Exam 5 Review:  Chapter 27 Male Duct System II

urethra - The  narrow duct which transport urine (and semen in males during ejaculation) from the urinary bladder to the external environment; its wall consists of an inner mucosa of pseudostratified columnar epithelium proximally and stratified squamous epithelium distally, a lamina propria of loose fibrous connective tissue containing spongy erectile tissue, a muscularis with thin circular and longitudinal layers of smooth muscle innervated by the ANS, and an outer adventitia of loose fibrous connective tissue; dispersed throughout the urethra are mucous urethral glands which secrete mucous into the urethral canal; it is short (1-2) inches) in females and exits in the cleft between the labia and between the clitoris and the vagina; it is longer in males (8-10 inches) and exits at the tip of the penis; in males, it is subdivided by location into three parts:  the prostatic urethra within the prostate gland, the membranous urethra which extends from the base of the prostate to the base of the penis, and the spongy urethra which extends through the penis.

prostatic urethra - The first and proximal division of the urethra in males which lies within the prostate gland and receives the distal ends of both ductus deferens and the ducts of the prostate gland itself; its wall consists of four layers -- see definition of urethra above.

membranous urethra - The second and middle division of the urethra in males which lies between the prostate gland and the base of the penis and receives the ducts of the bulbourethral glands; its wall consists of four layers -- see definition of urethra above.

spongy urethra - The third and distal division of the urethra in males which lies between the base and the tip of the penis; its wall consists of four layers -- see definition of urethra above.

seminal vesicles - Paired male accessory reproductive glands, elongated highly convoluted sacs lined by a low pseudostratified columnar secretory epithelium, located at the dorsal base of the urinary bladder which produce secretions which contribute 60% of the volume of semen; its secretions include fructose to provide nutrition for the spermatozoa, and a bicarbonate ions which counteracts the acidity of prostate secretions and the vagina; the walls contain two layers of smooth muscle, inner circular and outer longitudinal, to provide peristalsis to move the secretions into the ejaculatory ducts during ejaculation.

prostate gland - The largest male accessory reproductive gland, located at the base of the urinary bladder, which produces secretions which contribute 30% of the volume of semen; it is a rounded mass of 30-50 tubuloalveolar glands surrounding the prostatic urethra in three concentric layers; the glands either empty directly into the prostatic urethra or by small ducts; the secretory epithelium is supported by a fibroelastic stroma containing numerous smooth muscle bundles which contract during ejaculation; its secretion is slightly acidic, mucous, and contains citric acid, the natural antibiotic, seminalplasmin, and various enzymes, e.g., acid phosphatase and fibrinolysin, which contribute to successful fertilization.

bulbourethral glands = Cowper's glands - Small, paired male accessory reproductive glands, located near the base of the penis, which produces a thick alkaline mucous secretion which contributes <10% of the volume of semen; they begin secreting during arousal prior to ejaculation (pre-ejaculatory fluid); their secretion neutralizes any acid urine in the urethra and contributes to the lubrication for intercourse; they are homologous to the greater vestibular = Bartholin's glands in the female.

semen = seminal fluid - The viscous whitish mucous secretion of the male reproductive organs, released at orgasm by ejaculation, containing spermatozoa and secretions of the testes and epididymus, an alkaline secretion including fructose to nourish the spermatozoa from the seminal vesicles, an acidic secretion from the prostate with enzymes and seminalplasmin, and an alkaline mucous secretion from the bulbourethral glands; normal volume is 2-5 mL/ejaculation.

seminalplasmin - An antimicrobial protein added to the seminal fluid by the prostate gland which inhibits the growth of, as well as nucleic acid and protein synthesis in, various bacteria and yeasts.

List:

10.  the composition of the fluid from the seminal vesicles.

          water, electrolytes, bicarbonate buffer, fructose

11.  the composition of the fluid from the prostate gland.

          water, electrolytes, mucus, fructose, citric acid, seminalplasmin, and various enzymes, e.g., acid phosphatase and fibrinolysin

12.  the composition of the fluid from the male bulbourethral glands.

          water, electrolytes, bicarbonate buffer,  mucus