Steroid hormones

Definition

Steroid hormones are a class of lipophilic signaling molecules derived from cholesterol that play essential roles in regulating various physiological processes in the body. These hormones include cortisol, aldosterone, estrogen, progesterone, and testosterone, and they can easily cross cell membranes to bind to specific receptors, influencing gene expression and cellular activity.

5 Must Know Facts For Your Next Test

1. Steroid hormones are synthesized from cholesterol in the adrenal glands, gonads, and other tissues.
2. These hormones are categorized into two main groups: corticosteroids (like cortisol) and sex steroids (like testosterone and estrogen).
3. Due to their lipid-soluble nature, steroid hormones can diffuse through the lipid bilayer of cell membranes, allowing them to exert effects on target cells quickly.
4. Steroid hormones regulate a wide range of physiological processes, including metabolism, immune response, water balance, and reproductive functions.
5. Their action is typically slower than that of peptide hormones because they modify gene expression rather than triggering immediate cellular responses.

Review Questions

• What are the key differences between steroid hormones and peptide hormones in terms of structure and mechanism of action?
  • Steroid hormones are lipid-soluble molecules derived from cholesterol, allowing them to easily cross cell membranes. In contrast, peptide hormones are water-soluble chains of amino acids that cannot pass through cell membranes and typically bind to surface receptors. Steroid hormones exert their effects by directly influencing gene expression within target cells, while peptide hormones usually trigger a cascade of secondary messengers to effectuate cellular responses.
• Discuss how steroid hormones influence gene expression and cellular function.
  • Steroid hormones influence gene expression by binding to specific intracellular receptors that translocate to the nucleus upon hormone binding. This receptor-hormone complex then interacts with specific DNA sequences to either promote or inhibit transcription of target genes. This mechanism leads to alterations in protein synthesis within the cell, ultimately affecting various physiological functions such as metabolism and growth.
• Evaluate the role of steroid hormones in the body's stress response and how this relates to overall homeostasis.
  • Steroid hormones like cortisol play a crucial role in the body's stress response by modulating various physiological systems to maintain homeostasis during stressful conditions. Cortisol helps increase glucose availability for energy, suppresses inflammation, and aids in regulating blood pressure. By adapting metabolic processes and immune responses under stress, these hormones ensure that the body can cope effectively with challenges while striving to return to a balanced state once the stressor is removed.

Related terms

Cholesterol: A type of lipid that serves as a fundamental building block for steroid hormones and is crucial for maintaining cell membrane integrity.

Hormone Receptors: Proteins located on or within cells that bind to hormones, initiating a series of cellular responses, including changes in gene expression.

Endocrine System: A network of glands that produce and release hormones directly into the bloodstream, regulating bodily functions such as metabolism, growth, and reproduction.