ENDOCRINE ORGANS AND RESPIRATORY SYSTEM
ENDOCRINE ORGANS
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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only its target cells get exposed to aldosterone.
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only its target cells contain aldosterone receptors.
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it is able to enter nontarget cells.
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nontarget cells destroy aldosterone before it can produce any effect.
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Detailed explanation-1: -Aldosterone is a steroid hormone (mineralocorticoid ) that regulates salt-water balance in the body. Steroid hormones are lipophilic. They cross the cell membrane but can function only when they bind to specific receptors that are present only in the target cell.
Detailed explanation-2: -So why do hormones affect only their target cells in particular tissues? Because only those target cells have receptors for that particular hormone. Some hormones bind to receptors on the surface of target cells. Others enter the cells and bind to receptors in the cytoplasm or nucleus.
Detailed explanation-3: -Aldosterone causes an increase in salt and water reabsorption into the bloodstream from the kidney thereby increasing the blood volume, restoring salt levels and blood pressure.
Detailed explanation-4: -As lipid-soluble hormone forms a complex with its receptor, they together bind the DNA and induce the expression of certain genes. This means the action of steroid hormones is slower as they need to promote translation and transcription of the mRNA at the target gene.
Detailed explanation-5: -Hormones that bind to this type of receptor must be able to cross the cell membrane. Steroid hormones are derived from cholesterol and therefore can readily diffuse through the lipid bilayer of the cell membrane to reach the intracellular receptor (Figure 2).