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

Types of oxygenators, Types of Oxygenators a) Film Oxygenators b) ...

Types of Oxygenators a) Film Oxygenators b) Disc Oxygenators c) Bubble Oxygenators d) Membrane Oxygenators. Film and Disc Oxygenators are not used for clinical

Explain cyanotic heart disease breifly, Explain Cyanotic Heart Disease brei...

Explain Cyanotic Heart Disease breifly? Presence of cyanosis means deoxygenated blood reaching the systemic circulation bypassing the lungs i.e., right to left shunt. Uniform c

Significance of mitosis, Significance of Mitosis 1.      Reproduction ...

Significance of Mitosis 1.      Reproduction ;   William Bateson 1906 wrote, Whenever  I observe a dividing  cell under  the  microscope , I feel  as if the original act of  c

What do you determine by mantle, What do you determine by Mantle? A thi...

What do you determine by Mantle? A thin sheetlike membranous extension of visceral mass of molluscs which forms two flaps of skin. Mantle secretes the shell on the dorsal side

Explain the future challenges for neuroscience, Explain the Future challeng...

Explain the Future challenges for Neuroscience? When the analysis of single cells and even networks has progressed very nicely, there still remain many significant questions. A

What is calvin cycle, What is Calvin Cycle? The dark reactions of photo...

What is Calvin Cycle? The dark reactions of photosynthesis are also known as the Calvin cycle. This process synthesizes glucose molecules using carbon dioxide from the atmosphe

General characteristics of protozoans, General Characteristics of Protozoan...

General Characteristics of Protozoans The protozoans, are eukaryotes that form a group of about 80,000 single-celled organisms under the kingdom Protista. The unicellular leve

Precautions used during a fever in a human, During a fever in a human  ...

During a fever in a human   A.  shivering may occur when the actual body temperature is lower than the set point for body temperature during the fever.   B.  there is an inc

What is the importance of vitamin D, Importance of vitamin D Vitamin D ...

Importance of vitamin D Vitamin D is mainly involved in the  calcium and phosphate metabolism. It usually promotes absorption of calcium and inorganic phosphate from the intest

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