Physio: Male Reproductive Hormones

Question 1

Dihydrotestosterone (DHT) is primarily formed and active in which of the following locations?
A) Hypothalamus
B) Testes
C) Anterior pituitary
D) Target tissues

Answer 1

D) Target tissues

Found in the penis, scrotum, prostate

Question 2

Luteinizing hormone (LH) primarily stimulates the secretion of which hormone?
A) GnRH
B) FSH
C) Testosterone
D) Inhibin

Answer 2

C) Testosterone

Question 3

Follicle-stimulating hormone (FSH) increases the secretory activity of which testicular cells, stimulating spermatogenesis?
A) Leydig cells
B) Theca cells
C) Granulosa cells
D) Sertoli cells

Answer 3

D) Sertoli cells

FSH activates aromatase to convert testosterone to Estradiol and Androsterone to Estrone

Question 4

Inhibin is a hormone released by the Sertoli cells that decreases the secretion of which hormone from the anterior pituitary?
A) LH
B) FSH
C) GnRH
D) Testosterone

Answer 4

B) FSH

Question 5

Discuss the biosynthesis of Testosterone.

Answer 5

Cholesterol > cholesterol demolase > Pregnenolone&raquo_space; 17a- hydroxylase > 17a- pregnenalone > 17,20 lysase > DHEA > 3b- hydrosteroid dehydrogenase and 5,4 isomerase > Androstenedione > 17b- hydrosteroid dehydrogenase > TESTOSTERONE

Question 6

List the receptors found on the following cells:
A. Grandulosa
B. Leydig cells
C. Theca cell
D. Seratoli cells

Answer 6

A. FSH and LH
B. LH
C. LH only
D. FSH

Question 7

State the two ways in which testosterone disperses once secreted by the Leydig cells.

Answer 7

1. It diffuses in seminiferous tubules then diffused into systematic circulation
2. Goes to the site of spermatogenesis

Question 8

In females, adrenal androgens contribute to which function?
A) Spermatogenesis
B) Ovulation
C) Libido
D) Milk production

Answer 8

C) Libido

Question 9

Adrenal androgens can serve as a source of which hormones during menopause in females?
A) Progesterone
B) Estrogens
C) Androstenediol
D) Testosterone

Answer 9

B) Estrogens

Question 10

Testosterone is produced in which specific location?
A) Anterior pituitary
B) Adrenal cortex
C) Ovaries
D) Testes

Answer 10

D) Testes

Question 11

Which specific cells in the testes are responsible for producing testosterone?

A) Sertoli cells
B) Germinal epithelium cells
C) Leydig cells
D) Granulosa cells

Answer 11

C) Leydig cells

Question 12

Which enzyme is mentioned as being involved in the biosynthesis steps of testosterone in Leydig cells?
A) Aromatase
B) 5alpha-reductase
C) 17beta-hydroxysteroid dehydrogenase
D) Cholesterol hydroxylase

Answer 12

C) 17beta-hydroxysteroid dehydrogenase

Question 13

Testosterone production in Leydig cells is stimulated by which hormone released from the anterior pituitary?

A) FSH
B) GnRH
C) Inhibin
D) LH

Answer 13

D) LH

Question 14

After being secreted by Leydig cells, testosterone diffuses out and penetrates across the basement membrane to get into which cells?

A) Interstitial cells
B) Sertoli cells
C) Blood capillaries
D) Germinal epithelium cells

Answer 14

B) Sertoli cells.

Once entry into the cell, it stimulates synthesis of proteins requires for spermatogenesis

Question 15

In Sertoli cells, testosterone stimulates the synthesis of proteins that regulate which process?

A) Testosterone synthesis
B) LH secretion
C) Spermatogenesis
D) Estradiol synthesis

Answer 15

C) Spermatogenesis

Question 16

FSH, via receptor stimulation on the Sertoli cell, activates which enzyme?
A) 5alpha-reductase
B) 17beta-hydroxysteroid dehydrogenase
C) Aromatase
D) Cholesterol desmolase

Answer 16

C) Aromatase

Question 17

The enzyme Aromatase converts Testosterone into which hormone?
A) DHT
B) Estradiol
C) Androstenedione
D) Inhibin

Answer 17

B) Estradiol

Question 18

Estradiol, converted from testosterone in Sertoli cells, diffuses back to which cells?

A) Hypothalamus
B) Anterior pituitary
C) Leydig cells
D) Blood capillaries

Answer 18

C) Leydig cells

Question 19

Estradiol diffusing back to Leydig cells stimulates synthesis of paracrine factors that reduce the responsiveness of Leydig cells to the stimulatory effect of which hormone?

A) FSH
B) GnRH
C) LH
D) Inhibin

Answer 19

C) LH

Question 20

Estradiol in Leydig cells can stimulate synthesis of proteins that reduce the synthesis of testosterone from which precursor molecule?

A) Androstenedione
B) DHEA
C) Estrone
D) Cholesterol

Answer 20

D) Cholesterol

Question 21

During embryonic life, testosterone production by testes is stimulated by fetal luteinizing hormone and which other hormone secreted by the placenta?
A) Estrogen
B) Progesterone
C) Chorionic gonadotropin
D) GnRH

Answer 21

C) Chorionic gonadotropin

Question 22

The neonatal surge in plasma testosterone shortly after birth is related to the activation of which axis?

A) Hypothalamic-anterior pituitary-adrenal axis
B) Hypothalamic-posterior pituitary-gonadal axis
C) Hypothalamic-pituitary axis
D) Adrenal-gonadal axis

Answer 22

C) Hypothalamic-pituitary axis

Question 23

In the bloodstream, circulating testosterone is primarily bound to which substances?
A) Free in plasma
B) Proteins like gonadal steroid-binding protein and albumin
C) Red blood cells
D) Lipids

Answer 23

B) Proteins like gonadal steroid-binding protein and albumin

Question 24

The function of protein binding for testosterone in the bloodstream is primarily to create which of the following?

A) A biologically inactive form for excretion
B) A soluble form for transport
C) A reservoir of testosterone
D) A form that can easily penetrate cell membranes

Answer 24

C) A reservoir of testosterone

Question 25

Which enzyme is present in target tissues like the prostate, scrotum, and penis, converting testosterone to dihydrotestosterone (DHT)? A) Aromatase B) 17beta-hydroxysteroid dehydrogenase C) 5alpha-reductase D) Cholesterol desmolase

Answer 25

C) 5alpha-reductase

Question 26

Compared to testosterone, Dihydrotestosterone (DHT) has which characteristic regarding its receptor interaction and biological effects? A) Lower affinity and less potent B) Lower affinity and more potent C) Greater affinity and less potent D) Greater affinity and more potent

Answer 26

D) Greater affinity and more potent

Question 27

Plasma levels of Dihydrotestosterone (DHT) are typically how does it compare to Testosterone? A) Much higher B) Slightly higher C) Similar D) Much smaller

Answer 27

D) Much smaller

Question 28

Testosterone is primarily metabolized in which organs? A) Testes and prostate B) Liver and kidney C) Hypothalamus and pituitary D) Adrenal glands and pancreas

Answer 28

B) Liver and kidney Testosterone is metabolized into an inactive, polar derivative that can be passed through the urine by the kidney

Question 29

The major products of testosterone metabolism that are biologically inactive polar derivatives are known as which of the following? A) Estrogens B) 17-ketosteroids C) Sulfates and glucuronides D) Dihydrotestosterone

Answer 29

B) 17-ketosteroids

Question 30

Native testosterone can be conjugated to form what water-soluble derivatives making them suitable for excretion in which medium?

Answer 30

Sulfates and glucuronides

Question 31

During embryonic life, which hormone promotes the development of the internal genital tract in males (epididymis, vas deferens, seminal vesicles, ejaculatory ducts)? A) DHT B) Antimullerian hormone C) Testosterone D) LH

Answer 31

C) Testosterone

Question 32

During embryonic life, which hormone promotes the development of the external genitalia in males? A) Testosterone B) Antimullerian hormone C) FSH D) DHT

Answer 32

D) DHT

Question 33

Which enzyme converts testosterone to DHT in the target tissues (e.g., male external genitalia and prostate) during embryonic development? A) Aromatase B) 17beta-hydroxysteroid dehydrogenase C) 5alpha-reductase D) Cholesterol desmolase

Answer 33

C) 5alpha-reductase

Question 34

Congenital deficiency of 5alpha-reductase in males during embryonic life results in which condition due to inadequate development of external genitalia? A) Hypergonadism B) Eunuchism C) Ambiguous genitalia (male pseudohermaphroditism) D) Benign prostate hyperplasia

Answer 34

C) Ambiguous genitalia (male pseudohermaphroditism)

Question 35

Brain development during embryonic life is influenced by the presence or absence of which hormone, shaping future sexual behavior? A) DHT B) Estrogen C) Testosterone D) Inhibin

Answer 35

C) Testosterone

Question 36

During puberty, sexual drive is stimulated by which hormone? A) DHT B) Inhibin C) LH D) Testosterone

Answer 36

D) Testosterone

Question 37

During puberty, prostate secretions are stimulated by which hormone? A) Testosterone B) FSH C) DHT D) LH

Answer 37

C) DHT

Question 38

During puberty, spermatozoa production in the testes is stimulated by which hormone? A) DHT B) GnRH C) Testosterone D) Inhibin

Answer 38

C) Testosterone

Question 39

Dihydrotestosterone (DHT) may contribute to the pathogenesis of which prostate condition in adulthood? A) Prostate cancer B) Prostatitis C) Benign prostate hyperplasia D) Prostate atrophy

Answer 39

C) Benign prostate hyperplasia

Question 40

A non-reproductive effect of testosterone listed in the source involves changes in plasma lipid profile due to altered synthesis of which lipoproteins in the liver? A) Increased HDL, reduced LDL and VLDL B) Reduced HDL, increased LDL and VLDL C) Increased HDL and VLDL, reduced LDL D) Reduced HDL and LDL, increased VLDL

Answer 40

A) Increased HDL, reduced LDL and VLDL

Question 41

Which non-reproductive effect of testosterone is mediated by the stimulation of erythropoietin production by the kidney? A) Increased red blood cell production B) Increased white blood cell count C) Decreased platelet count D) Decreased plasma volume

Answer 41

A) Increased red blood cell production

Question 42

Testosterone has which non-reproductive effect related to fat deposition? A) Decreased deposition of abdominal visceral fat B) Increased deposition of subcutaneous fat C) Increased deposition of abdominal visceral fat D) Conversion of fat to muscle

Answer 42

C) Increased deposition of abdominal visceral fat

Question 43

Testosterone exerts a non-reproductive feedback inhibition on the secretion of which hormones? A) FSH from anterior pituitary only B) LH from anterior pituitary only C) GnRH from hypothalamus only D) GnRH from hypothalamus and LH from anterior pituitary

Answer 43

D) GnRH from hypothalamus and LH from anterior pituitary

Question 44

Primary and secondary hypogonadism is caused by dysfunction in which organs?

Answer 44

Primary Hypo - dysfunction of testes leading to a decrease in testosterone Secondary - failure of the hypothalamus and anterior pituitary > LH and GnRH

Question 45

Primary hypogonadism may result from surgical removal of the testes, also known as what procedure? A) Vasectomy B) Orchidectomy (Castration) C) Epididymectomy D) Prostatectomy

Answer 45

B) Orchidectomy (Castration)

Question 46

Surgical removal of testes before the onset of puberty results in which specific condition? A) Hypergonadism B) Secondary hypogonadism C) Benign prostate hyperplasia D) Eunuchism

Answer 46

D) Eunuchism

Question 47

Which of the following physical characteristics is typically associated with eunuchism resulting from pre-puberty castration? A) Normal masculine hair distribution B) Increased skeletal muscle mass C) External genitalia remaining in an infantile state D) Voice regressing from bass quality

Answer 47

C) External genitalia remaining in an infantile state Other characteristics — Decrease body and pubic hair Thin bones Weak muscles Child like voice Gyneocomastia

Question 48

In eunuchism resulting from pre-puberty castration, blood levels of Luteinizing hormone (LH) and Follicle-stimulating hormone (FSH) are typically what, in response to low plasma testosterone? A) Considerably decreased B) Considerably increased C) Unchanged D) Slightly decreased

Answer 48

B) Considerably increased

Question 49

When castration is performed after puberty, the external genitalia typically regress to what extent? A) To an infantile state B) Not at all C) Slightly in size, but not to a childlike state D) Significantly in size, beyond a childlike state

Answer 49

C) Slightly in size, but not to a childlike state Other effects: Decrease in voice slightly Decrease sex drive Decrease muscles Thin bones Erection can occur but not as easily

Question 50

Hypothalamic eunuchism (secondary male hypogonadism) is often associated with a concomitant abnormality of which physiological center, leading to increased food consumption and obesity? A) Respiratory center B) Vasomotor center C) Feeding center D) Thermoregulatory center

Answer 50

C) Feeding center Secondary hypo is due to an decrease secretion of GnRH

Question 51

Increased production of testosterone (hypergonadism) in males most commonly occurs in patients with tumors of which testicular cells? A) Sertoli cells B) Germinal epithelium cells C) Leydig cells D) Myoid cells

Answer 51

C) Leydig cells This causes an increase development of external genital organs Increase in sex characteristics If in early infants, it increases the sex characteristics, bone and muscles early but the adult height is not normal.

Question 52

During embryonic life, Testosterone promotes the development of the internal genital tract in male. What is the effect of the testosterone and antimullerian hormone during this period?

Answer 52

The testosterone differentiate the wolfferian duct to ejeculatory ducts, seminal vesicles, vas deferens and epidydmis. The antimullerian duct causes atrophy of the Müllerian duct.

Question 53

FSH acts on the Sertoli cells of the tested to stimulate and product what?

Answer 53

Stimulate spermatogenesis Production of Inhibin Note: If FSH is block, Inhibin levels decrease and regression of spermatogenesis occurs.