Download 3 HORMONES from SMALL INTESTINE

DIGESTIVE SYSTEM
drg. ANIS A. MAKKY, MKes
ORAL BIOLOGY DEPARTEMENT
AIRLANGGA UNIVERSITY
SURABAYA, APRIL 16, 2007
SMALL INTESTINE
major organ of both :
digestion and absorption
this convoluted tube extends :
from the pyloric sphincter to the
ileocecal valve
20 feet long ?
3 regions:
duodenum, jejunum, and ileum.
DUODENUM
10" long
much of it is retroperitoneal
the common bile duct :
delivering bile from the liver and gallbladder
main pancreatic duct :
delivering pancreatic juice from the
pancreas
JEJUNUM
it’s about 8' long
extends between the duodenum
and the ileum
ILEUM
it’s extends from the jejunum to
the ileocecal valve
it’s about 12' long.
HISTOLOGY
mucosa has intestinal glands (cavities) :
for secretion of intestinal juice
mucosa also has circular folds, villi &
microvilli :
for increased surface area
“brush border” has many enzymes
“brush border” has many enzymes
(embedded in plasma membranes) :
1. several carbohydrate-digesting enzymes
2. peptidases
3. nucleosidases
4. enterokinase
epithelial cell “shedding”
important enzyme activator.
PLICAE CIRCULARES
large deep
permanent folds of the mucosa and
submucosa
they slow the movement of chyme
(more time for digestion/absorption)
they increase the surface
VILLI
fingerlike projections of the mucosa
they also increase the surface area
within the core of each villus is a capillary bed
and a lacteal :
for transport of the absorbed nutrients.
• between the villi exist pits :
intestinal glands or ‘crypts of Lieberkuhn’
• the cells lining these pits secrete :
intestinal juice (mucus, enzymes, etc.),
lysozyme-secreting cells, and stem cells.
in the proximal duodenum :
the submucosa houses Brunner's glands secrete
an alkaline mucus to help neutralize the acidic
chyme (coming from the stomach)
INTESTINAL PHASE OF
REGULATING DIGESTION
1. chyme enters duodenum
2. three hormones secreted from SI mucosa
3. receptors in SI mucosa sense food
or chemical presence in duodenum
4. neuronal activation of sympathetic NS
or inhibiton of parasympathetic NS
REGULATING of ABSORPTION
C L P, Ca2+, Fe2+ :
duodenum & jejunum
bile salt, vit.B12,H2O,electrolite : ileum
monosacharide & amino acid :
secreted into cappilar
lipid :
secreted into central lacteal
absorption of H2O : passive (osmotic gradient)
mucosa epithelial cell of intestine :
collect to form tubulus is like kidney :
* functions as Na+/K+ pump within basolateral
membrane
* can stimulates absorption of NaCl & H2O
within ileum
3 HORMONES from SMALL INTESTINE
1. gastric inhibitory peptide (GIP) :
* fatty acids in chyme : induce GIP secretion
* inhibits gastric secretion
* inhibits gastric “churning”
* activates insulin secretion
2. secretin :
inhibits gastric secretion
3. cholecystokinin (CCK) :
* fatty acids in chyme : induce CCK secretion
* CCK slows gastric emptying
LARGE INTESTINE
function :
* absorb water
* then eliminate them as feces
compared to the small intestine :
diameter is bigger but its length is far shorter
(only about 5')
their tone causes the LI wall to pucker into
pocketlike sacs called ‘haustra’
LI : significant numbers of bacterial colonies
they enter via both the anal canal and the oral
cavity and colonize the LI
in the LI, they metabolize and ferment
indigestible carbohydrates
they also synthesize B vitamins as well as
vitamin K.
haustral contractions move material from
one haustrum to another and aid in mixing
mass movements : slow waves of peristalsis
one stimulus of colonic mass movements
is the presence of food within the stomach
this is known as the gastrocolic reflex.
feces enter and stretch the rectal wall :
initiate the defecation reflex
this results in :
* the contr. of the sigmoid colon and rectum
muscularis
* the relaxation of the internal anal sphincter
* contr. diafragma
higher input determines whether the external
sphincter remains :
contracted or relaxes.
prolonged diarrhea may result in :
* dehydration
* acidosis
* and other electrolyte imbalances
if water absorption >> than normal :
due to waste moving too slowly through the
colon  constipation !!!
BREAK DOWN OF LIPID
fats are not digested until the small intestine
there they are first emulsified by bile
and then acted upon by pancreatic lipase
most ingested fats are broken down into glycerol,
monoglycerides, and fatty acids
fatty acids & monoglycerides :
passively enter intestinal epithelial cells 
they're combined with cholesterol & proteins 
form chylomicrons
BREAK DOWN OF PROTEIN
protein digestion begins in the stomach : pepsin
in the SI, protein digestion continues with trypsin
and many other proteases
the end result : free amino acids
amino acids enter the intestinal epithelial cells
via cotransport with sodium
DEFECATION
after absorption of electrolite & H2O : colon
forming of feces : in the colon
feces in the rectum :
pressure of rectum   reflex of defecation
problems : constipation (absorption >>)
diarrhea (absorption <<)
DEFECATION MECHANISM
pressure of rectum 

contraction of m.longitudinal of rectal

support by parasimpathetic stimulation (n. pelvic)

feces enter canal anal

sphincter anal internal & external relaxation

feces exit from anal
DIARE
fast movement of fecal matter through
colon
excretion of excess fluid together feces
etio
: enteritis, psychogenic, colitis
ulcerative
Tx : change fluid & electrolite that lost
(saline iv & glucose)
1. cholera :
* enterotoxin released by bacteria of cholera
* enterotoxin stimulates active transport of
NaCl followed by H2O into lumen
* iritation of mucosa
* secretion , motility 
* electrolite & fluid secretion from crypts
Lieberkuhn   10-12 L/hr
* reabsorp colon  6-8 L/hr
2. celiac sprue :
* intestinal mucosa rupture
* disturb of absorption by consumption
of gluten
3. lactose intolerance
COLITIS ULCERATIVE
etiology : idiophatic, alergy
destructive immune
secretion 
motility 
colon wall : inflamation & ulcer
MORNING SICKNESS
• nausea , vomitus
• prevalence : * 51.4 % : nausea; 9.2 % : vomitus
*1: 500 gravid  hiperemesis gravidarum
• prolonged :12-22 weeks
• etio : * HCG 
* estrogen 
* deficiency B6
* gastric emptying : time >>
NAUSEA – VOMITING MECHANISM
• stimulasi pusat muntah di medula, yang mengendalikan zona
pemicu kemoreseptor (Chemoreceptor Trigger Zone – CTZ)
di otak
• Peristaltik lambung menurun
• Tonus duodenum & jejunum meningkat
• Reflux lambung
• Kontraksi lambung, kontraksi diafragma, kontraksi otot abdomen
• Isi lambung keluar
PENATALAKSANAAN
• Kasus yang berat :
– Obat-obatan :
• Sedatif : fenobarbital
• Vitamin : B1 dan B6
• Antiemetik (bila diperlukan)
– Terapi psikologik dan isolasi
– Cairan parenteral
Pusat muntah (batang otak)
Aferen
Eferen
GIT/vestibular, korteks serebri,
CTZ (chemoreceptor Trigger Zone)
otak (korteks)
impuls ke diafragma, otot abdomen,
lambung serta esofagus.
Pusat muntah
Saluran lambung-usus,
Jantung, testis
organ
keseimbangan
Chemoreceptor Trigger Zone
(CTZ)
Metoklopramid
Domperidone
neuroleptika
Anti histamin
LIVER
THANK YOU