Lecture 35 Flashcards
What are the accessory structures of the male reproductive system?
The penis and scrotum
What is the function of the scrotum?
To house testes away from the body to maintain temperature at 34 Celsius which is optimal for spermatogenesis
What are the two muscles of the scrotum?
The dartos and cremaster muscles
Where is the dartos muscle?
Lines inside of the the scrotum, deep to the skin, superficial to the testes
What is the function of the cremaster muscle?
To contract for heat conservation
How many spermatic cords are there?
Two
Where does the spermatic cord run?
Between the abdomen and testis
What does the spermatic cord contain?
Ductus deferen, blood vessels, nerves and lymphatics
What is the venous plexus?
Testicular veins that create web-like structure to increase surface area for temperature regulation
What is the penis?
A cylindrical organ with the root, body and glands that are covered by prepuse/foreskin
What are the functions of the penis?
Urination and copulation
How many erectile tissues does the penis contian?
Three
What are the three erectile tissues within the penis?
The two corpora cavernosa and one corpus spongiosum
What are the corpora cavernosa tissues?
The primary erectile tissues at the dorsal aspect of the penis
What is the corpus spongiosum?
The ventral aspect of the penis, containing the urethra and forming the bulb and glands
What carried spermatozoa into the female reproductive tract?
Seminal fluid, containing spermatozoa called semen
What is seminal fluid produced by?
Seminal vesicles, prostate gland and the bulbourethral grands
What are the seminal vesicles?
Two glads posterior to the bladder and lateral to the ampulla that produce a viscous secretion that makes up about 60% of semen.
What is the function of the fluid from the seminal vesicles?
It is alkaline to protect sperm against the acidic environment of the urethra and vagina
What is the prostate gland?
A gland that lies inferior to the bladder and wraps around the prostatic urethra. It produces about 30% of semen that is slightly acidic and milky that contributes to sperm activation, viability and motility
What does the fluid from the prostate glands contain?
Prostate-specific antigen
What are the bulbourethral glands?
Two glands located in the urogenital diaphragm that open into the spongy/penile urethra. They contribute about 5% of semen volume.
What is the function of the fluid from the bulbourethral glands?
To lubricate and neutralise the acidity in the urethra prior to ejaculation
What makes up the last 5% of semen?
Spermatozoa
What is a vasectomy?
A surgical method of sterilisation in males that cuts the ductus deferens
What is gametogenesis?
The formation of gametes
What is gametogenesis called in males?
Spermatogenesis
What is gametogenesis called in females?
Oogenesis
What controls gametogenesis?
Hormones
How does gametogenesis occur?
Via mitosis and meiosis
What must the cells be to undergo gametogenesis?
Haploid
How many chromosomes does a cell originally have?
46
What produces gametes?
Two cycles of cell division, meiosis 1 and 2
What is meiosis 1?
Where 2 haploid cells are produced from one diploid cell
What is meiosis 2?
Each cell produced from meiosis 1 divided to produce 2 haploid cells with 23 chromosomes
What is spermatogenesis?
The process by which spermatogonia are transformed to mature spermatozoa
Where does spermatogenesis occur?
In the seminiferous tubules
When does spermatogenesis occur?
From puberty onwards
What is spermatogenesis 1?
The process by which spermatogonia divide by mitosis into 2 daughter cells (diploid). One spermatogonium (type A) stays at the basement membrane of the seminiferous tubule
What is spermatogenesis 2?
The second spermatogonia (type B) differentiates into a primary spermatocyte (diploid) which undergoes meiosis 1 and forms two secondary spermatocytes (haploid)
What is spermatogenesis 3?
The two secondary spermatocytes undergo meiosis 2 to form spermatids (haploid) which differentiate into spermatozoa with a head, body and tail via spermiogenesis. These are released into the lumen
What are the reproductive hormones produced by the hypothalamus?
Gonadotropin-releasing hormone (GnRH)
What are the reproductive hormones produced by the anterior pituitary gland?
Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) which are both gonadotropin hormones
What are gonadotropin hormones?
Hormones that act of the gonads
What are the extra hormones in males?
Inhibin from nurse cells and testosterone from interstitial endocrine cells
What is testoserone?
A type of androgen, a group of steroid hormones responsible for male characteristics like maturation of sex organs, spermatogenesis, secondary sex characteristics and libido (sex drive)
What are synthetic androgens?
Steroids - used for therapeutic purposes
What does LH stimulate?
Testosterone prduction
What does FSH and testosterone control?
Spermatogenesis
What does FSH stimulate?
Production of inhibin
What is the negative feedback loop?
Increased inhibin suppresses FSH and increased testosterone suppresses LH and GnRH
