The Male Reproductive Sytem Flashcards
What is the basic structure of the male gonads
Epididymis, ductus deferens and testes
What is the dual function of the male gonads
-Testes secrete large amounts of androgens and small amounts of oestrogens
- Gametogenesis (spermatogenesis in males) to produce gametes
Describe the basic anatomy of the male reproductive system
Testis, epididymis, vas deferens, seminal vesicle, prostate, ejaculatory duct, bulbourethal gland, penis
What is the role of the testes
Contains globules where spermatogenesis will occur
What is the role of the epididymis
Sperm produced are deposited here and travel as they mature
What is the role of the vas deferens
Inactive sperm produced are stored here for up to. 3 months
What is the role of the seminal vesicle
Produces some of the components that make up the semen that dilutes the sperm to form the ejaculate
What is the role of the prostate
Prostate gland creates remaining component of semen, mostly muscle providing switch between urinary tract and ejaculatory tract
What is the role of the ejaculatory duct
Everything is mixed to form semen and expelled
What is the intratubular compartment
Component of testes that contains stem cells involved in sperm production
What is the peritubular compartment
Component of testes that contains leading cells e.g. hormale cells, muscle cells and blood vessels to support spermatogenesis
What are spermatids
Small round cells that undergo spermaiogenesis to form spermatozoa (sperm)
What is a spermatozoom
Matured spermatids with a smaller nucleus, little cytoplasm and prominent tail
How do sperm propel themselves
Micro tubular structures within their tail
What is the acrosome
Membrane covering head of sperm that acts as a lysosome and contains hydrolytic enzymes to digest the egg membrane
Why are the hydrolytic enzymes in the acrosome only activated during the acrosomal reaction in the fallopian tube
Enable fertilisation and prevents digestion of other cell membranes that aren’t the egg
How many days does spermatogenesis take
72
How often do groups of spermatogonia enter spermatogenesis
Every 16 days
Why are spermatogenesis cycles consistent
To ensure that not all spermatogonia enter spermatogenesis at the same time along the entire length of the seminiferous tubule
What type or types of cell division does spermatogenesis involve
Mitosis and meiosis
Describe the 6 steps in spermatogenesis
1) spermatogonial stem cells (SSC) divide by mitosis to produce daughter spermatogonia (2n)
2) at least one spermatogonium remains in the stem cell population
3) majority id spermatogonia migrate away from basal laminate (in testes) and differentiate into primary spermatocytes (2n)
4) primary spermatocytes enter meiosis 1 to form 2 secondary spermatocytes (n)
5) each secondary spermatocyte enters meiosis 2 within 20 minutes to form spermatids (n)
6) Initial products of meiosis 1 and 2 are four spermatids linked with cytoplasmic bridges
Describe the development of a spermatogonial stem cell to a mature sperm
Spermatogonial stem cells, spermatogonium, primary spermatocytes, secondary spermatocytes, spermatids, mature sperm cell
What are the 5 main functions of the Sertoli cells
1) guide sperm towards lumen by forming and re-forming junctions
2) Blood testes barrier as tight junctions to provide immunologically safe environment
3)Secrete fluid to move immobile sperm to epididymis
4) transfer nutrients
5) phagocytosis of residual cytoplasm and dead sperm
What are Sertoli cells
Companion cells that surround the dividing cells
Where do sperm undergo further maturation after spermatogenesis
Epididymis
Why do spermatozoa undergo decapacitation in the epididymis
To prevent spermatozoa undergoing the acrosome reaction before coming into contact with an oocyte (egg)
Where are sperm stored
Vas deferens
What happens in the vas deferens upon stimulation of the penis
Undergoes peristaltic contractions to propel sperm into urethra during intercourse for ejaculation
What does the epididymis epithelium secrete and what is the function of this
Seminal fluid, enables spermatozoa to become increasingly motile/tail activation
What controls spermatozoa decapacitation in the epididymis
Testosterone-ABP complexes and testosterone from the blood
Describe the composition of semen
Sperm (10%) and seminal fluid (90%)
What is the pH of seminal fluid
6.5
What buffers seminal fluid
Phosphate and bicarbonate ions
What percentage of semen volume is secreted by the seminal vesicles
60-70%
What secretes fructose and why
Seminal vesicles, for sperm motility
What secretes semenogelins and why
Seminal vesicles, and to induce semen coagulation after ejaculation so no sperm has advantage for fertilisation
What percentage of semen volume is secreted by the prostate gland
20-30%
What is PSA
prostate specific antigen that is a protease that liquefies coagulated sperm after a few minutes and can be used as an indicator of prostate health
Where is PSA secreted from
Prostate gland
What else does the prostate gland secrete and why
Citrate, zinc, spermine and acid phosphatase to form thin milky fluid
What are the Bulbourethral glands/cowpeas glands
Peas sized gland embedded in urethral sphincter that emptied the penile urethra in response to sexual excitement/ prior to emission and ejaculation of semen
How does the bulborethral gland prepare for ejaculation
Secretes mucus to lubricate, cleanse and buffer the urethra
What is the average sperm count
60-100 x10^6 /ml of semen
What is the average ejaculate volume
1.5-5 ml
What three factors may mean someone is considered infertile
- sperm count <20x10^6 /ml semen
- less than 50% motile sperm
- <60% normally conformed sperm
What is internal insemination
Separation of vaginal wall and deposition of semen at the distal end of the vaginal lumen near the cervix by the penis
Describe how erection is neurovascular event
During flaccid state blood flow to corpus cavernous is vasoconstricted (via helicine arteries), sexual arousal stimulated parasympathetic nerves innervate vascular muscle of HA to release nitric oxide, which activates cGMP, decreasing Ca2+ and causing vasodilation/relaxation enabling blood flood to CC/ erection
What are the Leydig cells
Steriodogenic stromal cells that synthesis androgens
What is DHT
Dihydrotestosterone, which is testosterone converted by 5alpha-reductase
What is the function of DHT
Masculination of external genitalia in utero, puberty
What is the function testosterone
Regulate Sertoli cell function, effects on fat metabolism and deposition of abdominal adipose tissue, promote bone growth and protein anabolism
