Unit 3 Male Reproduction

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The male reproductive system

Consists of a pair of male gonads, the testes, which produce sperm. Two excretory channels, the ductus deferens (or vas deferens) and the prostate. The ejaculatory ducts which are the seminal vesicles and a pair of bulbourethral glands which produce secretions that are added in to the final product of seminal fluid. The external genital organs include the penis, the scrotum, and the structures enclosed by the scrotal sac (testes, epididymides, spermatic cords, and part of the ductus deferens)

Testes

Ovoid bodies averaging 1.5" in length and 1" in width and depth enclosed in a saclike structure called the scrotum. Each testis divided into partial compartments that constitute the glandular substance of the testis and they are suspended in the scrotum by spermatic cords. Each compartment has cell producing convoluted tubules called seminiferous tubules that converge and unite to form 15-20 ductules that emerge from testis to enter the head of the epididymis.

Epididymis

Oblong structure that is attached to superior and lateroposterior aspects of the testis that has 2 functions. Storage of sperm and production of one of the components of seminal fluid, semen. The ductules leading out of testis enter the head and become continuous with coiled and convoluted ductules. These progressively unite to form the main duct which is continuous with the ductus deferens. After 1-3 wks sperm are finally mature and capable of fertilizing ovum.

Ductus Deferens (Vas deferens)

16-18" long and extends from the tail of the epididymis to the posteroinferior surface of the urinary bladder. Only its first part is convoluted. Ascends medially and joins other constituents of the spermatic cord which all emerge from scrotal sac and pass into pelvic cavity through inguinal canal. Near its termination it expands into an ampulla for storage of seminal fluid and then ends by uniting with the seminal vesicle to form the ejaculatory duct.

Seminal Vesicles

2 sacculated structures 2" in length, situated obliquely on lateroposterior aspect of bladder where they then slant inferiorly at the uterocystic junction to the base of the prostate. Each ampulla of the ductus deferens lies along the medial border of the seminal vesicle to from the ejaculatory duct. Secrete a thick liquid that forms a large part of seminal fluid and serves as an energy source for sperm motility after ejaculation, also secrete prostaglandin which increases contractions in female uterus assisting in the advancement of sperm toward fallopian tubes.

Ejaculatory ducts

Formed by union of the ductus deferens and duct of seminal vesicle. Average .5" in length and originate behind neck of bladder. The two ducts enter the base of the prostate and pass through the substance of the gland opening into the prostatic urethra. These ducts eject sperm into urethra before ejaculation. Dependent upon sexual activity and freq of ejaculation sperm can remain up to 1 month w/out loss of fertility.

Prostate

Accessory genital organ that encircles the proximal portion of the male urethra and extends from the bladder neck to the pelvic floor. Composed of muscular and glandular tissue and the ducts of the prostate open into the prostatic portion of the urethra and secrete a thin slightly alkaline fluid that neutralizes condition of vaginal tract. Older men suffer from prostate enlargement and as the gland enlarges it presses on the urethra obstructing it making it difficult to urinate.

Why are a vast majority of testicular scans performed?

Palpable mass or enlarged testis.

Glans penis

The bulbous head or tip of the penis

Rete testis

Seminiferous tubules that have united and converged

Bulbourethral gland

Largest mucus-producing glands in the male system. Pea sized organs located just above bulb of penis, one on each side of urethra. Like prostate they form a part of the seminal flid and aid in lubrication of vaginal tract.

Penile urethra

7-8" long extends from internal orfice in the bladder to an external opening at end of penis called meatus. Conveys urine from the bladder and carries sperm along with thier accompanying secretions outside the body

Vesiculography

Radiographic exam of the seminal vesicles after contrast is injected for anatomic abnormalities and pathology related to male sterility. Exact same procedure as epididymography except centering is between the ASIS and pubic symphasis. These are not performed anymore due to imaging advancements in other modalities.

Epididymography

Special procedure utilizing contrast for radiographic demonstration of the epididymis to investigate anatomic abnormalities or pathology. Pt is anethesized and placed supine, surgical incision exposes the vas deferens and needle is placed in epididymis direction. Contrast is injected and exposure taken at RD signal centered to scrotum, penis should not superimpose over scrotum.

Epididmovesiculography

General term applied to radiographic exam of the seminal ducts performed in the investigation of selected genitourinary abnormalities such as cysts, abscesses, tumors, inflammation, and sterility. Water soluble iodinated used for all.

Cavernosography

Radiographic investigation of the corpora cavernosa to determine physiological conditions of the penis, most current use is for evaluation of erectile impotence. This exam can also be indicated to visualize the anatomy of penile trauma. The exam demonstrates the smooth muscle relaxing allowing blood in to engorge organ and vasoconstriction of veins leading away mechanism such as is the case in sexual stimulation. Pt must void prior to exam, scout film taken w pt supine with top IR at ASIS, site is numbed and injected with stimulant to induce erection, contrast is injected and observed with images taken AP, RPO, and LPO.

Prostatography

Radiographic investigation of the prostate gland. Ultrasound and MRI often used and cystograms performed for BPH. Bowel and bladder empty, pt prone places part of interest closer to IR, CR angled 20 degrees cephalic aimed at anus region with suspended expiration. Not a common procedure.

Function of the male reproductive system

Formation of sperm

Primary organs of the male reproductive system

Two gonads (testes) responsible for sperm production

Accesory organs of the male reproductive system include

Series of ducts that aide in the transport of sperm with specialized glands that provide sperm nourishment as well as lubrication and neutralization of vaginal tract during sex

When do the testes normally descend into the scrotum and the problems caused if they don't

2 months before birth, undescended testes is called cryptorchidism which could cause permanent sterility if left unfixed due to the increased temperature of the abdomen which is where they live prior to descending, treatment is often testosterone administration

What is responsible for changes during male puberty such as hair growth on body and face and voice deepening?

Testosterone

Vasectomy

Surgical procedure that severs the vas deferens, can result in sterility. Interrupts route from epididymis to the exterior.

The penis is composed of 3 cylindrical masses of erectile tissue, they are...

2 larger and more superior of the cylinders are known as corpora cavernosa and the smaller more inferior one contains the urethra and is known as the corpus spongiosum.

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