Male Reproductive System II Flashcards
What is the scrotum made up of?
Scrotum is a sac of skin lined with a superficial fascia, made up of testes, epididymis and spermatic cords
Ductus derferens are enclosed in a spermatic cord which is found in the scrotum
What is the function of the scrotum?
Spermatogenesis occurs optimally at around ~34C
By having testes outside body allows easier regulation in the testes
Dartos muscle lines scrotum and wrinkles the skin, reducing surface area to help for thermoregulation
Cremaster muscle encloses spermatic cord and covers testes , when contracts draws testes closer to body for thermoregulation
What is the spermatic cord?
The spermatic cord run between testes and abdomen, contain testicular arteries, lymphatic supply, nerve supply, venous plexus (in a network surrounding artery allowing for counter exchange of heat between warm and cool blood) and ductus deferens
What is the penis?
Penis has two functions - urination and copulation (inseminates the female)
Three main parts - root (adjacent to abdominal wall, adhered in the urogenital triangle), body (mobile) and glans (covered by foreskin/prepuce)
Three columns of erectile tissue, form crura
What are the three erectile tissues that make up the penis?
Two corpora cavernosa form crura - main erectile tissue in penis, found on the dorsal aspect of the penis (when flaccid it is ventral, when erected dorsal), fill with blood during erection
Single corpus spongiosum - situated on ventral aspect of penis (ventral when erect, dorsal when flaccid), where urethra runs through, forms bulb and glans
What are the accessory glands?
Spermatozoa require transport medium to transport semen from male reproductive tract into female reproductive tract
Seminal fluid is mostly produced by three types of accessory glands : seminal vesicles, prostate gland and bulbourethral glands
Seminal fluid provides protection for spermatozoa along female reproductive tract as female tract is acidic, fluid activates spermatozoa, need an energy supply for activation
What are the seminal vesicles?
Seminal vesicles are paired structures found posterior to bladder, lateral to ampulla of ductus deferens. Produce viscous alkaline secretion which helps protect sperm against acidic environment of vagina and urethra.
Produce greatest volume of semen, 60%
What is the prostate gland?
Wraps around prostatic urethra, inferior to bladder. Produces around 30% of volume of the total semen. Contains PSA (prostate-specific antigen), contributes to sperm activation, viability (survival) and motility
What are the bulbourethral glands?
Located in the urogenital diaphragm, open into spongy/penile region of urethra. Only contribute ~5% of seminal fluid however important as help lubricate urethra and remove any residual urine in urethral tract prior to ejaculation
Components of semen
60% from seminal vesicle
30% from prostate
5% from bulbourethral glands
5% from sperm/spermatozoa
What is a vasectomy?
Vasectomy is a surgical method of sterilisation in males, cut the ductus deferens meaning spermatozoa cannot be transported
Volume of seminal fluid stays the same however volume of semen decrease a bit
What is gametogenesis?
Production and formation of gametes (sex cells) under tight hormonal control and occurs via mitosis and meiosis (cells need to be haploid, 23 chromosomes)
Over view of meiosis
Same process in males and females, humans start with 46 chromosomes (diploid) and need to produce only 23 chromosomes (haploid). This occurs via meiosis I (two haploid cells produced from one original diploid cell) and meiosis II (each cell produced from meiosis I divides to produce two haploid cells with 23 chromosomes)
What is spermatogenesis?
Spermatogenesis is the formation of the male gamete and is the process by which spermatogonia undergo mitosis and meiosis and are transformed to mature spermatozoa. Spermatogenesis begins in puberty and occurs in the seminiferous tubules
What is spermatogenesis 1?
Spermatogonia divide by mitosis into two daughter cells, one spermatogonia stays at the basement membrane of the seminiferous tubule
This cell stays as these are stem cells so need to continue producing spermatogenic cells throughout the males lifespan - type A spermatogonia
Negative feedback loop for hormones in male reproductive system
GnRH released in hypothalamus and transported to anterior pituitary resulting in production of LH and FSH. LH acts on the interstitial endocrine cells and stimulates production of testosterone. FSH acts on nurse cells and with testosterone helps to regulate spermatogenesis
Inhibin provides negative feedback and suppresses FSH, testosterone provides negative feedback and suppresses LH and GnRH. Negative feedback loops maintain homeostasis for a steady state production of spermatozoa
