Steroid hormones — Choose the most accurate general statement about their source, transport, and target action

Introduction:
Steroid hormones (e.g., cortisol, aldosterone, estrogen, progesterone, testosterone) regulate metabolism, salt balance, and reproduction. This question asks which broad statement about their physiology is most accurate.

Given Data / Assumptions:

• Steroids are lipophilic small molecules derived from cholesterol.
• They circulate bound to carrier proteins in the bloodstream.
• They act primarily via intracellular receptors that regulate transcription.

Concept / Approach:
As endocrine hormones, steroids are synthesized in specialized glands (adrenal cortex, gonads, placenta) and delivered via blood to distant targets. Their hydrophobicity allows passive diffusion across plasma membranes, where they bind cytosolic or nuclear receptors to modulate gene expression.

Step-by-Step Solution:

Verification / Alternative check:
Clinical replacement of steroids (e.g., oral glucocorticoids) acts systemically, illustrating their ability to reach distant tissues and cross membranes to act on intracellular receptors.

Why Other Options Are Wrong:

• Hydrophilic and cannot penetrate membranes: false; steroids are hydrophobic and readily diffuse.
• Bind exclusively to cell surface receptors: incorrect; primary action is via intracellular receptors.
• Never enter blood: false; endocrine delivery is via blood.
• Cannot act distantly: contradicted by their classic endocrine roles.

Common Pitfalls:
Confusing steroids with peptide hormones (which require cell surface receptors) or with local paracrine mediators that do not travel far.

Final Answer:
are made in one location of the body but have their effects some distance away.