60 Questions
Which hormone is synthesized by the testes?
Testosterone
What is the primary hormone involved in normal follicular development?
Follicle-stimulating hormone
Which hormone is involved in the control of the menstrual and ovarian cycles?
Progesterone
What is the primary function of 17β-estradiol in the female reproductive system?
Regulating menstrual cycle
Which component is a part of the hypothalamic pituitary axis?
Luteinizing hormone
What is the primary outcome of hormonal control of fertility?
Induction of ovulation
How do hormonal contraceptives primarily act on the reproductive system?
Inhibiting ovulation
What is the consequence of 17β-estradiol deprivation?
Thinning of vaginal walls
How do progestogen only contraceptives (POCs) primarily act?
By thickening cervical mucus
What is the main consequence of the onset of menopause?
Decreasing number of follicles
What is the average age at which 90% of women experience menopause?
51.2 years
How do combined hormonal contraceptives (CHCs) act on the reproductive system?
By impairing LH production
What is the effect of 17β-estradiol deprivation on bone density?
Decreased bone density
What is the primary role of progestogens in hormonal contraceptives?
Thickening cervical mucus
What is the main cause of LH failure to stimulate ovulation?
Low estrogen levels
What is the consequence of LH failure to stimulate ovulation?
Anovulatory cycle
Which cells within the seminiferous tubules produce testosterone?
Leydig cells
What is the primary function of progesterone and 17β-estradiol?
Developing the endometrium and driving the development of secondary sexual characteristics
Which hormones are involved in the synthesis of estrogen and progesterone in the ovaries?
FSH and LH
What drives protein expression changes in various tissues due to testosterone?
Testosterone itself
Which cells aid in moving immobile spermatozoa within the testes?
Myoid cells
What is the action of FSH in the ovaries?
Promotes follicular maturation
What happens to testosterone levels with age post-puberty?
Gradually decreases
What is the main function of the corpus luteum?
Secreting progesterone following ovulation
What hormone weakens the wall of the follicle and stimulates ovulation?
LH
What disrupts normal spermatogenesis in males?
Dysfunction at the testes or hypothalamus/pituitary
What is the main hormone secreted by the corpus luteum?
Progesterone
What causes the joint action of thecal and granulosa cells to produce increasing amounts of 17βestradiol during the follicular phase?
FSH
What hormone increases negative feedback onto FSH during the follicular phase?
17β-estradiol
What is the main cause of subfertility in females?
Ovulatory defects or pelvic disorders
What is the primary role of inhibin in the male reproductive system?
Inhibiting the release of LH
Which hormone is responsible for the development and maintenance of male secondary sexual characteristics?
Testosterone
In the female reproductive system, what is the primary function of the theca cells?
Secretion of estrogen
What is the primary source of estrogen in postmenopausal women?
Adrenal glands
Which hormone is responsible for the development and maintenance of female secondary sexual characteristics?
Estrogen
What is the primary role of the corpus luteum in the female reproductive system?
Secretion of progesterone
Which hormone is responsible for promoting spermatogenesis by binding to sertoli cells?
Follicle-stimulating hormone (FSH)
What is the primary mechanism by which dihydrotestosterone exerts its effects?
Binding to intracellular receptors
What is the enzyme responsible for the conversion of testosterone to dihydrotestosterone?
5-alpha reductase
Which cells are responsible for the production of testosterone in the seminiferous tubules?
Leydig cells
What is the rate of decrease in testosterone production after puberty?
1% per year
Which hormone is correlated with increased aggression, particularly in lab animals?
Testosterone
Which cells are primarily responsible for the conversion of androgens into oestrogen in the ovaries?
Granulosa cells
What is the major type of oestrogen, and the primary one to be considered?
Oestradiol
What enzyme converts testosterone to DHT in cells most sensitive to it?
5α-reductase
Which hormone is involved in bone remodeling and maintenance, regulating bone density and adipose tissue deposition?
Oestrogen
What are the key roles of luteinizing hormone, oestradiol, and progesterone in the ovarian cycle?
Follicular phase, ovulation, and luteal phase
What are the main phases involved in the uterine cycle?
Menstruation, proliferative phase, and secretory phase
What is the primary source of estrogen in males?
Leydig cells
Which hormone regulates testosterone production in the testes?
Luteinizing hormone (LH)
What is the main function of myoid cells within the seminiferous tubules?
Temperature regulation
Which hormone is synthesized from cholesterol in the testes?
Testosterone
What is the role of Sertoli cells in the testes?
Supporting spermatogenesis
Which axis regulates testosterone production in the testes?
Hypothalamic-pituitary axis
Which hormone is responsible for the conversion of remaining cells into the corpus luteum, which produces progesterone?
Luteinizing hormone
What is the primary function of 17 beta oestradiol and progesterone?
Maintenance of the endometrium
What is the main enzyme responsible for converting testosterone to 17 beta oestradiol?
Aromatase
Which cells produce 17 beta oestradiol under the influence of luteinizing hormone?
Faecal and granuloma cells
What is the initial product of the synthesis pathway of estrogen and progesterone in the ovaries?
Cholesterol
What is the main function of granulosa cells in the synthesis of estrogen?
Conversion of testosterone to 17 beta oestradiol
Study Notes
Endocrine Control of Ovarian and Menstrual Cycles
- The conversion of androgens to estrogens is promoted by FSH in granulosa cells, which highly express aromatase.
- The menstrual cycle is dictated by the ovarian cycle, with the luteal phase having an average duration of 28+/-7 days and involving the corpus luteum.
- FSH promotes follicular development, while LH degrades the follicular wall and promotes ovulation, and later the formation of the corpus luteum, which secretes progesterone.
- The joint action of thecal and granulosa cells produces increasing amounts of 17βestradiol during the follicular phase.
- 17β-estradiol from the graafian follicle increases negative feedback onto FSH, and once it surpasses a certain level, feedback switches and becomes positive.
- The LH surge weakens the wall of the follicle and stimulates ovulation, while also stimulating the remaining thecal and granulosa cells to produce progesterone instead of 17βestradiol.
- The corpus luteum produces progesterone for ~ 10 days following ovulation, maintaining the endometrium and increasing vascularization, and thickening the cervical mucus.
- Progesterone is most prominently elevated during the luteal phase of the ovarian cycle.
- Subfertility in males can arise from disruptions in normal spermatogenesis, sperm transport, production of seminal plasma, or penetration of cervical mucus by sperm.
- Spermatogenesis depends on the joint action of FSH and testosterone, and male hypogonadism usually arises from dysfunction at the testes or hypothalamus/pituitary.
- Subfertility in females can arise from ovulatory defects or pelvic disorders, with age being a controlling factor due to age-dependent loss of ovarian follicles.
- With decreasing follicular number, there is an increasing likelihood of FSH not locating a follicle properly, and about 90% of women experience menopause at an average age of 51.
Ovarian Hormone Synthesis and Function
- Ovaries are the site of hormone synthesis and not spermatogenesis in biological females.
- Primordial follicles in the ovary develop into graphene follicles, leading to ovulation.
- Follicle stimulating hormone stimulates the development of faecal and granuloma cells in the secondary follicle.
- Faecal and granuloma cells produce 17 beta oestradiol, the major estrogen, under the influence of luteinizing hormone.
- Luteinizing hormone is responsible for ovulation and the conversion of remaining cells into the corpus luteum, which produces progesterone.
- The synthesis of estrogen and progesterone in the ovaries involves the action of follicle stimulating hormone and luteinizing hormone.
- The synthesis pathway of these hormones involves the conversion of cholesterol into progesterone, followed by the androgen pathway leading to testosterone, and finally into 17 beta oestradiol.
- Granulosa cells have high levels of aromatase, which converts testosterone to 17 beta oestradiol, and LH promotes androgen production in these cells.
- The joint action of faecal and granuloma cells is crucial for the production of estrogen.
- Steroid hormones such as estrogen and progesterone act as transcription factors and bind to specific proteins for their function.
- The primary function of 17 beta oestradiol and progesterone is the development and maintenance of the endometrium.
- The synthesis and function of estrogen and progesterone involve classical negative feedback mechanisms and are essential for the female reproductive system.
Test your knowledge of the endocrine control of ovarian and menstrual cycles with this quiz. Explore the roles of follicle-stimulating hormone (FSH), luteinizing hormone (LH), estrogen, and progesterone in the regulation of female reproductive processes. Learn about factors affecting fertility in both males and females, including ovulatory defects, subfertility, and menopause.
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