This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
Iodine is transpoed to the thyroid gland by ? 
Select and explain. 
A. Active transpo, B. Diffusion, C. Passive transpo, D. Pinocytosis
A: Active transpo
Answer: A: Active transpo 
Explanation: Ans. is 'a' i.e., Active transpo Iodine uptake for thyroid hormone synthesis:Iodine uptake mediated by thyroid follicular cells from the blood plasma is the first step for the synthesis of thyroid hormones.This ingested iodine is bound to serum proteins, especially to albumins.The rest of the iodine which remains unlinked and free in bloodstream, is removed from the body through urine.Basolateral membrane of thyroid cells (follicular cells) have active transpo system for iodine uptake - Na+ : I- sympoer (NlS) (Secondary active transpo).This trapping stimulated by TSH,