Reproductive Hormones and Physiology: Menstrual Cycle, Ovulation, Pregnancy Tests, and Menopause

What is the purpose of Lab 4?

To understand the neurohormonal regulation of reproduction and the physiology behind over-the-counter ovulation and pregnancy tests.

What does the hypothalamic-pituitary-gonadal (HPG) axis regulate?

The hormone receptors that regulate reproduction in both males and females.

What hormone levels change during the menstrual cycle?

Luteinizing hormone (LH) levels change during various days of the cycle.

What is the role of estrogen in the female reproductive cycle?

Estrogen levels can lead to positive or negative feedback affecting hormone secretion.

What is the endocrine role of the placenta during pregnancy?

The placenta produces hormones like human chorionic gonadotropin (hCG).

How do over-the-counter ovulation and pregnancy tests function?

They measure hormone levels to determine ovulation or pregnancy status.

What is the average duration of a menstrual cycle?

The average menstrual cycle lasts 28 days, with a normal range of 24-35 days.

What is the significance of the LH surge?

The LH surge triggers ovulation of an oocyte from the Graafian follicle.

What hormones are involved in the regulation of the female reproductive cycle?

Estrogen, progesterone, luteinizing hormone (LH), and follicle-stimulating hormone (FSH).

What is the function of gonadotropin-releasing hormone (GnRH)?

GnRH controls the secretion of gonadotropins (FSH and LH) by the anterior pituitary.

What is the role of FSH in reproduction?

FSH is required to initiate and maintain gametogenesis (production of gametes).

What happens during negative feedback in males?

As androgen levels increase, GnRH, FSH, and LH secretion decreases.

How does estrogen affect feedback in females?

Estrogen alternates between producing negative and positive feedback on GnRH and gonadotropin release.

What is the long-loop feedback pathway?

It involves gonadal sex hormones binding to receptors on the hypothalamus and anterior pituitary to alter hormone secretion.

What is the short-loop feedback pathway?

It involves pituitary gonadotropins (FSH and LH) binding to receptors on the hypothalamus to alter GnRH release.

What are gametes?

Gametes are reproductive cells, specifically spermatozoa (sperm) in males and oocytes in females.

What is the role of the anterior pituitary in reproduction?

It secretes gonadotropins (FSH and LH) that act on the gonads.

What physiological factors could affect Jack and Jill's ability to conceive?

Jack's stress and decreased sex drive, and Jill's weight, age, and menstrual cycle regularity.

What is the role of kisspeptin in the reproductive cycle?

Kisspeptin may influence GnRH release, particularly in the context of estrogen feedback.

What is oogenesis?

Oogenesis is the process of egg (oocyte) development in females.

What is spermatogenesis?

Spermatogenesis is the process of sperm development in males.

What is the significance of the Graafian follicle?

It is the mature ovarian follicle that releases an oocyte during ovulation.

How does obesity affect fertility in couples trying to conceive?

Obesity can lead to hormonal imbalances that may affect ovulation and sperm production.

What is the relationship between stress and male fertility?

Stress can lead to decreased sex drive and hormonal changes that affect sperm production.

What are the physiological effects of high estrogen levels before ovulation?

High estrogen levels lead to positive feedback, increasing GnRH and LH secretion.

What is the role of testosterone in male reproduction?

Testosterone is a key androgen that regulates male reproductive functions and characteristics.

What is the difference between positive and negative feedback in hormonal regulation?

Positive feedback amplifies hormone secretion, while negative feedback reduces it.

What is the role of meiosis in reproduction?

Meiosis reduces the chromosome number by 50% to ensure a normal number of chromosomes when egg and sperm combine.

What does the corpus luteum secrete?

The corpus luteum primarily secretes progesterone, which prepares the endometrium for pregnancy.

What hormone is secreted from the developing placenta after fertilization?

Human chorionic gonadotropin (hCG) is secreted from the developing placenta.

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

If fertilization does not occur, the corpus luteum degenerates, leading to a decline in estrogen and progesterone, resulting in the onset of menses.

How do over-the-counter ovulation tests work?

Ovulation tests detect LH in urine; a positive result occurs when the test band is as dark or darker than the control band, indicating fertility.

What does a positive pregnancy test indicate?

A positive pregnancy test indicates the presence of hCG in urine, which is produced shortly after fertilization.

What hormones regulate spermatogenesis?

Spermatogenesis is regulated by FSH and LH, which are secreted by the anterior pituitary.

What is menopause?

Menopause is the cessation of reproductive cycles in females, typically occurring around age 51, due to the ovaries no longer responding to gonadotropins.

What are common symptoms of menopause?

Symptoms of menopause may include hot flashes, atrophy of genitalia and breasts, and osteoporosis.

What is perimenopause?

Perimenopause is the transition period before menopause, lasting two to eight years, during which hormonal changes occur.

What happens to estrogen levels during perimenopause?

Estrogen levels may initially be high but eventually drop as the ovaries lose their ability to produce hormones.

What is andropause?

Andropause refers to age-related changes in male reproductive hormones, particularly a gradual decrease in testosterone production.

What symptoms are associated with andropause?

Symptoms may include reduced muscle mass, changes in sleep patterns, difficulty remembering things, decreased motivation, and erectile dysfunction.

What is the function of testosterone in males?

Testosterone influences secondary sex characteristics and regulates GnRH and gonadotropins.

How does the LH surge relate to ovulation?

The LH surge triggers ovulation, typically occurring 36 hours after the surge.

What is the significance of the endometrium during pregnancy?

The endometrium is prepared for implantation of the blastocyst and supports early pregnancy.

What is the role of FSH in male reproduction?

FSH stimulates spermatogenesis by acting on Sertoli cells in the testes.

What triggers the release of LH from the anterior pituitary?

Activation of GnRH receptors promotes the secretion of LH from the anterior pituitary.

What is the relationship between hCG and the corpus luteum during pregnancy?

hCG maintains the corpus luteum and its secretion of progesterone and estrogen during pregnancy.

What indicates a negative result on an ovulation test?

A faint or absent test line indicates that the woman is not ovulating.

What is the average age of onset for menopause in the United States?

The average age of onset for menopause is around 51 years.

What happens to FSH levels during perimenopause?

FSH levels rise higher to stimulate estrogen production as the ovaries lose their ability to make hormones.

What is the typical time frame for hCG levels to double during early pregnancy?

hCG levels typically double every 72 hours for the first 8-11 weeks of pregnancy.

What is the primary function of the corpus luteum?

The primary function of the corpus luteum is to secrete hormones that maintain the endometrium for potential pregnancy.

What is the role of Leydig cells in male reproduction?

Leydig cells produce testosterone in response to LH stimulation.