Male reproductive system Flashcards
What are the male gonads?
The testes which produce sperm. they sit outside the body to regulate temperature at around 2 degrees below body temp for optimum spermiogenesis.
What is the process of spermatogenesis?
It takes 72 days. It involves meiosis and mitosis. Spermatogonia stem cells divide via mitosis and produce two daughter spermatogonia, at least one will stay with the stem cell population. The majority will move away and and differentiate into primary spermatocytes. They enter the first meiotic division and form two secondary spermatocytes, and each will enter the second meiotic division within 20 mins, they form spermatids. These are what undergo spermiogenesis to form spermatozoa (sperm).
What are Sertoli cells?
They guide the sperm towards the lumen and secrete a fluid that allows the immobile sperm to flow. they also allow the transfer of nutrients, feeding the cells what they need. They undergo phagocytosis to replenish cytoplasm that the sperm uses up during maturation. It also assures no dead sperm or waste gets into the body.
What is the epididymis?
This is where the sperm spends approximately one month for further maturation. The sperm become increasingly unidirectional motile (form shape and can direct). They undergo decapacitation to prevent them from undergoing the acrosome reaction before coming in contact with an oocyte (egg).
What is the Vas Deferens?
This is a thick muscular layer that is innervates by the sympathetic nervous system. It undergoes peristalsis upon tactile stimulation of the penis. The contractions coincide with contraction of the seminal vesicles and prostate glands. The contractions cause sperm and seminal fluid to mix. The purpose of this is to propel sperm into the urethra (emission) during intercourse. This precedes ejaculation.
What is the seminal vesicle?
This secretes 60-70% of semen volume. It secretes semenogelins to help coagulate the semen after ejaculation. It secretes fructose which is a critical nutrient for sperm mobility.
What is the prostate?
This secretes 20-30% of semen volume. It secretes citrate, zinc, spermine and acid phosphate to form a thin milky fluid. It secretes prostate-specific antigen which liquifies coagulated sperm after a few minutes. It is used as an indicator for prostate health.
What is the bulbourethral gland?
pea sized gland located in the sphincter of the urethra. It empties into the penile urethra in response to sexual excitement, prior to emission and ejaculation. It secretes a mucus to cleanse, lubricate and buffer the urethra.
What is the penis?
Muscular organ designed to separate the walls of the vagina and deposit semen at the distal end of the vaginal lumen near the cervix.
How is semen composed?
10% sperm and 90% seminal fluid. The sperm count should be 60-100x10^6/ml of semen.
What is an erection?
Neuromuscular event. During the flaccid state, blood flow to the corpus cavernous via the helicine arteries is vasoconstricted. Sexual arousal stimulates parasympathetic nerves that innervate vascular smooth muscle of helicine arteries to release nitric oxide. This causes muscle relaxation and vasodilation, blood flows into the cavernous spaces, resulting in engorgement.
What hormones help control spermiogenesis?
Dihydrotestosterone (DHT) - testosterone is converted to this by 5alpha-reductase. It is required for the masculinization of the penis.
Testosterone - regulates Sertoli cell function. promotes bone growth and protein anabolism.
