Digestive system 2.2: Liver, Intestin and Colon

Question 1

What enzyme conjugates bilirubin and wat is the product?

Answer 1

Conjugée par glucu ronyl transférase en bilirubine di glucu ronide

Question 2

True or False,

Unlike most sels biliares, bilirubine is mostly eliminated

Answer 2

True
➢ 15% réabsorbé dans cycle entérohépatique
➢ 85% éliminée dans selles

Question 3

What is urobilinogen and what why is it important?

Answer 3

It is the product of the de conjugated bilirubin in the intestins

It is important becasue this is what will beccome stercobilibin (feces color)
and urobilin (urine yellow color)

Question 4

Ictère pre vs intra-hépatique:vs Ictère post-hépatique:

Answer 4

First of, ictere = Accumulation de bilirubine dans le plasma

Ictère pré-hépatique:
increased destruction of RBC in the Vx without the involvement of the liver
Relâche de bilirubine non-conjuguée → no issues in the liver
And so, increase in bilirubine non-conjuguée → no issues in the liver

Ictère intra-hépatique:
Problem in the liver
Often an issue in glucuronyltransférase → more non-conjugated
Often also from destruction of hepatocytes due to cirrhose
Overall an increase in conjugated an non-conjugated

Ictère post-hépatique:
Some obstruction in the exit route → means the liver did its job
And so, we are likely to have conjugated bilirubin in the blood

Question 5

Vascularization of intestin?

Answer 5

Vascularisation: artère mésentérique supérieure

Question 6

What is the site of regeneration in the intestin and why is this important?

Answer 6

Villosities, Cells come from Cryptes de Lieberkühn

Villosities are in constant regeneration →

Important because if there is an infection in the tract, in 3-6 days all will be renouvèle

Question 7

Resseau neuro for motricity in the intestin grele?

Answer 7

Contractions circulaires et longitudinales

Circulaire = Plexus Meissner

Longitudinal = Auerbach

Question 8

Explain Reflexe Péristaltique in the intestin.

Answer 8

Implique muscle circulaire

Serotonin initiates the reflex:
Something comes, intestins grows, mechanoriceptors lead to seretonin release

Contraction muscle lisse en amont (ACh + Substance P)
Relaxation muscle en aval (VIP,NO)

Question 9

Complexe migratoire moteur (CMM)

Answer 9

These are contractions during not eating

These cannot be initiated the same way as peristaltism due to the lack of mechanoreceptor activation

Where does it come from? →
Cajal cells that initiate it in the stomach propagates
As such stimulated by Motiline (inter-digestion hormone)

Question 10

Why is Complexe migratoire moteur (CMM) important

Answer 10

Assures the unidirectional flow of material

Prevents a collection of bacteria in the intestins

Although bacteria are important, too many of them can be dangerous

Question 11

Facteurs qui inhibent motricité grêle:

Answer 11

Sécrétine
Glucagon
Somatostatine (inhibe contractions post-prandiales surtout)

Question 12

Absorption volumes in the digestive tract:

Answer 12

9-10 L de sécrétions arrivent au grêle par jour:
➢7 L de contenu gastrique, biliaire, pancréatique, etc.
➢2 L de la diète
➢ Grêle réabsorbe 7-8 L
➢ Côlon réabsorbe le reste 1.5L
produit final ~200 mL

Question 13

Sodium vs Chlore in absortpion?

Answer 13

Reabsorption of Na+ = reabsortpion of water + reabsorption of Cl-
Secretion of Chlore = secretion of water

Question 14

What is the best absorption section in the intestins and why?

Answer 14

➢Jejunum: jonctions lâches

Question 15

What is the link of hydration and sodium in terms of intestinal tract?

Answer 15

If we drink a lot of water but we do not have a lot of sodium, we are likely to not reabsorb the water -> diarrhea

Question 16

SGLT1: function and potential issue

Answer 16

Glucose and Galactose reabsorption

Coupled with sodium

No sodium = no reabsorption

Question 17

GLUT5: funtion and type

Answer 17

Passive Reabsorption of Fructose

Question 18

GLUT2 function

Answer 18

Allows for the reabsorption into the blood vessels after the absortpiopn of glucose, galactose and fructose

Question 19

How are sodium and glucose absorption related

Answer 19

SGLT1 is a symporter

it uses the potential energy of sodium to transport glucose

in any case, this means that Absorption optimale Na+(et donc aussi H2O) nécessite glucose ou galactose

and that absorption de glucose needs sodium

Question 20

The absoption of proteins broken into Di- et tri- peptides absorbés via

Answer 20

➢ Di- et tri- peptides absorbés rapidement par PEPT1
This is why it is easier to absorb di and tri peptides

Question 21

What absorption issue would lead to a deficit of vitamins A D E K?

Answer 21

Problem in lipid absorption

Question 22

IF you have an issue in micelle formation, what can you not absorb and what can you still?

Answer 22

You cannot absorb large fatty acids
you can still absorb short chain fatty acids

Question 23

What is the site of absorption for B12 ?

Answer 23

Absorption iléon terminal (récepteur cubuline)

Question 24

Why would someone who is lactose intolerant have diarrhea?

Answer 24

Because, when the breakdown of glucides is done in the intestins, for this person there is no lactase.

As such, a concentration of large lactose molecules will be found in the intestins

Due to this increase in osmolarity, water will be secreted to balance

-> diarrhea

Question 25

What stimulates water secretion in the intestins?

Answer 25

➢Infections (bactériennes, virales, parasitaires, etc.)

➢Distension intestinale (présence de chyme)
➢Obstruction intestinale (distension +++)

Question 26

What is the main role of the colon?

Answer 26

Stockage de contenu intestinal: surtout caecum et recto-sigmoïde

Question 27

True or False,

The colon is a vital organ

Answer 27

False,

Non indispensable: colectomie a des conséquences physiologiques mais surmontables

This is because there is no nutriment absorption only electrolytes
And so bowel will be very liquid but you can still survive