Histology of Large Intestine, Appendix, Pancreas and Gallbladder

Question 1

What are the two main functions of the large intestine?

Answer 1

absoprtin of water

secretion of mucus to lubricate the dehydrated feces

Question 2

True or false: the large itnestine has no villi or plicae circulares.

Answer 2

true

Question 3

Describe the epithelium of the large intestine?

Answer 3

absoptive columnar epithelium with goblet cells and some enteroendocrine cells

no paneth cells really

stem cells down at the lower half of the cryps

Question 4

Why is the lamina propria partly obscured in the large intestine?

Answer 4

the intestinal glands extend down to the musclaris mucosae

Question 5

What type of tissue is contained in the lamina propria besides CT?

Answer 5

lymphatic tissue - both in diffuse and nodular form

Question 6

How many layer sof smooth muscle are present in the muscularis externa of the large intestine?

Answer 6

two: inner cirular layer and outer longitudinal layer

Question 7

What makes the outer longitudinal layer of smooth muscle in the large intestine different from that in the small intestine?

Answer 7

the small intestein’s outer longitudinal layer is continuous all the way around, while the large itnestein’s is separated into three longitudinal bundles called teniae coli

note - they coalesce back together over the rectum

Question 8

What parts of the large itnestine have a serosa and which have an adventitia?

Answer 8

transverse colon and sigmoid colon have a serosa

ascending and descending have an adventitia

Question 9

How does the rectum relate to the large intestine?

Answer 9

it’s actually just the last 6-8 inches of the large intestine, so morphologically very similar

Question 10

How do the cell populations change as you enter the rectum?

Answer 10

you have more goblet cells and fewer absoprtive cells (which makes sense teleologically)

Question 11

What is the last 1-1.5 inches of the large intestine called?

Answer 11

the anal canal

Question 12

Describe the epithelium of the anal canal?

Answer 12

The superior part is simple columnar

then it changes to stratified squamous at the anus (non=keratinizing at first, but switching to keratinizing as you exit)

Question 13

The internal anal sphincter is made from which of the muscle layers? How about the external sphincter?

Answer 13

inner circular layer of the muscularis externa

the external sphincter is skeletal muscle

Question 14

The appendix is morphologically similar to what organ?

Answer 14

the large intestine - makes sense because it’s off the cecum

Question 15

Describe the epithelium of the appendix>

Answer 15

simple columnar epithelium with absorptive cells, goblet cells, enteroendocrine cells, paneth cells and undifferentiated cells

Question 16

True or false: the appendix does not have any crypts.

Answer 16

False - they are present but not well developed

Question 17

What is the primary difference between the appendix and the res tof the large intestine?

Answer 17

the appendix has way more lymphocytes and lymphatic nodules - aboslutely tons

Question 18

What obscures the lamina propria in the appendix?

Answer 18

lymphocytes

also sort of obliterates the muscularis mucosae and some of the submucosa

Question 19

True or false: the appendix has no fat in the submucosa.

Answer 19

false - there can be considerable fat present

Question 20

What are the layers of the muscularis externa in the appendix?

Answer 20

inner circular and outer longitudinal again (but taenia coli aren’t present)

Question 21

THe pancreas looks similar to what salivary gland?

Answer 21

parotid

Question 22

What are the 4 components to the pancreatic duct system?

Answer 22

excretory ducts
intralobular ducts
intercalated ducts
acinus

Question 23

Which is more prevalent: excretory ducts or intralobular ducts?

Answer 23

excreotyr ducts are way more prominent. The intralobular ducts are insignificant

Question 24

Are the secretory alveoli of the pancreas entirely serous or mucous? What do they secrete?

Answer 24

entirely serous - secrete the zymogens of digestive enzymes

Question 25

What is the basis for the eosinophilic staining of the apical cytoplasm of the secretory alveoli in the pancreas?

Answer 25

the zymogen granules

Question 26

What’s unique about the intercalated ducts in the pancreas?

Answer 26

their termination extends INTO the acinus, which is totally distinct for the pancreas

results in nuclei of the intercalated duct cells present in the center of the acinus - called a centro-acinar cell

Question 27

While msot of the pancreas is basophilic staining. What is the light staining bits (mostly)?

Answer 27

islets of langerhans

Question 28

Since the exocrine pancreas secretes many substances, what organelles are highly prevalent in pancreatic cells?

Answer 28

RER and prevalent golgi apparatus for making and packaging proteins

Question 29

Which has a capsule and prominent connective tissue: pancreas of parotid?

Answer 29

parotid

Question 30

Which has more fat cells, pancreas or parotid?

Answer 30

parotid - pancreas has no fat at all

Question 31

Which has more striated ducts - pancreas or parotid?

Answer 31

parotid - they’re common in the parotid and very difficult to see in the pancreas

Question 32

Which has centro-acinar cells, pancreas or parotid?

Answer 32

pancreas

Question 33

Where does the pancreas get it’s sympathetic supply? Parasympathetic?

Answer 33

sympathetic from the celiac plexus

parasympathetic from the vagus

Question 34

What does autonomic inenrvation seem to do for the exocrine pancreas?

Answer 34

appears to alter sensitivity of membranes to hormones that stimulate secretory activity

with vagal stimuation increasing secretion

Question 35

What cells secrete secretin?

Answer 35

S cells in the duodenum and ileum

Question 36

What does secreting do?

Answer 36

it simulates the pancreatic DUCT CELLs to secrete an alkaline fluid containing high amounts of bicarb in order to neutralize acid chyme coming from the stomahc and provide a neutral pH for pancreatic enzymes

Question 37

What cells secrete cholecystokinin? In response to what?

Answer 37

I cells in response to fat in the lumen

Question 38

What does CCK stimulate for the pancreas?

Answer 38

release of enzymes and zymogens

Question 39

What are the three functions of the gallbladder?

Answer 39

reservour for bile when it’s not needed

concentrates the bile

releases the bile to the duodenum

Question 40

What will CCK stimulate for the gallbladder?

Answer 40

it will bind to receptors on smooth muscle cells ot gallbladder muscularis externa to cause muscle contraction - makes bile propel out of the GB

binds to receptors on the smooth muscle of the sphicnter of oddi to relax it and allow bile to enter the duodenum

Question 41

Describe the mucosa of the gall bladder?

Answer 41

it’s a simple tall columnar epithelium with microvilli

Question 42

What is a unique bit about the lamina propria of the gall bladder?

Answer 42

it’s loose connective tissue with lots of folds. invaginations form sinuses called Rokitansky-aschoff sinuses

Question 43

Does the gall bladder have a serosa or adventitia?

Answer 43

trick question…

where it’s adjacent to the liver there is an adventitia

where it doesn’t touch the liver is a serosa