Lecture 34 - Pelvis and Perineum, Male reproductive system Flashcards
The reproductive system
Differs greatly between males and females
Gonads
Organs where gametes (sex cells) are produced
Female gonads
Ovary Produce oocytes (colloquially known as eggs)
Male gonads
Testes
Produce spermatozoa
Genitalia
Allow for coitus so that gametes can fuse to form an embryo (fertilisation)
The pelvis
Bony basin between the trunk and the lower limbs made up of several components Hip bones (ilium (winged and most superior and largest part), pubis (bone that makes up the pubic symphysis), ischium) + sacrum + coccyx
The pelvic inlet
The arrangement of the pelvis that creates the upper cavity or space between the hip bones and sacrum.
Pelvic outlet
The arrangement of the pelvis that creates the lower cavity between the bony landmarks of the coccyx, the pubic symphysis and the ischial spines.
Pelvic inlet and outlet
Pelvic inlet is open
Pelvic outlet is closed by muscles (always closed by the pelvic floor musculature)
Inlet is always bigger than the outlet
What are the two pelvic subdivisions?
False/greater pelvis
True/lesser pelvis
False/greater pelvis
Superior region
Above pelvic inlet
Contain GI tract
True/lesser pelvis
Inferior region
Between the inlet and the outlet
Contains the internal reproductive organs
Male vs female pelvis
Female - function is to support pregnancy as foetus develops but also for the birthing process
Broader subpubiz angle
Oval shaped inlet
Straighter coccyx
Differences in bony structures due to adaptations for pregnancy
Subpubic angle of greater than or equal to 100 degrees
Male Narrower subpubiz angle Heart shaped inlet Curved coccyx Subpubic angle of below 90 degrees
Pelvic floor (pelvis diaphragm)
Closes over pelvic outlet
Two muscles - Levator ani and Coccygeus - these muscles provide a sling which supports all of the internal organs
Openings in the pelvic floor (2 or 3 depending on sex) - urethra, anal canal, vagina (females only)
Two muscles of the pelvic floor
Levator ani
Coccygeus
Openings in the pelvic floor
Urethra
Anal canal
Vagina (females)
Deep transverse perineal muscle
The function of the muscle is fixation of the perineal body (central tendon of perineum), support of the pelvic floor, expulsion of semen in males and last drops of urine in both sexes.
How many openings for female?
3
How many openings for males?
2
Urogenital triangle
Anterior
Urethral opening and external genitalia
In females you also find the opening called the vagina
Anal triangle
Posterior
Anal canal and fat
Male perineum
Region inferior to the pelvic floor and between the upper region of the thighs
Includes external genitalia and anus
Two triangular divisions called the urogenital triangle (anterior) and the anal triangle (posterior)
Internal reproductive organs are found in the cavity enclosed by the ___________ pelvis
True/lesser
The external genitalia is found in the ________ triangle of the perineal region
Urogenital
Openings in the male pelvic floor include
Urethra and the anus
Openings in the female pelvic floor include
Urethra, anus and the vagina
Functions of the male reproductive system
To produce spermatozoa (sperm/male gamete)
Transport spermatozoa into the female reproductive tract
What is the male reproductive system made up of?
Testes (male gonad)
Reproductive tract/duct
Accessory structures and glands
Male reproductive tract
The path that the sperm travels along includes the testes, epididymis, ductus deferns, ejaculatory duct and the urethra
Testes
Production of spermatozoa
Paired structure found in the scrotum tissue structure
Also makes hormones such as testosterone and inhibin
Epididymis
A long, narrow, convoluted tube, part of the spermatic fact system, that lies on the posterior aspect of each testicle, connecting it to the vans deferens
Three regions - head, body and tail
Tightly coiled tube where sperm maturation occurs - not able to swum yet, gain the ability to be motile in the epididymis, do not swim up ductus deferns, only swim when they are mixed with the seminal fluid
Sperm enter from the seminiferous tubules and exit via the ductus deferns
Ductus (van) deferens
The main duct through which semen is carried from the epididymis to the ejaculatory duct
Also known as vas deferns Continues from the epididymis Starts in the spermatic cord Covered by smooth muscle Runs behind the urinary bladder Dilates to form the ampulla
Sit of sperm storage and it is stored here until ejaculation takes place and if it is not used in ejaculation then it is removed through the urethra through urination
Provides a passage way for sperm into the pelvic cavity proper
Ampulla
The ampulla of ductus deferens is an enlargement of the ductus deferens at the fundus of the bladder which acts as a reservoir for sperm.
Ejaculatory duct
Either of the paired ducts in males, formed by the junction of the seminal ducts with the vas deferns, that pass through the prostate and empty into the urethra, and through which semen is ejaculated.
Small region that opens into the urethra
Formed by the union of the duct from the seminal vesicle and the ampulla
Opens in the prostatic urethra
Sits meal to the seminal vesicles
Seminal vesicle
Key role in producing components of the seminal fluid
Prostate gland
A gland in male mammals surrounding the urethra at the base of the bladder that controls release of urine from the bladder and secretes a fluid that is a major constituent of semen
Bulbourethral gland
a pair of pea shaped exocrine glands located posterolateral to the membranous urethra. They contribute to the final volume of semen by producing a lubricating mucus secretion.
Urethra
For urine and ejaculation
Prostatic urethra is surrounded by the postage and then through the pelvic floor it is known as the membranous urethra and from here the spongy/penile urethra
Epithelium changes from transitions to columnar to stratified squamous as you go through each region of the urethra
Penis
The penis is the male sex organ. In addition to its sexual function with ejaculation, the penis acts as a medium for urine to leave the body.
Scrotum
The scrotum is a sac of skin that hangs from the body at the front of the pelvis, between the legs. Contains the testes. These are two oval-shaped glands responsible for producing and storing sperm.
What does the scrotum contain?
Two testes (singular is testis) Two epididymides (singular is epididymis) Two spermatic cords (with part of the ductus deferens)
Testes produce…
Sperm, testosterone and inhibin
Location of testes
Lie in the scrotum - outside of the body
Testes are surrounded by
Dense fibrous capsule - the tunica albuginea
Semineferous tubules
Seminiferous tubules are located within the testes, and are the specific location of meiosis, and the subsequent creation of male gametes, namely spermatozoa.
Testes have lobules containing seminiferous tubules
Tubules join to form rete testis
Join to form ductules leading to the epididymis
Interstitial endocrine (Leydig) cells produce testosterone (key to regulating the male reproductive system because of its role in producing testosterone) - located adjacent to the seminiferous tubules in the testes
Nurse (sertoli) cells produce inhibin (supporting developing spermatozoa as well as having a hormonal role) - located within the seminiferous tubules
Spermatogenic cells: Spermatogonia and spermatozoa at various stages of development
Surrounded by a basement membrane, germ cells are around the basement membrane
Rete testis
network of delicate tubules located in the hilum of the testicle (mediastinum testis) that carries sperm from the seminiferous tubules to the efferent ducts.
Intestinal endocrine (leydig) cells
Interstitial endocrine (Leydig) cells produce testosterone (key to regulating the male reproductive system because of its role in producing testosterone) - located adjacent to the seminiferous tubules in the testes
Nurse (sertoli) cells
Nurse (sertoli) cells produce inhibin (supporting developing spermatozoa as well as having a hormonal role) - located within the seminiferous tubules
Spermatogenic cells
Spermatogenic cells: Spermatogonia and spermatozoa at various stages of development
Myoid cells
Transport spermatozoa when it is ready
Three sections of the male urethra
Prostatic
Membranous
Spongy/penile
Urinary/urethral sphincters
External - skeletal muscle, voluntary control of urination
Internal - detrusor muscle (smooth muscle therefore involuntary)
Closes bladder ensuring sperm ejaculated through the urethra
Retrogade ejaculation - sphincter does not close, therefore sperm ends up in the bladder - want to prevent this because it would dilute the semen due to there being the presence of urine also
Internal urinary sphincter
Internal - detrusor muscle (smooth muscle therefore involuntary)
Closes bladder ensuring sperm ejaculated through the urethra
Retrogade ejaculation - sphincter does not close, therefore sperm ends up in the bladder - want to prevent this because it would dilute the semen due to there being the presence of urine also
External urinary sphincter
External - skeletal muscle, voluntary control of urination
Where does spermatogenesis occur?
In the seminiferous tubules within the testes
The path of sperm summary
From the seminiferous tubules, the spermatozoa travel into the epididymis, the ductus deferens, the ejaculatory ducts and finally the urethra
What prevents the sperm ending up in the bladder during ejaculation?
Internal urethral sphincter which is made up of the detrusor muscle that closes over the bladder - closes during ejaculation to prevent sperm ending up in the bladder
What are the three regions of the epididymis called?
Head
Body
Tail
Where would you find a spermatogonia?
Found within the seminiferous tubules and they are found close to the basement membrane of these tubules
