Reproductive System Flashcards
Name the structures in the male reproductive system
Penis
Scrotum
Testes (2 testicles)
Epididymis
Vas deferens
Prostate gland
Urethra
Seminal vesicles
Name the external parts of the male reproductive system
Penis
Scrotum
Testes (which are contained inside the scrotum)
Name the internal parts of the male reproductive system
Prostate gland
Seminal vesicles
Vas deferens
Urethra
What arteries supply the testes ?
The testicular arteries which arise from the abdominal aorta.
Each testicular artery is separate from each other.
Where is venous drainage in the testes ?
Venous drainage on the :
Right - to the vena cava
Left - to the renal vein
What is the function of the scrotum ?
This is a loose bag of skin that suspends the testes outside the body.
Describe the surrounding material of the scrotum ?
The skin is wrinkled and contains smooth muscle.
It has a midline raphe and is divided by a septum.
What is the function of the penis ?
The organ used for urination and sexual intercourse.
Describe the internal structure of the penis
It has spongy tissue which can fill with blood to cause an erection. It contains the urethra, which carries both urine and semen.
What is the function of the testes ?
These are a pair of glands that sit in the scrotum, on the outside of the body.
They produce sperm and testosterone, which is the male sex hormone.
What are the testes covered by ?
Tunica albuginea which is a fibrous layer.
Describe the external structure of the testis
The testis is surrounded by the ‘TUNICA ALBUGINEA’, which sends fibrous projections called septa towards the center of the testis.
Function of septa
Partition each testis into around 20 lobules, each containing between 1-4 seminiferous tubules.
Describe the internal structure of the testis
The testis contains seminiferous tubules which is where sperm is synthesised.
The seminiferous tubules come together to form a series of straight tubules which enter a small network of tubules called the rete testis.
Once the sperm make it through the rete testes, they go through the efferent ducts to the epididymis.
What is the function of the epididymus ?
This is a highly coiled tube that lies at the back of the testes.
All sperm from the testes must pass through the epididymis, where they mature and start to ‘swim’.
What are gonads ?
The reproductive organs
What do the male gonads produce ?
Sperm - which is produced by spermatogenesis
What is outside the seminiferous tubules ?
Outside the tubule, there’s connective tissue with capillaries, as well as Leydig cells.
What are Leydig cells ?
Leydig cells produce testosterone
What are Sertoli cells ?
Large cells that extend from the margin all the way to the lumen of the tubule.
What is the function of Sertoli cells ?
Sertoli cells provide nutrients to developing sperm cells, and contribute to the blood-testis barrier by only allowing certain molecules, like testosterone, in the seminiferous tubule.
What is sperm production under the command of ?
The hypothalamus.
What is the function of the hypothalamus in male reproductive system ?
The hypothalamus is a part of the brain that secretes gonadotropin-releasing hormone, or GnRH.
Function of GnRH in Male reproductive system
That GnRH travels to the nearby pituitary, which secretes LH and FSH, which reaches the gonads.
What hormones does the pituitary gland release in the male reproductive system ?
Follicle stimulating hormone
Luteinising hormone
What is the function of LH in the male reproductive system ?
LH binds to Leydig cells, and stimulates the production of testosterone.
What is the function of FSH in the male reproductive system ?
FSH binds to Sertoli cells, making them produce androgen binding protein - or ABP, for short - which allows more testosterone to cross the blood-testis barrier and enter the seminiferous tubule.
Describe the process of spermatogenesis
Spermatogonia - diploid cells - have 46 chromosomes
Primary spermatocytes - 23 chromosomes
Secondary spermatocytes - 23 chromosomes, but only one chromatid (so right no of chromosomes and DNA)
Spermatids
Spermatozoa
What hormones are involved in regulation of spermatogenesis ?
FSH and Testosterone
Describe the main structure of sperm
Head
Midpiece
Tail
Describe the head of the sperm
At the head is the acrosome, which contains enzymes that will help penetrate the oocyte - the female gamete.
Also contains the nucleus which contains the genetic material.
Describe the midpiece of the sperm
The mid piece is loaded with mitochondria that provide the sperm with energy to move.
Describe the tail of the sperm
Specialised flagellum which propels the sperm forward
What happens during ejaculation ?
During ejaculation, the sperm that have matured exit through the tail of the epididymis, and enter the vas deferens.
What happens once the sperm are in the vas deferens ?
The left and right vas deferens go behind the bladder and descend along the posterior bladder wall.
Here, they dilate in a region called the ampulla, before narrowing again to continue as the ejaculatory ducts, which empty out into the first portion of the urethra.
What is the function of the vas deferens ?
This is a thick-walled tube joined to the epididymis. It carries sperm from the epididymis up to the prostate gland and urethra.
What is the function of the prostate gland ?
This is a walnut-sized gland that sits in the middle of the pelvis.
The urethra runs through the middle of it. It produces the fluid secretions that support and nourish the sperm.
What is the function of the urethra ?
This is a tube that extends from the bladder to the external opening at the end of the penis.
The urethra carries both urine and sperm.
What is the function of the seminal vesicles ?
These are 2 small glands above the prostate gland that make up the majority of the fluid in semen.
What is spermination ?
Release of mature spermatozoa into the seminiferous tubule lumen.
How is urination separated from ejaculation ?
Now, the urethra is also the way urine exits the body, but during ejaculation, the bladder sphincter right above the prostate contracts, and that prevents urine from mixing with semen.