Microscopic anatomy of the Gut, Liver and Pancreas Flashcards
In the image below what does number 1 depict?

- lumen of the GIT
In the image below what does number 2 depict in the 4 layers that is present in the GIT?

- mucosa
- epithelium + lamina propria = mucosa
In the image below what does number 3 depict in the 4 layers that is present in the GIT?

- submucosa
In the image below what does number 4 depict in the 4 layers that is present in the GIT?

- muscularis propria
In the image below what does number 5 depict in the 4 layers that is present in the GIT?

- serous
In the colon the haustra are small segmented pouches of bowel which give the colon its segmented appearance. They are formed by circumferential contraction of the inner muscular layer of the colon. Do the haustra go across thew whole lumen?
- no
- how to determine between large and small intestines

In the small intestines there are circular folds of mucous membrane called the valvulae conniventes. Do these transverse the whole of the small intestines wall?
- yes
- this is how to determine between large and small intestines

When looking at the folds of the colon, does it relate to one gland of something else?
- no
- it is where the submucosa has been folded over
- the mucosa then surrounds the submucosa

What is the major cell type in the glands (crypts) of the large intestines?
- goblet cells
In the histology section of the colon below, what do the numbers 1, 2 and 3 relate to?

1 - lamina propria
2 - muscularis mucosa
3 - gland
If inflammatory cells are found on histology of the colon, are these pathological?
- no, can be normal
- if neutrophil they are always pathological

Although neutrophiuls are always pathological in the colon, does that mean all inflammatory cells are pathological?
- no
- some are always present
What do the glands, epithelia and lamina propria make up?
- mucosa

What are the 4 major componenets of the submucosa?
- fat
- connective tissue
- lymphatics
- blood vessels

What is the muscularis propria composed of?
- muscle
- circular muscle
- longitudinal muscle
In the muscularis propria there are 2 layers of mucsle, what are the layers from closest to the lumen first?
1 - circularis muscles
2 - longitudinal muscles
In the appendix there is one large difference to the histology when comparing it to the colon. What is this?
- contains lymphoid follicles

What are the tenia coli in the colon?
- 3 seperate longitudinal ribbons of smooth muscle
- present on ascending, transverse, descending and sigmoid colons
- they contract causing haustra to shorten and move stool

What is the function of the tenia coli?
- contact to facilitate peristalsis
What are the epiploic appendices also commonly known as the omental appendices?
- peritoneum filled with fat
- protect blood vessels of colon

Although the anal canal contains the majority of the layers as the rest of the GIT, what one layer does it not contain, and instead what is present?
- no serosa/peritoneum
- fat is present instead
Where the anal canal meets the rectum, what happens to the glandular make up of the rectal canal?
- changes from glandular to non-keratinizing squamous epithelium

In the small intestines what 2 layers compose the architecture of the glands?
- crypts (bottom)
- villi

Paneth cells, which are highly specialized secretory epithelial cells located in the small intestinal crypts of Lieberkühn produce dense granules contain an abundance of antimicrobial peptides and immunomodulating proteins that function to regulate the composition of the intestinal flora. Are they located anywhere specifically in the small intestines?
- throughout
- but bottom of crypts

In the ileum and duodenum there are specific names given to the glands. What are the names of these?
- ileum = payers patches
- duodenum = brunners glands
Brunner’s glands are cuboidal epithelium only located in the submucosa of the duodenum. What is their function?
- secrete an alkaline (HCO3-) fluid containing mucin
- protects the mucosa from the acidic stomach contents entering the duodenum
Payers patches are only located in the submucosa of the ileum. What is their function?
- small masses of lymphatic tissue or aggregated lymphoid nodules
- important part of the immune system
In the small intestines, in addition to the villi there is something that is important for absorption (especially fats) and immunity that is not present in the colon. What are these called?
- lymphatic lacteals

What is the name given to crypts in the small intestines?
- crypts of Lieberkuhn
Which are longer the crypts or the villi, and why is this important?
- villi are always longer to help with absorption
- if not then its pathological
- seen in coeliac disease
What are the cell types labelled 1 and 3, and the area labelled as 2 in the histology image below?

1 = enterocytes
2 = lamina propria
3 = goblet cells
The liver is contained within a capsule, what tissue type is the liver capsule composed of?
- collagen
- no collagen in liver tissue

Does the parenchyma (functional tissue) of the liver contain collagen?
- no
- only present in pathology
The liver is composed of lots of hexagon like shapes, what is the name given to these hexagons?
- lobules
The liver is composed of lots of hexagon like shapes called lobules. What is present at the corners of the lobules?
- portal triads
- contain hepatic artery, portal vein and lymphatics

What is located at the centre of the hexagon like shapes called lobules of the liver?
- central vein

When blood arrives at the portal triad, which direction does it head towards?
- central vein in middle of lobule
What is the acinus of the liver?
- lobule divided into triangles
- base begins at portal triads and apex at central vein

The acinus of the liver are divisions of the lobules of the liver, where blood flows from the base (portal triad) towards the central vein (apex). This is called zonal heterogeneity. What is the importance of this?

- high O2 tension (base) to low O2 tension (apex)
- each zone performs a different function

What connective tissue type is the liver composed of?
- type 3 collagen
What is the main cell type of the iver?
- hepatocytes
What are hepatic cords?
- columns of hepatocytes
- extend from the portal region to central vein

The hepatic cords are columns of hepatocytes that extend from the portal region to central vein. What is the space between the hepatic cords called?
- liver sinusoids, or “capillaries” of the liver
- these are fenestrated and contain gaps

What are stellate cells of the liver?
- provide the liver with an ability to respond to injury and heal

What are Kupffer cells of the liver?
- liver macrophages present in sinusoids
- important in maintaining liver function
- Under physiological conditions, they are the first innate immune cells and protect the liver from bacterial infections.

What is the canal of herring?
- transitional site where hepatocytes turn into bile ducts

Hepatocytes create bile and then this is secreted into the bile canniculi towards what?
- portal triad and enters bile ducts

What colour do hepatocytes stain on histology?
- pink as they are eosinophilic
Do hepatocytes appear as perfect circles or have sides on hisotolgy and generally how many nucleus do they contain?
- multiple sides so not circular
- 1-2 nuclei
What is one of the primary and potentially most important functions of hepatcoytes?
- glycogen storage
Where are bile canaliculis located in the liver?
- inbetween hepatocytes

How is the bile created by the bile canaliculi retained in between hepatocytes ensuring it doesnt leak out?
- tight junctions

The image below is of a portal triad at the corner of a liver lubule, that wlll eventually drain into a central vein of the lobule. What do the numbers in the image below depict?

1 - portal vein (always the biggest)
2 - hepartic artery
3 - bile duct (lined by columnar epithelium)
What cells are part of the exocrine system of the pancreas?
- acinar cells

The acinar cells along with the pancreatic ducts are part of the exocrine system of the pancreas, what are they able to secrete?
- acinar cells = amylase, lipase and proteases
- pancreatic ducts = bicarbonate and H2O

What cells are part of the endocrine system of the pancreas?
- islets of langerhans

The islets of langerhans are part of the endocrine system of the pancreas. What do they secrete and which cells within the islets of langerhans secrete them?
- alpha cells = glucagon
- beta cells = insulin
What do numbers 1 and 2 denote in the histology section below?

1 - islets of langerhans
2 - acini containing acinar cells
In the acini which contains acinar cells, where would the duct be located and what is the name of this duct?
- located in the center
- celled centroacinar duct
What runs through the islets of langerhans?
- blood vessels
- endocrine are DUCTLESS so need to secrete into blood

The acini containing acinar cells of the pancreas are almost identical to which other ducts of the body?
- salivary glands
Is the spleen part of the GIT?
- no
- secondary lymphoid organ
The spleen is able to phagocytose old/damged cells, what are these cells?
- RBCs
The spleen is able to produce what that contribute towards the immune system?
- antibodies
The spleen is able to sequestrate what?
- platelets
In adults haematopoiesis occurs in the bone marrow, however, in the foetus this occurs somewhere else, where is this?
- the spleen
- can occur in some pathological conditions
Which organs tail is located at the hilium of the spleen?
- pancreas

The spleen is divided into 2 areas, what are these 2 areas?
- white pulp
- red pulp

The spleen is divided into 2 areas, what is the function of the white pulp?
- immune function
- lymphocytes (T and B cells)
- antibody production/immunity

The spleen is divided into 2 areas, what is the function of the red pulp?
- removal/phagocytosis of old/abnormal red cells and particulate matter
- RBCs and macrophages

What is dysentary?
- intestinal inflammation
- causes mild or severe stomach cramps and severe diarrhea
- mucus or blood in the feces
How can we distinguish between diarrhoea caused by infection and dietary intake?
- infections are generally acute and can cause flu like symptoms
- dietary can be chronic and do not cause flu like symptoms
Does coeiliac disease tend to cause abdominal pain?
- no
- bloating and flatulence (passing wind)
- indigestion
- constipation
- vomiting
The image below shows histology of the spleen. There are 2 parts to the spleen, the white and red pulp. Which is white and which is red pulp in numbers 1 and 2?

1 = white pulp
2 = red pulp
Which blood vessel supplies the spleen?
- the splenic artery

What is the blood flow through the spleen from the splenic artery?
- splenic artery
- splenic arteriole
- splenic capillaries
- sheathed capillaries
- cords of Billroth
- venous sinuses
What are the cords of billroth?
- located in the red pulp of the spleen between the sinusoids
- consist of fibrils and connective tissue cells with a large population of monocytes and macrophages