Lecture 7.B. - Mineral Absorption

Question 1

Absorption of Ca++ in the Duodenum is via the _______ route, while in the Jejunum and Ileum it is via the _______ route.

Answer 1

Transcellular

Paracellular

Question 2

Ca++ is brought into cells via CaT1 or _____ via diffusion down its concentration gradient. In the cell, Ca++ binds ______ for transport to the ______ and/or the Na+/Ca++ exchanger on the Basolateral side.

Answer 2

TRPV6

Calbindin

Ca++ ATPase

Question 3

Vit ____ stimulates absorption of Ca++ via all aspects of its mechs for absorption.

Answer 3

Vit D

Question 4

Dietary Fe+++ needs to be ______ before it can pass through _____, which moves it from the Lumen into the cell with H+ via facilitated diffusion.

Heme from red meats undergoes similar uptake via Facilitated diffusion by a Heme transporter –> Inside the cell, _____ is separated from Heme via ______, and it is then processed the same way as absorbed dietary Fe++.

Answer 4

Reduced

DMT1

Fe++

HO2

Question 5

If Fe++ is to be absorbed, it _____ (reversibly or irreversibly?) binds to ______. If it is to be excreted, it _______ (reversibly or irreversibly?) binds to _______ as Fe+++.

Answer 5

Reversibly

Mobilferrin

Irreversibly

Ferritin

Question 6

For absorbed Iron to be transported in the blood, it needs to be transported out of the basolateral side of the cell via ______ and simultaneously oxidized to Fe+++ by ______. The Fe+++ can then bind ______ in the blood.

Answer 6

Ferroportin 1 (FPN1)

Hephaestin

Transferrin

Question 7

When plasma Fe+++ levels are low, there will be excess unbound ______. This is detected by receptors on the basolateral side of ____ cells which then produce more ______ (which facilitates Fe++ absorption.)

Think about how this compares to crypt cell activity with Fe++ overload.

Answer 7

Transferrin

Crypt cells

Mobilferrin

With Fe++ overload, Crypt cells will produce more Ferritin.

Question 8

In Hereditarty Hemochromatosis, there is a defect in the ______ receptor, so it doesn’t recognize Transferrin bound to Fe++. Thus, crypt cells will continue to produce _____, thinking the body is deficient in Fe++.

Answer 8

TfR1 (Transferrin receptor)

Mobilferrin