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

Extraembryonic membranes the same in all vertebrates, Are the extraembryoni...

Are the extraembryonic membranes the same in all vertebrates? The presence of each extraembryonic membrane varies according to the vertebrate class. In fishes and amphibians

Guidelines for diabetic patients for healthy coping, Q. Guidelines for Diab...

Q. Guidelines for Diabetic Patients for Healthy Coping? Generally, a diabetic patient adapts to day to day stress effectively, as they accept their disease condition with the s

Explain the function of muscular tissue, How can the presence, localization...

How can the presence, localization and function of muscular tissue in beings of the phylum Annelida be explained? In these beings there are a longitudinal muscular layer under

How much dna is in each stage, In meiosis - starting from stage G1 through ...

In meiosis - starting from stage G1 through the completion of meiosis, how much DNA is in each stage/phase when referring to the nucleus of spermatagonia?

Explain about the dietary reference intakes, Explain about the Dietary Refe...

Explain about the Dietary Reference Intakes? Dietary Reference Intakes (DRIs) are relatively new to the field of nutrition. The DRIs are a set of four nutrient-based reference

Electron acceptor, Electron acceptor is a molecule which forms the part of...

Electron acceptor is a molecule which forms the part of the electron transport system which transfers electrons ejected by chlorophyll during the process of photosynthesis. Part o

Define the beer''s law - nutritional biochemistry, Define the Beer's Law -...

Define the Beer's Law - Nutritional  Biochemistry? Beer's law states that the concentration of a substance is directly proportional to the amount of light absorbed or inversely

Which of the vertebrate classes are warm-blooded, Which of the vertebrate c...

Which of the vertebrate classes (a) are 'warm-blooded', (b) reproduce by laying eggs?   (a) Birds and mammals are 'warm-blooded'. (b) Fish, Amphibia, Reptiles

List the causes of implant failure, List the causes of implant failure due ...

List the causes of implant failure due to improper surgical technique and placement. Failure due to surgical techniques and improper placement: a) Off axis / severe angulati

Nitrogen waste eliminated by beings of the class reptilia, Q. Which is the ...

Q. Which is the kind of nitrogen waste eliminated by beings of the class Reptilia? These beings excrete mainly uric acid this substance is less toxic than ammonia and it can be

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