Lecture 35: MALE REPRODUCTIVE SYSTEM 2 Flashcards
What does the scrotum do?
House the testes away from the body to maintain temperature at approximately 34 degrees
What is the scrotum lined by?
The dartos muscle which contracts to wrinkle the skin and reduce the surface area for heat exchange
What does the cremaster muscle do?
Contracts to bring testes closer to to the body 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?
Ductus deferens, blood vessels (testicular arteries and veins), nerves and lymphatics
What are the functions of the penis?
Urination and copulation (insemination)
What shaped organ is the penis?
Cylindrical
What are the components of the penis?
Root (bulb), body (mobile part) and glans covered by prepuce/foreskin
What are the erectile tissues in the penis?
Two corpora cavernosa (corpus cavernosum) and one corpus spongiosum
What is the main erectile tissue?
Corpus cavernosum
What erectile tissue is on the dorsal aspect?
Corpus cavernosum
What does the corpus spongiosum contain?
The urethra
What does the corpus spongiosum form?
Bulb and glans
What erectile tissue is on the ventral aspect?
Corpus spongiosum
How are spermatozoa carried into the female reproductive tract?
In seminal fluid (together called semen)
What is seminal fluid produced by?
Three accessory glands (seminal vesicles, prostate gland and bulbourethral gland)
What are the seminal vesicles?
Two glands located posterior to the bladder and lateral to the ampulla
What do seminal vesicles produce?
Viscous secretion
What portion of semen comes from the seminal vesicles?
60%
What are the properties of seminal fluid from the seminal vesicles?
Alkaline pH protects sperm against acidic environment in the male urethra and female vagins
Where are the prostate glands located?
Inferior to the bladder and wraps around the prostatic urethra
What amount of semen comes from the prostate gland?
30%
What is the seminal fluid from the prostate gland like?
Slightly acidic and milky
What does seminal fluid from the prostate gland contain?
PSA: prostate specific androgen
What does seminal fluid from the prostate gland contribute to?
Sperm activation, viability and motility
What is the remaining 5% of semen?
Spermatozoa
What are the bulbourethral glands?
Two glands located in the urogenital diaphragm
What do the bulbourethral glands open into?
The spongy/penile urethra
What amount of semen volume comes from the bulbourethral glands?
5%
What does the secretion from the bulbourethral gland do?
Lubricate and neutralise acidity in the urethra prior to ejaculation
What is vasectomy?
Surgical method of sterilisation in males
What happens in vasectomy?
Cuts the ductus deferens (cut ends tied or cauterised) so there is no spermatozoa in the semen
what is gametogenesis?
Formation of gametes (sex cells)
What is gametogenesis in males?
Spermatogenesis
What is gametogenesis in females?
oogenesis
What control is gametogenesis under?
Hormonal
How does gametogenesis occur?
Via mitosis and meiosis
What do cells in gametogenesis need to be?
Haploid (23 chromosomes)
What does the original cell in meiosis have?
46 chromosomes (is diploid/2n)
How many cycles of division to produce gametes?
2 (23 chromosomes=haploid/n)
What happens in meiosis 1?
2 haploid cells produced from 1 original diploid cell
What happens in meiosis 2?
Each cell produced from meiosis 1 divides to produce two haploid cells with 23 chromosome cells
What is spermatogenesis?
The process by which spermatogonia are transformed to mature spermatozoa (sperm)
When does spermatogenesis occur?
From puberty onwards
Where does spermatogenesis occur?
In the seminiferous tubules
What happens in spermatogenesis 1?
Spermatogonia divide by mitosis into 2 daughter cells (diploid-46 chromosomes)
What do Type A spermatogonium do?
Stay at the basement membrane of the seminiferous tubule
What do spermatogonia Type B do?
Differentiate into a primary spermatocyte (diploid) which undergoes meiosis 1
What does spermatogenesis 2 form?
2 secondary spermatocytes (haploid - 23 chromosomes)
What do secondary spermatocytes do?
Undergo meiosis 2 to form spermatids (haploid)
What do spermatids do?
Differentiate into spermatozoa with a head, body and tail via spermiogenesis
Where are spermatozoa released?
Into the lumen of seminiferous tubules
What is a gonadotropin?
A hormone that acts on the gonads
What is GnRH?
Gonadotropin releasing hormone produced by the hypothalamus
What is LH?
Luteinzing hormone (a gonadotropin) produced by the anterior pituitary
What is FSH?
Follicle stimulating hormone (a gonadotropin) produced by the anterior pituitary
Where is inhibin secreted from?
Nurse (sertoli) cells
Where is testosterone produced?
By interstitial endocrine (leydig) cells
What is testosterone a type of?
Androgen
What are androgens?
A group of steroid hormones
What are androgens responsible for?
Male characteristics (maturation of sex organs, spermatogenesis, secondary sex characteristics, libido)
What are synthetic androgens?
Steroids for a therapeutic response
What does GnRH stimulate?
The anterior pituitary to release LH and FSH
What does LH stimulate?
Production of testosterone (interstitial endocrine/leydig cells)
What does FSH stimulate?
Inhibit production by nurse cells
What hormones control spermatogenesis?
FSH and testosterone
What does inhibit do?
Suppresses FSH
What does testosterone do?
Suppresses LH, FSH and GnRH