GIT Histology 3

Question 1

Where do lymph vessels travel?

Answer 1

Lymph vessels accompany veins and drain in a similar pattern.

The thoracic duct begins behind the diaphragm (cisterna chyli) empties into left brachiocephalic vein and drains left thorax plus sub-diaphragm.

Right lymph trunk drains upper right hand quadrant to the right brachiocephalic vein.

There are many lymphovenous connections so that if one is blocked the other may be used

Question 2

What epithelium lines the rectum?

Answer 2

Simple columnar epithelium. Mostly goblet cells.

Question 3

What is present in the epithelium of the rectum besides the columnar cells?

Answer 3

Straight tubular intestinal glands (crypts)

Question 4

What Epithelium does the anal canal have?

Answer 4

Stratified squamous epithelium

Question 5

How does cell type change from rectum to anal canal?

Answer 5

Epithelium undergoes transition from simple columnar into stratified columnar into stratified squamous cells.

Question 6

What structures does the liver have that relate to bile production?

Answer 6

No secretory units as in salivary glands

Surrounded by well defined, thin connective tissue capsule, lobular structure exists but not clearly defined, interlacing of plates of cells (hepatocytes), all cells come in contact with blood, many products are delivered to blood.

Question 7

What kind of capillaries receive the products that the liver delivers into the blood?

Answer 7

Sinusois (Large irregular shaped capillaries)

Question 8

What organelles are abundant in hepatocytes?

Answer 8

Golgi apparatus

Lysosomes

Question 9

What is contained in liver parenchyma?

Answer 9

Organised plates of hepatocytes

Question 10

What is contained in liver’s connective tissue stroma?

Answer 10

It is continuous with outer fibrous capsule. Contains blood vessels, nerves, lymphatic vessels, and bile ducts.

Question 11

What do sinusoidal capillaries do?

Answer 11

Vascular channels are present between plates of hepatocytes where these blood vessels are found

Question 12

What are the perisinusoidal spaces?

Answer 12

Aka spaces of Disse they lie between sinusoidal endothelium and hepatocytes

Question 13

How is the liver organised?

Answer 13

Into hexagonal lobules.

Question 14

What goes through the center of a liver lobule?

Answer 14

Central veins that go into the hepatic vein.

Question 15

What is located on the corners of lobule?

Answer 15

Portal triads including: Portal vein, hepatic artery, bile duct and branches of porta hepatis.

Question 16

What are lobules in 3 dimensions?

Answer 16

Lobules are prisms with tapered ends.

Question 17

What is the most important functional lobule in the liver?

Answer 17

The acinus

Question 18

What are the types of lobules in the liver?

Answer 18

Classical (hexagonal)

Portal (Triad)

Acinus (Diamond shaped)

Question 19

Which lobules are most important for bile production?

Answer 19

Triads.

Question 20

What does the classical hepatic liver lobule look like?

Answer 20

Hexagonal prism

Delimited by interlobular tissue

Corners of prism: Portal triads

In cross-section, the lobule is filled by cords of hepatocytes that radiate from central vein. Separated by vascular sinusoids.

Direction of blood flow goes from triads to central vein.

A portal triad serves 3 lobules.

Question 21

What does the acinus do?

Answer 21

Emphasizes the secretory function of the liver.

Question 22

What is defined by the short and long axes of the acini?

Answer 22

Defined by terminal branches portal triad (along border between 2 classical lobules)

Long axis: Between 2 central veins closest to the short axis.

Question 23

What pathology can arise in different parts of the acini?

Answer 23

Zone 1 is closest to blood supply making them the last cells to die if circulation is impaired. However, they are the first to show morphogenic changes after bile duct occlusion.

Zone 3 are the first to show ischaemic necrosis, first to show fat accumulation and last to respond to toxic substances.

Question 24

What percentage of liver cells are hepatocytes?

Answer 24

~80%

Question 25

What do hepatocytes do?

Answer 25

Secrete bile (up to 1L/day)

Detoxify the blood.

Question 26

What separates hepatocytes from each other?

Answer 26

Separated by thin, disontinuous simple squamous epithlium which lines the sinusoids.

Question 27

What happens between hepatocytes and epithelial cells (in the perisinusoidal space of Disse)?

Answer 27

Contents of blood plasma can freely enter space of disse through openings in epithelium lining sinusoids.

Macrophages attached to the epithelium

Question 28

What is the role of kupffer cells?

Answer 28

To consume microorganisms that get into the bloodstream

Question 29

Where are hepatocytes located?

Answer 29

On sinusoidal surface: In microvilli.

Question 30

What is present In perisinusoidal space between endothelium and hepatocytes?

Answer 30

Only fluid no blood cells.

Question 31

Where are bile canaliculi located?

Answer 31

Between hepatocytes. They are separated by tight junctions.

Question 32

What do ito cells do?

Answer 32

They have a role in regeneration

Question 33

What does the gall bladder do?

Answer 33

Increases bile concentration by absorbing fluid from the bile.

Stores bile prior to secretion

Question 34

What kind of epithelium is located in the gall bladder?

Answer 34

Simple columnar epithelium with microvilli and no mucous cells.

Question 35

What cell types are present in the gall bladder?

Answer 35

No mucous cells

Highly folded epithelial layer when GB is empty.

No muscularis mucosae or submucosa

Few mucous glands near the neck

Thin outer fibromuscular coat.