Male reproductive physiology

Question 1

what are the testes?

Answer 1

male reproductive gland- functions to produce sperm

Question 2

what is the epididymis?

Answer 2

• a structure attached to the back of the testes
• contains ducts that allow storage of spermatozoa while they mature and then transports the spermatozoa to the vas deferans

Question 3

what is the vas deferans?

Answer 3

• important part of the male reproductive system
• a thick walled tube that transports sperm from the epididymis to the ejaculatory ducts in preparation for ejaculation

Question 4

what is the seminal vesicle?

Answer 4

• 2 tubular glands that lie behind the bladder of males
• they secrete fluid that contributes to semen

Question 5

what is the prostate gland?

Answer 5

• an accessory male reproductive gland
• secretes fluid that is a component of semen- adds sugars eg glucose and ATP to the sperm to make more mobile

Question 6

what are the bulbourethral glands?

Answer 6

• glands of the male reproductive system
• secrete alkaline fluid because the vagina is acidic

Question 7

what is spermatogenesis?

Answer 7

the formation of sperm

Question 8

where does spermatogenesis occur?

Answer 8

in the seminiferous tubules of the testes

Question 9

what are the functions of testosterone?

Answer 9

• spermatogenesis
• sexual maturation - puberty
• sexual differentiation

Question 10

what is the function of inhibin?

Answer 10

• negative feedback of FSH

Question 11

what is the function of anti-mullerian hormone?

Answer 11

• sexual differentiation

Question 12

what are the 2 main types of cells in the testis & what is their function?

Answer 12

1. leydig cells - testosterone
2. sertoli cells - AMH, inhibin and estrogen

Question 13

what are the effects of testosterone before birth?

Answer 13

• masculinizes the reproductive tract and external genitalia

Question 14

what are the effects of testerone on secondary sexual characteristics?

Answer 14

• induces the male pattern of hair growth - eg beard
• causes the voice to deepen - thickening of vocal cords
• promotes muscle growth

Question 15

what are the effects of testosterone on the male sex organs after birth?

Answer 15

• promotes growth and maturation of the reproductive system at puberty
• its essential for spermatogenesis
• maintains the preproductive tract throughout childhood

Question 16

what are the non reproductive actions of testosterone?

Answer 16

• exerts a protein anabolic effect
• promotes bone growth at puberty
• closes the epiphyseal plate after being

Question 17

what are the effects of testosterone administration?

Answer 17

• descrease on testicular size
• impairs fertility
• increased aggresive behaviour
• used in theraby of lacking libido

Question 18

what hormone is testosterone synthesis regulated by?

Answer 18

LH acts on the leydig cells

Question 19

what hormone acts on the sertoli cells?

Answer 19

FSH

Question 20

Describe the male hypothalamic - pituitary - gonadal axis

Answer 20

• hypothalamus produces GnRH
• GnRh stimulates FSH and LH release from pituitary gland
• FSH acts on sertoli cells
• LH acts on the leydig cells to produce testosterone
• testosterone has a negative feedback effect on LH and inhibin produced by the sertoli cells has a negative feedback effect on FSH

Question 21

what are myoid cells?

Answer 21

smooth muscle cells that surrond the seminiforous tubules

Question 22

what enzyme produces testosterone?

Answer 22

alpha reductase

Question 23

Describe the steps of spermatogenesis

Answer 23

• undifferentiated germ cells - **spermatogonia **
• through mitosis differentitaion - they become **primary spermatocytes **
• 1st meiotic division - they become** secondary spermatocytes**
• 2nd meotic division they become** spermatids**
• spermatids differentiate into spermatozoa

Question 24

what is the andropause?

Answer 24

• the male menopause
• the decline of testosterone with age due to decline in leydig and sertoli cells

Question 25

what is an alpha 5a reductase deficiency?

Answer 25

• autosommal recessive disorder - only effects males
• characteristics include - cyptorchidism - when one testes hasnt moved to its proper position after birth
• can be born with external female genitalia
• their bodies do not produce enough DHT - dihydrotestosterone

Question 26

what is secondary hypogonadism?

Answer 26

• ie hypogonadotrophic hypogonadism
• GnRH insufficiency
• hypopituitarism - may be caused by tumours , surgical trauma, kallman syndrome etc
• there is a reduction in testosterone and GnRH levels

Question 27

what is Kallmans syndrome?

and what is an essential distinguishing feature?

Answer 27

* inherited disorder of deficient GnRH production
* mutations in KAL1 gene inteferes with GnRH secreting neurons to hypothalamus during development
* characterised by infertility, absent/incomplete or partial puberty maturation, also hypogonadotrophic hypogonadism
* 50% of cases have anosmia (loss of smell) - distinguishes KALLMANS SYNDROME from other HH syndromes

Question 28

what is hyperprolactinemia?

what is it? what are potential causes? what does it cause in males vs females?

Answer 28

• presence of abnormally high levels of prolactin in the blood
• causes include benign functioning pituitary adenomas (that are secreting prolactin)
• other tumours that lower dopamine levels can also cause hyperprolactinemia
• in males it causes infertility and loss of libido
• in females it causes galactorrhea (secretion of milk from breast that is not associated with child birth) and amenorrhea

Question 29

what is androgen insensitivity syndrome?

Answer 29

• x linked recessive
• 3 types - complete, mild or partial
• characteristics include failure of male genital development and impaired secondary sexual development, female internal organs never present
• gender assignment is very challenging