Lecture 35: Male reproductive system II Flashcards
What does the scrotum contain?
3
- 2 testes
- 2 epididymides
- 2 spermatic cords
Why does the scrotum house the testes away from the body?
To maintain their temperature at approximately 34 degrees
What is the scrotum lined by?
The dartos muscle
What does the cremaster muscle within the scrotum do?
Contracts for heat conservation
How many spermatic cords are there?
2
Where do the spermatic cords run?
Between the abdomen and testes
What do the spermatic cords contain?
4
- Ductus deferens
- Blood vessels (Testicular arteries, veins and venous plexus)
- Nerves
- Lymphatics
What are the 2 functions of the penis?
- Urination
- Copulation
What are the 3 regions of the penis?
- Root (bulb)
- Body
- Glans covered by prepuce/foreskin
What cylindrical erectile tissues does the penis contain?
2
- 2 corpora cavernosa
- 1 corpus sponginosum
What is the main erectile tissue in the penis?
Corpora cavernosa (corpus cavernosum - singular)
What aspect of the penis is the corpora cavernosa?
The dorsal aspect
What aspect of the penis is the corpus spongiosum?
Ventral aspect
What does the corpus spongiosum contain?
The urethra
What does the corpus spongiosum form?
2
- Bulb
- Glans
What are spermatozoa carried to the the female reproductive tract in?
Seminal fluid
What is seminal fluid with spermatozoa called?
Semen
What 3 accessory glands is seminal fluid mostly produced by?
- Seminal vesicles
- Prostate gland
- Bulbourethral glands
Where are the seminal vesicles located?
2
- Posterior to the bladder
- Lateral to the ampulla
What do seminal vesicles produce?
Viscous secretion
What % of semen is made by the seminal vesicles?
60%
What does the alkaline pH nature of sperm protect against?
The acidic environment in the urethra and vagina
Where is the prostate gland located?
2
- Inferior to the bladder
- Wrapping around the prostatic urethra
What does the prostate gland produce?
A slightly acidic, milky fluid secretion
What does the prostate gland secretion contain?
PSA (prostate-specific antigen)
What does PSA contained in prostate gland secretion contribute to?
(3)
- Sperm activation
- Sperm viability
- Sperm motility
What % of semen is made by the prostate gland?
30%
Where are the bulbourethral glands located?
In the urogenital diaphragm
What % of semen is made by the bulbourethral glands?
5%
What do secretions of bulbourethral glands do?
Lubricate and neutralise acidity in the urethra prior to ejaculation
What is a vasectomy?
A surgical method of sterilisation in males
What occurs in a vasectomy?
The ductus deferens are cut then tied or cauterised
What is gametogenesis?
The formation of the gametes
What is gametogenesis in males called?
Spermatogenesis
What is gametogenesis in females called?
Oogenesis
What is gametogenesis under the control of?
Hormones
What does gametogenesis occur via?
2
- Mitosis
- Meiosis
What do cells need to be by the end of gametogenesis?
Haploid (contain 23 chromosomes)
How many chromosomes does an original cell contain?
46 chromosomes (diploid/2n)
After 2 cycles of cell division what is produced?
Gametes with 23 chromosomes (haploid)
What occurs in meiosis I?
2 haploid cells are produced from 1 original diploid cell
What occurs in meiosis II?
Each cell produced from meiosis I divides to produce 2 haploid cells with 23 chromosome cells
What is spermatogenesis?
The formation of the male gamete
Spermatogenesis is the process by which what happens?
Spermatogonia are transformed to mature spermatozoa (sperm)
Spermatogenesis occurs spontaneously from when?
Puberty onwards
Where does spermatogenesis occur?
In the seminiferous tubules
During the first stage of spermatogenesis what do spermatogonia divide by and into?
Spermatogonia divide by mitosis into 2 daughter cells
After spermatogonia divide into 2 daughter cells what do type A spermatogonia do?
They stay at the basement membrane of the seminiferous tubule
After spermatogonia divide into 2 daughter cells what happens to type B spermatogonia?
They differentiate into primary spermatocytes which undergo meiosis I
What do primary spermatocytes that have undergone meiosis I form?
2 secondary spermatocytes
What do secondary spermatocytes undergo and form?
Meiosis II to form spermatids (haploid)
What do spermatids differentiate into?
Spermatozoa with a head, tail and body
What do spermatids differentiate into spermatozoa via?
Spermiogenesis
What are spermatozoa released into?
The lumen of the seminiferous tubule
What is gonadotropin?
A hormone that acts on the gonads
What is (GnRH) gonadotropin releasing hormone produced by?
The hypothalamus
What is (LH) Luteinizing hormone (a gonadotropin) produced by?
The anterior pituitary gland
What is (FSH) follicle stimulating hormone (a gonadotropin) produced by?
The anterior pituitary
Where is inhibin produced?
Nurse (Sertoli cells)
Where is testosterone produced?
Interstitial endocrine (Leydig) cells
Testosterone is a type of what?
Androgen
What is androgen a group of?
Steroid hormones
What male characteristics is testosterone responsible for?
4
- Maturation of sex organs
- Spermatogenesis
- Secondary sex characteristics
- Libido
What are synthetic androgens (steroids) used for?
therapeutic purposes
What does LH stimulate?
The production of testosterone
What does FSH and testosterone control?
Spermatogenesis
What does FSH stimulate?
Inhibin production
What does inhibin suppress?
FSH
What does testosterone suppress?
LH & GnRH
