Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

FHB Exam 4: Endocrinology and Reproduction > Reproduction I/II: HPG Axis & Male Reproduction > Flashcards

Reproduction I/II: HPG Axis & Male Reproduction Flashcards

1
Q

What is the hormone that is absolutely required for the HPG axis to work?

A

gonadotropin-releasing hormone (GnRH), which must be released in a pulsatile manner at the median eminence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What do LH and FSH stimulate?

A

LH stimulates steroidogenesis in ovaries and testes, and FSH stimulates gametogenesis in ovaries and testes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is required to initiate GnRH release at the time of puberty?

A

kisspeptin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Mutations in KISS1 receptor cause what?

A

hypogonadotropic hypogonadism (and failure to enter puberty)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Are most of the regulatory hormones associated with regulation of GnRH inhibitory or stimulatory?

A

inhibitory

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is a specific inhibitor for FSH?

A

inhibin B (inhibits FSH beta subunit synthesis in gonadotropes)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What does activin do?

A

stimulates FSH beta, LH beta, and GnRH receptor synthesis in pituitary

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the pituitary gonadotropins, aka “tropic hormones”?

A

LH, FSH, TSH, hCG

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Which cells form the blood-testes barrier?

A

Sertoli cells (via tight junctions)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are some of the functions of FSH in male reproduction?

A
  • stimulates spermatogenesis and increases sperm motility
  • stimulates growth of seminif. tubules (primary determinant of testes size)
  • stimulates androgen-binding protein (ABP) to maintain high local testosterone
  • stimulates aromatase, inhibin, and growth factors
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Why is it important to keep a high LOCAL concentration of testosterone in the testes?

A

We don’t want a high concentration of testosterone in the circulation because it could shut down the HPG axis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are some of the functions of LH in male reproduction?

A
  • stimulates steroidogenesis from cholesterol
  • stimulates StAR protein
  • stimulates Leydig cell growth
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the role of aromatase in steroid metabolism?

A

converts testosterone to estradiol

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the role of 5alpha-reductase in steroid metabolism?

A

found in genital skin and prostate; converts testosterone into DHT

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Does testosterone or DHT have a higher affinity for androgen receptor (AR)?

A

DHT

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are examples of androgens we talked about?

A
  • DHEA
  • androstenedione
  • testosterone
  • DHT
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are the major enzymes for testosterone?

A
  • CYP17
  • 17betaHSD-type III (high-efficiency and unique to Leydig cells)
  • 5alpha-reductase and aromatase (convert testosterone to metabolites–DHT and estradiol)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Masculinization of the brain requires ___________.

A

T to E conversion

19
Q

What happens to excess testosterone?

A
  • less than 2% is excreted as free testosterone

- remainder is converted to 17-ketosteroids and DHT, then conjugated to soluble forms and excreted in the urine

20
Q

Why are men more vulnerable to CVD?

A

testosterone acts on the liver, causing increased LDL and decreased HDL; testosterone also causes an increased amount of abdominal visceral fat, thus increasing risk for CVD

21
Q

How does testosterone vs. DHT affect pubertal development?

A
  • testosterone: penis, seminal vesicles, musculature, voice, skeleton, spermatogenesis
  • DHT: scrotum, prostate, male pattern hair distribution, sebaceous glands
22
Q

How does testosterone vs. DHT affect fetal development of the male reproductive system?

A
  • testosterone: epididymis, vas deferens, seminal vesicles

- DHT: penis, penile urethra, scrotum, prostate

23
Q

What is cryptorchidism?

A

“hidden testis” due to failure of descent into scrotum; most common congenital abnormality of urogenital tract

24
Q

At which point in gestation does migration of the testes into the scrotum occur?

A

25-35 weeks

25
Q

Describe the functional anatomy of the testes.

A
  • each testis weighs ~40g with 80% germinal tissue and 20% supportive connective tissue
  • seminiferous tubules make up ~200 m of coiled mass
  • 100-200 million sperm produced per day
  • peritubular space: Leydig cells, myoid cells, blood supply
  • intratubular space: Sertoli cells, developing germ cells, lumen
26
Q

Explain the paracrine actions of inhibin and activin.

A

Inhibin and activin are named opposite of the action they are named for in the pituitary. So, in the testes, inhibin ACTIVATES LH-induced testosterone production in Leydig cells, and activin INHIBITS testosterone production in Leydig cells.

27
Q

Where does spermatogenesis, spermiogenesis, and spermiation occur?

A

seminiferous tubules

28
Q

What is the difference between spermatogenesis, spermiogenesis, and spermiation?

A
  • spermatogenesis: spermatogonia become 4 haploid spermatids
  • spermiogenesis: maturation of spermatids into spermatozoa
  • spermiation: release of spermatozoa from Sertoli cells into lumen of tubule
29
Q

Do spermatozoa continue to mature after being released into the lumen?

A

Yes! They are initially immobile and mature along the single tubule of the epididymis to gain motility. Spermatozoa are not fully mature until they enter the vaginal cavity.

30
Q

Erection is primarily under ______ control.

A

parasympathetic (sympathetic nerve activity is decreased, increasing the net effect of parasympathetics)

31
Q

Refers to the movement of ejaculate into the prostatic/proximal part of the urethra; under sympathetic control; sets the stage for ejaculation.

A

emission

32
Q

What is ejaculation triggered by?

A

It is a spinal reflex that is triggered by entry of semen into bulbous urethra from prostatic urethra.
(ANS, then spinal reflex)

33
Q

What are the 3 main categories of male reproductive dysfunction + examples?

A
  • Pre-testicular: primary (hypergonadotropic hypogonadism as in Klinefelter’s and enzyme deficiencies), secondary/tertiary (hypogonadotropic hypogonadism as in Kallmann’s and pituitary tumor)
  • Testicular: Klinefelter syndrome, cryptorchidism, varicocele
  • Post-testicular: ductal obstructions, premature ejaculation, impotence
34
Q

What is the most common cause of subfertility in men?

A

varicocele (dilated scrotal veins)

35
Q

What are the accessory glands in the male reproductive system?

A
  • semen
  • seminal vesicles
  • prostate
  • bulbourethral glands
36
Q

What is the composition of semen?

A

10% sperm, 70% fluid from seminal vesicles, 10-20% fluid from epididymis, prostate, bulbourethral glands

37
Q

Which are the important functions of the seminal vesicles?

A
  • secrete nutrients (like fructose and citric acid) that keep sperm alive in female reproductive tract
  • secrete prostaglandins that induce contractions of uterus and fallopian tubes to facilitate sperm transport
  • act as a buffer and keep pH in a narrow range to promote optimal survival/mobility
38
Q

What is the function of the prostate gland?

A

produces the first fluid to be expelled in ejaculate; contains alkaline secretions (neutralize vaginal secretions) and proteolytic enzymes (liquefy semen)

39
Q

What is the function of the bulbourethral (Cowper’s) gland?

A

secretes mucous into urethra upon arousal (pre-ejaculate)

40
Q

Is “free” PSA lower in malignant or benign cancer?

A

malignant

41
Q

What restricts blood flow to the penis in a flaccid state?

A

tonic contraction of helicine arteries

42
Q

What surrounds the penile urethra?

A

corpus spongiosum (erectile tissue)

43
Q

What does Viagra do?

A

inhibits phosphodiesterases that that would normally decrease cGMP in order to maintain chronic state of vasodilation

FHB Exam 4: Endocrinology and Reproduction (14 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions