Lecture 4

Question 1

what are Enterocytes:

Answer 1

epithelial cells in the crypts, located in between the villi continuously undergo mitosis

Important for nutrient absorption and to provide a barrier that prevents bacteria from entering the bloodstream or the lymphatic system

Question 2

how often is Enterocytes, layer of cells renewed

Answer 2

every 3-5 days,

Question 3

what are the hair like structures of the Enterocytes called

Answer 3

brush border

(where digestive enzymes are mostly found)

Question 4

Glycocalyx:

Answer 4

glycoproteins that maintain a stable environment for the enzymes to hold onto

Question 5

Enterocytes filter the nutrients depending on the type, If the nutrient is water soluble:

Answer 5

If the nutrient is water soluble, it enters capillaries which drain to the portal vein
which drains towards the liver (liver is the first organ that sees what is coming from digestion)

Nutrient → enterocyte → water soluble → capillaries → portal vein → liver

Question 6

Enterocytes filter the nutrients depending on the type, If the nutrient is fat soluble:

Answer 6

If the nutrient is fat soluble, it enters the lymphatic system

Fat soluble → lymphatic system

Question 7

Liver function:

Answer 7

Produces bile

Question 8

Is bile acidic or alkaline

Answer 8

alkaline
(pH about 7.6-8.6)

Question 9

bile composed essentially of…

Answer 9

bile acids, salts, cholesterol, phospholipids, and pigments and bilirubin/biliverdin

Question 10

what are bilirubin and biliverdin

Answer 10

waste products of hemoglobin degradation

• these are byproducts of the breakdown of RBCs; have a lifespan of about 3 months

Question 11

what make up 80% of the body’s total bile acids

Answer 11

Chenodeoxycholic and cholic acids

Question 12

when Bile acids conjugate with amino acid glycine it produces what

Answer 12

glycocheno-deoxycholic and and glycocholic acids

Question 13

when Bile acids conjugate with taurine it produces what

Answer 13

taurocholic

taurodeoxycholic

taurochenodeoxycholic acids

Question 14

When bile acids conjugate with sodium and potassium, what does it produce

Answer 14

bile salts

Question 15

function Bile Acids/Salts:

Answer 15

1.Detergents that emulsify large fat globules by fractionating them into small lipid droplets

2. Also serves to eliminate substances that cannot be excreted through the urine; ex. bilirubin - it binds to albumin in the circulation, but it is excreted in
   the faeces when released into the duodenum

Question 16

where is bile stored?

Answer 16

Gallbladder

Question 17

How does the gallbladder know when to release bile?

Answer 17

As soon as acidic chyme enters the duodenum, it senses it and sends a signal (CCK is released by enteroendocrine cells/I-cells) which stimulates the gallbladder to contract and release
bile into the small intestine

Acidic chyme → duodenum → release of CCK (via enteroendocrine cells)→ gallbladder release bile → small intestine

Question 18

Gallstones:
How is it formed:
result of formation:

Answer 18

Formed when bile becomes supersaturated with cholesterol

In-Depth explaination:
Cholesterol precipitates and provides a crystalline-like structure in which calcium, bilirubin, phospholipids, and other compounds deposit to form a ‘stone’

Causes inflammation in the gallbladder and may also block the flow of bile (choledocholithiasis) into the duodenum or clog the pancreatic duct and
cause pancreatitis

We don’t really know how the excessive formation of cholesterol occurs to begin this process of forming gallstones

Question 19

what does the pancreas release

Answer 19

Releases pancreatic juice containing bicarbonate (to buffer acidic product), electrolytes, and digestive enzymes

Question 20

How does the pancreas know how to release pancreatic juice?

Answer 20

As soon as acidic chyme enters the duodenum, it senses it and sends a signal (CCK is released by
enteroendocrine cells/I-cells) which stimulates the
pancreas to contract and release pancreatic juices into the small intestine

Same process as gallbladder

Question 21

what stimulates pancreatic exocrine secretion

Answer 21

Secretin
CCK
neuropeptide substance P
vasoactive intestinal polypeptide (VIP)

present in neurons within the gut stimulate pancreatic exocrine secretions

Question 22

Enzymes in pancreatic juice:

Answer 22

Trypsinogen, chymotrypsinogen, proelastase, and collagenase (proteases)

Question 23

Enzymes in pancreatic juice (for CHO digestion):

Answer 23

A-amylase

Question 24

Enzymes in pancreatic juice (for fat-digestion)

Answer 24

Pancreatic lipase and co-lipase

Question 25

Whatever is not digested in the small intestine goes into the….

Answer 25

large intestine

Question 26

chyme enters the large intestine through

Answer 26

ileum

Question 27

Lots of bacteria in the cecum, and if there is an imbalance or they don’t function properly, this causes an infection leading to…

Answer 27

Appendicitis

(Appendicitis is a medical condition characterized by the inflammation of the appendix. )

Question 28

path of chyme through large intestine

(look at notes on page 10 help understanding)

Answer 28

Ileum →
cecum →
ascending colon →
right hepatic flexure →
transverse colon →
left splenic flexure →
descending colon →
sigmoid colon →
rectum →
anal canal

Question 29

what lines the large intestine

Answer 29

endothelial cells

Question 30

Large Intestine primary function

Answer 30

To absorb water and electrolytes (5-7 litres of fluid per day)

Store faecal matter

Essentially dries and stores the undigested material present in the chyme

Question 31

The large intestine houses more than 400 different species of bacteria that can produce…

Answer 31

vitamin K (anti hemorrhagic)

biotin (coenzyme for carboxylase reactions)

short-chain fatty acids (acetic, propionic, and butyric acids)

Question 32

why does fibre plays a large role in bacteria

Answer 32

because it feeds bacteria

and these bacteria produce important molecules that play a role in our metabolism

short-chain fatty acids are derived from the fermentation of the fibre by bacteria

Question 33

Composition of the Faeces (don’t really gotta remember exact numbers just remember trend)

Answer 33

30% bacteria

30% undigested fibres and dried components of digested juice

10-20% fat

10% inorganic matter (minerals)

2-3% protein

Question 34

what are Probiotics

Answer 34

Bacteria that promote health and lowers risk of colon cancer, reduce cholesterol and BP, and support immune function and weight control

Question 35

what foods contain Probiotics

Answer 35

dairy, soy, yogurt, and dietary supplements

Question 36

what are Prebiotics

Answer 36

non-digestible substances that promote the growth and activity of beneficial microorganisms, such as bacteria, in the gastrointestinal tract

Question 37

what is food for bacteria in digestive system

Answer 37

Fibre (food for bacteria and allows their proliferation and survival in large intestine)