Hormones and Steroid Functions Quiz

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Questions and Answers

What is the primary function of hormones in the body?

To act as chemical messengers (correct)

To store energy in fat cells

To provide structural support to tissues

To serve as nutrients for cells

Which of the following hormones is classified as a steroid?

Aldosterone (correct)

Glucagon

Insulin

Epinephrine

Which chemical structure is characteristic of steroid hormones?

Amino acids

Cyclopentanoperhydrophenanthrene (correct)

Peptide chains

Cyclopentane

What type of hormones does the term 'androgens' refer to?

Male sex hormones Signup and view all the answers

Which steroid hormone is primarily involved in the regulation of fluid and electrolyte balance?

Cortisol Signup and view all the answers

What is the number of carbons in the chemical structure of Cholestane?

27 Signup and view all the answers

Which group of hormones includes progestins?

Pregnanes Signup and view all the answers

What is the main role of corticosteroids in the body?

Regulation of metabolism Signup and view all the answers

What is a primary therapeutic use of estrogens in postmenopausal women?

Hormone replacement therapy Signup and view all the answers

Which of the following is a side effect associated with the use of estrogens?

Gallstone formation Signup and view all the answers

Tamoxifen acts as which type of drug in breast tissue?

An estrogen receptor antagonist Signup and view all the answers

What distinguishes Selective Estrogen Receptor Modulators (SERMs) from other estrogenic drugs?

They have tissue-specific estrogenic activity Signup and view all the answers

Which drug is classified as an antiestrogen and is used as an ovulation stimulant?

Clomiphene citrate Signup and view all the answers

What is the mechanism of action of aromatase inhibitors?

They inhibit estrogen synthesis Signup and view all the answers

Which of the following is NOT a major side effect of estrogen usage?

Increased immunity Signup and view all the answers

Which of the following statements about toremifene is accurate?

It has a chloroethyl group instead of an ethyl group Signup and view all the answers

Which estrogen exhibits the greatest activity among estradiol, estrone, and estriol?

Estradiol Signup and view all the answers

What structural feature do all natural estrogens share?

A phenolic OH at C3 Signup and view all the answers

Which modification enhances the oral activity of estrogens?

Introduction of an ethinyl group at 17α-position Signup and view all the answers

Which of the following is a prodrug that is metabolized to ethinyl estradiol?

Mestranol Signup and view all the answers

What is the main reason for the rapid degradation of estradiol when administered orally?

Intestinal flora and liver inactivation Signup and view all the answers

What is the primary role of estrogens in the female body?

Control of menstrual cycle and pregnancy Signup and view all the answers

Which estrogen is known to be 15 to 20 times more orally active than estradiol?

Ethinyl estradiol Signup and view all the answers

Which mechanism is utilized to enhance the metabolic stability of orally active estrogens?

Hindering the β-face of 17β-OH Signup and view all the answers

Which structural class includes compounds with no angular 19-methyl group?

19-Norprogesterone (Norpregnanes) Derivatives Signup and view all the answers

What modification is made to 17α-hydroxyprogesterone to form Medroxyprogesterone Acetate?

Addition of a 6-methyl group Signup and view all the answers

What effect does the 17α-acetoxy group have on progesterone derivatives?

It decreases the rate of reduction of the 20-one. Signup and view all the answers

Which compound is primarily used in the treatment of breast and endometrial carcinomas?

Megestrol Acetate Signup and view all the answers

Which structural modification facilitates the formation of esters that are highly lipid soluble in 17α-hydroxyprogesterone derivatives?

Hydroxyl insertion at the 17α-position Signup and view all the answers

What is the primary advantage of using 19-norprogesterone derivatives over standard progesterone derivatives?

They exhibit better selectivity for the progesterone receptor. Signup and view all the answers

Ethisterone is categorized under which of the following structural classes?

Testosterone derivatives Signup and view all the answers

Which characteristic does the 17α-hydroxyprogesterone-17-caproate exhibit?

Given solely via intramuscular injection Signup and view all the answers

What is the primary effect of 19-nortestosterone derivatives as compared to testosterone?

Progestational activity Signup and view all the answers

Which compound blocks oxidation to the less active 17-one and is orally active?

Norethindrone Signup and view all the answers

What is a characteristic feature of Norgestrel and Levonorgestrel compared to Norethindrone?

They have a C13 ethyl group Signup and view all the answers

Which statement about Norgestimate is true?

It is a prodrug and metabolized to levonorgestrel Signup and view all the answers

What is the role of Norelgestromin in contraceptive methods?

Is the progestin component in the contraceptive patch Signup and view all the answers

Ethynodiol Diacetate requires which metabolic processes to produce its active form?

Hydrolysis of both esters and oxidation Signup and view all the answers

How is Levonorgestrel primarily administered in addition to orally?

Transdermal patches Signup and view all the answers

Desogestrel is characterized by which of the following?

It is rapidly metabolized to etonogestrel Signup and view all the answers

What is a key structural feature of Raloxifene that distinguishes it from other SERMs?

It has a carbonyl hinge linking a phenolic side chain to a benzothiophene ring. Signup and view all the answers

Which properties does Raloxifene exhibit on bone and cardiovascular systems?

Agonist properties. Signup and view all the answers

What is Fulvestrant's primary mechanism of action as a drug?

It is a pure antagonist devoid of any agonist activity. Signup and view all the answers

What specific effect does Fulvestrant have on tamoxifen-resistant breast cancers?

It prevents their growth. Signup and view all the answers

What are the non-steroidal aromatase inhibitors mentioned?

Aminoglutethimide and Anastrozole. Signup and view all the answers

What is unique about Exemestane's mechanism of inhibition?

It is an irreversible 'suicide' inactivator of aromatase. Signup and view all the answers

Which of the following agents is the first steroidal aromatase inhibitor approved for breast cancer treatment?

Exemestane. Signup and view all the answers

What consequence is associated with the lack of agonist action on endometrial tissue by Raloxifene?

No association with endometrial cancer. Signup and view all the answers

Study Notes

Steroidal Hormones

Steroidal hormones are chemical messengers synthesized in one organ system and distributed to other systems.
They regulate functions such as growth, metabolism, nutrient absorption, and fluid and electrolyte balance.
They are classified into different groups according to chemical structure and origin.
Steroids have a specific chemical skeleton: cyclopentanoperhydrophenanthrene.
Steroidal hormones include sex hormones, adrenocorticoids, chorionic hormones, thyroid hormones, parathyroid hormones, and pancreatic hormones.

Classification of Hormones

Pituitary hormones are categorized into anterior and posterior pituitary hormones:
- Anterior pituitary hormones include polypeptides (ACTH, LPH, PRL, GH) and glycoproteins (FSH, LH).
- Posterior pituitary hormones include polypeptides (oxytocin and vasopressin).
Hypothalamic hormones are polypeptides that act as releasing factors for pituitary hormones.
Gonad hormones (sex hormones) are steroids, subdivided into male (androgens, e.g., testosterone) and female (estrogens and progestins).
Adrenocortical hormones are steroids, including mineralocorticoids, glucocorticoids, and androgens.
Chorionic hormones are polypeptides (e.g., human chorionic gonadotropin (HCG), human chorionic mammotropin).
Thyroid hormones are iodoamino acids (e.g., T3, T4) and polypeptides (e.g., calcitonin).
Parathyroid hormones are polypeptides (e.g., parathormone).
Pancreatic hormones are polypeptides (e.g., insulin, glucagon).

Steroids' Chemical Skeleton

The basic skeleton of steroids is cyclopentanoperhydrophenanthrene, a fused ring structure.
The skeleton consists of three six-membered rings and one five-membered ring.

Angular Methyl Groups

Steroid structures often contain one or more angular methyl groups (CH3) attached to specific carbons in the ring system.
These groups are key structural elements influencing the properties of the steroid.

Side Chain at 17th Position

Many steroid hormones have a side chain attached at the C17 position.
The side chain's structure and composition are specific to different hormone types.

IUPAC Names of Hormones

Specific hormones are associated with specific numbers of carbons, which define their IUPAC ring names (e.g., Estrane, Androstane, Pregnane, Cholane, Cholestane).

Steroid Hormone Action

Steroid hormones bind to intracellular receptors, forming complexes that regulate gene expression and protein synthesis.
The steroid-receptor complexes bind to DNA and interact with transcription factors, initiating the transcription of mRNA.
Elevated mRNA levels result in increased protein synthesis in the endoplasmic reticulum.
These proteins (enzymes, receptors, secreted factors) lead to steroid hormonal response, regulating cell function, growth, and differentiation.

Sex Hormones

Sex steroids are involved in primary and secondary sex characteristics.
Natural sex steroids are produced by the gonads (ovaries or testes), adrenal glands, or by conversion from other sex steroids in tissues like the liver or fat.

Female Sex Hormones (Progestins)

Progestins are grouped into Estrogens and Progestins.
The primary function of female sex hormones is reproductive system development and control of menstruation and pregnancy.
They also control secondary sex characteristics.
Progesterone is the key endogenous steroid hormone that acts at progesterone receptors (PRs).
Progesterone is produced in the ovaries, testes, and adrenal glands.
Common progestin uses are birth control, rectification of hormonal deficiency (HRT), and management of dysfunctional uterine bleeding, dysmenorrhea, and endometriosis.

Metabolism of Progesterone

Progesterone has weak oral activity due to rapid liver metabolism, into inactive metabolites.
These metabolites are excreted in the urine.
A crucial urinary metabolite specific to progesterone metabolism is 5β-pregnane-3α,20α-diol and its conjugates.

Structural Classes of Progestins

Progestins are compounds that share similar biological activity patterns to progesterone
- Progesterone derivatives (e.g., 17α-hydroxyprogesterone derivatives).
- 19-Norprogesterone (Norpregnanes) Derivatives.
- Testosterone (androstane) derivatives.
- 19-Nortestosterone (estrane) derivatives.
- Spironolactone derivative (Drospirenone).

Progesterone Derivatives

These compounds are characterized by insertion of a hydroxyl group at the 17a-position, which promotes the formation of lipid-soluble esters.
17a-ester hinders reduction to the 20-ol, promoting oral use.
This structure allows for oral use.
Examples include 17a-acetoxyprogesterone, and 17α-hydroxyprogesterone-17-caproate.

Medroxyprogesterone Acetate

A 6-methyl group is introduced into the 17-hydroxyprogesterone structure.
This reduces the rate of reduction in the 4-ene-3-one system and that of the 20-one, thus promoting oral use.

Megestrol Acetate

A double bond is introduced between carbon positions 6 and 7, increasing progestin activity.

19-Norprogesterone Derivatives

These progestin derivatives lack the angular 19-methyl group on the progesterone molecule.
Examples include nomegestrol acetate.

Testosterone Derivatives

Ethisterone is a 17a-ethynyl derivative of testosterone.
This derivative is effective as an oral progestin.

19-Nortestosterone Derivatives

Norethindrone is a 17a-ethinyl-19-nortestosterone derivative.
Norethindrone and norethindrone acetate are orally active as progestins.

Ethynodiol Diacetate

A prodrug of norethindrone that uses hydrolysis of esters and oxidation of the C3 alcohol.
This process yields the active progestin.

Norgestrel and Levonorgestrel

These have an ethyl group instead of a methyl group at C13.
They show progestational activity and reduced androgenic effects.
Norgestrel is a racemic mixture, while levonorgestrel is the active levorotatory enantiomer.

Norgestimate

19-nortestosterone, a 3-oxime prodrug, readily metabolized to 17-deacetylnorgestimate.
This is an orally active progestin used with estrogens.

Norelgestromin

The progestin component in the contraceptive patch (Ortho-Evra).

Desogestrel

Is an active prodrug, rapidly metabolized to etonogestrel.

Gestodene

Progestin component in Gynera oral contraceptive.

Antiprogestins

Antiprogestins are substances that compete with progesterone for its receptor and keep it from activating the receptor.
Mifepristone is a PR antagonist used to induce abortion.

Selective Estrogen Receptor Modulators

SERMs are drugs that only act in certain tissues.
Tamoxifen is an ER antagonist in breast tissue but an agonist in endometrium, liver, bone, and cardiovascular systems.

Clomiphene Citrate

An ovulation stimulant that is also a SERM.
Clomiphene is a mixture of two geometric isomers.

Tamoxifen

A triphenylethylene SERM used to treat breast carcinoma.

Toremifene

Structurally similar to tamoxifen, with a chloroethyl group instead of an ethyl one.

Raloxifene

A benzothiophene derivative.
Has antagonist activity in the endometrium and breast tissue.
Has agonist activity on bone and cardiovascular system.

Fulvestrant

A pure antagonist structurally based on estradiol structure, and an alkyl chain at position 7.
This compound does not have agonist activity.

Aromatase Inhibitors

Aromatase inhibitors block aromatase, an enzyme, thereby reducing estrogen levels.
- Steroidal: Testolactone and Exemestane
- Non-steroidal: Aminoglutethimide, Anastrozole, Letrozole
Important to differentiate the mechanism of actions of these drugs and their use as treatment.
Exemestane is an example of one of these drugs.

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Description

Test your knowledge on the functions and classifications of hormones in the human body. This quiz covers key concepts about steroid hormones, their structures, and roles in regulating various bodily functions. Ideal for students studying biology, biochemistry, or related fields.