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

Explain the lectins or haemagglutinins, Explain the Lectins or Haemagglutin...

Explain the Lectins or Haemagglutinins? These are sugar binding proteins, having the ability to bind and agglutinate red blood cells (RBCs). You will find that they occur in mo

Determine the concept of neuropsychological test, Determine the concept of ...

Determine the concept of neuropsychological test A neuropsychological test therefore is defined as behavioural procedure that is particularly sensitive to the condition of the

Cartoon, A dialogue and cartoon between haemoglobin and chlorophyll

A dialogue and cartoon between haemoglobin and chlorophyll

Excretory system - kidney, Kidney - 2 in number. Dark red. Sl...

Kidney - 2 in number. Dark red. Slightly flattened. Bean shaped. 10 cm. long, 5 cm wide and 4 cm thick (In rabbit 20-25 mm). Weighing 150 gm in male 135 gm in fema

What is mefloquine, What is Mefloquine Mefloquine is taken once weekly,...

What is Mefloquine Mefloquine is taken once weekly, but recent reports of serious psychiatric adverse effects have prompted the manufacturer, along with the FDA, to strengthen

Explain the reproductive system, Explain the Reproductive System? The h...

Explain the Reproductive System? The human reproductive system produces not only reproductive organs and gametes, but also sex hormones, which have far-reaching effects on huma

Define nutrition counseling - management of eating disorders, Define Nutrit...

Define Nutrition Counseling - Management of Eating Disorders? Nutrition counseling can be used to accomplish a variety of goals, such as reducing behaviours related to the eati

What is the monohybridism, What is the monohybridism? The Monohybridism...

What is the monohybridism? The Monohybridism is the study of only one characteristic in the crossing of two pure individuals (hybridization) for that characteristic.

Tropical seasonal forests - ecosystem, Tropical seasonal forests - Ecosyste...

Tropical seasonal forests - Ecosystem Tropical seasonal forests occur in regions where total annual rainfall is very high but segregated into pronounced wet and dry periods. T

Relation between the hypophysis and the hypothalamus, Q. What is the relati...

Q. What is the relation between the hypophysis and the hypothalamus? The hypothalamus is a part of the brain situated just above the hypophysis and the hypothalamus gets centra

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