Male Physiology Flashcards
What are the eight male reproductive organs?
Testicles
Epididymis
Spermatic cord
Seminal vesicles
Prostate gland
Urethra
Bulbourethral glands
Penis
Where are the testicles located?
Scrotum
What are the two functions of the testes?
To produce sperm
To produce testosterone
What shape are the testes?
Ellipsoid
Explain the structure of the testes
They consist of a series of lobules, each containing seminiferous tubules, which are supported by interstitial tissue
What three cell types make up the seminiferous tubules?
Germ Cells
Sertoli/Sustentacular Cells
Leydig/Interstitial Cells
Where are germ cells found in the testes? What is their function?
They line the basement membrane of the seminiferous tubules
They produce sperm
Where are sertoli cells found in the testes? What is their function?
They are spaced in between the germ cells
To support sperm and inhibin production
Where are leydig cells found in the testes? What is their function?
They are found in the interstitial tissue surrounding the seminiferous tubules
To produce testosterone
Describe the course of spermatozoa in the testes
Once the spermatozoa have been produced in the seminiferous tubules, they travel through the tubules into the rete teste
Ducts known as efferent tubules then transport the sperm from the rete testes to the head of the epididymis
What is the rete testes?
The site at which all the seminiferous tubules merge together
What is the inner layer that covers the testes?
Tunica vaginalis
What are the two layers of the tunica vaginalis?
Visceral - inner
Parietal - outer
What is found between the two layers of the tunica vaginalis?
Fluid
What is tunica vaginalis formed from?
Parietal peritoneum
What are the two functions of the tunica vaginalis?
It lubricates the surfaces of the testes
It allows for friction-free movement
What is the outer layer that covers the testes?
Tunica albuginea
What is the function of the tunica albuginea?
It penetrates the parenchyma of each testicle dividing it into lobules
Where is the epididymis located?
The posterolateral aspect of each testicle
What is the function of the epididymis?
It acts as a storage site of sperm before ejaculation
The sperm are stored here for three months
What are the three divisions of the epididymis?
Head
Body
Tail
In which epididymis division is sperm specifically stored?
Head
Where is the epididymis head located?
It is the most proximal part
What is the epididymis head formed from?
The efferent tubules of the testes
What is the epididymis body formed from?
The heavily coiled duct of the epididymis
Where is the epididymis tail located?
It is the most distal part
What originates at the epididymis tail?
Vas deferens
What is the spermatic cord?
It refers to a collection of vessels, nerves and ducts that run from the inferior abdomen to the testes
Where is the spermatic cord formed?
The opening of the inguinal canal, known as the deep inguinal ring
What structure does the spermatic cord pass through to reach the scrotum?
It passes through the inguinal canal via the superficial inguinal ring
Where is the vas deferens located?
It is a component of the spermatic cord
It travels from the epididymis, through the inguinal region, to the posterior aspect of the bladder
What is the function of the vas deferens?
To transport mature sperm from the epididymis to the urethra
What are the seminal vesicles?
They are a pair of glands located between the bladder fundus and the rectum
What is the function of the seminal vesicles?
To produce multiple secretions into semen
What do the seminal vesicles combine with? What does this form?
Vas deferens
Ejaculatory duct
Where does the ejaculatory duct drain into?
The prostatic urethra
What is the largest accessory gland in the male reproductive system?
Prostate gland
Where is the prostate gland located inferiorly to?
Bladder neck
Where is the prostate gland located superiorly to?
External urethral sphincter
Where is the prostate gland located anteriorly to?
Rectum
What is the function of the prostate?
To secrete proteolytic enzymes into semen, which act to break down clotting factors in the ejaculate
This allows the semen to remain in a fluid state, moving throughout the female reproductive tract for fertilisation
What is the function of the urethra?
To transport both semen and urine from the bladder to the external urethral orifice
What are the four anatomical divisions of the urethra?
Pre-prostatic
Prostatic
Membranous
Spongy
What type of glands are the bulbourethral glands - exocrine or endocrine?
Exocrine
In which perineal pouch are the bulbourethral glands located?
Deep
What are the bulbourethral glands located posterolaterally to?
Membranous urethra
What are the bulbourethral glands located superiorly to?
Bulb of the penis
Where do the bulbourethral gland ducts open into?
The proximal part of the spongy urethra
What is the function of the bulbourethral glands ?
To contribute the final volume of semen by producing a lubricating mucus secretion containing glycoproteins
What are the two functions of the penis?
Sexual intercourse
Micturition
Describe the physiology of an erection
During erotic stimulation, the penis becomes engorged with blood
What is ejaculation?
The semen moves out of the urethra through the external urethral orifice
What is remission?
When the penis returns to a flaccid state after ejaculation
What is micturition?
When the urethra carries urine from the bladder to the external urethral orifice
Which axis controls the male reproductive system?
Hypothalamic-pituitary-gonadal (HPG) axis
What is the HPG axis?
The hypothalamus releases gonadotrophin-releasing hormone (GnRH)
This stimulates the anterior pituitary gland to produce luteinising hormone (LH) and follicle stimulating hormone (FSH)
What is the overall function of LH and FSH?
To stimulate the production of testosterone
To stimulate the production of sperm
What cells does FSH bind to?
Sertoli cells in the testes
What are the two functions of FSH?
To stimulate sperm production
To synthesis proteins for the production and action fo steroid hormones
What cells do LH bind to?
Leydig cells in the testes
What is the function of LH?
To produce testosterone
What are the four functions of testosterone?
Spermatogenesis
Libido (sexual drive) maintenance
Secondary sexual characteristics development
External genitalia growth
What type of feedback system regulates the male reproductive system?
Negative feedback system
What two negative feedback systems regulate the male reproductive system?
As the levels of testosterone increase, there is increased suppression on the hypothalamus and anterior pituitary to suppress the release of GnRH, LH and FSH.
As the levels of inhibin increase, there is increased suppression on the hypothalamus and anterior pituitary to suppress the release of GnRH, LH and FSH.
What is spermatogenesis?
It is an ongoing differentiation process in the seminiferous tubules of the testes that results in the production of sperm from primordial germ cells
When does spermatogenesis start and end?
Puberty, which is generally around 10-16 years old
This process continues throughout life
What are the two phases of spermatogenesis?
Spermatocytogenesis
Spermiogenesis
What are spermatogonia?
They are the initial pool of diploid cells (2n)
What is spermatocytogenesis?
Spermatogonia divide by mitosis to give two identical cells, referred to as A1 spermatogonia and B spermatogonia
A1 spermatogonia are used to replenish the pool of spermatogonia, which allows males to be fertile throughout their adult life.
B spermatogonia will eventually form mature sperm.
Type B spermatogonia are known as primary spermatocytes (2n) and are undergo two meiotic divisions…
- Meiosis I results in the production of two haploid cells, known as secondary spermatocytes (n).
- Meiosis II results in the production of four haploid cells, known as spermatids (n).
What is spermiogenesis?
It is the process in which the spermatids undergo remodelling and differentiation into mature sperm, which are capable of fertilisation
This process occurs as the spermatids travel along the seminiferous tubules until they reach the epididymis
From the seminiferous tubules, cells will travel to the rete testis
This acts to concentrate the sperm by removing excess fluid
The cells then move to the epididymis where the sperm is stores and undergoes the final stages of maturation
How long does spermatogenesis take?
64 days
Is spermatogenesis continuous or intermittent?
Continuous - multiple spermatogenic processes are occurring simultaneously within the same seminiferous tubule
