This document discusses several topics related to the digestive system: 1. It describes the spatial and temporal variations in microbial composition throughout the gastrointestinal tract and over time. 2. It outlines two opposing models of how taste qualities are encoded in the peripheral nervous system - the labelled-line model and the across-fibre pattern model. 3. It provides an overview of the histological organization of the digestive tube, including descriptions of cells in the digestive tract like enterocytes.

1. SISTEMA DIGESTIVO

2. Spatial and temporal aspects of intestinal microbiota composition.
A: variations in microbial numbers and composition across the length of the gastrointestinal tract.
B: longitudinal variations in microbial composition in the intestine.
C: temporal aspects of microbiota establishment and maintenance and factors influencing
microbial composition.
Sekirov Inna; Shannon L. Russell; L. Caetano M. Antunes and B. Brett Finlay.
2010. Gut Microbiota in Health and Disease. Physiological Reviews 90: 859-

5. Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins
There are two opposing views of how taste qualities are encoded in the periphery.
a, In the labelled-line model, receptor cells are tuned to respond to single taste modalities — sweet, bitter, sour,
salty or umami — and are innervated by individually tuned nerve fibres. In this case, each taste quality is
specified by the activity of non-overlapping cells and fibres.
b,c, Two contrasting models of what is known as the 'across-fibre pattern'. This states that either individual TRCs
are tuned to multiple taste qualities (indicated by various tones of grey and multicoloured stippled nuclei), and
consequently the same afferent fibre carries information for more than one taste modality
(b), or that TRCs are still tuned to single taste qualities but the same afferent fibre carries information for more
than one taste modality
(c). In these two models, the specification of any one taste quality is embedded in a complex pattern of activity
across various lines. Recent molecular and functional studies in mice have demonstrated that different TRCs
define the different taste modalities, and that activation of a single type of TRC is sufficient to encode taste
quality, strongly supporting the labelled-line model.

9. Organización histológica global del tubo digestivo

10. Estómago

11. El enterocito es parte de la unidad estructural y funcional del sistema digestivo.
Membrana especializada en el transporte de moléculas
Tipos de celulas en el tracto digestivo

12. Blood
capillaries
Lacteal
Microvilli
brush border
Tight junction
Desmosome
Cell membrane
Mitochondrion
Rough
endoplasmic
reticulum
Ribosome
Golgi’s
saccule
Nucleus
Enterocyte Brush border
Glycocalyx
Glycocalyx
Actin
filaments
Cell
membrane
Myosin
filaments
Terminal
web
Fig. 2-6, p. 30Pácha J Physiol Rev 2000;80:1633-1667
ORGANIZACIÓN DEL ENTEROCITO

13. YEYUNO
Las Células Madre de los
enterocitos se encuentran en
«las criptas de lieberkûhn»
los enterocitos tienen un
tiempo de vida de 3 a 5 dias
Yeyuno: ácido fólico o vitamina B9
CICLO CELULAR

14. se absorben la vitamina B12 y las sales biliares
ÍLEON

16. APENDICE CECAL

17. Vesícula biliar

18. Hígado: HEPATOCITO
H (hepatocito)

19. PÂNCREAS(H.E)
N:núcleo,n:nucléolo,Ac:ácino,
Gz:grânulos de zimogênio
PÁNCREAS