Gonad Hormones
_________ cells function in a nutritive and supportive role somewhat analagous to the glial cells of the CNS. They produce inhibin, which feeds back on the anterior pituitary and hypothalamus to regulate FSH release.
Sertoli
Fill in The Blank _____________________is the principal hormone of the testis. It is synthesized from cholesterol in Leydig cells. The secretion of ________________ from Leydig cells is under control of luteinizing hormone at a rate of 4-9 mg/day in adult males.
Testosterone
What condition is associated with undescended testes?
(cryptorchidism)
The onset of menopause is usually associated with what hormone changes? a) Decreased estrogen, testosterone, and androgens b) Decreased estrogen, FSH, LH, and progesterone c) Decreased estrogen, and progesterone, and increased LH and FSH d) Decreased estrogen and progesterone, normal LH and FSH
C) Decreased estrogen, and progesterone, and increased LH and FSH In menopause, estrogen production decreases to where the menstrual cycle and ovarian follicle maturation stop. The decreased estrogen causes the pituitary release of LH and FSH. In menopause, the FSH at midcycle is higher than LH. The increased LH causes the ovaries to secrete testosterone and androgens
Which of the following hormones stimulates the conversion of testosterone to 17-Beta-estradiol in ovarian granulosa cells? a) ACTH b) Estradiol c) FSH d)GnRH e) hCG f) Prolactin g) Testosterone
C) FSH Testosterone is synthesized from cholesterol in ovarian theca cells and diffuses to ovarian granulosa cells, where it is converted to estradiol by the action of aromatase. FSH stimulates the aromatase enzyme and increases the production of estradiol
Select the hormone which when elevated is associated with galactorrhea, pituitary adenoma, and amenorrhea. A) E2 B) Progesterone C) Follicle-stimulating hormone (FSH) D) Prolactin
D) Prolactin Serum prolactin may be increased from hypothalamic dysfunction or pituitary adenoma. When levels are greater than five times the URL, a pituitary tumor is suspected. Prolactin is measured by enzyme immunoassay (EIA).
The biologically most active, naturally occurring androgen is: a) androstenedione b) cortisol c) epiandrosterone d) testosterone
D) testosterone Testosterone is the most biologically active androgen in the embryonic stage and later effects sperm production and secondary sex characteristics. Cortisol is a corticosteroid Dehydroepiandrosterone (DHEA) and androstendione are made in small amounts by the testes [Bishop 2018, p460]
What is the primary precursor of natural estrogens?
DHEA
most potent estrogen and used to evaluate ovarian function
Estradiol (E2)
Trophoblast cells of placenta produce _____
HCG
FSH acts on the Sertoli cells to maintain spermatogenesis. The Sertoli cells also secrete _________,which is involved in negative feedback of FSH secretion.
Inhibin
Males with _________________ _________________ (47 XXY) have an additional X chromosome, resulting in small testes and low testosterone levels. Puberty is often delayed or incomplete.
Kleinfelter syndrome
Inhibin (produced by ________ cells) inhibits the secretion of FSH from the anterior pituitary
Sertoli
17-ketosteroids aka
androgens
Which of the following hormones acts by an inositol 1,4,5-triphosphate (IP3)-Ca2+ mechanism of action? a) 1,25-Dihydroxycholecalciferol b) Progesterone c) Insulin d) PTH e) Gonadotropin-releasing hormone (GnRH)
e) Gonadotropin-releasing hormone (GnRH) GnRH is a peptide hormone that acts on the cells of the anterior pituitary by an inositol 1,4,5-triphosphate (IP3)-Ca2+ mechanism to cause the secretion of FSH and LH.
Virilization
is a condition that causes a female to develop male-pattern hair growth and other masculine traits.
Fill in The Blank The _____ phase begins about day 14 and is characterized by an increase in production of progesterone and estrogen form the corpus luteum and a reduction of circulating FSH and LH
luteal
Progesterone secreted by
ovaries and placenta
Fill in the Blank The ______________ ________ occurs after ovulation, during the second half of the monthly cycle when there is progesterone dominance. There is copious secretion of a nutritive fluid from the endometrial glands in preparation for implantation of an embryo at this time.
secretory phase
Progesterone
steroid hormone with 21 carbons that induces secretory activities of the endometrium for implantation
Actions of testosterone in males
- Differentiation of epididymis, vas deferens, and seminal vesicle - Pubertal growth spurt -Cessation of pubertal growth spurt (epiphyseal closure) -Libido -Spermatogenesis in Sertoli cells (paracrine effect) -Deepening of voice - Increased muscle mass -Growth of penis and seminal vesicles - Negative feedback on anterior pituitary
menstrual cycle
- Follicular Phase - Ovulation - Luteal Phase •Duration approximately 28 days
Fill in The Blank The ___________ ___________occurs in the first half of the cycle prior to ovulation and is under the influence of high estrogen levels
.proliferative phase
A total testosterone measurement includes
1) free testosterone 2) albumin-bound testosterone 3) SHBG-bound testosterone
When pituitary adenoma is the cause of decreased estrogen production, an increase of which hormone is most frequently responsible? a) Prolactin b) FSH c) LH d) TSH
A) Prolactin Prolactinoma can result in anovulation because high levels of prolactin suppress release of LHRH (gonadotropin-releasing hormone), causing suppression of Growth Hormone (GH), FSH, and estrogen. Prolactinoma is the most commonly occuring pituitary tumor accounting for 40-60%. Adenomas producing FSH have a frequency of about 20%
Which step in the steroid hormone pathway is required for the development of female secondary sex characteristics, but not male secondary sex characterisitics? a) Aldosterone synthase b) Aromatase c) Cholesterol desmolase d) 17,20-Lyase e) 5-alpha-reductase
B Aromatase catalyzes the conversion of testosterone to estradiol in the ovarian granulosa cells. Estradiol is required for the development of female secondary sex characteristics
select the main estrogen produced by the ovaries and used to evaluate ovarian function. a) Estriol (E3) b) Estradiol (E2) c) Epiestriol d) Hydroxyestrone
B) Estradiol (E2) E2 is the major estrogen produced by the ovaries and gives rise to both estrone (E1) and E3. E2 is used to evaluate both ovarian function and menstrual cycle dysfunction.
The hormone that triggers ovulation is: A) Follicle-stimulating hormone (FSH) B) Luteinizing hormone (LH) C) Thyroid-stimulating hormone (TSH) D) human chorionic gonadotropin (hCG)
B) Luteinizing hormone (LH) luteinizing hormone triggers ovulation which then turns the follicle into the corpeus luteum
Where do Androgens come from?
C19 steroids produced by the Leydig cells (testes) and the adrenal cortex
In a 35-day menstrual cycle, ovulation occurs on day: a) 12 b) 14 c) 17 d) 21 e) 28
D) 21 Menses occurs 14 days after ovulation, regardless of cycle length. Therefore, in a 35-day menstrual cycle, ovulation occurs on day 21. Ovulation occurs at the midpoint of the menstrual cycle only if the cycle length is 28 days.
The biochemical structure of all the hormones secreted by the anterior pituitary, posterior pituitary, and pancreas can best be described as which of the following? a) Amino acid deriviatives b) Catecholamines c) Glucocorticoids d) Peptides e) Steroid hormones
D) Peptides In the human body there are three basic types of hormones: peptides(protein derivatives), amino acid derivatives, and steroid hormones Some examples of peptide hormones are those produced in the anterior pituitary (growth hormone, adrenocorticotropin, thyroid stimulating hormone, follicle-stimulating hormone, luteinizing hormone, and prolactin) the posterior pituitary (vasopressin and oxytocin) and the pancreas (insulin and glucagon) Amino acid derivatives include tyrosine and triiodothyronine, as well as the catecholamines dopamine, epinephrine, and norepinephrine. Glucocorticoid hormones (e.g. cortisol) are a specific type of steroid hormone produced by the adrenal cortex Steroid hormones include the hormones produced in the adrenal cortex (cortisol and aldosterone), the ovaries (estrogen and progesterone), the testes (testosterone), and the placenta (estrogen and progesterone)
A 50-year-old woman presents with fatigue, insomnia, hot flashes, night sweats, and absence of menses for the last five months (secondary amenorrhea). Her urine hCG test is negative. Laboratory tests revealed decreased serum estrogen and increased serum FSH and LH levels. Which of the following is the most likely cause of this individuals clinical signs and symptoms? A) 17-hydroxylase deficiency of the adrenal cortex B) prolactin-secreting tumor of the anterior pituitary C) gonadotropin-releasing hormone-secreting tumor of the hypothalamus D) menopause E) menarche
D) menopause Menopause refers to cessation of menstrual cycles and females, while menarche refers to the first menstrual cycle. Characteristics of menopause include elevated gonadotropins (FSH is the best indicator), secondary amenorrhea, hot flashes, decreased federal secretions, and night sweats. In addition, atrophy begins in estrogen -dependent tissues, such as the Regina. Gradual loss of bone density can lead to osteoporosis. (Kumar, p 1027. Noble, pp315-316, 359-364)
____ acts on Sertoli cells to maintain spermatogenesis in males
FSH
Fill in The Blank The hypothalamus secretes _______, which is responsible for the secretion of both gonadotropic hormones, LH and FSH, from the anterior pituitary
GnRH
Testosterone is the major androgen synthesized and secreted by the _______ cells
Leydig
If a patient had a luteal phase defect, which hormone would most likely be deficient? a. Estrogen b. Progesterone c. FSH d. Prolactin
b
The major difference between male and female sex hormone production is that: A. Estrogen is not produced in the male B. Sex hormone production in the male is relatively constant C. LH has no apparent action in the male D. In the male, GnRH does not cause the release of FSH
b
Which of the following target tissues is incapable of producing steroidal hormone? a. Testis b. Ovary c. Adrenal medulla d. Adrenal cortex
c
What is Sex hormone binding globulin (SHBG)?
carrier protein for steroid hormones only produced in the liver
Androgen secretion by the testes is stimulated by: a. FSH b. Testosterone c. Gonadotropins d. LH
d
Actions of dihydrotestosterone
■ Differentiation of penis, scrotum, and prostate ■ Male hair pattern ■ Male pattern baldness ■ Sebaceous gland activity ■ Growth of prostate
Fill in The Blank Continued progesterone secretion by the corpus luteum is essential to early pregnancy. If implantation of an embryo occurs, the trophoblast cells of the developing placenta secrete the LH analogue ___________ ________________ ____________________ which rescues the corpus luteum until the developing placenta assumes the production of progesterone.
human chorionic gonadotropin (hCG),
Kallmann syndrome is a gene (not chromosomal) defect, which leads to lack of GnRH neurons. The condition is more common in males due to X-linked inheritance of one of the causative genes. The syndrome causes ______________________ ___________________Patients with Kallmann syndrome also have decreased or absent sense of smell (anosmia).
hypogonadotropic hypogonadism.
Phases of the human sexual response.
A. The male sexual response involves penile erection in the excitement phase, emission of sperm and seminal plasma into the urethra in the plateau phase, a single orgasm associated with ejaculation, and a resolution phase with penile detumescence. B. The same phases are represented in the female sexual response, although the plateau and orgasm phases are more variable. There may be an extended plateau without orgasm, a short plateau with orgasm, or multiple orgasms due to the lack of a refractory period.
The chemical structure of cholesterol, which is the common precursor in sex-steroid biosynthesis.
All sex steroids contain the basic cyclopentanophenanthrene molecule, which consists of three 6-carbon rings and one 5-carbon ring.
Biosynthesis of testosterone.
Although the main secretory product of the Leydig cells is testosterone, some of the precursors also enter the circulation.
C Progesterone is secreted during the luteal phase of the menstrual cycle
Blood levels of which substance are described by curve B? a) Estradiol b) Estriol c) Progesterone d) FSH e) LH
Which step in steroid hormone biosynthesis, if inhibited, blocks the production of all androgenic compounds but does not block the production of glucocorticoids? a) Cholesterol ---> pregnenolone b) Progesterone--->11-deoxycorticosterone c) 17-hydroxypregnenolone--->dehydroepiandrosterone d) Testosterone--->estradiol e)Testosterone--->dihydrotestosterone
C The conversion of 17-hydroxypregnenolone to dehydroepiandrosterone is catalyzed by 17,20-lyase. If this process is inhibited, synthesis of androgens is stopped.
Levels of which of the following hormones are high during the first trimester of pregnancy and decline during the second and third trimesters? A) ACTH B) Estradiol C) FSH D) GnRH E) HCG F) Oxytocin G) Prolactin H) Testosterone
E) HCG During the first trimester of pregnancy, the placenta produces human chorionic gonadotropin (hCG), which stimulates estrogen and progesterone production by the corpus luteum. Peak levels of HCG occur at about the 9th gestational week and then decline. At the time of the decline in HCG, the placenta assumes responsibility for steroidogenesis for the remainder of the pregnancy
During the menstrual cycle, ovulation occurs after: a. a sharp rise in LH b. the release of activin c. a surge in progesterone d. the gradual decrease in estrogen levels
a
major estrogen secreted by placenta from DHEA in pregnant women
Estriol(E3)
About the time of ovulation at midcycle, under the influence of high estrogen and low progesterone, the mucus is thin and readily allows passage of sperm.
Estrogen helps sperm Enter
Fill in The Blank In males _______ activates the seminiferous tubules for sperm production
FSH
Progesterone functions
Female sex hormone • Regulate menstrual cycle, secreted by corpus luteum • Prepare uterus for implantation of embryo • Thermogeniceffect - body temp rises after ovulation •Maintain pregnancy, majorly secreted by placenta •Promotes development of breasts for milk secretion • Minor amount from adrenal cortex •Its derivatives like 19-nortestosterone as oral contraceptives
_____ acts on the Leydig cells to promote testosterone synthesis. Testosterone acts via an intratesticular paracrine mechanism to reinforce the spermatogenic effects of FSH in the Sertoli cells
LH
Fill in The Blank In males LH binds to the ___________ cell receptors to enhance the conversion of cholesterol to testosterone
Leydig
Effects of gonadotropins at the testis.
Luteinizing hormone (LH) stimulates the Leydig cells to secrete testosterone. Follicle-stimulating hormone (FSH) stimulates the secretion of androgen-binding protein by the Sertoli cells into the lumen of the seminiferous tubules.
A 20-year-old male patient presents to the doctor's office complaining about continuous growth, lack of facial hair development, and smaller penis and testicles than his college friends. Laboratory values include total testosterone 1 ng/mL and LH 1.5 mU/mL. Thyroid-stimulating hormone and prolactin levels are normal. He has no history of medications, drug use, or disease. GnRH stimulation test over a 7-day period produces elevations in circulating levels of LH. Continued growth in this case is caused by: A) Increased estrogen production B) Decreased inhibin release C) Decreased testosterone production D) Decreased sensitivity to LH stimulation
The correct answer is C. Explanation: The presentation of this young male patients with decreased testosterone explains why he has not developed secondary sexual characteristics normal for his age. Increased estradiol production would have led to epiphyseal closure.
Changes in selected plasma hormone concentrations during pregnancy.
The early peak of chorionic gonadotropin rescues the corpus luteum, which is responsible for the early rise in progesterone secretion. The placenta assumes production of progesterone by about gestation week 9. Estrogen secretion begins later because maturation of the fetal adrenal glands, which supplies androgen precursors to the placenta, is necessary for estrogen production.
The terms menstrual cycle and ovarian cycle are both used to describe a sequence of events that recurs approximately every 28 days.
The first day of menstrual bleeding defines day 1 of a menstrual cycle.
B Curve A shows basal body temperature. The increase in temperature occurs as a result of elevated progesterone levels during the luteal (secretory) phase of the menstrual cycle. Progesterone increases the set-point temperature in the hypothalamic thermoregulatory center
The increase in at point A is caused by the effect of: a) estrogen on the anterior pituitary b) progesterone on the hypothalamus c) FSH on the ovary d) LH on the anterior pituitary e) prolactin on the ovary
C The curve shows blood levels of estradiol. During the luteal phase of the cycle, the source of estradiol is the corpus luteum. The corpus luteum prepares the uterus to recieve a fertilized egg.
The source of the increase in concentration at point D is the: a) ovary b) adrenal cortex c) corpus luteum d) hypothalamus e) anterior pituitary
Where in the adrenal gland are androgens formed?
Zona Reticularis
A midcycle LH surge will stimulate which of the following events: a. a decrease in FHS b. a decrease in progesterone production c. an increase in fsh d. anovulation
a
Bioavailable testosterone
free testosterone and albumin-bound testosterone
Later in the menstrual cycle, high concentrations of progesterone promote the secretion of thicker mucus, which resists the passage of sperm.
progesterone helps prevent passage of sperm
The ovulatory phase (days 13-15).
Ovulation occurs at the midpoint of a normal menstrual cycle, triggered by an LH surge. Ovulation occurs about 12 hours after the peak LH concentration.
What common substrate is used in the biosynthesis of adrenal steroids, including androgens and estrogens? a) cortisol b) catecholamines c) progesterone d) cholesterol
d) cholesterol All adrenal steroid hormones (including cortisol and progesterone) are enzymatically derived from cholesterol. Catecholamines are not steroid hormones [Bishop 2018, p442]
In the developmental progression from childhood through puberty to menopause, all of the following statements regarding levels of FSH and LH are true EXCEPT: A FSH is suppressed from birth to 20 months of age. B LH is increased during the neonatal year (birth to 20 months). C LH and FSH levels are reduced during childhood before puberty. D At the onset of puberty, pulsatile gonadotropin-releasing hormone (GnRH) drives pituitary FSH and LH levels. E LH and FSH levels rise sharply after menopause.
A After birth and the loss of placenta-derived steroids, gonadotropin levels rise. FSH levels are much higher in girls than in boys. This rise in FSH results in ovarian activation (evident on ultrasound) and increased inhibin B and estradiol levels. Studies that have identified mutations in TAC3, which encodes neurokinin B, and its receptor, TAC3R, in patients with GnRH deficiency indicate that both are involved in control of GnRH secretion and may be particularly important at this early stage of development. By 12-20 months of age, the reproductive axis is again suppressed, and a period of relative quiescence persists until puberty. At the onset of puberty, pulsatile GnRH secretion induces pituitary gonadotropin production. In the early stages of puberty, LH and FSH secretion are apparent only during sleep, but as puberty develops, pulsatile gonadotropin secretion occurs throughout the day and night. Gonadotropin levels are cyclic during the reproductive years and increase dramatically with the loss of negative feedback that accompanies menopause (Chap. 412)
B
A 22-year-old woman presents with a 6-month history of amenorrhea. She had normal menarche until 6 months ago. Over the last year she has had a 30lb weight gain. During this time, she also noted worsening acne and some upper-lip terminal hair growth. Her hCG, prolactin, TSH, and FSH are all normal. What would be your next step? a) Pelvic ultrasound b) Total testosterone and DHEAS levels c) LH and estradiol levels d) Pituitary MRI e) Adrenal CT scan
A 19-year old woman comes to the office complaining of galactorrhea. She has never been pregnant. Which hormone is most likely to be responsible for this situation? A) Prolactin B) Estrogen C) Progesterone D) Thyroxine E) Cortisol
A) Prolactin Prolactin is the major stimulator of breast milk production. Overproduction of prolactin leads to galactorrhea. Estrogen progesterone, thyroxine, and cortisol are all needed for proper breast development but play no role in actual milk production. (Braunwald, 15/e, pp2169-2170)
Which of the following functions of the Sertoli cells mediates negative feedback control of follicle-stimulating hormone (FSH) secretion? a) Synthesis of inhibin b) Synthesis of testosterone c) Aromatization of testosterone d) Maintenance of the blood-testes barriere
A) Synthesis of inhibin Inhibin is produced by the Sertoli cells of the testes when they are stimulated by FSH. Inhibin then inhibits further secretion of FSH by negative feedback on the anterior pituitary. The Leydig cells synthesize testosterone Testosterone is aromatized in the ovaries
Which of the following are characteristic of the secretory phase of the menstrual cycle? a) It precedes ovulation b) It depends on progesterone secretion by the corpus luteum c) It coincides with the development of ovarian follicles d) It coincides with a rapid drop in estrogen levels e) It produces ischemia and necrosis of the stratum functionale
B The secretory phase of the menstrual cycle depends on progesterone secretion and follows the proliferative (follicular) phase. The menstrual phase occurs after the secretory phase. During the follicular phase (approximately days 4 to 16), estrogen produced by the ovaries drives cell proliferation in the base of the endometrial glands and the uterine stroma. The proliferative phase culminates with ovulation. The secretory phase (approximately days 16 to 25) is characterized by high progesterone levels from the corpus luteum, a tortuous appearance of the uterine glands, and apocrine secretion by the gland cells. During this phase, maximum endometrial thickness occurs. The menstrual phase (approximately days 26 to 30) is characterized by decreased glandular secretion and eventual glandular degeneration because of decreased production of both progesterone and estrogen by theca lutein cells. Contraction of coiled arteries and arterioles leads to ischemia and necrosis of the stratum functionale.
Which set of results is most likely in a female with hypogonadotropic ovarian failure? a) Increased LH, FSH, and estrogen b) Decreased LH, FSH, and estrogen c) Decreased prolactin and estrogen d) Increased LH and FSH, and decreased estrogen
B) Decreased LH, FSH, and estrogen HypOgonadotropic ovarian failure is the result of pituitary dysfunction. It may be caused by low levels of both LH and FSH, or it may be caused by high levels of prolactin as in prolactinoma, since prolactin will inhibit LHRH and result in low LH and FSH.
A patient biopsy is reviewed by a pathologist. She diagnoses the tumor as originating from Leydig cells. The tumor would most likely produce which of the following? a) Calcitonin b) Progesterone c) Androgens d) FSH e) Parathyroid hormone
C) Androgens A Leydig cell (i.e. , interstitial cell) is regulated by luteinizing hormone (LH), also known as interstitial cell-stimulating hormone (ICSH), secreted by gonadotrophs in the anterior pituitary. Leydig cells are located between the seminiferous tubules and are responsible for the production of testosterone. Leydig cells normally synthesize and release testosterone in response to LH that is produced by gonadotrophs in the anterior pituitary. Leydig cell tumors develop in males between 20 and 60 years of age and produce androgens, estrogens, and sometimes glucocoriticoids Calcitonin is produced by C cells in the thyroid Progesterone is synthesized by corpora lutea under the influence of LH FSH plays a key physiological role in both males (spermatogenesis) and females ( regulation of follicular growth) and is produced and released by gonadotrophs in the anterior pituitary
When should progesterone be measured when evaluating an adult female for anovulation? a) At the onset of menses b) During the first 7 days of the menstrual cycle c) At the midcycle just after LH peaks d) At the end of the menstrual cycle
C) At the midcycle just after LH peaks Progesterone is often measured along with LH, FSH, estrogen, and prolactin to evaluate femal infertility and dysmenorrhea. Progesterone is produced by the corpus luteum and levels are very low during the early follicular phase of the cycle. Progesterone is release by the corpus luteum following the LH surge that occurs 1-2 days prior to ovulation and is an indication that ovulation occurred. Low progesterone at midcycle indicates that ovulation did not occur. This is often the case in polyovarian cyst syndrome.
Which statement best describes the relationship between luteinizing hormone (LH) and follicle-stimulating hormone (FSH) in cases of dysmenorrhea? a) Both are usually increased when there is pituitary adenoma b) Increases in both hormones and a decrease in estrogen signal a pituitary cause of ovarian failure c) Both hormones normally peak 1-2 days before ovulation d) In menopause, the LH level at the midcycle peak is higher than the level of FSH
C) Both hormones normally peak 1-2 days before ovulation In women, serum or urine LH and FSH are measured along with estrogen and progesterone to evaluate the cause of menstrual cycle abnormalities and anovulation. Both hormones show a pronounced serum peak 1-2 days prior to ovulation and urine peak 20-44 hours before ovulation. Normally the LH peak is sharper and greater than the FSH peak; however, in menopause, the FSH usually becomes higher than LH.
A 52-year-old female presents to the office with a complaint of hot flashes. You suspect menopause. Which of the findings below would confirm your diagnosis? A) Normal androgen level B) Normal or low estrogen level C) Normal prolactin level D) High FSH and LH E) High androgen level
D) High FSH and LH In both premenopausal and menopausal women, androgen levels may be normal or high, estrogen levels normal, and prolactin level normal. Androgen production can be in the ovary or in the adrenal gland. Estrogen production is mainly in the ovary prior to menopause and in the periphery by conversion of testosterone in menopause. The amount of estrogen during menopause is a function of the patient's amount of adipose tissue. High FSH and LH are the hallmarks of a lack of adequate ovarian production of both estrogen and progesterone, the chemical markers of menopause, due to lack of negative feedback.
Which step in steroid hormone biosynthesis occurs in the accessory sex target tissues of the male and is catalyzed by 5alpha-reductase? a) Cholesterol---> pregnenolone b) Progesterone---> 11-deoxycorticosterone c) 17-hydroxypregnenolone--->dehydroepiandrosterone d) Testosterone-->estradiol e) Testosterone--->dihydrotestosterone
E) Testosterone--->dihydrotestosterone Some target tissues for androgens contain 5alpha-reductase, which converts testosterone to dihydrotestosterone, the active form in those tissues
Fill in The Blank Both ________ and _____ levels peak at ovulation
FSH LH
Estrogen and progesterone receptor assays are useful in identifying patients who are likely to benefit from endocrine therapy to treat which of the following? a) ovarian cancer b) breast cancer c) endometriosis d) amenorrhea
b About 55-60% of patients whose breast tumors demonstrate estrogen receptors (ER) respond well to endocrine therapy. Ovarian cancer can be monitored with CA-125 tumor marker FSH and LH are often used to monitor the menstrual cycle
In males, pituitary luteinizing hormone (LH): A. Stimulates ejaculation of semen. B. Induces Sertoli cells to produce sperm. C. Has no know reproductive function. D. Induces Leydig cells in the testes to produce testosterone.
d
Secretion of LH and FSH from the pituitary gland in males normally is suppressed by: A. Estrogen B. Cortisol C. Prostate-specific antigen D. Testosterone
d
The most potent of the following estrogen is: A. Estrone B. Estriol C. Testosterone D. Estradiol
d
The onset of menopause is usually associated with what hormone changes? a. Decreased estrogen, FSH, LH and progesterone b. Decreased estrogen and progesterone, and normal FSH and LH c. Decreased estrogen, testosterone, and androgen d. Decreased estrogen and progesterone, and increased FSH and LH
d
Which hormone is responsible for an increase in body temperature at the time of ovulation? a. LH b. Estradiol c. Estrogen d. Progesterone
d
Which of the following explains the suppression of lactation during pregnancy? a) Blood prolactin levels are too low for milk production to occur b) Human placental lactogen levels are too low for milk production to occur c) The fetal adrenal gland does not produce sufficient estriol d) Blood levels of estrogen and progesterone are high e) The maternal anterior pituitary is suppressed
d) Blood levels of estrogen and progesterone are high Although the high circulating levels of estrogen stimulate prolactin secretion during pregnancy, the action of prolactin on the breast is inhibited by progesterone and estrogen. After parturition, progesterone and estrogen levels decrease dramatically. Prolactin can then interact with its receptors in the breast, and lactation proceeds if initiated by suckling.
The source of estrogen during the second and third trimesters of pregnancy is the: a) corpus luteum b) maternal ovaries c) fetal ovaries d) placenta e) maternal ovaries and fetal adrenal gland f) maternal adrenal gland and fetal liver g) fetal adrenal gland, fetal liver, and placenta
g) fetal adrenal gland, fetal liver, and placenta During the second and third trimesters of pregnancy, the fetal adrenal gland synthesized dehydroepiandrosterone-sulfate (DHEA-S), which is hydroxylated in the fetal liver and then transferred to the placenta, where it is aromatized to estrogen. In the first trimester, the corpus luteum is the source of both estrogen and progesterone
Elevated estrogen levels during the menstrual cycle result in which of the following? a) Decrease LH levels b) Downregulate FSH receptors on granulosa cells c) Increase FSH levels d) Increase the ciliation of the epithelial cells of the oviduct e) Decrease synthesis and storage of glycogen in the vaginal epithelium
d) Increase the ciliation of the epithelial cells of the oviduct Estrogen levels increase during the maturation of ovarian follicles, which results in a concomitant increase in ciliation and height of the oviductal lining cells. Increases in the number of cilia serve to facilitate movement of the ovum. Increased estrogen levels also decrease FSH levels and cause an LH surge. Elevated estrogen levels result in increased secretion of lytic enzymes, prostaglandins, plasminogen activator, and collagenase to facilitate the rupture of the ovarian wall and the release of the ovum and the attached corona radiata. Following ovulation, during the luteal phase of the cycle, the theca and granulosa cells are transformed into the corpus luteum under the influence of LH. Ovulation occurs near the middle of the menstrual cycle and is associated with an increase in basal body temperature that appears to be indirectly regulated by elevated estrogen levels, with Il-1 functioning as the endogenous pyrogen. Estrogen also upregulates FSH receptors on granulosa cell membranes and enhances synthesis and storage of glycogen in the vaginal epithelium
Synthesis of milk by the mammary gland specifically requires which of the following? a) Oxytocin b) Production of prolactin by the corpus luteum c) The influence of vasopressin d) Placental lactogen e) Neurohumoral reflexes
d) Placental lactogen The mammary gland enlarges during pregnancy in response to several hormones, including prolactin synthesized by the anterior pituitary, estrogen and progesterone synthesized by the corpeus luteum, and placental lactogen. The alveoli at the end of the duct system respond to those hormones by cell proliferation, which increases the size of the mammary glands. Growth continues throughout pregancy; however secretion is most notable in late pregnancy. Milk is synthesized in the alveoli and is stored in their lumina before passage through the lactiferous ducts to the nipples. Oxytocin is required for the release of milk from the mammary gland through the action of myoepithelial cells that surround the alveoli and proximal (closer to the alveolus) portions of the duct system. Oxytocin is NOT required for milk synthesis. Neurohumoral reflexes are involved in the suckling-milk ejection response.
Estrogen production in the ovary
requires the cooperative function of the theca and granulosa cells under the control of luteinizing hormone (LH) and follicle-stimulating hormone (FSH). HSD, hydroxysteroid dehydrogenase; OHP, hydroxyprogesterone.
A 30-year old woman has the anterior lobe of her pituitary gland surgically removed because of a tumor. Without hormone replacement therapy, which of the following would occur after the operation? a) Absence of menses b) Inability to concentrate the urine in response to water deprivation c) Failure to secrete catecholamines in response to stress d) Failure to secrete insulin in a glucose tolerance test e) Failure to secrete PTH in response to hypocalcemia
A) Absence of menses Normal menstrual cycles depend on the secretion of FSH and LH from the anterior pituitary Concentration of urine in response to water deprivation depends on the secretion of ADH by the posterior pituitary. Anterior pituitary hormones are not involved in the direct effect of glucose on the beta cells of the pancreas or in the direct effect of Ca2+ on the chief cells of the parathyroid gland
Which of the following hormones is often decreased by approximatlely 25% in the serum of pregnant women who have a fetus with down syndrome? a) Estriol (E3) b) hCG c) Progesterone d) Estradiol (E2)
A) Estriol (E3) E3 is produced in the placenta and fetal liver from dehydroepiandrosterone derived from the mother and fetal liver. E3 is the major estrogen produced during pregnancy, and levels rise throughout gestation. Serum free E3 is often lower than expected for the gestational age in a pregnancy associated with Down syndrome. The combination of low serum free estriol, low alpha-fetoprotein, high hCG, and high inhibin A is used as a screening test to detect Down syndrome.
Which of the following results is most likely in an adult male with primary testicular failure? a) Increased LH, FSH, and decreased testosterone b) Decreased LH, FSH, and testosterone c) Decreased testosterone, androstenedione, and FSH d) Increased androstenedione, decreased testosterone, and normal FSH
A) Increased LH, FSH, and decreased testosterone Primary testicular failure produces a picture that is hypergonadotropic. The LH and FSH are increased because the pituitary gland is normal and responds to decreased free testosterone. Androstenedione is an adrenal androgen and is unaffected. In testicular failure secondary to pituitary deficiency (hypOgonadotropic testicular failure), the LH, FSH, and testosterone are low.
Which of the following is substances is converted to a more active form after its secretion? a) Testosterone b) Triiodothyronine (T3) c) Reverese triodothyronine (rT3) d) Angiotensin II e) Aldosterone
A) Testosterone Testosterone is converted to a more active form (dihydrotestosterone) in some target tissues T3 is the active form of thyroid hormone rT3 is an inactive alternative form of T3 Angiotensin I is converted to its active form, Angiotensin II, by the action of ACE. Aldosterone is unchanged after it is secreted by the zona glomerulosa of the adrenal cortex
A 36-year old woman with galactorrhea is treated with bromocriptine. The basis for bromocriptine's action is by acting as an agonist for: a) dopamine b) estradiol c) FSH d) GnRH e) hCG f) oxytocin g) prolactin
A) dopamine Prolactin secretion by the anterior pituitary is tonically inhibited by dopamine secreted by the hypothalamus. If this inhibition is disrupted (e.g., by interruption of the hypothalamic-pituitary tract), then prolactin secretion will be increased, causing galactorrhea. The dopamine agonist bromocriptine stimulates the tonic inhibition by dopamine and inhibits prolactin secretion
The principle of positive feedback is illustrated by the effect of: a) PO2 on breathing rate b) glucose on insulin secretion c) estrogen on follicle-stimulating hormone (FSH) secretion at midcycle d) blood [Ca2+] on PTH secretion e) decreased blood pressure on sympathetic outflow to the heart and blood vessels
C) estrogen on follicle-stimulating hormone (FSH) secretion at midcycle The effect of estrogen on the secretion of FSH and LH by the anterior lobe of the pituitary gland at midcycle is one of the few examples of positive feedback in physiologic systems. Increasing estrogen levels at midcycle cause increased secretion of FSH and LH. The other options illustrate negative feedback
A 30-year old man presents with low libido and erectile dysfunction. He had normal pubertal development, and his symptoms started about 4 months ago. His total testosterone level is decreased at 150ng/dL (normal 300-1000ng/dL). This is confirmed on a repeat early morning blood draw. His LH and FSH are in the normal range. Which of the following laboratory tests are appropriate in the next phase of your evaluation? a) Iron studies b) Prolactin level c) Karyotype d) A and B e) A and C
D
A 55-year-old woman stopped menstruating approximately 3 months ago. Worried that she may be pregnant, she decides to have a pregnancy test. The result is negative. Which of the following series of test results will confirm that the woman is postmenopausal? a) Decreased LH, decreased FSH, increased estrogen b) Decreased LH, increased FSH, decreased estrogen c) Increased LH, decreased FSH, decreased estrogen d) Increased LH, increased FSH, decreased estrogen e) Increased LH, increased FSH, increased estrogen
D) Increased LH, increased FSH, decreased estrogen During menopause, there is a loss of functioning follicles in the ovaries such that GnRH-stimulated LH and FSH secretion do not result in normal estrogen secretion. The low estrogen levels cannot inhibit gonadotropin secretions in a negative-feedback fashion, resulting in very high levels of LH and FSH.
Fill in The Blank Estrogen levels peak at the end of the ___________phase of the menstrual cycle, creating positive feedback to the hypothalamus and pituitary gland. This increases the number of GnRH spikes per 24 hours, causing a surge of both follicle-stimulating hormone (FSH) and luteinizing hormone (LH). It is the surge of LH, in combination with the high estrogen levels, that induces ovulation
follicular
Fill in The Blank FSH levels are particularly high in ____________________women because inhibins, which exert selective negative feedback on FSH secretion, are no longer produced by the ovary.
postmenopausal
Fill in The Blank Estrogen _______ commences just before ovulation, initiates a feedback signal to the hypothalamus, and causes the LH surge.
secretion
