An enzyme found in the liver catalyzes the rate determining step in the synthesis of cholesterol. If these people have a particular allele that produces a slow-working enzyme or an enzyme that does not work at all, they'll produce less cholesterol. This in turn will reduce the down regulation of LDL receptors. The presence of these extra receptors will increase the amount of dietary cholesterol that will be absorbed form the blood. Beta-1 receptors are the receptors on the heart for norepinephrine from the sympathetic nervous system.
Aldosterone usually increases sodium reabsorption in the kidney.
Here it is blocked by an antagonists, so less sodium will be reabsorbed, less water will follow, and the blood volume will decrease. The greater the heart muscle is stretched, i.e the greater volume of blood that enters, the stronger the contraction, and the greater the volume of blood ejected in one stroke. A. Adrenal cortex. B. Cholesterol is needed there to synthesize steroid hormones such as cortisol. HDL may bring cholesterol to adrenal, 7.