Sex Hormones and Androgens Overview

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Questions and Answers

What are sex hormones also known as?

Gonkadocorticoids

Sex steroids

Gonadal steroids

Both A and B (correct)

What hormones are produced in the adrenal cortex's zona fasciculata?

Androgens

Glucocorticoids (correct)

Estrogens

Mineralocorticoids

What clinical outcomes are associated with 21-Hydroxylase deficiency?

Delayed puberty in males

Ambiguous genitalia at birth in females (correct)

Primary amenorrhea in females

Excessive cortisol production

What is the first step in the synthesis of androgens from cholesterol?

Conversion to pregnenolone Signup and view all the answers

Which of the following hormones is primarily produced in the renal medulla?

Epinephrine Signup and view all the answers

What deficiency is known to cause excess androgen production and virilization in females?

21-Hydroxylase deficiency Signup and view all the answers

What happens if there is an enzyme deficiency in the steroid synthesis pathways?

Buildup of steroid precursors occurs Signup and view all the answers

Which of the following is a characteristic of 17α-Hydroxylase deficiency?

Decreased production of sex hormones and cortisol Signup and view all the answers

What triggers the conversion of androgens to estrone in the ovarian follicles?

LH stimulation of theca cells Signup and view all the answers

During which phase of the ovarian menstrual cycle does the dominant follicle develop and ovulate?

Follicular phase Signup and view all the answers

Which estrogen is predominantly produced during pregnancy?

Estriol (E3) Signup and view all the answers

What role does aromatase play within the ovaries?

Converts androgens into estrogens Signup and view all the answers

What occurs when estrogen levels peak in the menstrual cycle?

LH surge is triggered Signup and view all the answers

Which cells closest to the oocyte produce estrogen upon FSH stimulation?

Granulosa cells Signup and view all the answers

What is the primary function of the theca cells in the ovarian follicles?

Produce androgens for estrogen biosynthesis Signup and view all the answers

Which hormone primarily stimulates ovulation through its surge?

LH Signup and view all the answers

What is the role of FSH in ovarian physiology?

Promotes the maturation of oocytes Signup and view all the answers

What is the result of the pulsatile release of GnRH from the hypothalamus?

Stimulation of the anterior pituitary to release FSH and LH Signup and view all the answers

What is the primary consequence of 21-hydroxylase deficiency in congenital adrenal hyperplasia?

Reduced cortisol levels Signup and view all the answers

What is the result of excess androgens in females due to congenital adrenal hyperplasia?

Development of male external genitalia Signup and view all the answers

What role does LH play in the testes?

Promotes testosterone synthesis Signup and view all the answers

Which cell type in the testes is responsible for forming the blood-testis barrier?

Sertoli cells Signup and view all the answers

What symptom is expected in an individual with aldosterone deficiency as a result of adrenal hyperplasia?

Metabolic acidosis Signup and view all the answers

What is the function of 5 alpha-reductase in relation to testosterone?

Convert testosterone to DHT Signup and view all the answers

Which enzyme is crucial for the conversion of androstenedione to estrogen?

Aromatase Signup and view all the answers

What characterizes the Sertoli cells in the testes?

Protect and nourish spermatids Signup and view all the answers

What primarily causes the high systemic levels of adrenal androgens during the 7th week of gestation in females with CAH?

Deficiency of 21-hydroxylase Signup and view all the answers

Which hormone feedback loop regulates testosterone synthesis in males?

Negative feedback on GnRH, LH, and FSH Signup and view all the answers

How many million sperm does the male reproductive system produce daily?

120 million Signup and view all the answers

What is a key difference between the functions of Leydig and Sertoli cells?

Sertoli cells protect developing gametes Signup and view all the answers

Which of the following consequences results from the accumulation of steroid precursors due to enzyme deficiencies?

Salt-wasting crisis Signup and view all the answers

What type of metabolic disruption occurs due to cortisol deficiency?

Aberrant carbohydrate metabolism Signup and view all the answers

Which structure is primarily responsible for secreting progesterone during the luteal phase?

Corpus luteum Signup and view all the answers

What physiological effect does progesterone have on the uterine myometrium after ovulation?

Inhibits contractions Signup and view all the answers

During which phase of the menstrual cycle are estrogen and progesterone levels at their lowest?

Menstruation Signup and view all the answers

Which phase of the endometrium corresponds with the ovarian luteal phase?

Secretory phase Signup and view all the answers

What is the primary outcome of progesterone withdrawal if conception does not occur?

Uterine lining shedding Signup and view all the answers

Which of the following statements accurately describes the role of progesterone before ovulation?

Prepares the uterus for pregnancy Signup and view all the answers

Which hormone primarily takes over progesterone production if conception occurs?

Human chorionic gonadotropin Signup and view all the answers

What is the typical duration of the luteal phase in the menstrual cycle?

14 days Signup and view all the answers

What physiological change occurs in the ovaries during the luteal phase?

Transformation of the corpus luteum Signup and view all the answers

What is the primary function of progesterone during the menstrual cycle?

Thicken and maintain the endometrial lining Signup and view all the answers

What event triggers the release of an egg during ovulation?

Surge in luteinizing hormone Signup and view all the answers

What happens to the corpus luteum if fertilization does not occur?

It degenerates and hormone production stops Signup and view all the answers

During which phase of the menstrual cycle is the endometrium prepared for potential implantation?

Luteal phase Signup and view all the answers

What is the average duration of menstrual flow considered normal?

4-7 days Signup and view all the answers

What initiates the menstrual cycle after menstruation?

Degeneration of the corpus luteum Signup and view all the answers

What signifies the start of menses?

Ischemic endometrial tissue disintegration Signup and view all the answers

What term describes the cells that invade the endometrium during implantation?

Trophoblasts Signup and view all the answers

What volume of blood loss during menses is generally considered abnormal?

More than 80 mL Signup and view all the answers

Study Notes

Sex Hormones Overview

Known as sex steroids, gonadocorticoids, and gonadal steroids.
Essential for sexual development and reproduction.
Major types include estrogen, progesterone, and testosterone.

Androgens and Steroidogenesis

Cholesterol is converted into pregnenolone, which then undergoes modifications in the adrenal cortex.
DHEA and androstenedione serve as precursors for estrogen.
Androgens promote skeletal growth, pubic and axillary hair development during puberty.

Adrenal Hormone Production

Renal medulla produces epinephrine and norepinephrine.
Adrenal cortex layers produce:
- Zona glomerulosa: mineralocorticoids (aldosterone)
- Zona fasciculata: glucocorticoids (cortisol)
- Zona reticularis: androgens and estrogens.

Congenital Adrenal Hyperplasia (CAH)

21-Hydroxylase Deficiency:
- Causes: Impaired cortisol and aldosterone production.
- Symptoms: Accumulation of steroid precursors and excess androgen leading to virilization in females.
- Severe cases can lead to adrenal crisis from aldosterone deficiency.
17α-Hydroxylase Deficiency:
- Causes: Decreased sex hormones and cortisol.
- Symptoms: Delayed puberty, lack of secondary sexual characteristics, hypertension from aldosterone absence.

Adrenal Hyperplasia Effects

Deficiencies in aldosterone lead to salt-wasting crises, electrolyte imbalances, and hypotension.
Cortisol deficiency affects carbohydrate metabolism.
Excess androgens can lead to ambiguous genitalia in females and unnoticed virilization in males.

Mechanism of Steroidogenesis

Pregnenolone flows through cortex zones; enzyme deficiencies prevent hormone modifications.
CAH results in high adrenal androgens causing female fetal genital ambiguity.

Androgens and Their Pathways

DHEA sourced from zona reticularis stimulates androgen secretion.
Androstenedione converts to testosterone or estrone.
Testosterone is produced by Leydig cells, affects various tissues, and is converted to DHT (dihydrotestosterone) in target tissues.

Testicular Structure and Function

Testes contain seminiferous tubules, Leydig cells (testosterone production), and Sertoli cells (spermatid protection).
Sertoli cells protect spermatids and form the blood-testis barrier.
Testes produce around 120 million sperm daily.

Gonadotropins in Male Physiology

GnRH stimulates FSH and LH production from the anterior pituitary.
LH promotes testosterone synthesis, while FSH promotes spermatogenesis alongside testosterone.
Testosterone secretion is relatively constant, unlike the female hormonal cycle.

Testosterone Key Facts

Produced primarily in the testes and adrenal glands.
98% is bound to SHBG or albumin; only 2% is active.
Functions through feedback inhibition on GnRH, LH, and FSH secretion.

Estrogens and Aromatization

Estrone (E1), Estradiol (E2), and Estriol (E3) are key estrogens:
- E1: Converted from androstenedione by aromatase.
- E2: Derived from testosterone via aromatization.
- E3: Produced in pregnancy from DHEAS in the placenta.

Ovarian Anatomy and Function

Ovaries consist of an inner medulla (blood vessels) and outer cortex (follicles).
Theca and granulosa cells synthesize estrogen in response to FSH and LH.
Granulosa cells convert androgens to estrogens and release them into circulation.

Gonadotropin Role in Female Physiology

GnRH triggers a pulsatile release of FSH and LH from the anterior pituitary.
LH stimulates theca cells for androgen production, while FSH promotes estrogen production from granulosa cells.
Peak estrogen stimulates the LH surge, leading to ovulation and corpus luteum formation, marking the luteal phase.

Estrogen and Progesterone Regulation

Estrogen and progesterone control the ovarian menstrual cycle, influencing follicle development and ovulation processes.

Progesterone Production

Secreted by the adrenal glands, corpus luteum, and placenta.
During the follicular phase, the ovary and adrenal glands each contribute approximately 50% of progesterone production.
The corpus luteum secretes high amounts of progesterone during the luteal phase.
Stimulates endometrial thickening to prepare for implantation of the blastocyst.
If conception occurs, the placenta takes over progesterone production; if not, the corpus luteum regresses, leading to decreased hormone levels and menstrual shedding.

Effects of Progesterone

Before Ovulation:
- Prepares the uterus by transitioning the endometrium from a proliferative to a secretory state.
- Withdrawal triggers menstruation due to uterine lining shedding.
- Influences sexual response in the brain and acts as a vasodilatory agent, reducing sodium retention.
After Ovulation:
- Organizes endometrial vasculature for implantation.
- Inhibits uterine contractions and counters oxytocin effects.
- Promotes breast tissue growth for lactation while inhibiting early milk protein synthesis.

Menstrual Cycle Overview

Lasts between 21 to 35 days, with Day 1 marking the first day of menses.
Consists of follicular phase (pre-ovulation) and luteal phase (post-ovulation).
The luteal phase is consistently about 14 days long.
Involves three endometrial phases: menstrual, proliferative, and secretory.

Uterine Phases of the Menstrual Cycle

Controlled by estrogen and progesterone.
Proliferative Phase: Increased estrogen leads to rising endometrial thickness during the follicular phase.
Secretory Phase: Post-ovulation, progesterone organizes endometrial vasculature in preparation for embryo implantation.

Menses

If no conception occurs, the corpus luteum degenerates, halting progesterone and estrogen production.
Without these hormones, the endometrium becomes ischemic, leading to menstrual shedding.
Normal menstrual duration: 3-7 days with blood loss of approximately 30-80 mL; >7 days is generally deemed abnormal.
Abnormal patterns include excessive bleeding >80 mL and scant bleeding <20 mL.

Fertilization and Implantation

Fertilization initiates zygote division, leading to implantation as a blastocyst approximately 6 days later.
Trophoblasts, embryonic cells that invade the endometrium, form the placenta.
Trophoblasts secrete hCG to maintain corpus luteum, mimicking LH effects to sustain progesterone production until placental maturity.

Menstrual Cycle Phases

Follicular Phase (Days 1-14):
- FSH release from the anterior pituitary promotes follicle growth and estrogen production.
- Estrogen rebuilds the endometrial lining post-menstruation.
Ovulation (Around Day 14):
- A surge of LH, triggered by elevated estrogen, causes follicle rupture and egg release.
- Estrogen peaks prior to LH surge, then slightly decreases during ovulation.
Luteal Phase (Days 15-28):
- The ruptured follicle converts to the corpus luteum, secreting progesterone and some estrogen.
- Progesterone prepares the uterus for embryo implantation, inhibiting further ovulation.
- If pregnancy does not occur, the corpus luteum degenerates, leading to a drop in progesterone and estrogen, initiating menstruation.

Key Points

The LH surge is essential for ovulation.
Progesterone's role includes maintaining the uterine lining and preventing further ovulation.
Estrogen levels rise during the follicular phase, peak before ovulation, and moderate during the luteal phase.
Physiological changes include follicular maturation and endometrial preparation, with shedding following an unsuccessful implantation.

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Description

This quiz delves into the world of sex hormones, also known as sex steroids, and their role in sexual development and reproduction. It explores the conversion of cholesterol into androgens and their impact during puberty, including skeletal growth spurts. Test your understanding of key terms and concepts associated with these crucial hormones.