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Histology

he wall of the stomach is made of the same four layers as most of the rest of the alimentary canal, but with adaptations to the mucosa and muscularis for the unique functions of this organ. In addition to the typical circular and longitudinal smooth muscle layers, the muscularis has an third layer of muscle, the oblique muscle layer ( [link] )which allows the stomach to vigorously churn food, mechanically breaking it down into smaller particles.

Histology of the stomach

This diagram shows the histological cross-section of the stomach. The left panel shows the stomach and the center panel shows a magnified view of a small region including the epithelium and the gastric glands. The right panel shows a further magnification of the mucosa and the different cell types are labeled.
The stomach wall is adapted for the functions of the stomach. In the epithelium, gastric pits lead to gastric glands that secrete gastric juice. The gastric glands (one gland is shown enlarged on the right) contain different types of cells that secrete a variety of enzymes, including hydrochloride acid, which activates the protein-digesting enzyme pepsin.

The stomach mucosa’s epithelial lining consists only of surface mucus cells, which secrete a protective coat of alkaline mucus. A vast number of gastric pits dot the surface of the epithelium, giving it the appearance of a well-used pincushion, and mark the entry to each gastric gland    , which secretes a complex digestive fluid referred to as gastric juice .

Although the walls of the gastric pits are made up primarily of mucus cells, the gastric glands also include chief cells and parietal cells. Cells that make up the area of the pyloris secrete mucus and a number of hormones, including the majority of the stimulatory hormone, gastrin    . The much larger glands of the fundus and body of the stomach, the site of most chemical digestion, produce most of the gastric secretions. These glands are made up of a variety of secretory cells. These include parietal cells, chief cells, mucous neck cells, and enteroendocrine cells.

Parietal cells —Located primarily in the middle region of the gastric glands are parietal cells which produce both hydrochloric acid (HCl)    and intrinsic factor    . HCl is responsible for the high acidity (pH 1.5 to 3.5) of the stomach contents and is needed to activate the protein-digesting enzyme, pepsin . The acidity also kills much of the bacteria you ingest with food and helps to break down proteins, making them more available for enzymatic digestion. Intrinsic factor is a glycoprotein necessary for the absorption of vitamin B 12 in the small intestine.

Chief cells —Also located primarily in the gastric glands are chief cells , which secrete pepsinogen    , the inactive substance that will convert to pepsin. HCl is necessary for the conversion of pepsinogen to pepsin. Enteroendocrine cells —Finally, enteroendocrine cells which are also found in the gastric glands secrete various hormones. Do not take notes on table below.

[link] describes the digestive functions of important hormones secreted by the stomach.

Hormones Secreted by the Stomach
Hormone Production site Production stimulus Target organ Action
Gastrin Stomach mucosa, mainly G cells of the pyloric antrum Presence of peptides and amino acids in stomach Stomach Increases secretion by gastric glands; promotes gastric emptying
Gastrin Stomach mucosa, mainly G cells of the pyloric antrum Presence of peptides and amino acids in stomach Small intestine Promotes intestinal muscle contraction
Gastrin Stomach mucosa, mainly G cells of the pyloric antrum Presence of peptides and amino acids in stomach Ileocecal valve Relaxes valve
Gastrin Stomach mucosa, mainly G cells of the pyloric antrum Presence of peptides and amino acids in stomach Large intestine Triggers mass movements
Ghrelin Stomach mucosa, mainly fundus Fasting state (levels increase just prior to meals) Hypothalamus Regulates food intake, primarily by stimulating hunger and satiety
Histamine Stomach mucosa Presence of food in the stomach Stomach Stimulates parietal cells to release HCl
Serotonin Stomach mucosa Presence of food in the stomach Stomach Contracts stomach muscle
Somatostatin Mucosa of stomach, especially pyloric antrum; also duodenum Presence of food in the stomach; sympathetic axon stimulation Stomach Restricts all gastric secretions, gastric motility, and emptying
Somatostatin Mucosa of stomach, especially pyloric antrum; also duodenum Presence of food in the stomach; sympathetic axon stimulation Pancreas Restricts pancreatic secretions
Somatostatin Mucosa of stomach, especially pyloric antrum; also duodenum Presence of food in the stomach; sympathetic axon stimulation Small intestine Reduces intestinal absorption by reducing blood flow

Questions & Answers

where we get a research paper on Nano chemistry....?
Maira Reply
nanopartical of organic/inorganic / physical chemistry , pdf / thesis / review
Ali
what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
Google
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
hey
Giriraj
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
revolt
da
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
ya I also want to know the raman spectra
Bhagvanji
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
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Source:  OpenStax, Digestive system. OpenStax CNX. Feb 23, 2015 Download for free at http://legacy.cnx.org/content/col11761/1.1
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