to readily and chemotherapy
3
Q
Role of salivary glands
A
Produce saliva
Produce enzymes
4
Q
Role of oral cavity
A
Receive food
Chew food
5
Q
Lining of salivary gland
A
Secretory glandular epithelium
6
Q
Secretory glandular epithelium
A
Lots of cytoplasm containing granules
7
Q
Sjorgren’s syndrome
A
Autoimmune disease of salivary glands
No saliva production
Dry tongue
8
Q
Function of oesophagus
A
Swallows food
9
Q
Muscles in oesophagus walls
A
Circular and longtitudinal layers of muscle
Coordinate contractions to push food down into stomach
10
Q
Lining of oesophagus above thoracic diaphragm
A
Stratified Squamous non-keratinising epithelium
Underneath is a thin lamina propria and narrow muscularis mucosa of smooth muscle
Oesophageal submucous glands (secrete mucus that lubricates food as it is swallowed)
11
Q
4 parts of stomach
A
Cardia
Fundus
Body
Pylorus
12
Q
2 ends of stomach
A
Oesophagus—> cardiac sphincter
Pyloric sphincter—> duodenum
13
Q
Function of stomach
A
Digestion of food
14
Q
Gastric fundic mucosa
A
Located in fundus of stomach
Produce mucus
15
Q
Role of mucus in the stomach
A
Layer of mucin on inner lining buffers between the acid of the lumen of the stomach and the epithelium
16
Q
Gastric body mucosa
A
Located in body of stomach
Contains:
parietal cells that produce hydrochloric acid
Chief cells that produce pepsinogen and lipase
17
Q
Parietal cells
A
Produce hydrochloric acid
Rich in the enzyme carbonic anhydrase
Source of intrinsic factor essential for the absorption of vitamin B12
Occur mostly in upper parts of the glands, close to the gastric pits
18
Q
Chief cells
A
Produce pepsinogen and lipase (digestive enzymes)
19
Q
Suffix -ogen
A
Inactive form of enzyme
20
Q
Pepsinogen
A
Produced and secreted by chief cells
Broken down by stomach acid into pepsin
21
Q
Gastric antral mucosa
A
Glands which produce mucin
22
Q
Helicobacter pylori
A
Lives in mucin of stomach
Causes inflammation and ulcers
23
Q
Structure of intestines- 4 layers
A
Lumen —> mucosa —> submucosa —> muscularis propria—> serosal surface
24
Q
What epithelium lines the small and large intestine
A
Glandular epithelium containing endocrine cells
25
Submucosa of intestines
Loose connective tissue
Contains glands and lymphoid tissue
Loose collagen and blood vessels
26
Muscularis propria
Smooth muscle
Controlled by autonomic nervous system
Ganglion cells sit between circular and longitudinal muscle layers
27
Hirschsprung’s disease
A congenital absence of ganglion cells at the bottom of the intestine, rectum and colon
28
Interstitial cells of Cajal
Located in muscular wall of bowel
Pacemaker cells of muscle contraction
Can form tumours
29
Gastrointestinal stromal tumours
Caused by interstitial cells of Cajal
Mutation in C-kit gene
Commonly benign
30
Serosal surface
Simple squamous epithelium
Contains blood supply of gut
31
Mesentry
Attaches bowel to posterior abdominal wall
32
What covers the gut in the peritoneal cavity
Mesothelial cells
33
Crypts
U-shaped long columns
Transit cells at top
Potential stem cells
Stem cells
Paneth cells
34
3 parts of small intestine
Duodenum
Jejunum
Ileum
35
Name of large intestine
Colon
36
Anatomy of duodenum
Joined to pyloric end of stomach
C shaped
Pancreatic duct and common bile duct enters
Stuck to retroperitoneum
37
Ampulla of vater
Entrance of pancreatic duct into duodenum
38
Jejunum
Coils of small bowel as attached to flexible mesentry
39
Function of duodenum
Digests food
Absorbs food
Resists bugs
40
Anatomy of small intestine
Villi
Crypts (producing new cells to form villi) in between villi
Lymphocytes
41
Villi
Finger-like projections of small intestine covered in epithelium to increase surface area
Have microvilli on surface
42
Mucosa-associated lymphoid tissue (MALT)
Release lymphocytes in the gut
43
Giardia lambila
Protozoanal bugs cover mucosa and prevent absorption of nutrients
Leads to diarrhoea, weight loss, tiredness and malnutrition
44
Coeliac disease
Allergy to gliadin (gluten) in wheat
Loss of villi (villous atrophy)
Crypt hyperplasia (larger than normal)
Lymphocytes react with gliadin- killing cells of duodenal epithelium
Malabsorption
45
Role of Jejunum and ileum
Digest food
Absorb food
Resist bugs
46
Jejunum and ileum
Villi and micorvilli
47
Caecum
Joins ileum and large intestine
48
Appendix
Projects from caecum
Role unsure
49
Lining of appendix and colon
No villi
Flat glandular mucosal surface
50
Function of colon
Primarily absorbs water
Absorbs food
Resists bugs
51
4 parts of colon
Ascending colon
Transverse colon
Descending colon
Sigmoid colon
52
Hepatic flexure
Point where colon bends near liver
Ascending ——> transverse
53
Splenic flexure
Transverse—> descending
54
Ulcerative colitis
Inflammation of the colon
Only affects the mucosa
Sharp distinction between normal and diseased tissue
55
Lamina propria
Loose fibrous connective tissue
56
Gut as a muscular tube
Exception stomach
Lumen
Epithelium on a basement membrane
Lamina propria
Muscularis mucosae
Submucosa
Muscularis propria (inner circular layer and outer longitudinal layer)
Adventitia
(Serosa)
57
Stomach walls
Epithelium on a basement membrane
Lamina propria
Muscularis mucosae
Submucosa
Muscularis propria (innermost oblique layer, middle circular layer, outermost longitudinal layer)
Adventitia
Serosa
58
3 layers of stomach muscularis propria
Innermost oblique layer
Middle circular layer
Outermost longitudinal layer
59
Where does the oral cavity extend from
Lips to palatoglossal folds
60
What is the outlet of the oropharynx protected by
Ring of lymphoid tissue (palatine and lingual tonsils)
61
What do the salivary glands secrete
Saliva that contains enzymes and lubricants that aid the passage and digestion of ailments
Secrete bacteriostatic agents and products that protect and promote the growth of the mucosal lining of the GI tract
62
3 pairs of salivary glands
Parotid
Submandibular
Sublingual
63
Mucosal covering of the lip
Stratified squamous epithelium
keratinising ——> non-keratinising at margin of skin to mouth
64
Ventral surface of tongue
Stratified squamous non-keratinising epithelium
65
Dorsal surface of tongue
Stratified squamous keratinising epithelium due to constant abrasion of this surface
66
Papillae
Located on dorsum of the tongue
Tall, pointed filiform papillae are most common and cover whole anterior 2/3 of tongue
Less numerous mushroom shaped fungi form papillae are found on tip and sides of tongue
Pale-staining taste buds embedded in epithelium on lateral sides of these papillae
V-shaped row of dome-shaped circumvallate papillae separate the anterior 2/3 and posterior 1/3 of tongue - also bear taste buds
67
What separates the anterior 2/3 and posterior 1/3 of tongue
A v-shaped row of dome-shaped circumvallate papillae
Bear taste buds
68
Where are mushroom shaped fungiform papillae located
Tip and sides of tongue
69
Where are tall, pointed filiform papillae located
Whole of anterior 2/3 of tongue
70
Parotid salivary glands
Produce a watery enzyme-rich secretion (serous secretion) rich in alpha amylase that digests starch
Lie anterior to the ear on both sides of the face and enter the mouth via ducts adjacent to the 1st upper molar teeth
Contain lymph nodes
71
Acini
Spherical clumps of serous gland cells in parotid gland
72
Parotid gland secretory cells
All serous
Pyramidal in shape
Spherical nucleus
Cytoplasm full of rER and apex of cell contains prominent secretion granules
73
What do the parotid acini drain into
Ducts lined by a simple cuboidal epithelium that may become stratified at the distal end
74
Sublingual salivary glands
Lie beneath the tongue and discharge their secretions into the floor of the mouth by a series of ducts either side of the frenulum of the tongue
75
Structure of sublingual glands
Branched tubular-acinar glands
Produce a sticky mucus-rich secretion that helps to lubricate the mouth and bolus of food
Secretory cells appear swollen - filled with pale staining mucus granules
Oval nucleus is squashed to base of the cell
76
What do the sublingual tubular-acinar drain into
Ducts lined by simple or stratified cuboidal epithelium
(Cells appear pinker)
77
Orbicularis oris muscle
Ring of muscle that surrounds the mouth
78
Major constituent of secretion of the sublingual gland
High molecular weight mucopolysaccharide
Absorbs large amounts of water so are very good lubricants
79
Serous Demi-lunes
Half-moon shaped clusters of serous cells that lie at the closed ends of the branched mucus-secreting tubules that make up part of the submandibular gland
80
Submandibular salivary glands
Well-defined globular glands
Lie subcutaneously below the mandible, either side of the tongue
Discharge by a pair of ducts in to the frenulum of the tongue
81
Frenulum of the tongue
small fold of mucous membrane extending from the floor of the mouth to the midline of the underside of the human tongue
82
Structure of submandibular glands
Branched tubulo-acinar type
Often interspersed with fat
Display 2 types of secretory cells:
1. Pale staining mucus-producing cells
2. Darker staining enzyme producing serous cells
Serous cells form acini or lie at the closed ends of the tubules forming Demi-lunes
83
What do submandibular glands produce
A mixed secretion, part mucus and part an enzyme-rich secretion
84
Sources of epidermal growth factor that promotes growth of epithelium in GI tract
Parotid and submandibular glands
85
Epiglottis structure
Covered by a stratified squamous epithelium
Posterior surface = pseudo stratified columnar ciliates epithelium (respiratory epithelium)
Internally:
Plate of elastic cartilage
Submucosa often contains lymph nodules and salivary glands
86
3 components of mucosa
- a lining epithelium that is often folded
- a layer of connective tissue (lamina propria) that often contains lymphoid tissue
- muscularis mucosa= a ring of smooth muscle
87
Meissner’s plexus
A rich plexus of nerves part of the enteric nervous system in the submucosa of the gut tube
Regulates the mucosa and processes of absorption and secretion
88
Auerbach’s plexus
Nerves of the enteric nervous plexus between two layers of muscle in muscularis propria
Regulates much of the contractile activity of the gut
89
Lining of oesophagus below thoracic diaphragm
Simple columnar epithelium
Can become the site of pathological change
Thicker muscle layer
90
Submucosa of oesophagus
Contains sero-mucous glands whose secretions lubricate the oesophagus
At distal end = contains many large, thin-walled veins (may become the site of oesophageal varicosities)
91
Muscularis externa of oesophagus
Composed mainly of skeletal muscle
At distal end - mostly composed of smooth muscle
92
Rugae
Visible longtitudinal folds of mucosa in stomach
93
Lining of stomach
simple columnar epithelium punctuated by gastric pits into which the gastric glands drain
94
Muscularis propria of stomach layers
3- additional oblique layer of fibres closest to the mucosa that helps to churn up the food within the stomach
95
Gastric glands of 4 sections of stomach
fundus and body show very similar histological structure particularly with respects to their gastric glands.
The cardia and pylorus have a different histological appearance.
mucosa of the stomach contains many tubular glands within its mucosa. These fill the lamina propria and discharge their secretions into gastric pits that communicate with the lumen of the stomach.
96
Mucus neck cells
provide a lubricatory, acid-resistant mucus
97
Types of gastric glands in fundus and body of stomach
Mucus neck cells
Parietal cells
Chief cells
98
Types of gastric glands in cardiac and pylorus of stomach
Mucus neck cells
99
Varicosities
occur when your veins become enlarged, dilated, and overfilled with blood. Varicose veins typically appear swollen and raised, and have a bluish-purple or red color.
100
Site of oesophageal varicosities
Submucosal layer at distal end of oesophagus
101
Gastric pits
Several tall straight or branched glands open into each gastric pit
102
Purpose of elastic tissue in stomach
Cause collapse of the stomach on emptying
Helps prevent the perforation of the stomach wall by sharp fragments of bone (particularly well-developed in carnivores)
103
Normal pH of gastric juice
2
104
Structure of parietal cells
Globular shape
Stain bright pink with H&E
Surface deeply invaginated to form intracellular canaliculi
Contain many mitochondria
105
Structure of chief cells
Pyramidal shape
Occupy deeper parts of the gastric glands
Part of cytoplasm stains blue with H&E
Cells contain secretion granules
106
For which tissue constituent does pepsin have an affinity
It digests proteins but has a particular affinity for collagen
-facilitates break down of meat by attacking the connective tissue between the muscle fibres
107
Pyloric region gastric glands
Shorter than those of the body or fundus
Coiled rather than straight
Mainly mucus neck cells
Contains:
- isolated cells that produce gastrin and a bombesin-like peptide
- endocrine cells that produce serotonin, somatostatin and vasoactive intestinal peptide (VIP) = regulate breakdown and delivery of foodstuffs to the duodenum
108
What do the endocrine cells in the gastric glands of the pyloric region of the stomach produce and why
Serotonin, somatostatin and vasoactive intestinal peptide (VIP)
- regulate breakdown and delivery of foodstuffs to the duodenum that occurs during the digestion process
109
Plicae circulares
Circular folds of the lining of the intestines
Increase surface area available for absorption
110
Where are Plicae circulares most numerous
Jejunum
111
Where are Plicae circulares least numerous
Distal part of colon
112
Lining of villi
Simple columnar epithelium with 2 main cell types:
1. Enterocytes - absorptive cells
2. Goblet cells- mucus secreting cells
113
What do villi contain
In its core - a small arteriole, a thin walled venule and a blind-ended lymphatic (lacteal)
Smooth muscle cells that rhythmically shorten the villus, milking the blood and lymph from the villus
114
Role of venules and lacteals in villus
Carry absorbed nutrients to the liver
115
Crypts of Lieberkühn
Straight tubular glands between the villi of the intestine
Contain a stem cell population
Newly formed cells migrate from the crypts in to the surface of the villi and are eventually sloughed off from the tips
116
Enterocytes
Absorptive cells in villi of intestines
Each cell possesses around 300 microvilli
Have specific receptor complexes that allow the uptake of certain immunoglobulins that subsequently form part if the system of passive immunity - most active in neonate in response to immunoglobulins in mother’s first milk (colostrum) but declines in significance within a few months
117
How long is the process of stem cells —> being sloughed off villi
5 days
118
Microvilli
Surface covered in well-developed glycocalyx that acts as a filter and as an anchorage for exo-enzymes
Most nutrients absorbed by this pathway
Stains intensely by Periodic Acid Schiff (PAS) due to high concentration of hexose sugars in glycocalyx
119
Length of duodenum
12 inches (30 cm)
120
Structure of duodenum
Relatively smooth lining with few plicae circulares
Villi are broad-leaf structures
Relatively few goblet cells
Submucosa filled by Brunner’s gland
121
Brunner’s glands
Mucous secreting cells in duodenum- alkaline secretion helps to neutralise the chyme emerging from the stomach
122
Which of the 2 layers of the muscularis extema is thicker
The inner circular layer is 4 or 5 times thicker than the outer longitudinal layer
123
Paneth cells
Differentiated cells found at the bottom of the crypts and villi
Secrete lysozyme - play an important role in regulating bacterial flora of the gut as it breaks down bacterial cell walls
Bright pink-staining granules
124
Structure of Jejunum
Close packed plicae circulares
Long and narrow villi
Relatively short crypts
Many goblet cells present
Lymph nodes present in the Lamina propria
Variable in thickness submucosa - very loose
125
Structure of the ileum
Less tightly packed plicae circulares
Shorter villi
Goblet cells increase in numbers towards distal end
Peyer’s patches in submucosa
126
Peyer’s patches
Large patches of lymphoid tissue present in the submucosa of the ileum
127
Vermiform appendix
Arises from the caecum
Lined by simple columnar epithelium with goblet cells
No villi
Only a few rudimentary crypts
Lamina propria and submucosa filled with lymphoid tissue (amount declines with age)
No muscularis mucosa
Muscularis externa - 2 layers of smooth muscle
Taenia coli originate at base of appendix and run whole length of large intestine
128
Lining of colon
No intestinal villi
Mucosa consists of close packed crypts that mainly contain Enterocytes and goblet cells
Lamina propria restricted in volume due to packed nature of crypts
Prominent muscularis mucosa
Mucosa and submucosa have lymph nodules embedded within them as part of GALT system
Muscularis externa = thickened inner circular layer and taenia coli
129
Taenia coli
3 longtitudinal bands of smooth muscle that compose outer layer of colon muscularis externa
130
Lining of rectum
Simple columnar epithelium
131
Lining of anal canal
Stratified squamous epithelium that becomes keratinising at its distal end
Submucosa contains fat and prominent internal plexus of veins (anal varicosities)
Smooth muscle of Muscularis externa is thickened to form internal anal sphincter
Surrounded by striated muscle of external anal sphincter
132
Where is the striated muscle of the external anal sphincter derived from
Pelvic bowl
133
Peri-anal skin
Contains hair follicles and modified sebaceous glands
134
Where are sweet taste buds located on tongue
Mainly at the tip
135
Where are salty taste buds located on tongue
Either side towards the front of the tongue
136
Where are sour taste buds located on tongue
Either side towards the back of the tongue
137
Where are bitter taste buds located on tongue
Across the whole back of the tongue
138
Where are immunoglobulins in parotid saliva produced
Plasma cells resident in the gland produce immunoglobulin A (IgA)
Are discharged in the saliva where they combine with proteinaceous secretory pieces also produced by the glands
139
Function of immunoglobulins in parotid saliva
Complexes are protected from digestion which allows the IgAs to reach the intestine unmodified
140
Dental plaque
Calcified deposit rich in dead or dying oral bacteria and food debris
141
Striated duct
Part of the duct of the parotid gland
Result of deep invaginations of the basal plasmalemma of the cells and large elongated mitochondria that lie perpendicularly between them
Capable of secretion and reabsorption of water and ions from the saliva
142
Do salivary enzymes continue to function in the stomach
Have a neutral pH optima so are inactivated by the acid environment of the stomach
In bolus of food, enzymes are shielded from gastric juices so continue to act until bolus is dispersed
143
Function of gastrin
Promotes the secretion of HCl by the parietal cells in the body and fundus of the stomach
144
Which cells secrete gastrin
Endocrine secreting cells in pyloric region of stomach and duodenum
145
2 parts of intrinsic innervation of gut
Auerbach’s plexus
Meissner’s plexus
146
What lines most of the mouth
Stratified squamous non-keratinising epithelium over a loose fibrous connective tissue storms
147
Where are the circumvallate papillae
Between anterior 2/3 and posterior 1/3 tongue
148
Function of filiform papillae
Roughen surface of the tongue- aids mastication
149
Unique structure of posterior 1/3 of tongue
Epithelium overlies a lymphoid infiltrate (part of Waldeyer’s ring)
- blue layer when stained with H&E
150
In which gland are all acini serous
Parotid
151
In which glands are acini mostly mucous
Sublingual gland
Buccal glands
Lingual glands
152
Are mucous or serous acini dark staining
Serous
153
What feature confirms oesophageal origin of cells
Squamous lined ducts in lamina propria
154
What type of acini cells are in submandibular gland
Both serous and mucous acini
155
Which two parts of stomach are histologically the same
Gastric body and gastric fundus
156
Features of gastric antrum
Long crypts that branch
Lined by mucous-secreting cells
Lack parietal cells
157
What percentage of the thickness of the antrum and pylorus is superficial zone of the mucosa
More than half
158
What percentage of the thickness of the cardia is superficial zone of the mucosa
50%
159
What do parietal cells secrete
Intrinsic factor
HCl
160
Features of lining of small intestine
Crypts and villi
161
What do Brunner’s glands secrete
Bicarbonate-rich alkaline secretion
162
Where are Brunner’s glands found
Duodenum
163
Which cells lie below epithelium in ileum
Lymphoid cells (MALT) - Peyer’s patch
164
How to tell difference between appendix and colon
Lymphoid tissue in appendix
165
Which part of GI tract does not have villi
Appendix
Colon
166
Which cells lie below epithelium in duodenum
Brunner’s glands
167
Where is Auerbach’s plexus
Muscularis propria
168
Where is Meissener’s plexus
Submucosa of gut tube
169
Colorectal histology
Same whole length from caecum —> rectum
