Lecture 31 Monogastric Secretions (Pancreatic, Hepatobiliary, Intestinal)

Question 1

What are functions of the liver?

Answer 1

Production of important compounds: e.g. cholesterol, bile
Detoxification
Storage of micronutrients
Blood sugar balance (glycogen storage)
Protein synthesis e.g albumin, acute phase proteins etc.
Immune functions

Question 2

Name the three vessels found in the portal triad

Answer 2

bile duct
portal vein
hepatic artery

Question 3

What is the name of the vessel in which blood from the portal vein and hepatic artery drains into after flowing through sinusoids in the hepatic lobule?

Answer 3

Central vein or Terminal Hepatic Vein

Question 4

What large vessel does the central vein lead to?

Answer 4

Caudal vena cava (carried to this via the hepatic veins)

Question 5

As blood runs towards the central vein, bile runs toward the _____ in the triad

Answer 5

Bile duct

Question 6

What is the name for the specialized macrophages within the hepatic sinusoids>

Answer 6

Kupffer cells

Question 7

A small space between the sinusoid endothelial layer and the hepatocytes

Answer 7

space of disse

Question 8

A cell that lies within the space of Disse: normally inactive, but will produce fibrous scar tissue to wall off the area if any damage occur to the hepatocytes.

Answer 8

stellate cell

Question 9

What is in bile? (5)

Answer 9

1. Bile salts
2. Cholesterol
3. Bilirubin
4. Electrolytes
5. Water

Question 10

Where is bile secreted into immediately from hepatocytes?

Answer 10

Bile canaliculus

Question 11

What compound, which is a product of hemoglobin breakdown, gives bruises their yellowish colour?

Answer 11

Bilirubin

Question 12

What acid do hepatocytes conjugate bilirubin with?

Answer 12

Glucuronic acid

Question 13

What is the cause of the yellowish discolouration noted in jaundice patients?

Answer 13

Unconjugated bilirubin being deposited into tissues.

Question 14

Conjugated bilirubin can be converted by colonic bacteria into _______ and __________ which gives the brown colour of feces

Answer 14

urobilinogen and stercobilin

Question 15

What compound gives urine a distinct yellow colour?

Answer 15

Urobilinogen

Question 16

Toxins or wastes generally undergo a two‐phase process before they are excreted into the bile: 1. ___________________________________________
2. the compound made much more water‐soluble and permits it to remain soluble in the bile.

Answer 16

1. the compound undergoes change its structure sufficiently so that it is no longer a danger;

Question 17

Toxins or wastes generally undergo a two‐phase process before they are excreted into the bile: Toxins or wastes generally undergo a two‐phase process before they are excreted into the bile: 1. the compound undergoes change its structure sufficiently so that it is no longer a danger;
2. ______________________________________________________________________

Answer 17

2, the compound made much more water‐soluble and permits it to remain soluble in the bile.

Question 18

Amino acid most commonly used to form bile salts:

Answer 18

Taurine (it becomes taurocholic acid when bound to cholesterol)

Question 19

How are bile salts formed?

Answer 19

By conjugating cholesterol with an amino acids

Question 20

Are bile salts polar or non polar?

Answer 20

Highly polar and thus very water soluble

Question 21

Which hormone is responsible for increasing bile production and secretion?

Answer 21

Cholecystokinin (CCK)

Question 22

_________ part of bile salts will be on the inside of the micelle, and the _________ part will be on the outer surface of the micelle.

Answer 22

Lipophilic, hydrophilic

Question 23

What exocrine function does the pancreas have?

Answer 23

To produce enzymes responsible for digesting foods: amylase, protease, lipase

Question 24

What two inputs increase the production and secretion of pancreatic enzymes?

Answer 24

CCK and vagal stimulation

Question 25

What hormone is responsible for the pancreas to increase secretion of alkaline solution?

Answer 25

Secretin

Question 26

Why does the pancreas also secrete an alkaline solution?

Answer 26

Because its enzymes need an optimal pH to work (7-8) and it is important to increase the low pH chyme leaving the stomach

Question 27

Describe the way the small intestine mucosa looks

Answer 27

There are villi (projections) and crypts (invaginations), the enterocytes are also covered in microvilli

Question 28

What can change the lengths of the villi of the small intestine?

Answer 28

The smooth muscle of the internal muscularis mucosa which is embedded in the submucosal layer.

Question 29

Unique aggregates of B and T lymphocytes, macrophages, and dendritic cells in the submocosa of the ileum

Answer 29

Peyers patches

Question 30

Where are intestinal stem cells located?

Answer 30

Within the crypts

Question 31

How do crypt enterocytes differ from villus ones?

Answer 31

The crypt enterocytes are secreting chloride, sodium, and water to facilitate absoprtion by absorptive enterocytes. Once migrated to the top of the villus the enterocytes job is to absorb.

Question 32

What do goblet cells do?

Answer 32

Secrete mucus

Question 33

Enteroendocrine cells - what are their functions?

Answer 33

Monitor pH, osmolarity, and composition of the ingesta in the lumen.
Secrete hormones (CCK and secretin)

Question 34

Paneth cells - what are their function?

Answer 34

To protect crypt stem cells by producing antibacterial/fungi/viral secretions

Question 35

What type of epithelium lines the crypts and villi of the small intestine?

Answer 35

Simple columnar with microvilli

Question 36

What is an M cell or a dome cell?

Answer 36

An immune cell which can capture pathogens and present them to other immune cells to determine if an immune response is needed. they are sentinel cells.

Question 37

How long does it take for crypt cells to reach the villous tip?

Answer 37

4-5 days

Question 38

How is blood supplied to the small intestinal villus?

Answer 38

Hairpin Arrangement:
A central arteriole emerging from the submucosal artery
carries oxygenated blood upward toward the villous tip. At the tip, a capillary network ramifies outward and is collected into venules and veins, which progress downward at the periphery just beneath the epithelium.

Question 39

What is CFTR?

Answer 39

the cystic fibrosis transmembrane conductance regulator, a cyclic AMP-dependent chloride channel. As chloride moves through this channel, fluid is drawn into the lumen of the intestine as Na+ moves to follow the Cl-

Question 40

How is fluid driven into the lumen of the small intestine?

Answer 40

Through the help of CFTR which pumps Cl- out of the cell into the lumen. Since Na+ follows to even the electric gradient, water naturally follows.

Question 41

Which part of the enterocytes does the fluid follow the NaCl secretion through?

Answer 41

Through areas of tight junctions

Question 42

How does bacteria like chloera affect the enterocytes which leads to severe diarrhea?

Answer 42

Bacteria activate adenylate cyclase lead to chloride channels being stuck in the open position due to elevated levels of cAMP. this causes fluid to be drawn into the lumen in higher than normal levels since NaCl is being moved.

Question 43

How does colon mucosa differ from small intestine?

Answer 43

There are no villi (but there are crypts)

Question 44

What is a comparable structure to the Peyers patches found in the colon?

Answer 44

Lymphoid Follicles

Question 45

Name the four layers of the GI tract starting on the side of the lumen

Answer 45

Mucosa
Submucosa
Muscularis mucosa (external)
Serosa