Male reproductive tract Flashcards
What are the two roles of the reproductive system?
Reproduce
Production of reproductive hormones
What is involved in reproducing?
Produce gametes
Fertilisation & development of fetus
What is involved in production of reproductive hormones?
Development & function of reproductive system
Development of sex-specific body form
Normal sex specific behaviour
What is the role of gonads (testes)?
Produce sperm and hormones
What is the role of associated ducts?
Transport, store & mature sperm
What is the role of accessory glands?
Produce seminal fluid
What are the accessory glands?
Seminal glands
Prostate glands
Bulbo-urethral glands
What are the external genitals?
Penis
Scrotum
Describe the adult testis
Flattened egg shape- 4cm
In scrotum
Why are the testis in the scrotum
For temperature regulation
3 degrees celsius cooler than internal body temp
What are the endocrine functions of the testis
Produces hormones directly into blood stream
What are the exocrine functions of the testis?
Production and release of sperm, leave organ within ducts
How is the sac in the scrotum divided?
Divided internally by connective tissue septum
Externally by raphe/ridge
What is on the outer layer of the scrotum?
Skin, CT & smooth muscle
What is the base of the scrotum covered with?
Pubic hairs
Why is temperature regulation important in the scrotum?
Sperm needs to be 3 degrees celsius lower than internal body
If it’s too warm sperm can’t be produced efficiently and there is an increased mutation rate
How is temperature regulation controlled?
By muscles
Which smooth muscle controls temperature regulation?
Dartos- reduces scrotum size by firming up skin, sac less spacious spacious, pulls testes closer in
Which skeletal muscle controls temperature regulation?
Cremaster- pull testes nearer body, physically pulls testes closer to the body, less likely to loose heat
What makes up the testis?
Tunica albuginea
Tunica vaginalis
What is the tunica albuginea comprised of?
Septa subdivided into roughly 300 lobules
Lobules= 1-4 seminiferous tubules (roughly 0.5 km per testis)
Tubules empty into efferent ductules
Loose connective tissue surrounds tubules interstitium
What is the tunica vaginalis comprised of?
Closed sac of serous membrane
Serous fluid, visceral layer connecting to testes, parietal layer further out
What is the rete testis?
Connect efferent tubules to epididymis
What is interstium?
Loose connective tissue between seminiferous tubules (produce important hormones)
What is spermatogenesis?
The process in which spermatozoa are produced from spermatogonial stem cells by way of mitosis and meiosis
What is the initial process in spermatogenesis?
The initial cells in this pathway are called spermatogonia, which yield primary spermatocytes by mitosis
How many sperm are produced everyday?
70-100 million
How long is the cycle of spermatogenesis?
64 days
How long throughout the males life does spermatogenesis occur?
puberty to death
What happens when sperm leave testis?
Not fully mature, sit in epididymis where they gain motility and are stored within epididymis
How long can sperm survive in the female environment?
48 hours
What is the commonest cancer in young men?
Testicular germ cell cancer
What does testicular germ cell cancer cause?
Reduced fertility
Where does the testis descent begin?
Near kidneys
Where do testis descend to?
Into the scrotum
When does testis descent begin?
7 month in utero
What does INSL3 hormone do?
Insulin-like 3
Regulates growth and differentiation of gubernaculum, and thus mediating intra-abdominal testicular descent
What is descent controlled by?
Androgens- controlling own descent as they are released by testis
What can be the cause of abnormal descent?
2-4% cryptochidism (absence of one or both testes from the scrotum)
30% premature
70% spontaneous descent
What is the risk factor that comes with abnormal descent?
Testis cancer
What is the inguninal canal?
Bilateral passeageway at anterior abdominal wall between deep and superfifical inguinal rings
What does the ingunial canal contain?
Illioinguinal nerve
Spermatic cord
Arteries, nerves and veins
Vas deferens
What is the Epididymis?
Coiled tube roughly 7m long
Head, body and tail
Lined by silia
What does the epididymis do?
Recycles damaged spematozoa
Stores and matures spermatozoa (12-16 days)
What is the ductus (vas) deferens?
Strong muscular tube- seminal vesicle join to form seminal fluid
Where does the ductus deferens come from?
Ascends from epidiymis, through inguinal canal, to pelvis, roughly 30cm long
What does the ductus deferens do?
Enlargens post- ampulla- joins seminal vesicle duct= ejaculatory duct
Where does ductus deferens empty?
Into prostatic urethra- important for fluid to form with sperm (join here)
What happens to the ductus deferens during a vasectomy?
Cut and Ligated
What are seminal vesicles?
Paired glands
Post/inf to urinary bladder
Roughly 5 cm
Smooth muscle wall- contract
What do seminal vesicles do?
Produces & stores semen:
Contributes 60% volume
Fructose (sugar) & prostaglandins (hormone)
Alkaline secretion- vagina acidic, neutralises and allows sperm to survive
Where and what is the size of the prostate gland?
Walnut size- roughly 3-4 cm diameter
Inferior to bladder
Surrounds prostatic urethra
What type of gland is the prostate gland?
Smooth muscle gland Smooth muscle contraction Produces semen (30%) Secretions- slightly alkaline Prostate- specific antigen
What infections can occur in the prostate gland?
Infections:
• Protatitis
• Benign hyperplasia
• Prostate cancer
Urethra comes through middle of prostate gland
Smooth muscle for contraction
Aging- prostate swells can cause cancer in males or can stop men being able to urinate
How much semen do men have?
2-5ml
How much sperm is in a ml of semen?
50-150 million
What issues may men that have less than 20 million sperm have?
Struggle to conceive, sub fertile
Where does fluid in semen come from?
Accessory glands (95% volume)
Basic pH
Fructose, nutrients and liquid to swim
What is ejaculation?
Expulsion from urethra
Peristaltic contraction of smooth muscles in ducts, glands, pelvic floor & base of penis
What is the dual function of the urethra in males?
Urinary
Reproductive
What is the length of the urethra?
20cm long, 3 segments
What are the 3 segments of the urethra?
Prostatic urethra
Membranous urethra
Spongy (penile) urethra
Describe the prostatic urethra
Receives ejaculatory & prostatic ducts
Describe the membranous urethra
Shortest
Describe the spongy (penile) urethra
Through corpus spongiosum to external orifice
Receives bulbourethral gland ducts
What does the root and the bulb of the penis do?
Connects penis to pelvic bone
What does the shaft of the penis do?
Columns of erectile tissue
Blood sinuses
Corpus spongiosum-ventral
Cavernose (paired)- dorsolateral
What does the glans of the penis do?
Prepuce/foreskin- circumcision
What disrupt the endocrine system in male reproduction?
Chemicals in the environment
Can affect reproductive development in utero
What are the effects of a disrupted endocrine system?
Structure of testes and also fertility
Structure of the penis
Risk of testicular cancer
Testis descent
