Define about the paracellular route - calcium, Biology

Assignment Help:

Define about the Paracellular Route - Calcium?

It involves passive Ca transport through the tight junctions between mucosal cells. The salient features include:

  • It is independent of nutritional and physiological regulation.
  • It is concentration-dependent and occurs when there is an increased intake or a person is taking supplements.
  • It occurs throughout the small intestine, ileum being the important site.

Thus, we can say that most Ca absorption takes place in the small intestine. There is some evidence, which suggests that not more than 4% (8 mg) of dietary Ca is absorbed by the colon per day. The unabsorbed component which appears in the faeces together with the unabsorbed component of digestive juice calcium is known as endogenous faecal calcium. The faeces, therefore, contain unabsorbed dietary calcium and digestive juice calcium that was not reabsorbed. True absorbed calcium is the total amount of calcium absorbed from the calcium pool in the intestines and therefore contains both dietary and digestive juice components.

Net absorbed calcium is the difference between dietary calcium and, faecal calcium and is numerically the same as true absorbed calcium minus endogenous faecal calcium. At zero calcium intake, all the faecal calcium is endogenous and represents the digestive juice calcium which has not been reabsorbed; net absorbed calcium at this intake is therefore negative to the extent of about 200 mg (5 mmol). When the intake reaches about 200mg (5 mmol), dietary and faecal calcium becomes equal and net absorbed calcium is zero. As calcium intake increases, net absorbed calcium also increases, steeply at first but then, as the active transport becomes saturated, more slowly until the slope of absorbed or ingested calcium approaches linearity with an ultimate gradient of about 5 -10%. True absorption is an inverse function of calcium intake, falling from some 70 % at very low intakes to about 35% at high intakes. There are several factors which influence the amount of calcium absorbed through the intestine. These factors can thus be related to the bioavailability of calcium. The subsequent discussion will look at these factors in detail. But first we shall look at the excretion of unabsorbed calcium.


Related Discussions:- Define about the paracellular route - calcium

How many cells are in the human body, How many cells are in the human body?...

How many cells are in the human body? According to "The Handy Science Answer Book" noted by the Science and Technology Department of the Carnegie Library of Pittsburgh (1994) th

Agro industrial-biological evaluation of feedstuff, Biological evaluation ...

Biological evaluation A small livestock unit if attached with a mill will be of immense help. Since inspite analyzing for various mycotoxins still we face some problems, at lea

Explain the plating method - pure culture techniques, Explain the Plating M...

Explain the Plating Method - Pure Culture Techniques? Plating method is one of the commonly employed methods for getting a pure culture.  The procedure involves the separation

Chiropterophily - cross-pollination, Chiropterophily - Cross-pollination ...

Chiropterophily - Cross-pollination Pollination brought about by bats is called cheiropterophily. Bats which feed at night and do not see very well, are frequent pollinators i

State what is genetic engineering, State what is Genetic engineering Ge...

State what is Genetic engineering Genetically engineered plant-incorporated protectants are created by a process that utilizes  several dissimilar modern scientific techniques

Photosynthesis, in a school laboratory, what is usually regarded as evidenc...

in a school laboratory, what is usually regarded as evidence that photosynthesis has occurred in plants

Inhibitor proteins - enzyme-activity control, Inhibitor Proteins - Enzyme-a...

Inhibitor Proteins - Enzyme-activity Control One kind of inhibitor protein found in higher plants is an endopeptidase which degrades nitrate reductase thus causing irreversibl

What is the genotypical proportion of the gametes, Which is the type of gam...

Which is the type of gamete (for a given trait) produced by a dominant homozygous individual? What is the genotypical proportion of these gametes? What about a recessive homozygous

Respiration, lesson plan practical requirements

lesson plan practical requirements

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd