Digestive system 2.2: Liver, Intestin and Colon Flashcards
What enzyme conjugates bilirubin and wat is the product?
Conjugée par glucu ronyl transférase en bilirubine di glucu ronide
True or False,
Unlike most sels biliares, bilirubine is mostly eliminated
True
➢ 15% réabsorbé dans cycle entérohépatique
➢ 85% éliminée dans selles
What is urobilinogen and what why is it important?
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)
Ictère pre vs intra-hépatique:vs Ictère post-hépatique:
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
Vascularization of intestin?
Vascularisation: artère mésentérique supérieure
What is the site of regeneration in the intestin and why is this important?
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
Resseau neuro for motricity in the intestin grele?
Contractions circulaires et longitudinales
Circulaire = Plexus Meissner
Longitudinal = Auerbach
Explain Reflexe Péristaltique in the intestin.
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)
Complexe migratoire moteur (CMM)
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)
Why is Complexe migratoire moteur (CMM) important
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
Facteurs qui inhibent motricité grêle:
Sécrétine
Glucagon
Somatostatine (inhibe contractions post-prandiales surtout)
Absorption volumes in the digestive tract:
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
Sodium vs Chlore in absortpion?
Reabsorption of Na+ = reabsortpion of water + reabsorption of Cl-
Secretion of Chlore = secretion of water
What is the best absorption section in the intestins and why?
➢Jejunum: jonctions lâches
What is the link of hydration and sodium in terms of intestinal tract?
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
SGLT1: function and potential issue
Glucose and Galactose reabsorption
Coupled with sodium
No sodium = no reabsorption
GLUT5: funtion and type
Passive Reabsorption of Fructose
GLUT2 function
Allows for the reabsorption into the blood vessels after the absortpiopn of glucose, galactose and fructose
How are sodium and glucose absorption related
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
The absoption of proteins broken into Di- et tri- peptides absorbés via
➢ Di- et tri- peptides absorbés rapidement par PEPT1
This is why it is easier to absorb di and tri peptides
What absorption issue would lead to a deficit of vitamins A D E K?
Problem in lipid absorption
IF you have an issue in micelle formation, what can you not absorb and what can you still?
You cannot absorb large fatty acids
you can still absorb short chain fatty acids
What is the site of absorption for B12 ?
Absorption iléon terminal (récepteur cubuline)
Why would someone who is lactose intolerant have diarrhea?
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
What stimulates water secretion in the intestins?
➢Infections (bactériennes, virales, parasitaires, etc.)
➢Distension intestinale (présence de chyme)
➢Obstruction intestinale (distension +++)
What is the main role of the colon?
Stockage de contenu intestinal: surtout caecum et recto-sigmoïde
True or False,
The colon is a vital organ
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
