Week 2

Question 0

What is CCK secreted by?

Answer 0

I cells

Question 1

What does the Sphincter of Oddi relax in response to?

Answer 1

CCK-PZ

Question 2

What stimulates CCK secretion?

Answer 2

Fatty acids and some aa

Question 3

Where is secretin secreted from?

Answer 3

S cells.

Question 4

What stimulates secretin release?

Answer 4

Acid in SI

Question 5

What does CCK cause?

Answer 5

Pancreatic secretion and gall bladder emptying.

Question 6

What does secretin cause?

Answer 6

Cause bicarbonate secretion from ducal cells in liver and pancreas?

Inhibits gastric acid.

Question 7

How is bile charged?

Answer 7

Bile is negatively charged and it’s components are secreted by hepatocytes.

Question 8

What do the bile ducts add to the bile?

Answer 8

Bile ducts add bicarbonate, water and salt. These are stimulated by secretin and the process involved CFTR. (cystic fibrosis link)

Question 9

What does the gallbladder reabsorb and secrete?

Answer 9

The gall bladder reabsorbs salt and water.

It secrete protons which acidify bile, preventing Ca2+ precipitate forming (preventing gallstones)

Question 10

What do the pancreatic ducts secrete?

Answer 10

The pancreatic ducts secrete bicarbonate, effect increased by CCK (via vagus).

CFTR is needed, so in cystic fibrosis secretions become thick and cause pancreatic fibre.

Question 11

What does the pancreas secrete?

Answer 11

Procarboxypeptidases, protease inhibitors and pancreatic alpha amylase.

Question 12

What do the crypts in small intestine secrete?

Answer 12

The crypts in the small intestine secrete bicarbonate.

Question 13

What is the name of the circular folds of the small intestine?

Answer 13

The circular folds are called pilca circulares to increase the surface area.

Question 14

How is a migrating motor complex (MMC) stimulated and how often?

Answer 14

MMC’s are stimulated by motilin and when emoty a MMC is generated every 90 minutes.

Question 15

What is a MMC?

Answer 15

It is caused by muscular contractions which move substances along. The behind bolus contracts and front relaxes.

The longitudinal smooth muscle contracts reducing length between segments.

Question 16

Where is mucus secreted from?

Answer 16

Goblet cells.

Question 17

What absorbs glucose and galactose?

Answer 17

SGLT1 absorbs glucose and galactose (sodium glucose transporter)

Question 18

How is fructose absorbed?

Answer 18

Fructose is passively absorbed by Glut5 transmitter.

Question 19

How is trypsin activated?

Answer 19

Enterokinases from crypt cells activate trypsin.

Question 20

What are di/tri peptides taken up by?

Answer 20

Di and tri peptides are taken up by Na+ linked active transporters and small amounts are taken up by endocytosis.

Question 21

How is fat digested?

Answer 21

Bile salts break up lipid micelles before pancreatic lipase cleaves off fatty acids leaving monoglycerides which combine with bile salts and are emulsified.

This diffuses across brush border and repackaged as chylomicra.

Question 22

How are bile salts recycled?

Answer 22

Salts are actually absorbed into distal ileum and a deconjugated becoming lipophillic.

Question 23

How is iron absorbed?

Answer 23

Iron is absorbed into cell via a proton gradient. Iron is carried by ferriportin out of the cell.

Iron is reoxidised to Fe3+ by hephaestin before binding to transferrin when carried in blood

Question 24

Where is calcium absorption and how?

Answer 24

Calcium absorption occurs early in duodenum. It is controlled by Vitamin D and parathyroid. If low PTH released and kidney reabsorbs more calcium. If acidotic calcium fails to bind to albumin. Hypercalcaemia.

Question 25

Which vitamins are fat soluble?

Answer 25

Vitamins A,D,E and K are fat soluble.

Question 26

What do water soluble vitamins require to be absorbed?

Answer 26

Water soluble vitamins require Na+ linked transporter to be absorbed.

Question 27

How does vitamin B12 get absorbed?

Answer 27

Vitamin B12 can only be absorbed when bound to intrinsic factor (from gastric parietal cells)

Question 28

The large intestine is designed to move substances much, but what are the two ways it can?

Answer 28

Haustration: slow movement of circular muscles squeeze contents. Mass Movement: formulated into large peristaltic waves, cleans through large bowel.

Question 29

How is large intestine motility coordinated?

Answer 29

Motility is mostly intrinsic via enteric nervous system triggered by gastrocolic reflex (increased motility in response to stretch receptors in stomach). But the orthocolic reflex also has an effect. (Stimulated by standing upright and then reclining over night)

Question 30

Digestion in the large intestine is carried out by bacteria, not human enzymes. What do they digest?

Answer 30

Fibre to short chain fatty acids (secondary active transport by Na+ transporter). Urea to amino acids Bilirubin to urobilinogen and stercobilins. Bile acids to secondary bile acids Conjugated bile acids to unconjugated.

Question 31

How is salt absorbed in the large intestine?

Answer 31

EnaC channels allow Na+ transport! causing Cl- flux followed by water. This is stimulated by aldosterone.

Question 32

How is chloride secreted in large intestine?

Answer 32

Chloride secretion stimulated by cyclic AMP and Ca2+. Cholera and E. Coli increase cAMP. C diff increases Ca2+

Question 33

What does the pectinate line of rectum mark?

Answer 33

Signifies end of upper 2/3(hind gut) to lower 2/3(proctodeum). Also marks where epithelium becomes stratified squamous from columnar.

Question 34

What are lamina proprial lymphocytes?

Answer 34

They are mostly T helper cell related (CD4) TH1 - cell mediated response TH2 - antibody mediated response TH17 - cell mediated (related to irritable bowel syndrome).

Question 35

What are the two types of bases to disease of mucosal immune system?

Answer 35

Two types are failure to establish oral tolerance and failure to maintain oral tolerance.

Question 36

What is oral tolerance?

Answer 36

Oral tolerance is the immunological unresponsiveness from orally administered antigen. This prevents a response to normal flora occurs through T reg cells. Fine balance between TH 1,2 and 17 (eradication) and T reg (toleration of pathogens).

Question 37

Are food allergies a failure to establish or maintain oral tolerance?

Answer 37

Food allergies are a failure to establish oral tolerance.

Question 38

How are food allergies caused?

Answer 38

Food allergies are caused by IgE hypersensitivity and mast cells. An example of T cell mediated immunity is coeliacs and protein enterocolitis.

Question 39

What happens in coeliac disease?

Answer 39

T cell mediated hypersensitivity to wheat gluten. HLA DQ2 allele in 95% of patients. Causes villi wasting away. T cells attack villi.

Question 40

What is food protein induced endocolitis syndrome (FPRIES)?

Answer 40

Food protein induced endocolitis syndrome mimics food allergy but resolves with time. It is a cell mediated T cell reaction it soy, cow milk, egg, fish, rice or chicken.

Question 41

What is inflammatory bowel disease?

Answer 41

Breakdown of oral tolerance. CD4 t helper cell mediated. Crohns most commonly affects ileum and colon. NOD2 mutation, involved in intercellular processing of bacterial antigens

Question 42

How would you treat Crohns?

Answer 42

To treat Crohns you would use T helper cell inhibitors, T reg cell proliferators add attenuated helminths.

Question 43

Why is it hard to develop mucosal vaccines?

Answer 43

It is hard to develop mucosal vaccines as it is hard to induce immune activation and not oral tolerance.

Question 44

Give an example of an inert delivery system?

Answer 44

An example of an inert delivery system would be vibrio cholerae enterotoxin.

Question 45

What are inert delivery systems?

Answer 45

Enteric coated capsules, biodegradable microspheres.

Question 46

Give an example of a live recombinant system.

Answer 46

Antivirulent salmonella or E. coli enterotoxin.

Question 47

Give an example of a plant derived antigen.

Answer 47

Bordetella pertussis (part of whooping cough vaccine)