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

Skin, SKIN - Largest organ of body. It is covered by hair...

SKIN - Largest organ of body. It is covered by hairs or pelage i.e. pillifera. Study of skin is dermatology. Outermost covering of body. Skin is elastic and

Which are specialized conductive tissues of the plants, Which are specializ...

Which are specialized conductive tissues of the plants? Vascular tissues of the plants are the phloem and the xylem. The Xylem is the plant tissue that forms the vessels that c

How to use subcellular fractionation and a western blot, A virus capsid con...

A virus capsid containing vimentin, your protein of interest, gets into the cell nucleus and is broken down with the DNA being released. It is unknown whether the capsids themselve

Treatment of water for industrial use, Water is widely used in various proc...

Water is widely used in various process applications in industry. Other major industrial uses are boiler feed water and cooling water. The king and degree of treatment of water in

Determine effects of probiotics on animals, Determine Effects of probiotics...

Determine Effects of probiotics on Animals? Let us briefly examine the effects that have been reported (remember most of it has been on animals): 1. In animals, probio

Ecology, three types of trophic pyramids

three types of trophic pyramids

Abdomen - hypertension, The purpose of examining the abdomen should be for ...

The purpose of examining the abdomen should be for detection of renal artery bruit and abnormal kidney masses like kidney tumours and polycystic kidneys. Aortic abdominal aneurysms

Define deficiency and toxicity of vitamin d, Define Deficiency and Toxicity...

Define Deficiency and Toxicity of Vitamin D? Infants constitute a population at-risk for vitamin D deficiency because of relatively large vitamin D needs brought about by their

Define biosynthesis and secretion of thyroid hormones, Define Biosynthesis ...

Define Biosynthesis and Secretion of Thyroid Hormones? Histologically, the functional cells of the thyroid gland are arranged in follicles, which surround a central lumen conta

Types of asexual reproduction, TYPES OF ASEXUAL REPRODUCTION ...

TYPES OF ASEXUAL REPRODUCTION 1 . Binar y fission - Amoeba 2. Multipl e fission -

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