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GI Histology Flashcards

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1
Q

What cell type are the oral cavity, oropharynx and laryngopharyx covered by?

A

Stratified squamous epithelium which is generally not keratinised

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2
Q

What cell type are the nasal cavity and nasopharynx covered by?

A

Respiratory epithelium

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3
Q

Describe the cellular structure of the anterior 2/3 of the tongue

A
  • Stratified squamous epithelium
  • Thin on ventral surface
  • Thick with papillae on dorsal surface
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4
Q

Describe the cellular structure of the posterior 1/3 of the tongue

A

Covered by smooth stratified squamous epithelium which, except for the circumvallate papillae, lacks papillae but does have substantial lymphoid aggregates in the submucosa

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5
Q

Papillae are generally present in the anterior or posterior part of the tongue?

A

Anterior

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6
Q

What is absent in filiform papillae?

A

Tastebuds are absent

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7
Q

What are papillae?

A

Projections of the lamina propria taking out the epithelium along with that (NOT a projection of the epithelium)

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8
Q

What is the composition of a tonsil?

A

A collection of lymphoid follicles (lymphocytes)

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9
Q

The pharynx includes a ring of lymphoid tissue made up of what components?

A
  • Palatine tonsils
  • Tubal tonsls
  • Lingual tonsils
  • Pharynegeal tonsils (adenoids)
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10
Q

What are the 3 parts of the mucosa?

A
  • Epithelium - sits on a basal lamina
  • Lamina propria - loose connective tissue
  • Muscularis mucosa - thin layer of smooth muscle
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11
Q

What is the submucosa made up of?

A

Dense irregular connective tissue

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12
Q

What is the muscularis externa made up of?

A

Two thick layers of smooth muscle :
- an inner circular layer
- an outer longitudinal layer

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13
Q

What is the serosa / adventitia made up of?

A

Outer layer of connective tissue that either suspends the digestive tract or attaches it to other organs

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14
Q

What layer are the glands in the oesophagus and duodenum present in?

A

Submucosa (NB : All other glands in the GI tract are found in the lamina propria)

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15
Q

Transition from _____ _____ epithelium of the oesophagus to the _____ _____ epithelium of the cardia of the stomach

A

stratified squamous, simple columnar

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16
Q

At the bottom of the gastric pits are _____ _____ _____

A

1-7 gastric glands

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17
Q

What is the role of chief cells of the gastric glands?

A

Digestive enzyme secreting cell

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18
Q

What is the role of parietal cells of the gastric glands?

A

Hydrochloric acid producing cell

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19
Q

What are the characteristics of gastric pits in the cardia of the stomach?

A

Deep gastric pits that branch into loosely packed, tortuous glands

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20
Q

What are the characteristics of gastric pits in the body of the stomach?

A

Shallow gastric pits with long straight gastric glands

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21
Q

What are the characteristics of gastric pits in the body of the pylorus?

A

Deep gastric pits with branched, coiled gastric glands at a higher density than in the cardia

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22
Q

How is the muscularis externa of the stomach unusual?

A

Contains an additional innermost layer - this is oblique to the usual circular and longitudinal muscle layers and is located internal to the circular layer. This layer aids the churning action of the stomach.

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23
Q

How is the pyloric sphincter formed?

A

In the transition from the stomach to the duodenum, the inner, circular layer of smooth muscle thickens markedly to form the pyloric sphincter (PS)

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24
Q

What is the name given to the pits ‘drilling’ downwards into the lamina propria, found in between the bases of adjacent villi?

A

Intestinal glands or the crypts of Lieberkuhn (prominent in small intestine)

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25
What are the three anatomically and histologically distinct segments of the small intestine?
- Duodenum - Jejunum - Ileum
26
Since the oesophagus and duodenum both contain glands in their submucosa, how can they be differentiated histologically?
Analysis of their epithelium : - Oesophagus - non-keratinised, stratified, squamous epithelium - Duodenum - simple columnar epithelium
27
What segment of the small intestine has the tallest villi?
Jejunum
28
In which segment of the small intestine are Brunner's glands found?
Duodenum, found in submucosa
29
What are the plicae circularis?
- Permanent and prominent mucosal folds - Circular in shape - Found across mucosa and submucosa of the jejunum - Villi, e.g. tallest villi in jejunum, located on plicae circularis
30
In which segment of the small intestine are the shortest villi found?
Ileum
31
What are Peyer's patches and where specifically are they found?
- Aggregations of lymphoid follicles - Characteristic of the ileum - Found in submucosa and often extend into the lamina propria
32
What are the different cell types of the small intestine epithelium?
- Enterocytes - Goblet cells - Paneth cells - Enteroendocrine (neuroendocrine) cells - Stem cells
33
What is the structure and function of enterocytes?
- Structure - tall columnar cells with a brush border - Function - principal absorptive cell Also most numerous cells
34
What is the function of goblet cells?
To produce mucin to protect the epithelium and lubricate the passage of material
35
Where are Paneth cells located and what is their function?
- Location - found at the base of the crypts of Lieberkuhn - Function - they have a defensive function and have a role in regulating bacterial flora (secrete lysozyme and definsins)
36
Which segment of the small intestine are Paneth cells found in?
Jejunum
37
What is the function of enteroendocrine (neuroendocrine) cells?
To produce hormones that contribute to the control of secretion and motility (e.g. gastrin, cholecystokinin (CCK), vasoactive intestinal peptide (VIP))
38
Where are (small intestinal epithelial) stem cells located and what is their function?
- Location - base of the crypts of Lieberkuhn - Function - they divide to replenish epithelium
39
The duodenum receives the acidic, partly digested semifluid material called _____ from the stomach
chyme
40
What do Brunner's glands (present in the submucosa of the duodenum) do when they are stimulated by the presence of chyme?
They produce a thin, alkaline mucous to neutralise the chyme
41
Lacteal (tiny lymphatic vessels) are found rough where in villi?
Core / centre
42
What is an example of a unicellular gland?
Goblet cells
43
Does the large intestine have villi?
No, but there are mucosal folds
44
What are the two main types of cells of the large intestinal epithelium, and what are their functions?
- Absorptive cells - for removal of salts and thereby water - Goblet cells - for the secretion of mucous to lubricate the colon (this creates a 'slippery' environment for the faeces to travel to the rectum)
45
In the large intestine, the outer, longitudinal smooth muscle is distinct. It is not continuous, but is found in 3 muscular strips called _____ _____.
teniae coli
46
The appendix is an extension of what structure?
Caecum
47
What are some structural characteristics of the appendix?
- Similar to the rest of the colon - Far less crypts - Typically a circular arrangement of lymphoid tissue in the submucosa and often the lamina propria (tends to decline with age)
48
What epithelial cell type is the appendix lined by?
Simple columnar epithelium
49
What epithelium is found in the anal canal?
Non-keratinised stratified squamous epithelium
50
What epithelium is found in the surrounding skin of the anal canal?
Keratinised stratified squamous epithelium
51
The digestive tract has its own nervous system called the _____ _____ _____.
enteric nervous system
52
Where does the enteric nervous system receive input from?
Autonomic nervous system (but the enteric nervous system is capable of coordinating gut motility locally)
53
The interconnected network of fibres of the enteric nervous system have two plexuses, one in the _____ (_____) and one between the muscle layers of the _____ _____ (_____).
submucosa (submucosal), muscularis externa (myenteric)
54
What does the myenteric plexus control?
Gut motility
55
What is a group of neurons living outside the brain and spinal cord called?
A ganglion (plural is ganglia)
56
What is the function of the submucosal plexus?
- Controls the muscle of the muscularis mucosae - Helps regulate secretion in the epithelium
57
What are the parenchyma of the liver and pancreas composed of?
Glandular epithelial cells
58
The liver oxidises what to produce energy?
Triglycerides
59
What different substances does the liver synthesise?
- Plasma lipoproteins - Cholesterol - Plasma proteins (albumin, clotting factors, etc) - Bile (also secretes bile, exocrine gland)
60
The liver converts carbohydrates and proteins into _____ _____ and _____.
fatty acids, triglycerides
61
The liver regulates blood glucose concentration by what processes?
- Glycogenesis - Glycogenolysis - Gluconeogenesis
62
The liver detoxifies what substances?
- Metabolic waste products - Toxins and drugs
63
The liver stores what substances?
- Glycogen - Some vitamins - Iron
64
What is the liver covered by?
A collagenous connective tissue capsule (Glisson's capsule), which is in turn covered by a layer of mesothelial cells (simple squamous epithelium) derived from the peritoneum
65
What are the components of the portal triad?
- Hepatic portal vein - Hepatic artery - Bile duct
66
Portal tracts include branches of?
- Hepatic portal vein - Hepatic artery - Bile ductule - Lymphatic vessels, usually
67
Bile ductules are lined by what type of cells?
Simple cuboidal cells called cholangiocytes
68
How are hepatocytes (cells of the liver) arranged?
- They form plates or sheets of cells with spaces in between for blood to flow through - These blood channels are called sinusoids
69
What is the space of Disse?
The sinusoids are lined by endothelial cells and there is a narrow space between these lining cells and the hepatocytes. This space is called the space of Disse (or the perisinusoidal space) and microvilli of the hepatocytes project into the space.
70
What is the parenchyma of the liver supported by?
Reticular fibres (type III collagen) along with some type I collagen
71
Where are hepatic stellate cells / Ito cells found?
Scattered in the space of Disse
72
Stellate cell characteristics and roles
- Modified fibroblasts - Make connective tissue - Store vitamin A within fat droplets in their cytoplasm - In some pathological conditions, e.g. cirrhosis, they transform into myofibroblasts and produce scar tissue in the liver
73
Kupffer cells characteristics and roles
- Found scattered within the sinusoids - Resident macrophages - They remove particulate matter from the blood and help remove worn out red blood cells
74
Bile is an alkaline solution containing what substances?
- Water - Ions - Phospholipids - Bilirubin - pigment which results from the breakdown of hemoglobin in the spleen, and when excreted in the bile, is the principal cause of the brown colour of feces - Bile salts - necessary for the emulsification of fats in the digestive tract
75
All hepatocytes produce _____. _____ flows via _____ _____ toward the bile ducts in the _____ _____ and thence to the hepatic ducts.
bile, Bile, bile canaliculi, portal tracts
76
The bile canaliculi are small channels (1µm dia.) formed by _____ junctions in the cell membranes of adjacent hepatocytes.
tight
77
The gall bladder is a muscular sac lined by what?
- Simple columnar epithelium backed by a lamina propria of loose connective tissue - This is rich in blood vessels and lymphatic vessels - Then a coat of smooth muscle and an outer collagenous layer of adventitia
78
What does the gallbladder store and modify?
Bile
79
Describe the mucosa of the gallbladder when empty
Folded
80
Describe the mucosa of the gallbladder when distended
Flattened
81
Does the gallbladder have glands?
No
82
Does the gallbladder have tall columnar epithelial cells with a brush border?
Yes
83
What is cholecystitis?
Inflammation of the gallbladder
84
What is special about the pancreas as a gland?
It is both an exocrine and endocrine gland
85
Exocrine pancreas functions
- Produces about a litre of digestive juices daily containing : -proteases to break down proteins -lipases to break down lipids -nucleases to breakdown DNA/RNA -amylase to break down starch, etc These enter the duodenum via the pancreatic duct.
86
Endocrine pancreas functions
Consists of small, scattered islands of tissue called islets of Langerhans, which produce a number of hormones including insulin and glucagon.
87
The basal part of the cells of the pancreatic acinus are typically basophilic due to what?
Extensive RER
88
The apical part of the cells of the pancreatic acinus is often very eosinophilic due to what?
The presence of zymogen (pre-enzyme) granules
89
The main pancreatic duct joins the common bile duct and opens into the duodenum on a papillae :
The hepatopancreatic ampulla (of Vater)

Gastrointestinal (1 decks)

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