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Old 04-27-2012
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GIT Mechanism of Vitamin Absorption!

Self-made question, watch out for mistakes (they are possible)
=======================================

A 40-old car-sales manager was working hard the previous year and now presents with the following symptoms: he has poor coordination of hands, speech and eye movements. You notice poor overall body coordination, loss of vibratory sensation in the lower extremities. Blood analysis shows anemia. You suspect a vitamin deficiency due to a chronic inflammatory process of the partially retroperitoneal abdominal organ. Through what mechanism is the vitamin absorbed from the intestine?

a. passive diffusion.
b. active uniporter
c. active symporter
d. active cotransporter.
e. voltage-gated channel
f. transmitter-gated channel
g. g-protein linked receptor
h. enzyme-linked receptor.
i. LDL-receptor

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Old 04-27-2012
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B12?

so ummmm H?
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First I'm assuming its B12 due to the peripheral neuropathy symptoms. Second I know B12 is absorbed through the IF-B12 complex, however I know IF is a glycoprotein but my problem is classifying it as an enzyme.
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h. enzyme-linked receptor.
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Its Vitamin E deficiency (Cerebellar ataxia, anemia due to oxidative stress)
not B12 because only one year is mentioned (+ speech and eyes are not involved in b12 deficiency I believe)

Fat soluble vitamins are absorbed via uniporter, an active carrier mechanism (Fatty acid Transporter [FAT])

Answer b
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Thanks for the answer. What tricked me is the fact that I immediately though eye=B12 instead of optic nerve=B12 and eye muscles= Vit E.

Here the medscape Vitamin B-12 Associated Neurological Diseases Clinical Presentation
Quote:
The neurologic features are attributable to pathology in the peripheral and optic nerves, posterior and lateral columns of the spinal cord (subacute combined degeneration), and in the brain. aInterestingly, hematologic and neurologic manifestations are occasionally dissociated. An inverse correlation in the severity of both manifestations has been suggested. In patients with neuropsychiatric abnormalities, 28% lack anemia or macrocytosis.
Didn't release that Vit E also involved the Eye- From MedscapeVitamin E Deficiency Clinical Presentation
Quote:
Patients with vitamin E deficiency may show signs and symptoms of hyporeflexia that progress to ataxia, including limitations in upward gaze.
Patients may present with profound muscle weakness and visual-field constriction.
Patients with severe, prolonged vitamin E deficiency may develop complete blindness, cardiac arrhythmia, and dementia.
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Biochemistry-, Gastrointestinal-Tract-, Physiology-, Step-1-Questions

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