601. Which of the following is FALSE?
A. Osmolality of jejunum contents is iso-osmotic to plasma
B. Sodium is actively pumped out of colon via 2° active transport
C. Cholera toxin produces toxin that binds Na!K/CI pump, resulting in increased chloride secretion.
D. Potassium is actively absorbed in small intestine
E. Potassium is secreted into colon

602. Which of the following is FALSE?
A. Calcium is actively transported out of intestinal lumen in the upper small bowel via CaIH ATPase.
B. Presence of protein facilitates calcium & magnesium absorption.
C. Only 3-6% of ingested iron is absorbed
D. Ferric form of iron is well absorbed
E. Iron absorption is increased in presence of vitamin C

603. Which of the following is TRUE?
A. Heme absorption is more efficient than iron absorption because it is more water-soluble.
B. Iron & calcium can be precipitated in intestinal lumen by phosphate &oxlate.
C. Iron absorption predominately occurs in upper small bowel
D. 70% of iron in the body is stored as hemoglobin
E. All of the above.

604. Which of the following statement is TRUE?
A. T3 is converted to T4 in the periphery
B. T4 is more metabolically active than T3
C. Thyroglobulin is synthesized in thyroid cells
D. T3 & T4 are synthesized in thyroid cells
E. All of the above

605. Iodine is mainly excreted in:
A. Bile
B. Urine
C. Sweat
D. Expired air
E. All of the above

606. Which enzyme is used to catalyze formation ofT3 & T4?
A. Tyrosine peroxidase
B. Thyroglobulin peroxidase
C. Iodotyroiside deiodinase
D. All of the above
E. None of the above

607. Which of the following is FALSE regarding circulating thyroid hormone?
A. Most circulating T4 is bound to Thyroid binding globulin (TBG)
B. Most circulating T3 is bound to albumin
C. Bound T3 & T4 are physiologically active
D. TBG has higher affinity for binding T3 &T4 than does albumin
E. T3 has shorter half life than T4

608. Which of the following is TRUE regarding drug effects on thyroid hormones?
A. Oral contraceptive pill increases concentration of thyroid binding globulin & so reduces free T3 & T4.
B. Prednisolone reduces concentration of thyroid binding globulin & so increases free T3 & T4.
C. Phenytoin & salicylates inhibits T3 & T4 binding.
D. Major tranquillisers increase the concentration of thyroid binding globulin & so increase total T3 & T4 but free T3 & T4 levels are normal.
E. All of the above

609. Which of the following regarding circulating T3 is FALSE?
A. 87% are from peripheral conversion ofT4.
B. It has 3-5x more rapid action on end organs than T4.
C. Conversion of T4 to T3 takes place in pituitary, liver & kidney
D. 113 of circulating T4 is converted into T3
E. All of the above

610. Peripheral conversion of T 4 to T3 is reduced in:
A. major bums & trauma
B. Selenium deficiency
C. Cirrhosis & renal failure
D. Fever
E. All of the above

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