GI Histo Flashcards
This is taken from the lip. What is the arrow pointing to?
The upper surface of the lip consists of hairy skin and the red arrow is pointing to a hair follicle
For the lips give
a) Mucosa
b) Fibers in connective tissue
c) Structures in the deep layers
a) Stratified squamous non-keratinising epithelium
b) sub-mucosa of collagen and elastin with small vessels to keep them moist
c) deep layers of skeletal muscle
What is the arrow pointing to?
The abrupt transition between stratified squamous keratinising epithelium and non-keratinising epithelium
On the inner lip, what opens on to the surface instead of hair follicles?
Sebaceous glands (Fordyce’s spots)
The tongue contains two types of skeletal muscle fibers.
Intrinsic and extrinsic.
What is the difference?
Intrinsic fibers attach to the fibrous connective tissue of the underlying mucosa
Extrinsic fibers attach to the lower jaw
What type of epithelium is on
a) the ventral (upper) surface of the tounge
b) the dorsal (lower) surface of the tounge
Ventral = SSNKE
Dorsal = SSKE (constant abrasion)
This has been taken from the tounge. What is it?
A small serous salivary gland
This has been taken from the tongue. What is?
Mucus secreting salivary gland
Where has this been taken from?
The tongue.
Contains mixed sero-mucous salivary glands
Lymph nodes - particullary in the posterior 1/3rd of tounge (linguninal tonsils)
Coarse multi-directional skeletal muscle bundles
Where has this been taken from?
The upper surface of the tounge
SSKE
Connective tissue
2 types of salivary glands
Large bundles of stirated muscle
The dorsal tongue surface has complex folds. What are these called and give the two types?
Papillae
Filiform papillae (threadlike) = most common, tall, pointed & cover whole anterior 2/3
Fingiform papillae (mushroom-like) = @ tip and sides. Have pale staining, spindle shaped taste buds w/ nerve & synaptic vesicles
Circumvallate papillae (V shaped row) @ margin between the ant 2/3 and post 1/3 of tongue
Where are the following tastes detected on the tongue?
a) Sweet
b) Salty
c) Sour
d) Bitter
a) Sweet = tip
b) Salty = front/side
c) Sour = further back
d) Bitter = whole back
What is shown here?
Part of the surface of the tongue.
2 paler staining taste buds embedded in the opposing sides of adjacent fungiform papillae.
What type of papillae is this?
Fungiform papillae
This has been taken near the surface of the tongue. What is it?
Small nerve in the sub-mucosa of the tongue
The parotid gland:
a) What is shown here?
b) What are the surrounding cells?
The parotid gland:
a) What is shown here? Stirated duct
b) What are the surrounding cells? Serous acini
The Parotid Gland:
a) What enzyme is the serous secretion rich in?
b) Where in the oral cavity do the ducts enter the oral cavity?
The Parotid Gland:
a) What enzyme is the serous secretion rich in? Alpha amylase (Starch digestion)
b) Where in the oral cavity do the ducts enter the oral cavity? Adjacent to the 1st upper molar teeth
The Parotid Gland:
Describe:
a) The secretory cells
b) The duct cells
Secretory cells = Pyramidal, spherical nuclei, basal cyt full of RER, apex contains prominent secretory granules (pink staining)
Duct cells = simple cuboidal (stratified @ distal end)
What is this?
A large parotid duct lined by stratified cuboidal epithelium.
What is this?
This is a large lymph node, a common feature of the parotid gland
The Parotid Gland
C - bottom is a nerve
D - is a lrage lymph node
Parotid saliva contains IgA (from plasma), combines with proteinous pieces so reaches intestine unmodified by amylase
Stirated duct - from invaginations, indicative of water reabsorbtion
Source of epidermal growth factor
a) Which gland has this been taken from?
c) What type of secretion does it produce?
b) What type of cells have stained pale?
Sublingual salivary gland
- Mainly mucus
- Pale staining secretory cells
- Branched tubular acinar glands
- Sticky mucus rich secretion (food bolus)
What is the arrow pointing to?
A darker staining duct of the sublingual salivary gland with simple cuboidal epithelium
Major consituent = polysaccharide
The sublingunal salivary gland:
What is the following structure?
Parasympathetic nerve ganglion showing a collection of nerve bodies.
Involved in secretion regulation
Describe the the submandibular gland.
What is shown on the left and the right of this picture?
Submandibular saivary glands (mixed)
- Well defined/globular
- Branched tubulo-acinar
- Interspaced with fat adipose
- Mixed = part mucus + part enzyme rich
The submandibular gland:
What are the red arrows pointing to?
Demi-lunes (half moons)
- Made by serous cells at closed ends of tubules
What is this?
The epiglottis @ the posterior of the tongue.
- boundary of the oropharynx and the laryngeal pharynx
The epiglottis:
a) What type of epithelium is this?
b) Where on the epiglottis would this not be found and what would be found instead?
Stratified squamous non-keratinising epithelium
Not found in the posterior lower surface - psuedo-stratified columnar ciliated epithelium (respiratory)
What does the epiglottis contain?
- Elastic cartilage plate
- Lymph nodules (submucosa)
- Salivary glands (submucosa)
This has been taken from the back of the tongue. What is it?
A mixed sero-mucous gland in the tongue
Pale staining = Mucous tubules
Darker staining = Serous element
What is this?
A taste bud surrounded by squamous epithelium
Which of the following are true?
a) This is serous acini
b) Central rounded nuclei
c) Ducts are lined by cuboidal/columnar epithelium
d) This is a parotid gland
c) Ducts are lined by cuboidal/columnar epithelium
This is a sublingunal gland
Basally located nuclei
Mucinous acini
Which of the following is true?
a) Mucus glands @ bottom
b) Serous glands @ top
c) This is a submandibular gland
d) Produces enzyme secretion rich in alpha amylase
This is a submandibular gland
Mixed
Serous @ bottom
Mucous @ top
From this image, work out what nerve is associated with this gland?
The facial nerve
Purely serous (granules)
Parotid
Give the layers of the gut tube
Mucosa = Inner most
Epithelium (folded), connective tissue (lamina propria - w/ lymphoid tissue), smooth muscle ring (muscularis mucosa)
Submucosa
Loose con tissue, glands, lymp tiss, bld vessels, Meissner’s plexus (enteric nervous system)
External muscle coat (Muscularis externa)
2 layers of smooth muscle, Auerbach’s plexus (ENS)
Serosa
Simple squamous epithelium
Where has this been taken?
The oesophagus
SSNKE
Thin lamina propria
Narrow muscularis mucosa (thicker @ gastiric end)
What happens to the epithelium of the oesophagus just below the thoracic diaphragm?
- Becomes simple columnar (same as gastric epith)
- Site of pathological change
Box D shows some of the muscle of the muscularis externa. What type of muscle is it and therefore from which region of the oesophagus do you deduce that this specimen of oesophagus was most likely to have been taken?
It is voluntary (striated) muscle typical of the proximal end of the oesophagus.
Muscularis externa:
Upper 1/3 = skeletal
Middle 1/3 = mixed
Lower 1/3 = smooth
Where is the most common place for oesophageal variosities?
The distal end
Sub-mucosa: Sero-mucous glands (lubrication), large thin walled veins
What are the visible longitudinal folds made by the stomach mucosa called?
Rugae
Describe gastric mucosa
- Simple columnar epithelium - produces acid resistant mucin
- Gastric pit invaginations
- Several tall staight/branched glands to each pit
- Submucosa = loose connective tissue with abundant vessels
- Muscularis externa = 3 layers of smooth muscle
Why does the muscularis mucosa of the stomach contain elastic?
Prevents the stomach collapsing on emptying
What are the green arrows pointing to?
Gastric pit invaginations
a) What is the name of the cells that the red arrows are pointing to?
b) Where are these found?
c) What are these cells rich in?
a) Parietal (oxyntic cells)
b) Found @ gastric glands of the body and fundus
@ upper part of gland close to pits
c) Rich in carbonic anhydrase
- Globular in shape & stain bright pink with H&E
- Cell surface invaginates. Contains many mitochondira = grainy appearance
- pH 2
- Source of intrinsic factor
What do these cells secrete?
- HCl
- Intrinsic factor for absorption of Vitamin B12
a) What cells are these?
b) Where are these found?
c) What do these cells secrete?
Cheif (zymogenic cells)
b) Deeper in gland neer the muscularis mucosa @ Body and fundus
c) Synthesis and secrete pepsinogen and lipases
- cytoplasm stains blue with H&E
What cells are shown in
a) Blue box
b) Red box
Blue = Cheif cells
Red = Parietal cells
Describe the gastic glands
Gastic glands
- Tubular @ mucosa
- Fill the lamina propria & discharge secretions into gastric pit
3 cells: Parietal (HCL & intrinsic factor) Cheif (pesinogen) Mucus neck cells (lubricant - acid resistant mucus)
Which of the following about the gastic glands at the cardiac and pyloric regions of the stomach are true?
a) Longer glands
b) Straight glands
c) Contain parietal cells but not cheif cells
d) Mainly contain mucous neck cells
Glands in the cardiac and pyloric regions are:
- shorter
- coiled
- composed mainly of mucous neck cells
What is produced in the pyloric region?
Gastrin
Where is this?
Gastroduodenal junction
Pylorus on the right
Duodenum on left
What is shown in box C (red)?
Smooth muscle that makes up the pyloric spincter
What is the name given to the folds of the intestinal lining?
a) Plicae circularis
b) Rugae
c) Haustrations
Intestinal lining folds = Plicae circularis
Highest @ jejenum
Lowest @ distal colon
For the intestinal villi, give:
a) Epithelium type
b) 2 main cell types
c) What each villus contains
For the intestinal villi:
a) Epithelium type = Simple columnar epithelium
b) 2 main cell types = enterocytes and goblet cells (short cell life, repleced by cells in the crypts)
c) Venule, arteriole, lacteal, smooth muscle “milks” blood and lymph from villus
- venules and lacteal to liver
What are the major absorpative cells of the small intestine?
Enterocytes
- 300 short microvilli on apical surface = Brush border
- Most nutrients are taken up this way
- Water and glucose can be taken up via intracellular pathways
What is found on the outer surface of the brush border of the small intestine?
Glycocalyx
- Filtration
- Anchorage for exo-enzymes
- High conc of hexose sugars = brush border stains magenta with PAS (periodic acid schiff)
Describe the duodenum
a) Lenght
b) How many goblet cells (lots/few)?
c) Submucosa
Duodenum
a) 12 inches long
b) few goblet cells (pale staining)
c) Submucosa contains mucus secreting brunner’s glands - the alakaline secretion neutralises the chyme
- the vili are broad and leaf like
Where has this been taken?
Duodenum
Submucosa has Brunner’s gland which aren’t present in the jejenum/ileum
Inner circular layer is thicker than outer longitudinal layer of muscularis externa
Where has the following been taken from?
Duodenum crypt
Crypts form new enterocytes and goblet cells
Dividing cells have very dark staining nuclei or sets of chromosomes
@bottom of crypts = DIFFERENTIATED PANETH CELLS
Secrete lysozyme - breakdown of bacterial cell walls
Regulate flora of gut
Bright pink cytoplasmic granules
From which part of the small intestine has this been taken from?
The duodenum
The submucosa here has Brunner’s glands (not found in the jejenum/ileum)
Alkaline secretions to neutralise stomach acid
What are the circular folds of the small intestine called?
Plicae circularis
Does the jejenum contain many/few goblet cells?
The jejenum contains many goblet cells
Where has this been taken?
Jejenum
Close-packed plicae circularis
MANY goblet cells
long narrow villi (finger like)
short crypts
loose submucosa (almost detached from muscularis externa)
no Brunner’s gland or Peyer’s patches
Lymph nodules at lamina propria but do not penetrate
submucosa
Give the differences between jejenum and ileum for:
a) Plicae circularis
b) Vili
Jejenum has more tightly packed plicae circularis, longer villi and shorter crypts
(less absorption occuring in the ileum)
Where has this been taken?
Ileum
Payer’s patches @ submucosa (lymphoid tissue) - these erupt the muscularis mucosa into the lamina propria layer
What is shown in the bottom here?
Muscularis externa
Sub muscosa is shown across the middle
What is shown in the eclipse?
Serosa (simple squamous) shown on the edge of the longitudinal muscle of the ileum
Describe the vermiform appendix
From caecum
Simple columnar epithelium - No villi
Goblet cells
Simple crypts
Lamina propria and submucosa full of lymphoid tissue
(declines w/ age)
Mo muscularis mucosa
Muscularis externa present
transverse smooth muscle at muscularis externa = taenia colis
fat filled
Where has this been taken from?
The appendix
Simple columnar epithelium
Rudimentary crypts with few goblet cells
Lamina propria and submucosa is full of lymphoid tissue
Does the large bowel have large amounts/little microscopic folding?
The large bowel has little folding
Explain the histological differences between the segments of the large bowel.
All 4 segments and caecum are histologically similar
No vili
The mucosa and the submucosa frequently have lymph nodules in them which are part of which system?
GALT - Gut assosiated lymphoid tissue
Describe the muscularis externa of the colon
Thickened inner circular layer - smooth muscle
Outer layer - drawn up to 3 longitudinal bands - Taeniae coli
What are the functions of hepatocytes?
1 - Creation and storage of energy in the form of glycogen and fats
2- Uptake, synthesis and excretion of biliruben and bile salts
3- Deamination of amino acids and the production of urea
4- Detoxification and inactivation of drugs by oxidation, mythelation and conjugation
5- Synthesis and sectretion of plasma proteins
What is this image?
Liver (Low magnification)
Polygonal liver lobules surrounded by a clear connective tissue septum.
Central vein in the centre and portal triad around the edge
Liver lobules contain chains of hepatocytes arranged in cords that converge onto a central vein. Name the structure which seperates the cords.
Sinusoids = thin walled, fenestrated capillaries - mixture of venous (70%) and arterial (30%) blood
Name the 2 molecules that hepatocytes normally store in large quantities in their cytoplasm
Glycogen (strach)
Triglyceride (fats)
What is this?
Portal trial
Hepatic artery, portal vein and bile duct
What are the paler and darker staining cells?
Chords of hepatocytes
Sinusoids (paler staining) in between - sinudoidal epithelial cells have darker and denser nuclei
Name the cells shown in blue
Kupffer cells
Found in the epithelial lining of the sinusoids between the chords of hepatocytes (pale pink)
Phagacytose the blood borne pathogens that pass through the liver
Involved in the production of biliruben that is taken up and excreted by hepatocytes
Describe the change in epithelium through the biliary tree
Smaller vessels = simple epithelium
Distal vessels = stratified epithelium
Give the epithelium of the gall bladder
Simple columnar epithelium (shown at the bottom of this picture)
Lining is thrown into folds - not villi
Small brush border - absorption of water to concentrate the bile
Describe the affects of secretin on the following cells
Secretin induces the release of alkaline solution from the centro-acini cells (green arrows) and small duct cells
What is this?
Large pancreatic duct
Simple columnar epithelium which can become stratified at the distal end
Sitting on dense connective tissue with acinar tissue alongside
Most of the secretions are from duct cells
What is the structure in the box?
An exocrine duct
