Calcium absorption from the intestine is promoted by:
A. Vitamin D
B. Vitamin A
C. Vitamin C
D. Vitamin B₁₂
Answer: Option A
Solution (By JKExamLibrary)
Active vitamin D (calcitriol) induces synthesis of calcium-binding proteins in the intestinal mucosa, enhancing calcium absorption. Calcium is vital for bones, teeth, blood clotting, and nerve-muscle function.
Consider statements about the human heart: 1. The left ventricle has the thickest wall. 2. The tricuspid valve is between the left atrium and ventricle. 3. The SA node is the natural pacemaker. Which are correct?
Explanation:
The left ventricle has the thickest muscular wall to pump blood at high pressure into the systemic circulation. The sinoatrial (SA) node generates impulses spontaneously, acting as the natural pacemaker. The tricuspid valve is located between the right atrium and right ventricle; the bicuspid (mitral) valve is on the left side. Thus, statements 1 and 3 are correct.
Explanation:
The left ventricle pumps blood into the aorta and to the systemic circulation. Its wall is the thickest because it must generate high pressure.
Explanation:
The Glomerular Filtration Rate (GFR) is the volume of fluid filtered from the renal glomerular capillaries into the Bowman's capsule per unit time. In a healthy adult, the normal GFR is approximately 125 ml per minute, which amounts to about 180 liters per day. Almost all of this filtrate is reabsorbed, leaving only 1.5 liters of urine.
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