A secreção gástrica
description
Transcript of A secreção gástrica
A secreção gástrica
extraído de: Vander, Sherman & Luciano, 2002 – WEBsite original: http://www.biocourse.com/mhhe/bcc/domains/quad/topic.xsp?id=000270
Veja mais em: http://mcb.berkeley.edu/courses/mcb136/topic/Gastrointestinal/Secretion_in_GI-Tract/
http://anatomy.iupui.edu/courses/histo_D502/D502f03/f03_labs/Lab11/Lab11f03.html
células mucosas
células principais
células parietais
muco e HCO3-
pepsinogênio
HCl e Fator Intrínseco
SECREÇÕES EXÓCRINAS
Veja mais em: http://mcb.berkeley.edu/courses/mcb136/topic/Gastrointestinal/Secretion_in_GI-Tract/
SECREÇÕES GÁSTRICAS
Veja mais em: http://mcb.berkeley.edu/courses/mcb136/topic/Gastrointestinal/Secretion_in_GI-Tract/
Interações das secreções gástricas
mucous
extraído de: Vander, Sherman & Luciano, 2002 – WEBsite original: http://www.biocourse.com/mhhe/bcc/domains/quad/topic.xsp?id=000270
The protection provided to the mucosal surface of the stomach by the bicarbonate-containing mucus layer is known as the gastric mucosal barrier. In man, the mucus layer is about 0.2 mm thick. Buffering by the bicarbonate-rich secretions of the surface epithelial cells and the restraint to convective mixing caused by the high viscosity of the mucus layer allow the pH at the cell surface to remain near 7, whereas the pH in the gastric juice in the lumen is 1 to 2.
COX1: atividade ciclooxigenase da PGH2-sintase). Berne et al., 2004 e outros: http://meds.queensu.ca/medicine/physiol/undergrad/phase2/phase2e/Ph2acid.htm
secreção de muco e HCO3- pelas
células epiteliais e mucosas
fluxo sangüíneo
camada mucosa (0,2mm)
Proteção mucosa
ACh(PS e SNE)
Mecanismos intracelulares de secreção ácidagástrica (célula parietal)
extraído de: Vander, Sherman & Luciano, 2002 – WEBsite original: http://www.biocourse.com/mhhe/bcc/domains/quad/topic.xsp?id=000270
Model for the regulation of gastric acid secretion. Shown are a parietal cell, an ECL cell, a D cell, and many of the important regulators of acid secretion. Parietal cells are stimulated by three main agonists: gastrin, histamine, and ACh. Gastrin binds to CCKB (gastrin/cholecystokinin-B)receptors on the parietal cell to evoke an increase in
intracellular calcium; histamine binds to H2 receptors, which primarily signal through increased cAMP; ACh binds to M3 receptors to stimulate an increase in intracellular
calcium. Parietal cell stimulation results in movement of H+/K+-ATPase pumps to the apical membrane to secrete acid. Histamine is released from ECL cells in response to gastrin stimulation as well as neuronal stimulation via PACAP (pituitary adenylate cyclase-activating polypeptide). Somatostatin (Sst) released from D cells inhibits acid secretion by reducing ECL cell histamine release, blocking gastrin release, and directly inhibiting parietal cell acid secretion. Annual Review of Physiology March 2003, Vol. 65, pp. 383-400 Samuelson and Hinkle, 2003
Regulação da secreção ácida gástrica
Olbe, Carlsson & Lindberg, 2003. Nature Reviews Drug Discovery 2, 132-139 (2003) http://www.nature.com/cgi-taf/DynaPage.taf?file=/nrd/journal/v2/n2/full/nrd1010_r.html
Regulação da secreção ácida gástrica e ações de drogas anti-ácidas:
Regulação da secreção ácida gástricana fase cefálica
http://arbl.cvmbs.colostate.edu/hbooks/pathphys/digestion/stomach/index.html
Regulação da secreção ácida gástricana fase gástrica
http://arbl.cvmbs.colostate.edu/hbooks/pathphys/digestion/stomach/index.html
SECREÇÕES EXÓCRINASPANCREÁTICA E HEPÁTICA
http://www.nlm.nih.gov/medlineplus/ency/imagepages/1090.htm
?
VOLUME SECRETADO PELO
PÂNCREAS NO INTESTINO DELGADO:
1,5 L/DIA
secreção hidro-eletrolítica
enzimas digestivas(proteases,
amilase e lipases)
Principais tipos celulares encontrados no pâncreas
Ilhotas de Langerhanshormônios: insulina (cél. β),
glucagon (cél. α), somatostatina (cél. δ) e polipeptídeo pancreático (cél. θ)
ilhota (células alfa: glucagon) ilhota (células beta: insulina)
ácinos e ilhota de Langerhanshttp://www.udel.edu/Biology/Wags/histopage/histopage.htm
HISTOLOGIA DO PÂNCREAS
PORÇÃO ENDÓCRINA (hormônios: glucagon, insulina, somatostatina e polipeptídeo pancreático)
PORÇÃO EXÓCRINA enzimas e secreção hidroeletrolítica
http://www.gastroslides.org/main/browse_deck.asp?tpc=6&mxpg=390&pg=2241#image
The relationships and major features of the units of the exocrine pancreas. The pancreatic acinar cells of the acinus have prominently stained zymogen granules in the apical area of the cell. The connecting ductule does not contain zymogen granules. The blue cell in the cartoon depicts the centroacinar cell at the border between the acinus and ductule. The centroacinar cell functions similarly to the duct cell. The major secretory products of the acinus are digestive proenzymes and enzymes with lesser amounts of water and ions. The major secretory products of the duct are water and ions.
http://www.gastroslides.org/main/browse_deck.asp?tpc=6&mxpg=390&pg=2243#image
AS SECREÇÕES EXÓCRINAS PANCREÁTICAS: água e eletrólitos
The relationships and major features of the units of the exocrine pancreas. The pancreatic acinar cells of the acinus have prominently stained zymogen granules in the apical area of the cell. The connecting ductule does not contain zymogen granules. The blue cell in the cartoon depicts the centroacinar cell at the border between the acinus and ductule. The centroacinar cell functions similarly to the duct cell. The major secretory products of the acinus are digestive proenzymes and enzymes with lesser amounts of water and ions. The major secretory products of the duct are water and ions.
http://www.gastroslides.org/main/browse_deck.asp?tpc=6&mxpg=390&pg=2243#image
AS SECREÇÕES EXÓCRINAS PANCREÁTICAS: água e eletrólitos
Neutralization of gastric acid delivered to the duodenum is necessary for optimal digestion and absorption of a meal. Several mechanisms that are not shown are involved in the neutralization process. First, the meal provides buffers from digestion of protein and triglycerides. That is, the peptides and fatty acid products act as pH buffers. Another neutralization process is absorption of hydrogen ion by the duodenal mucosa. Finally, the pancreas, biliary system and duodenal mucosa secrete bicarbonate into the duodenal lumen for neutralization.
http://www.gastroslides.org/main/browse_deck.asp?tpc=6&mxpg=390&pg=2287#image
Importância da secreção hidroeletrolítica pancreática, rica em HCO3
-, Na+ e água na digestãoNaHCO3 + HCl NaCl + H2O + CO2 (reabsorção)
The relationships and major features of the units of the exocrine pancreas. The pancreatic acinar cells of the acinus have prominently stained zymogen granules in the apical area of the cell. The connecting ductule does not contain zymogen granules. The blue cell in the cartoon depicts the centroacinar cell at the border between the acinus and ductule. The centroacinar cell functions similarly to the duct cell. The major secretory products of the acinus are digestive proenzymes and enzymes with lesser amounts of water and ions. The major secretory products of the duct are water and ions. http://www.gastroslides.org/main/browse_deck.asp?tpc=6&mxpg=390&pg=2243#image
AS SECREÇÕES EXÓCRINAS PANCREÁTICAS: ENZIMAS
(from duodenal epithelial cells)
-Amylase (no activation needed)
secreted by duodenal epithelium
(Enterokinase)
http://mcb.berkeley.edu/courses/mcb136/topic/Gastrointestinal
AS SECREÇÕES EXÓCRINAS PANCREÁTICAS: enzimas
lipase
(from duodenal epithelial cells)
-Amylase (no activation needed)
secreted by duodenal epithelium
(Enterokinase)
http://mcb.berkeley.edu/courses/mcb136/topic/Gastrointestinal
AS SECREÇÕES EXÓCRINAS PANCREÁTICAS: enzimas
lipase
Relative amounts (by weight) of the different classes of pancreatic digestive enzymes. Proteases are the most abundant class of enzymes.
http://www.gastroslides.org/main/browse_deck.asp?tpc=6&mxpg=390&pg=2273#image
(from duodenal epithelial cells)
-Amylase (no activation needed)
secreted by duodenal epithelium
(Enterokinase)
http://mcb.berkeley.edu/courses/mcb136/topic/Gastrointestinal
AS SECREÇÕES EXÓCRINAS PANCREÁTICAS: enzimas
lipase
ALFA-AMILASE PANCREÁTICA:
Lipase pancreática
A secreção serosa pancreática: lipase pancreática
A secreção serosa pancreática: alfa-amilase
Amilopectina (amido) da batata
maltose dextrina-limite
ligação 1:6ligação 1:4
maltotriosealfa-amilase
Produtos da hidrólise do AMIDO pela alfa-amilase glicose
OBS: reparou que é a mesma ação da alfa-amilase salivar?
Vander, Sherman e Luciano, 1997
A secreção serosa pancreática:a ativação das pró-proteases pancreáticas no intestino
delgado pela enteroquinase (da borda-em-escova)
extraído de: Vander, Sherman & Luciano, 2002 – WEBsite original: http://www.biocourse.com/mhhe/bcc/domains/quad/topic.xsp?id=000270
PRÓ-PROTEASES PANCREÁTICAS:
Tripsinogênio TripsinaENTEROQUINASE
QuimotripsinogênioPro-carboxipeptidases A e B
QuimotripsinaCarboxipeptidases
pró-proteases pancreáticas: proteases pancreáticas:
ATIVAÇÃO DAS ENZIMAS PROTEOLÍTICAS PANCREÁTICAS
A secreção serosa pancreática:a ativação das pró-proteases pancreáticas no intestino
delgado pela enteroquinase (da borda-em-escova)
EnzimasNa+, Cl-,
HCO3-, K+ e
H2O
Na+Cl- HCO3-K+
EnzimasNa+, Cl-,
HCO3-, K+ e
H2O
ductos intercalares células acinares
CCKCCK
SecretinaSecretina
H2O
+
+
AS SECREÇÕES EXÓCRINAS PANCREÁTICAS
REGULAÇÃO DA SECREÇÃO EXÓCRINA PANCREÁTICA
estimulação hormonal pancreática
A presença de gordura e de ácido no duodeno estimula a secreção endócrina intestinal das células endócrinas “S” e “I”.
As céls. “S” secretam a SECRETINA que estimula a secreção hidro-eletrolítica dos ductos pancreáticos
This image shows the stimulants for release of CCK from I cells and secretin release from S cells. Of note, the I cells and S cells “taste” the specific stimulants in the lumen of the gut to activate release of the hormones. The released CCK can mediate pancreatic secretion by either activating vagal sensory afferents that results in stimulation of pancreatic acinar cell secretion though a vago-vagal reflex involving the CNS or through the circulation (i.e. hormonal action). Secretin also acts through neural (not shown) and hormonal pathways on the pancreas stimulating secretion from both ductal cells and acinar cells. http://www.gastroslides.org/main/browse_deck.asp?tpc=2&mxpg=390&pg=1842#image
A REGULAÇÃO DA SECREÇÃO DOS DUCTOS PELA SECRETINA
REGULAÇÃO DA SECREÇÃO EXÓCRINA PANCREÁTICA
estimulação hormonal pancreática
A presença de gordura e de ácido no duodeno estimula a secreção endócrina intestinal das células endócrinas “S” e “I”.
As céls. “I” secretam a CCKque estimula a secreção serosa dos ácinos pancreáticos
This image shows the stimulants for release of CCK from I cells and secretin release from S cells. Of note, the I cells and S cells “taste” the specific stimulants in the lumen of the gut to activate release of the hormones. The released CCK can mediate pancreatic secretion by either activating vagal sensory afferents that results in stimulation of pancreatic acinar cell secretion though a vago-vagal reflex involving the CNS or through the circulation (i.e. hormonal action). Secretin also acts through neural (not shown) and hormonal pathways on the pancreas stimulating secretion from both ductal cells and acinar cells. http://www.gastroslides.org/main/browse_deck.asp?tpc=2&mxpg=390&pg=1842#image
A REGULAÇÃO DA SECREÇÃO DOS DUCTOS PELA CCK
Regulação das secreção exócrina pancéática (ductos e ácinos) pelos hormônios intestinais
http://arbl.cvmbs.colostate.edu/hbooks/pathphys/digestion/pancreas/control.html
The graphic in this image depicts the neurotransmission systems and neurotransmitters involved in regulating acinar and ductal secretion. The blue cell is called a centroacinar cell. These cells have characteristics more similar to ductal cells although their exact function is not known. Vagal efferents activate neurons in the intrapancreatic ganglia. Neurons from the ganglia then have processes that are in proximity to the parenchymal cells. These processes release the neurotransmitters, acetylcholine (Ach), gastrin releasing peptide (GRP) and vasoactive intestinal polypeptide (VIP) when their neurons are activated. Ach causes secretion from both acinar cells and ducts while all three neurotransmitters can cause secretion from acinar cells.
http://www.gastroslides.org/main/browse_deck.asp?tpc=2&mxpg=390&pg=1842#image
toxinas de escorpiõesinseticidas organofosforados
Exposição a inseticidas organofosforados (inibidores da acetilcolinesterase) ou toxinas específicas de escorpiões causam um aumento nos níveis de liberação de acetilcolina nas terminações nervosas, podendo causar pancreatite. A picada do escorpião Tityus serrulatus também tem sido causa de pancreatite.
(G. Robles-Diaz, Mexico).
RELEVÂNCIA CLÍNICA DE TAIS CONHECIMENTOS
http://www.gastroslides.org/main/browse_deck.asp?tpc=6&mxpg=390&pg=2317#image
A secreção exócrina hepática
http://www.nlm.nih.gov/medlineplus/ency/imagepages/1090.htm
Bile is a digestive fluid secreted by the liver and stored in the gallbladder which normally is released into the duodenum portion of the small intestine through the sphincter of Oddi. Bile, released after a meal containing fats, aids in absorption and digestion of the fat.
A secreção exócrina hepática: a bile
http://www.nlm.nih.gov/medlineplus/ency/imagepages/1090.htm
Veja mais em: http://mcb.berkeley.edu/courses/mcb136/topic/Gastrointestinal/Secretion_in_GI-Tract/
Função digestiva da bile: sais biliares
extraído de: Vander, Sherman & Luciano, 2002 – WEBsite original: http://www.biocourse.com/mhhe/bcc/domains/quad/topic.xsp?id=000270
Sais biliares e a emulsificação das gorduras
extraído de: Vander, Sherman & Luciano, 2002 – WEBsite original: http://www.biocourse.com/mhhe/bcc/domains/quad/topic.xsp?id=000270
Sais biliares e a emulsificação das gorduras:a formação das micelas para a digestão pela lipase pancreática
MICELA
extraído de: Vander, Sherman & Luciano, 2002 – WEBsite original: http://www.biocourse.com/mhhe/bcc/domains/quad/topic.xsp?id=000270
Resumo da emulsificação, digestão e absorção de gordura
extraído de: Vander, Sherman & Luciano, 2002 – WEBsite original: http://www.biocourse.com/mhhe/bcc/domains/quad/topic.xsp?id=000270
A circulação êntero-hepática dos sais biliares
extraído de: Vander, Sherman & Luciano, 2002 – WEBsite original: http://www.biocourse.com/mhhe/bcc/domains/quad/topic.xsp?id=000270
REGULAÇÃO DA SECREÇÃO BILIARProdução de bile+circulação êntero-hepática dos sais biliares e esvaziamento da vesícula biliar e relaxamento de Oddi pela CCK
?
?
extraído de: Vander, Sherman & Luciano, 2002 – WEBsite original: http://www.biocourse.com/mhhe/bcc/domains/quad/topic.xsp?id=000270
A secreção exócrina intestinal:mucosa e hidroeletrolítica
Enzimas do intestino delgado:enzimas da borda-em-escova (constitucionais)
para a digestão final de proteínas e carbohidratos
extraído de: Vander, Sherman & Luciano, 2002 – WEBsite original: http://www.biocourse.com/mhhe/bcc/domains/quad/topic.xsp?id=000270
Enzimas do intestino delgado:enzimas da borda-em-escova (constitucionais)
para a digestão final de proteínas e carbohidratos
A secreção exócrina intestinal:mucosa e hidroeletrolítica
LARGE INTESTINE
célula parietal
absorção da Vitamina B12
<>
http://www.uq.edu.au/vdu/HDUAnaemiaMegaloblastic.htm e http://www.animatedmedical.com/Pernanem/pernanem.html e http://www-ermm.cbcu.cam.ac.uk/03006434h.htm
Fator Intrínseco e a absorção da Vit. B12
Células “G” secretoras de GASTRINA
http://calloso.med.mun.ca/~tscott/digest/digtut.htm
Regulação da secreção ácida gástricana fase intestinal
http://arbl.cvmbs.colostate.edu/hbooks/pathphys/digestion/stomach/index.html