Home › SMLE (Saudi Medical Licensing) › Physiology › The Endocrine System › Why must lipid-derived hormones travel to their …
Why must lipid-derived hormones travel to their target cell bound to a transport protein?
AThey are too large to cross a capillary wall
BThey are not soluble in the water-based blood
CThey are broken down by enzymes in the plasma
DThey carry a charge that repels the membrane
Answer & Solution
Correct answer: B. They are not soluble in the water-based blood
1. Steroid hormones share the hydrophobic character of cholesterol, so they do not dissolve in water.
2. Blood is water based, so a free steroid hormone cannot be carried in it.
3. Binding to a transport protein solves that, which is why steroids never travel free.
4. The same bound state slows their degradation, giving steroids a much longer half-life.
5. Size and charge are not the barrier: these molecules diffuse straight through a lipid bilayer once delivered.
_Source: OpenStax Anatomy and Physiology (CC BY 4.0), Ch 17 "The Endocrine System", section 17.2 Hormones_
Related questions
From which embryonic tissue does the anterior pituitary gland arise?The kidneys release erythropoietin in response to what?Stretching of the atrial wall releases atrial natriuretic peptide. What does that hormone Glucagon makes the liver take up amino acids and convert them into glucose. What is this rWhich cells take up glucose without needing insulin at all?Insulin appears to act through which kind of receptor?Insulin raises glucose uptake mainly through which cellular action?Between which two values is blood glucose concentration tightly maintained?