Steroid Hormones Overview
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Steroid Hormones Overview

Learn about how steroid hormones interact with cells and the differences between steroid hormones and protein hormones. Explore the sources of cholesterol and how steroid hormones are derived from it.

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@GallantTin

Questions and Answers

Which type of steroid hormone is required for the development of female secondary sex characteristics?

Estrogens

Where is the main site of synthesis for androgens like testosterone?

Testis

What is the function of glucocorticoids like cortisol?

Required for adaptation to stress

Which region of the adrenal cortex is responsible for synthesizing mineralocorticoids like aldosterone?

<p>Zona glomerulosa</p> Signup and view all the answers

What is the purpose of steroid hormones according to the text?

<p>To serve as a major form of communication between different organs and tissues</p> Signup and view all the answers

Which hormone is responsible for the synthesis of testosterone from cholesterol in Theca cells?

<p>Luteinizing Hormone (LH)</p> Signup and view all the answers

What type of receptors do steroid hormones typically interact with?

<p>Intracellular receptors</p> Signup and view all the answers

Which second messenger system is activated by Gonadotropin Releasing Hormone (GnRH) signaling?

<p>Phospholipase C</p> Signup and view all the answers

What is the function of DAG (Diacylglycerol) in hormonal signaling pathways?

<p>Activates protein kinase C</p> Signup and view all the answers

How do inhibitory receptors affect adenylate cyclase activity according to the text?

<p>Inhibit adenylate cyclase activity</p> Signup and view all the answers

Which statement accurately describes the process of how steroid hormones enter the cell?

<p>They are derived from dietary precursors and then absorbed through the cell membrane.</p> Signup and view all the answers

What is the role of aromatase in steroid hormone biosynthesis?

<p>It synthesizes an aromatic ring in the steroid nucleus.</p> Signup and view all the answers

Which organ is primarily responsible for the production of cholesterol in the human body?

<p>Liver</p> Signup and view all the answers

In what way is estrogen receptor action pathway different from testosterone mechanism of action?

<p>Estrogen may act by promoting increased action by acting on eNOS, which is not a mechanism of action for testosterone.</p> Signup and view all the answers

What disorder can result from enzyme deficiencies in steroid biosynthesis pathways?

<p>Disorders of sexual maturation</p> Signup and view all the answers

Which enzyme is responsible for synthesizing estradiol specifically in the ovary?

<p>Aromatase</p> Signup and view all the answers

What is the predominant estrogen in postmenopausal women, predominantly derived from adrenal production?

<p>Estrone</p> Signup and view all the answers

What effect does inhibition of the enzyme 11 beta OHSD have on mineralocorticoid levels in tissues?

<p>Increases mineralocorticoid levels</p> Signup and view all the answers

What potential consequence could arise due to AME (Apparent Mineralocorticoid Excess)?

<p>Hyperkalemia</p> Signup and view all the answers

In individuals with Androgen Insensitivity Syndrome, what happens as a result of an inactivating mutation in the Androgen Receptor?

<p>Development of female phenotypic features</p> Signup and view all the answers

What effect does high cortisol levels have on CRH and ACTH secretion?

<p>Decrease CRH secretion and decrease ACTH secretion</p> Signup and view all the answers

What hormone is synthesized from acetate by virtually all tissues in humans?

<p>Cholesterol</p> Signup and view all the answers

Study Notes

Steroid Hormones

  • Estrogen is the type of steroid hormone required for the development of female secondary sex characteristics.
  • The main site of synthesis for androgens like testosterone is the Leydig cells of the testes.

Adrenal Cortex

  • The zona glomerulosa region of the adrenal cortex is responsible for synthesizing mineralocorticoids like aldosterone.
  • Glucocorticoids like cortisol have a function of regulating energy metabolism, immune response, and stress response.

Functions and Mechanisms

  • The purpose of steroid hormones is to regulate various physiological processes, including development, growth, and maintenance of tissues.
  • Steroid hormones typically interact with intracellular receptors, which are transcription factors that regulate gene expression.
  • Gonadotropin Releasing Hormone (GnRH) signaling activates the IP3/DAG (Inositol triphosphate/Diacylglycerol) second messenger system.
  • DAG (Diacylglycerol) in hormonal signaling pathways activates protein kinase C, which phosphorylates and activates downstream targets.

Inhibitory Receptors

  • Inhibitory receptors affect adenylate cyclase activity by decreasing cAMP production, thereby reducing the activity of downstream targets.

Steroid Hormone Entry and Action

  • Steroid hormones enter the cell by diffusing through the plasma membrane and binding to intracellular receptors.
  • The estrogen receptor action pathway is different from the testosterone mechanism of action in that it involves a ligand-dependent nuclear receptor that regulates gene expression.

Biosynthesis and Enzymes

  • Aromatase is the enzyme responsible for converting androgens to estrogens in steroid hormone biosynthesis.
  • The liver is primarily responsible for the production of cholesterol in the human body.
  • 17,20-Lyase is the enzyme responsible for synthesizing estradiol specifically in the ovary.
  • Estrone is the predominant estrogen in postmenopausal women, predominantly derived from adrenal production.

Disorders and Consequences

  • Enzyme deficiencies in steroid biosynthesis pathways can result in disorders such as congenital adrenal hyperplasia (CAH).
  • Inhibition of the enzyme 11 beta OHSD has the effect of increasing mineralocorticoid levels in tissues.
  • Apparent Mineralocorticoid Excess (AME) can lead to a potential consequence of hypertension and fluid retention.

Androgen Insensitivity Syndrome

  • In individuals with Androgen Insensitivity Syndrome, an inactivating mutation in the Androgen Receptor results in the inability to respond to androgens, leading to feminization.

Cortisol and Stress Response

  • High cortisol levels have the effect of reducing CRH and ACTH secretion through negative feedback.
  • Cholesterol is synthesized from acetate by virtually all tissues in humans.

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