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

What is the formula for photosynthesis, What is the formula for photosynthe...

What is the formula for photosynthesis? H 2 O + 6CO 2 + Light Energy ----> C 6 H 12 O6+ 6O 2 6 molecules of water + 6 molecules of carbon dioxide --->1 molecule of glucose

Define absorption, Define Absorption, Storage and Elimination of Vitamin D?...

Define Absorption, Storage and Elimination of Vitamin D? As we have already mentioned earlier, all fat-soluble vitamins share a common metabolic fate. Vitamin D is absorbed al

Medicinal value - conservation of wildlife, Medicinal Value - Conservation ...

Medicinal Value - Conservation of Wildlife About 40% of all drugs used throughout the world have active ingredients extracted from plants and animals. The world-wide annual sa

Explain thalamus and hypothalamus, Q. Explain Thalamus and Hypothalamus ? ...

Q. Explain Thalamus and Hypothalamus ? Thalamus and Hypothalamus: The thalamus is situated in the forebrain at the uppermost part of the diencephalon (posterior part of the for

Cleavage of fructose-1, Cleavage of fructose-1,6-bisphosphate Aldolase...

Cleavage of fructose-1,6-bisphosphate Aldolase cleaves  fructose-1, 6-bisphosphate to dihydroxyacetone phosphate and glyceraldehyde-3-phosphate in the reversible reaction.

S-gene, S-Gene The S-gene has been suggested to be a super gene comple...

S-Gene The S-gene has been suggested to be a super gene complex with several linked genes. It is supposed to have at least six (may he more) closely-linked genes which determi

What is mendels crosses in genetics explain breifly, What is Mendel's Cross...

What is Mendel's Crosses in genetics explain breifly? Mendel found that if he transferred pollen from a green-seed strain to a yellow-seed strain and vice versa, in a process c

Crab, What are the excretory organs of crab

What are the excretory organs of crab

Oxygen - factors influencing functions of nitrogenase, Oxygen - Factors Inf...

Oxygen - Factors Influencing Functions of Nitrogenase Oxygen is a strong inhibitor of N 2 -fixation because it blocks both the synthesis as well as the activity of nitrogenase

Find human anatomy & physiology laboratory manual, I can not find Human Ana...

I can not find Human Anatomy & Physiology Laboratory manual 10th edition cat version by Marieb/mitchell in expertsmind homework help, I have the text book just need to make sure I

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