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

Why iron is required as a part of haemoglobin, Why Iron is required as a pa...

Why Iron is required as a part of haemoglobin? As a part of haemoglobin, iron is required for the transport of oxygen, to all cells in the body. Thus, haemoglobin is critical f

What are some examples of parasitism, What are some examples of parasitism?...

What are some examples of parasitism? Classical instances are the parasites of humans (host), as the trypanosome that causes Chagas' disease, the HIV virus (AIDS), the bacteria

What are the factors that for influencing photosynthesis, What are the fact...

What are the factors that for influencing photosynthesis also interfere with the gross primary productivity? Mostly water and light, but also mineral salts, temperature and car

Show some fungal diseases transmitted by animal feces, Q. What are some fun...

Q. What are some fungal diseases transmitted by animal feces? Pigeon and Bat feces can carry Histoplasma capsulatum, the fungus agent of histoplasmosis. The infection is transm

Chloroplast, Chloroplasts is the disk-like organelles with the double memb...

Chloroplasts is the disk-like organelles with the double membrane found in eukaryotic plant cells; contain thylakoids and are the site of the photosynthesis. ATP is produced durin

Kinds of hermaphroditism, Kinds of Hermaphroditism Depending upon the...

Kinds of Hermaphroditism Depending upon the timing of maturity of the gonads, hermaphroditism can be of two types 1. Simultaneous hermaphroditism . Both male and female g

Classification of carbohydrates - degree of polymerization, Define Classifi...

Define Classification of Carbohydrates - Degree of Polymerization? Classification on the basis of Degree of Polymerization (DP) Carbohydrates are classified by their degree

Determine the food-searching activity, The Svalbard ptarmigan (Lagopus mutu...

The Svalbard ptarmigan (Lagopus mutus hyperboreus) is a small herbivorous bird that lives permanently on the island chain of Svalbard. Svalbard is located in the Arctic Circle, app

How walking benefits for the health, Walking In the process of walking ...

Walking In the process of walking the motion of the two legs is coordinated so that one foot or the other is always in contact with ground. Walking is the best form of exercise

Explain protease inhibitors, Protease inhibitors (PIs) Protease inhibi...

Protease inhibitors (PIs) Protease inhibitors prevent cleavage of protein precursors essential for HIV maturation, infection of new cells and viral replication. Use of a prote

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