Photo created by the author with canva AntiDiuretic Hormone|vasopressin |Endocrinology Keywords : What is anti-diuretic hormone. What are the main functions of ADH? What is vasopressin? Herring bodies| Magnocellular neurosecretory neurons | Prepropressophysin| Neurophysin II Table of contents 1. Introduction 2. Site of secretion 3. Regulation of secretion 4. Mechanism of secretion 5. Functions Introduction In this article, we will learn about anti-diuretic hormones in detail, including the site of secretion, the regulation of its secretion, the mechanism of action, and more. About’ totalphysiology.com.’ This article is part of my mission to provide trustworthy recent health information to support the general public, patients, and professionals globally. Here, you will find human Physiology and health-related topics. This article is intended for all learners and medical care providers. This activity aims for learners to better apply the latest scientific knowledge.
© 2021 Google
Dietary fiber | Healthy diet
Keywords: carbohydrate, polysaccharide, microbiota, sources, recommended dose.
Dietary fibre is also known as roughage. A type of
carbohydrate that the human body cannot
digest - cannot be completely broken
down by human digestive enzymes. It occurs in foods of plant origin for
example fruits, vegetables, nuts, seeds,
beans, cereals and whole grains. It may
be defined in many ways.
Widely accepted definition: all polysaccharides and lignin, which are not
digested by the human gastrointestinal system.
Physiological
definition: the dietary component resistant to degradation by mammalian
enzymes.
Chemical
definition: The sum of non-starch polysaccharides and lignin-a major dietary
insoluble fibre source.
Components
of dietary fibres:
Dietary
fibre has two main components 1. Soluble fibre and 2.Insoluble fibre. Their chemical compositions
are different. They are grouped according to their solubility, viscosity and
fermentability.
Soluble
fibre = fermentable fibre or prebiotic fibre dissolves
in water and generally fermented in the colon
by gut flora into gases and short-chain fatty acids and other
physiologically active substances.
Soluble
fibre is usually viscous and delays gastric emptying
which results in an extended feeling of fullness. Soluble fibre may be non-viscous e.g. Inulin, wheat
dextrin, resistant starches.
Regular
intake of soluble fibre such as oat or barley lowers low-density lipoprotein
and cholesterol.
Examples
of water-soluble fibres are :
Insulin-
present in the diverse plant.
Pectin:
present in the fruit skin, vegetables.
Raffinose:
present in legumes.
Insoluble fibre does not dissolve in water for example –wheat bran, cellulose, and lignin. Some insoluble fibre –resistant starches can be fermented in the colon. Coarsely ground Insoluble fibre triggers the secretion of mucus in the large intestine providing bulky stool, but finely ground insoluble fibre does not have this effect and can have a constipating effect.
Examples of water-insoluble fibres :
Cellulose: A polysaccharide found in the cell walls of
all plants are one of the main
components of insoluble dietary fibre -cereals, fruit, vegetables.
Hemicellulose-
present in cereals, bran, legumes.
Hexoses-
present in wheat, barley.
Pentose-
present in rye, oat.
Lignin
– present in vegetables, cereals, stones of fruit.
Mechanism
of action: They change the nature of the contents of the GIT and change the absorption of nutrients. Some Soluble fibre absorbs water and becomes viscous substances. Some soluble fibre is fermented in the
colon. Generally, soluble fibre is fermented more than insoluble fibre in
the colon. Some insoluble fibre makes the bulk of stool. Some insoluble fibre may
be slowly fermented in the colon in addition to the faecal bulking effect.
Dietary fibres perform three main functions: bulking, viscosity and
fermentation. The viscosity of dietary fibres reduces post-prandial blood
glucose concentration. Dietary fibres interact with pancreatic and succus entericus and their substrates. It reduces the
activity of digestive enzymes. Dietary fibres are essential to digestion and help promote
regular bowel movements, lower blood sugar and cholesterol and may help reduce
a person’s calorie intake. It decreases the risk of coronary heart disease and
diabetes.
Functions
of bile acids are reduced as they may be trapped in the high luminal viscosity or because they may bind to dietary fibre.
The
dietary fibres are not digested
in humans as they lack the necessary enzymes to split the glycosidic bond and not absorbed in the small intestine, they pass
into the large intestine relatively intact. In the large intestine, they are fermented to short-chain fatty acids, hydrogen, carbon
dioxide and fatty acids by gut flora microbiota. Almost all of these short-chain fatty acids
are absorbed in the colon and have several possible actions on the gut mucosa. The
major short-chain fatty acids are Butyrate, Propionate and acetate.
Butyric
acid appears to be used as a fuel by the colonic mucosa as the preferred energy
source for colonic cells colonocytes.
Propionic acid affects cholesterol metabolism in the liver.
Acetate
enters the peripheral circulation to be metabolized by peripheral tissues.
Functions
of short-chain fatty acids :
1.
Stimulate gene expression of glucose transporters in the intestinal mucosa, regulating
glucose absorption.
2.
Stabilize blood glucose levels by regulating insulin release from the pancreas and
liver control of glycogen breakdown.
3. Suppress cholesterol synthesis by the liver.
4.
Stimulate the production of T helper cells, antibodies. leukocytes, cytokines etc –have a role in immune
mechanism.
5.
Raise the acidity in the colon, causing increase absorption of dietary
minerals.
6.
Improve barrier properties of the colonic mucosal layer, inhibiting inflammatory and adhesion irritant mechanism
contributing to the immune system and
protect from carcinoma colon.
Overall
short-chain fatty acids affect the major regulatory system, such
as blood glucose lipid levels, intestinal
immune functions and colonic environment.
Recommended
dose: The FDA (Food and Drug Administration
)recommends 28 gm of dietary fibre per day in a 2000 calorie diet. Dietary
fibre is even more important for older people.
Sources
are fruits, vegetables, nuts, seeds beans and whole grains. If it is not
present in dietary fibre may be given as dietary supplements. Fibre-rich processed
foods are also available. The amount of fibre present in common foods are:
Cooked
dry beans: half cup: 8.0 gm
Dark
green vegetables: half cup: 6.5
gm
Orange vegetables: half cup: 2gm
Starchy
vegetables: half cup: 1.7 gm
Whole
grain: 28 gm 2.5
gm
Fruit: half cup 1.0
gm.
Internal link:
https://totalphysology20.blogspot.com/2021/02/glands-we
must know
https://totalphysology20.blogspot.com/2021/03/small intestine we must know
https://totalphysology20.blogspot.com/2021/04/large
intestine we must know
https://totalphysology20.blogspot.com/2021/05
/bile- we must know
https://totalphysology20.blogspot.com/2021/05
/gut-brain axis- we must know
https://totalphysology20.blogspot.com/2021/05
/liver functions- we must know
External link:
https://en.m.wikipedia.org>wiki
https://www.sciencedirect.com>topics
https://www.betterhealth.vic.gov.au>
https://www.healthline.com>nutrition
https://www.nestle.in
.nutrients >di
Please follow on email and Twitter,
#health #carbohydrate
#microbiota #polysaccharide #recommendeddose #sources #fibre #fiber #dietry #enzyme
Comments
Post a Comment