The scientist who developed the first successful heart-lung machine was:
A. Christiaan Barnard
B. John Gibbon
C. Willem Kolff
D. Michael DeBakey
Answer: Option B
Solution (By JKExamLibrary)
John Gibbon developed the heart-lung machine and performed the first successful open-heart surgery using it in 1953. Barnard did first heart transplant.
Explanation:
Humans are ureotelic—they excrete nitrogenous waste mainly as urea, which is less toxic than ammonia and requires moderate water for excretion. Ammonia is excreted by aquatic animals, uric acid by birds and reptiles (to conserve water), and creatinine is also excreted but is a minor component compared to urea.
Explanation:
The spinal cord is a long tubular bundle of nervous tissue extending from the medulla oblongata to the level of the first/second lumbar vertebra (L1-L2), where it tapers into the conus medullaris. Below this, nerves form the cauda equina. It transmits impulses between the brain and body and coordinates reflexes.
Explanation:
Aldosterone, secreted by the adrenal cortex, increases sodium reabsorption (and water follows) and potassium secretion in the distal tubule and collecting duct. ADH increases water reabsorption only. Renin is an enzyme, natriuretic peptides inhibit sodium reabsorption.
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