Reproductive system: Male reproductive tract Flashcards
What happens if the testes don’t descend?
Males are infertile –> Cryptorchidism
Label the diagram
Label the diagram
What is the movement of sperm from formation to ejaculation?
It is produced in the seminiferous tubules which then coalesces in the rate testis. The sperm then seperate again into the epididymis and then is transported by the vas deferens over the bladder and through the ejactulatory duct and out the penis
What does the epididymis do?
It matures sperm, gives it the ability to be motile and fertilise and reabsorbs liquid (therefore concentrates it)
How long does it take for sperm to get its motile and fertilising abilities?
10-14 days
Where are sperm stored primarily?
Vas deferens
What is the average length of the vas deferens? Where does it run from?
45cm
Runs from the epididymis up and around the bladder down to ejaculatory duct
What is the purpose of the seminal vesicles?
Secretes a mucoid substance that is alkaline, contains fructose, prostaglandins and clotting proteins
What might the function of prostaglandins be?
Induce contractions in the female reproductive tract
What are the three components of ejaculatory fluid?
1 - Prostatic fluid
2 - Sperm
3 - Seminal vesicle fluid
What is the purpose of the prostate fluid?
It is a secretion that is slightly acidic, contains citrate (for ATP), contains calcium and phosphate and contains Prostate Specific Antigen
What is the purpose of the clotting proteins in seminal vesicles?
Holds the seminal fluid in the vagina (like a clot) to prevent it from falling out
What is the purpose of Prostate Specific Antigen (PSA)?
Breaks down the co-agulum after a few minutes from the seminal vesicular fluid allowing the sperm to continue moving up to the fallopian tube
What is the composition of semen?
Sperm = 10%
Seminal vesicle fluid = 60%
Prostatic fluid = 30%
What is the pH of the semen? Explain
7.5, the strong base of the seminal vesicular fluid and the prostatic fluid buffer each other
What is Benign Prostatic Hyperplasia (BPH)?
It is excessive growth of the prostate gland
What happens as the prostate gland grows?
As the prostate gland grows it is unable to expand outwards because the bladder is hard, this causes inwards growth which results in the prostatic urethra (shared duct into penis for both reproduction and urinal removal) being restricted
What is the affect of the prostatic urethra being restricted?
It means that bladder cannot empty completely which causes weakening of the bladder and potential urinary tract infections which could spread to the kidney and cause kidney disease
What are some non-invasive methods of treating Benign Prostatic Hyperplasia (BPH)?
Using Selective 5 α - reductase inhibitors finasteride and dutasteride
What does the Selective 5 α - reductase do?
It is an enzyme which converts testosterone into its more potent form, dihydrotestosterone
What do the Selective 5 α - reductase inhibitors do?
They (i.e. finasteride and dutasteride) inhibit Selective 5 α - reductase so that testosterone is not convert into dihydrotestosterone
How does reducing the amount of dihydrotestosterone stop BHP?
BHP is an androgen dependent disease. By removing the more potent androgen, dihydrotestosterone, the prostate growth can be stopped or reversed
Prostate cancer is a major disease, who many cancer cases in men are caused by prostate cancer?
29%
How is prostate detected?
The amount of PSA produced (Prostate Specific Antigen) increases with prostate cancer and this can be detected
What are some of the ways to cure prostate cancer?
Androgen depletion (using Selective 5 α - reductase inhibitors, castration or inhibition or androgen synthesis), block the androgen receptors or perform a prostatectomy (prostate surgery)
In New Zealand PSA testing is NOT recommended for men, why is this?
PSA testing has a high number of false positives, the cancer is relatively benign (most people die with, rather than because of it) and to treat it with surgery causes a high rate of complications such as incontinence, erectile disfunction and death
What are the main structures of the penis?
Corpora cavernosa, corpus spongiosum and penile urethra
What is the function of the Corpora cavernosa?
The main erectile tissue that fills with blood to make the penis stiff
What is the function of the corpus spongiosum?
Surrounds the penile urethra and prevent occlusion (closing) during erection
What is the function of the penile urethra?
Conduct the semen and urine
What causes an erection?
NO (Nitrogen oxide) and Prostaglandin E1 causes the smooth muscle of the corpora cavernosa to relax (vasodilation). This then causes blood to easily get into the corpora cavernosa and also closes the vein that drains it resulting in a large increase in internal pressure creating an erection
During an erection, how is the penile urethra kept open?
The spongy urethra also fills with blood creating outwards pressure preventing the corpus cavernosa from completely closing
How does viagra create an erection?
Viagra inhibits phosphodiesterase, an enzyme that breaks down GMP (GMP is the 2nd intracellular messenger that reduces Ca2+ inside a cell causing muscle relaxation). By preventing the break down of GMP, there can be more relaxation therefore more blood fills the corpus cavernosum
