fisiologi sekresi&absopsi-blok digest12
Post on 03-Apr-2018
221 Views
Preview:
TRANSCRIPT
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
1/67
dr. Mustofa, M.ScLAB. FISIOLOGI FKIK UNSOED
FISIOLOGI SISTEMPENCERNAAN
Sekresi & Absorpsi
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
2/67
1. Describe the secretion of the oral cavity juice.
2. Describe the secretion of gastric juice and the
roles of stomach in absorption.
3. Explain the functions of the intestinalsecretions, and discuss the regulation of
secretory activities.
4. Describe the secretion and regulation of theaccessory digestive organs.
5. Describe the intestinal absorptive processes
Learning Objective
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
3/67
1. AN OVERVIEW OF THE STRUCTURE ANDFUNCTION OF THE DIGESTIVE TRACT
2. ORAL CAVITY AND ASSOCIATED GLANDULAR
ORGANS
3. THE STOMACH
4. THE SMALL INTESTINE AND ASSOCIATED
GLANDULAR ORGANS
5. THE LARGE INTESTINE
Outline
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
4/67
Heart
Liver
ABSORPTION
SECRETION
Large intestine
Rectum
AnusMouth
Food andwater
StomachHepatic
Portal vein
Small intestineSalivary glands
MOTILIT
Y
FECES
enzim asam, dll
VitaminC, D, B2, B12, dll
ProteinMineral
Karbonhidrat
Lipid
Adapted by:Dr. Andreanyta Meliala, PhD.
Vitamin KAir, Elektrolit
AktifitasBAKTERI
PembentukanGas CO2, Metana, dll
FLATUS
Digestion
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
5/67
Secretion: Includes both exocrine and endocrine
secretions. Exocrine:
HCl, H20, HC03-, bile, lipase, pepsin, amylase, trypsin,
elastase, and histamine are secreted into the lumen of theGI tract.
Endocrine: Stomach and small intestine secrete hormones to help
regulate the GI system.
Gastrin, secretin, CCK, GIP, GLP-1, guanylin, VIP, andsomatostatin.
Functions of the GI Tract (Continued)
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
6/67
Absorption:
Process of the passage of digestion(chemical subunits) into the blood or
lymph.
Functions of the GI Tract (Continued)
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
7/67
nutrients
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
8/67
GIT Regulation
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
9/67
GIT Regulation
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
10/67
Composition and function of
saliva
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
11/67
Major salivary components
Mucin 1 (MG1)
sIgA
Mucin 2 (MG2)
Lactoferrin
Peroxidases
AmylasesCarbonic anhydrases
Proline-rich proteins
Lysozyme
StatherinsHistatins
1 10 100 1000 10000
Size (kDa)
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
12/67
Multifunctionality
Salivary
Families
Anti-
BacterialBuffering
Digestion
Mineral-
ization
Lubricat-
ion &Visco-
elasticity
Tissue
Coating
Anti-
Fungal
Anti-
Viral
Carbonic anhydrases,
Histatins
Amylases,
Mucins, Lipase
Cystatins,
Histatins, Proline-
rich proteins,
Statherins
Mucins, Statherins
Cystatins, Mucins,
Proline-rich proteins, Statherins
Histatins
Cystatins,
Mucins
Cystatins,
Histatins, Mucins,
Peroxidases
adapted from M.J. Levine, 1993
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
13/67
Mucin Functions
Tissue Coating Protective coating about hard and soft tissues
Concentrates anti-microbial molecules at
mucosal interface
Lubrication
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
14/67
Mucin Functions (contd)
Aggregation of bacterial cells
Bacterial adhere to mucins may result in
surface attachment, or Mucin-coated bacteria may be unable to
attach to surface
Bacterial adhesion
Mucin oligosaccharides mimic those on
mucosal cell surface
React with bacterial adhesins, thereby
blocking them
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
15/67
Amylases
Hydrolyzes (1-4) bonds of starches
Maltose is the major end-product (20% is
glucose)
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
16/67
Lingual Lipase
Secreted by von Ebners glands oftongue
Involved in first phase of fat digestion
Hydrolyzes medium- to long-chain
triglycerides
Important in digestion of milk fat in
new-born
Unlike other mammalian lipases, it is
highly hydrophobic and readily enters
fat globules
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
17/67
Statherins
Calcium phosphate salts of dental enamelare soluble
Supersaturation of calcium phosphates
maintain enamel integrity Statherins prevent precipitation or
crystallization of supersaturated calcium
phosphate in ductal saliva and oral fluid
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
18/67
Proline-rich Proteins (PRPs)
Inhibit calcium phosphate crystal growth
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
19/67
Calculus formation
Calculus forms in plaque despite
inhibitory action of statherin and PRPs in
saliva Proteolytic enzymes of oral bacteria or
lysed leukocytes may destroy inhibitory
proteins Plaque bacteria may produce their own
inhibitors
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
20/67
Lactoferrin
Nutritional immunity
Some microorganisms (e.g., E. coli) have
adapted to this mechanism by producingenterochelins.
bind iron more effectively than lactoferrin
iron-rich enterochelins are then reabsorbed by
bacteria
Lactoferrin, with or without iron, can be
degraded by some bacterial proteases.
In unbound state, a direct bactericidal effect
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
21/67
Lysozyme
Present in numerous organs and most body fluids Sources of oral LZ:
major and minor salivary glands, phagocytic cells
Biological function
Classic concept of anti-microbial activity of LZ is based on
its muramidase activity (hydrolysis of(1-4) bondbetween N-acetylmuramic acid and N-acetylglucosamine
in the peptidoglycan layer.
Gram negative bacteria generally more resistant thangram positive because of outer LPS layer
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
22/67
Other anti-microbial activities of
LZ Muramidase activity (lysis of peptidoglycan
layer)
Cationic-dependent activation of bacterial
autolysins disrupts membranes
Aggregation of bacteria
Inhibition of glucose uptake and acidproduction
De-chaining of streptococci
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
23/67
Histatins
A group of small histidine-rich proteins
Potent inhibitors ofCandida albicans
growth
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
24/67
Cystatins
Are inhibitors of cysteine-proteases Are ubiquitous in many body fluids
Considered to be protective against unwanted
proteolysis bacterial proteases
lysed leukocytes
May play inhibit proteases in periodontal
tissues
Also have an effect on calcium phosphate
precipitation
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
25/67
CCK :
Cholecytokinin
GIP:
Gluc-dep. Insulino-
Tropic peptide
Each hormone:
Feedback
Multiple Targets
Major GIT hormone
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
26/67
Mekanisme lokal:
Prostaglandin, histamin, dan bahan kimia
lain yg dilepaskan ke cairan interstitial dapat
berpengaruh pada sel sekitar
Mesenger lokal ini penting dalam kordinasi
tanggap terhadap perubahan pH lokal,rangsang fisik atau kimia lain.
GIT Regulation
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
27/67
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
28/67
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
29/67
1.Chyme in the duodenum witha pH less than 2 or containingfat digestion products (lipids)
inhibits gastric secretions by
three mechanisms.
2.Sensory vagal action potentials
to the medulla oblongata(green arrow) inhibit motor
action potentials from the
medulla oblongata (pink arrow).
3.Local reflexes inhibit gastricsecretion (orange arrow s).
4.Secretin, gastric inhibitorypolypeptide, and cholecystokinin
produced by the duodenum
(brown arrows) inhibit gastric
secretions in the stomach.
Intestinal Phase
Secretin, gastric inhibitory
peptide, cholecystokininCirculation
pH
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
30/67
Stomach (continued)Insert fig. 18.5
Stomach
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
31/67
Secrete gastric juice:
Goblet cells: mucus.
Parietal cells: HCl and intrinsic factor.
Chief cells: pepsinogen.
Enterochromaffin-like cells (ECL):histamine and serotonin.
G cells: gastrin. D cells: somatostatin.
Stomach: ghrelin.
Gastric Glands
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
32/67
HCl Production Parietal cells
secrete H+ intogastric lumen byprimary activetransport, throughH+/ K+ATPasepump.
Parietal cellsbasolateralmembrane takes
in Cl-
against itselectrochemicalgradient, bycoupling itstransport withHC03
-.
Insert fig. 18.8
HCl production
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
33/67
HCl production is stimulated:
Indirectly by gastrin.
Indirectly by ACh. ACh and gastrin stimulate release of
histamine.
Histamine: Stimulates parietal cells to secrete HCl.
HCl production
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
34/67
Makes gastricjuice very acidic. Denatures
ingested proteins
(alter tertiarystructure) sobecome moredigestible.
Activates
pepsinogen topepsin. Pepsin is more
active at pH of 2.0.
Insert fig. 18.9
HCl Function
Digestion and Absorption in the
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
35/67
Proteins partially digested by pepsin.
Carbohydrate digestion by salivary
amylase is soon inactivated by acidity.
Alcohol and aspirin are the only
commonly ingested substances
absorbed.
Digestion and Absorption in the
Stomach
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
36/67
Parietal and chief cells impermeable to
HCl.
Alkaline mucus contains HC03
-.
Tight junctions between adjacent
epithelial cells.
Rapid rate of cell division (entireepithelium replaced in 3 days).
Prostaglandins inhibit gastric secretions.
Protective Mechanisms of Stomach
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
37/67
Usus halus
Getah pencernaan di Usus
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
38/67
Getah Pankreas
Getah Empedu
Getah usus halus
Getah pencernaan di Usushalus
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
39/67
1,8 L /hari1. Kelenjar Brunner: di mukosa duodenum,
merangsang sekresi:
Mukus: melindungi mukosa duodenum dari iritasi
HCl & pepsin
Buffer :me pH (khime dlm duodenum pH: 1-2 sp7-8)
2. Kripte Lieberkuhn
Produksi enzim, cairan isotonik dan alkalin
Getah Usus halus
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
40/67
3. Enterosit vili
menghasilkan: amilase, enterokinase,
lipase, peptidase, disakaridase, yang
tidak dikeluarkan ke lumen namun akan
memecah lemak, protein, karbohidrat
begitu absorbsi dimulai
Getah Usus halus
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
41/67
1500 cc / hari
Mengandung: bikarbonat, elektrolit: Na,K,Cl,enzim
Mempunyai 2 fungsi:
1. Endokrin: sel endokrin sekresi insulin & glukagon2. Eksokrin: berasal dari sel asinus dan epitel: keduanya
menghasilkan cairan disebut cairan pankreas
(pancreatic juice) yg dikeluarkan ke usus halus.
enzim yang dikeluarkan sel asinus berguna untuk memecah
khime menjadi molekul kecil yang mudah diabsorbsi.
Sel epitel mengeluarkan air & ion untuk mengencerkan
khime & sebagai buffer
Getah Pankreas
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
42/67
Pengaturan sekresi melalui pengendalian
hormon. Bila khime masuk duodenum,
maka duodenum mengeluarkan hormon :
1. sekretin: memacu pankreas sekresi buffer
air dengan pH 7,5-8,8 dan buffer
bicarbonat serta fosfat
2. kolesistokinin: rangsang produksi dan
sekresi enzim pankreas
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
43/67
Pengaturan sekresi
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
44/67
Pengaturan sekresi
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
45/67
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
46/67
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
47/67
digestive enzymes secreted as inactive precursors(zymogens) to prevent autodigestion
important proteolytic enzymes are t ryps in,chymotryps inandcarboxypept idases
other enzymes are-
panc reatic l ipase panc reatic amylase
t ryps inogenis activated byenteropeptidasewhichis secreted by intestinal mucosa in response to
chyme trypsin then activates the other proenzymes
t ryps ininh ib i torsecreted to delay activation oftrypsinogen
Enzim pankreatik
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
48/67
F O O D
Aktifasi enzimatik
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
49/67
cephal ic phase~15% mainly causes secretion ofenzymes into the acini - vagus mediated
gastr ic phase~15% gastric distension by means of
vago-vagal reflex evokes enzyme secretion
gastrin release by antral lumen causing more enzymerelease
intest inal phase~70% -pancreatic HCO3 secretion
strongly stimulated when duodenal pH is acid - S
cellssecrete secretin into the blood and thisstimluates pancreatic duct cells
chyme also causes I cellsto release CCKwhich
causes pancreatic enzymes to be secreted (mainly
due to peptones and fatty acids)
Fase sekresi pankreas
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
50/67
Stimuli of Pancreatic Secretion
ACh - parasympathic vagus nerves as well as
myenteric cholinergics Gastrin - liberated during gastric phase ofstomach secretion
CCK (cholecystokinin) - secreted by duodenaland upper jejunal mucosa when food enters
small intestine these 3 all stimulate production of digestive
enzymes by the acini and act via IP3 to releaseintracellular Ca
Secretin - same duodenal and upper jejunalmucosa but secretin acts via cAMP on the ductalcells to increase HCO3 secretion
Ab b i h l
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
51/67
Pengiriman nutrientdari saluran cerna ke
sirkulasi, terutama tjd di usus halus
permukaan yang luas.
Absopsi efisien bila:
1. Bentuk hasil pencernaan baik
2. Permukaan absorpsi adekuat
3. Kecepatan/ waktu transit nutrientdi usus halus
4. Kofaktor dan atau karier spesifik
Absorbsi usus halus
Ab b i h l
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
52/67
1. Absorbsi air dan elektrolit
membranintestinalsangat permeabel
terhadap air
Air diserap menggunakan osmot ic gradient
Sebagian besarnutrientdiserap oleh
yeyunum
Absorbsi usus halus
Ab b i h l
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
53/67
brush border
permukaan absorbsi Na via Na channeldan Na-nutrient
cotransporter
Na dipompa ke darah oleh Na-K ATPase
Absorbsi usus halus
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
54/67
Ab b i h l
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
55/67
2. Pencernaan & absorpsi karbohidrat
300g / hari
Polisakarida kompleks: 64% pati, 0.5%
glikogen
Disakarida: 26% sukrosa, 6.5% laktosa,
3% MALTOSA
Hidrolisis lengkap 80% glucosa, 14%fruktosa, 5% galaktosa kapiler
Absorbsi usus halus
C b h d t b ti
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
56/67
Carbohydrate absorption
pancreatic juices cannot further hydrolyse
oligosaccharides brush borderoligosaccharidases
brush border lactase, sucrase-isomaltase andmaltase release monosaccharides (glucose,galactose and fructose)
glucose and galactose taken up by SGLT1 fructose by GLUT5
all three transported via GLUT2 out into theportal vein and to the liver
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
57/67
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
58/67
In a normal diet, bulk is Carbs, 250-800 g (ex. Atkins)
+ 125 g protein, +25-160 g fat.
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
59/67
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
60/67
Fat absorption
lipids- mainly triacylglycerols
1 - large oil droplets (shearing forces in gut)
2 - emulsified oil drops with bile salts
pancreatic lipase at oil-water interface
3 - formation of micelles
micelles come to the absorptive surface of gut
monoglycerides and free fatty acids are then
absorbed
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
61/67
4. inside cells resynthesis of triacylglycerols, cholesterol
and phospholipids to chylomicrons
5. secreted into lacteal and to systemic circulation to
adipose tissue where the chylomicron is stripped of its
triacylglycerols and chylomicron remnant goes to liver -dietary cholesterol to liver. free fatty acids are also
synthesised to prostaglandins (can act as local gut
hormones)
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
62/67
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
63/67
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
64/67
Product Absorption pathway
Carbohydrates Fru Facilitated diffusion
Glu/Gal Active Transport / Sodium
Protein Amino Acids Active transport / Sodium
Proteins (except.) endo-exocytosis
(infants mainly)
Fat Free Fatty Acids Diffusion
Monoglyc. Diffusion
Vitamins (fat) A, D, E, K Diffusion (via micelles)
Vitamins (water) B-12 Binds to Intrin. Factor.
Endocytosis
Iron Active Transport
then into ferritin
kolon
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
65/67
kolon
kolon
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
66/67
Sekresi:mukus yang diproduksi oleh sel goblet untuk
pelumas feses dan epitel
HCO3- , untuk menyeimbangkan asam produksi
bakteri
kolon
kolon
-
7/28/2019 Fisiologi Sekresi&Absopsi-blok Digest12
67/67
Absorbsi :
airOsmosis
elektrolit
vitamin yg dihasilkan kerja bakteri:
Vitamin K: larut lemak, untuk pembekuan darahBiotin: larut air, penting untuk metabolisne glukosa
Vitamin B5: asam pantotenat: larut air, untuk membuat
hormon steroid & beberapa neurotransmiter
Bakteri mengubah bilirubin menjadi urobilinogen
(diabsorpsi ke sirkulasi, dibuang melalui urin) dan
sterkobilin
kolon
top related