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Home , Foreskin, Penis, Prostate, Seminal vesicles, Sexual stimulation, Spermatic cord

Discussion question: (4-A) Let’s Talk about the Parts of the • What are some slang terms for male Chapter 4 genitalia? Keep track of how many terms your group knows. ! • Are these terms positive or negative?! Male Sexual • Why do people tend to use “nicknames” & Physiology for parts of the male sexual anatomy? • What do the nicknames we use for male genitalia say about our thoughts or opinions about male genitalia? !

The Penis Internal structure of the penis: top view The Penis (internal, in • Penis: consists of internal root, external shaft, & .! (between glans and the body) pelvic cavity) Male Sexual Anatomy (cont.) • Root: portion of the penis that extends internally into the pelvic cavity.! • Shaft: length of the penis btwn. glans and body wall.! • Glans: head of the penis; has many endings.! • Cavernous bodies: two tube-like structures in shaft of the penis that engorge with during arousal.! • , blood vessels, fibrous tissue, and three • Spongy body: cylinder in shaft, extends to form the parallel cylinders of spongy tissue.! penile glans. Also engorges with blood during arousal.! (engorge with blood (head of the (expands during arousal) • There is no and little muscular tissue penis; lots of to form • : a covering of over the penile glans.! nerve endings) the glans) (although there are muscles at the base of the penis)! Fig 5.1a Interior structure of the penis: (a) view from above.

External penile structures “, you’re small. There ain’t no Penis size man or woman out there who will ever get pleasure from that thing.” • What is “average” length anyway?! • Corona: the rim of the – 5.1 - 5.7 inches (much less than you see or hear about in adult movies or penile glans! Think/write/share:! ). • Frenulum: thin strip of skin connecting the glans to the Is bigger better?! shaft on the underside of the penis!

Both are highly sensitive areas to the touch!

Fig 5.2 This figure, a view of the underside of the penis, shows the location of the corona and frenulum—two areas on the penis that harbor a high concentration of sensitive nerve endings. Penis size Penis size Penile Augmentation (phalloplasty) • Much more variation in flaccid penis size than in erect • Penis lengthening: involves severing of ligaments that attach • More men are concerned about penis size than their penile root to pelvic bone! female partners are.! penis size. ! – Comparisons in the locker-room don’t mean much.! – Inside part of the penis drops down! • “Bigger is better” isn’t always the case! • Penile girth enhancement: usually – Most women achieve through clitoral, not vaginal, injecting fat from other areas of the body.! stimulation! • Possible dangers and warnings:! – Obsession w/penis size results from a “penis-centered” idea of – Some loss of sensation, scarring, changed --great sex can happen w/no penis at all! ! angle of ! – Penis could actually end up being shorter due to scar tissue causing penis to retract further into body! – Injected fat can be rejected by the body, causing a lumpy, misshapen appearance! • Most men who elect to have phalloplasty in fact do not have undersized .!

Scenes from “Private Dicks” and testes Scrotum and testes (external) • Scrotum (or scrotal sac):! – Pouch of skin that encloses the testes! • 2 chambers inside scrotum; each contains one testis! – Normally hangs loosely from body wall! • cold temperatures and sexual stimulation will cause it to move closer to the body.! • Testis! (inside) – Male gonad inside scrotum that produces and sex ! • Spermatic cord! – A cord attached to the testis inside the scrotum that contains the , blood vessels, nerves, and muscle fibers! Fig 5.3 The scrotum and the testes. The spermatic cord can be located by palpating the scrotal sac above either with thumb and forefinger.

Internal structures of the scrotum Internal structures: the Testes Structures inside the testis • Two functions:! • Seminiferous !

(contains vas deferens, 1) Secrete male hormones! – Thin, highly coiled structures where blood vessels, nerves, and cremasteric muscle) 2) Produce sperm: testes must hang below sperm production occurs.! the body to be at the proper temperature • Interstitial cells! for sperm production.! (sperm-carrying tube) – Major source of ! – Located between seminiferous • Development! tubules! (muscle fibers that control testis the position of the testis – First form inside the ! in the scrotal sac) (where sperm mature and ! are stored temporarily) • – During fetal development they migrate to the scrotum! – Site of sperm maturation! – : undescended testis ! – Runs along back of testis! • Affects 3-4% of male infants and 30% of premature male infants.! • Vas deferens! Fig 5.4 Internal structures of the scrotum. This illustration shows portions of the scrotum cut away to reveal the cremasteric muscle, spermatic cord, vas deferens, and • May resolve on its own or may require .! – Sperm-carrying tube! a testis within the scrotal sac. – Begins at the testis and ends at the .! Cross-section of seminiferous Analagous structures in Vas deferens Interstitial cells: secrete androgens male and female sexual anatomy • After sperm mature in the (more on this will be covered in Gender Chp.) Vas epididymis, they go deferens into the vas deferens! • Vas deferens travel up Male! Female! through scrotum inside Glans! ! spermatic cord, and Foreskin! ! deposit sperm into Shaft! minora! urethra! Scrotal sac! ! Testes! ! • : male procedure in which both vas deferens are severed, then tied off or blocked so sperm can not flow out into ! Spermatogenic cells: produce sperm Immature sperm

A sperm’s gland long journey • Walnut-sized gland at • Pair of small glands adjacent Seminal vesicle to end of vas deferens! the base of the bladder. ! !!Vas deferens Whole journey • Secrete an alkaline (basic) • Secretes milky, slightly takes ~75 days! fluid! alkaline (basic) fluid during – Has high sugar content that (~30% of Prostate #! Urethra helps sperm motility by volume of semen)! gland giving them lots of energy! – Alkalinity helps neutralize the acidity of the male – This fluid is the greatest urethra and the female vaginal tract to help portion of the volume of sperm survive.! %! semen released during $! ejaculation (~70%)! Seminiferous tubules "!

What is the Cowper’s glands Semen “P spot”? • Pea-sized glands that • Volume per ejaculation: about 1 teaspoon! • It’s the prostate! attach to urethra just – Depends on length of time since last ejaculation, • Prostate stimulation is below prostate gland! duration of arousal before ejaculation, and age.! performed to:! • Secrete an alkaline fluid • Fluids from: !! – Produce orgasm/pleasure! during – Seminal vesicles (almost 70%)! – Prevent/relieve various (before ejaculation, Cowper’s – Prostate gland (about 30%)! slang term = “pre-cum”)! gland causes of enlarged prostate! – (possibly) a tiny bit of fluid from Cowper’s glands • Neutralizes acidity of male urethra and helps depending on time of secretion! lubricate flow of semen through the urethra.! • Sperm! • May possibly contain (or wash through) a few – Between 200 - 500 million sperm per ejaculation! active, healthy sperm (potential problem for the withdrawal – Only about 1% of total volume.! method of ).! Summing up: What causes an erection? How blood inflow helps maintain erection Moving Mature Sperm Out • Brain sends message to blood vessels inside • Inside the penis: like a tube within a tube! cavernous and spongy bodies in the penis to relax – When the inner tube fills with blood and Seminal Vesicles! and dilate (open up).! flaccid erect expands, it fills the space between the tubes • Produce majority of Semen – Fluid w/Sugars, nutrients for sperm (70% of semen by volume)! • dilation cause blo that and blocks the outflow of blood, helping to Prostate Gland! causes lots of blood to maintain erection.! • Produces milky substance to neutralize acid in urethra to help sperm survive (29%)! flow into cavernous and Cowper’s Gland! spongy bodies in the penis! • Produce fluid to lubricate and neutralize acid in urethra before ejaculation (ie pre-cum <1%)! • Blood inflow >>> blood outflow, producing an Vas Deferens! • moves sperm (<1%) to Urethra! erection.! Epididymis! • Erection is maintained by pressure of spongy and • Sperm Move Here from ! cavernous bodies against the skin!

Ejaculation Review: Kegel Exercises—for men too! Emission phase of ejaculation (phase 1) • WHY! • Contractions in the prostate, seminal vesicles, and vas • Ejaculation: the process by which semen is – All: prevent incontinence in older years! deferens force secretions into urethral bulb.! expelled through the penis outside the body.! – All: increase sensation & orgasmic intensity! • Both the internal and external urethral sphincters close, • Ejaculation is a separate process from orgasm, trapping semen in the urethral bulb! – Women: regain urinary control after and the two may not always occur childbirth! simultaneously.! (like a balloon) – Men: increase ejaculatory control! – It is possible for men to experience multiple w/o ejaculation.! • HOW! • 2 phases (see next slides for details): ! – Locate muscles! 1) Emission phase: semen collects in the urethral bulb! – Slow: Contract 10 sec, relax 10 sec, • This stage is usually sensed by the man as the repeat 10x (can start w/ 5 sec and work to 10)! “point of no return”! – Fast: Contract and relax rapidly 10-25x! 2) Expulsion phase: semen is expelled! – Can be done 3x a day!

Expulsion phase of ejaculation (phase 2) • : when semen is expelled Erection/ejaculation concept map • Collected semen is expelled out of the body by into the bladder instead of out of the penis! Each term is linked to 1 or more terms with rhythmic contractions of muscles surrounding the – Due to reversed function of the two arrows; labels across arrows define the urethral bulb and urethra.! urethral sphincters (internal sphincter relaxes and external sphincter connection between the terms • External urethral sphincter relaxes to allow semen out; contracts instead of the other internal urethral sphincter stays contracted to prevent way around).! • Cowper’s glands • ejaculation the escape of .! – Can result from prostate surgery, • seminal vesicles • blood vessels illness, , tranquilizers.! – Not harmful, but would cause • prostate gland • arousal signal in brain sterility and could be a sign of an underlying health problem.! • sperm • cavernous & spongy • : involuntary ejaculation • semen bodies during sleep! • Seminiferous tubules • erection – Also known as a wet dream! • epididymis • vas deferens – Mechanism not fully understood! • urethra • : surgical Contemplating circumcision “A circumcised penis is a healthier one” removal of the foreskin Potential medical benefits Potential medical risks! of the penis.! • Carousel graffiti! • Reduced rate of penile • Surgical complications! (from ~6/100,000 – , including • Short documentary! men to 1/100,000 men)! increased risk of MRSA! • Brief lecture! • Decreased rate of – ! UTI’s and STI’s – Coronal adhesions! • Think/write/share! st (especially in 1 year of life)! • Pain (documented w/ • Most of the medical measurement of b.p., benefits of circumcision rate, cortisol levels)! would likely be realized • Possible loss of in uncircumcised men sensitivity, issues for w/proper hygiene! female !

Circumcision: medical perspective “An uncircumcised penis has less ‘fun’ / “Most boys in the world are circumcised” is less ‘fun’ (think stimulation)” • American Academy of Pediatrics position:! Country! % circumcised! Actually, research shows that • International U.S. ! !! 55 - 60% ! – Procedure is not medically essential.! the opposite may be true: differences:! Canada ! !<15%! – Decision is left up to parents.! – If parents decide to circumcise, they should ask for • For men: removal of many fine-touch Australia ! !10 - 20%! analgesia to be used.! neuroreceptors ! reduces sensitivity! Europe ! !5 - 15%! • For women: !! (1999; reaffirmed in 2005)! – Presence of foreskin helps female lubrication last! • Ethnic differences! Ethnic group! % circumcised! – Sliding mechanism of foreskin can reduce friction Caucasian ! !81%! and chafing of vaginal tissue! Latino! !!54%! – More clitoral contact observed w/different type African-American !65%! of thrusting !

Discussion question: (#4-B) Male Genital Health Concerns • Cleanliness can reduce and build-up of • One of the rarest forms of cancer (approx. 1300 cases smegma (“cheesy” substance of glandular secretions and skin cells If you had a newborn son, would you have him in the U.S. each year)! circumcised? Why or why not?! that sometimes accumulates under the foreskin)! • Some men can develop a reaction to vaginal • Survival rate is less than half unless it is caught early.! (Or, if you have a son, has your perspective changed?) ! secretions.! • Usually begins as a small, painless sore on the glans or foreskin that eventually changes into a cauliflower-like • Injuries: ! mass that is chronically inflamed and tender.! – use of “cock rings” for > 30 min. can cut off blood • Risk factors: age over 50, history of multiple partners Provide at least two reasons that you would or supply and injure penile tissue! would not choose to have your son and STIs (especially herpes), poor genital hygiene, long – with vacuum devices can cause severe history of smoking.! circumcised, citing evidence presented in class! injuries! • Left untreated, will eventually destroy the penis and – Penile “fracture” can occur during intercourse--involves spread to nodes and beyond.! rupture of the cavernous bodies when penis is erect.! • can protect against STIs (more on this in Chp. 17)! Prostate Health Care Issues • Only 1% of that occur in males.! • 218,000 men diagnosed and 28,000 die each year in U.S.! • One of the most common cancers that occur in young men • : when prostate becomes enlarged and inflamed, usually due to infection! • One of the most frequently diagnosed cancer in men, and (age 15-34); half of cases are in men younger than 35.! second leading cause of cancer death (after cancer)! • Early stage: small mass within the testis that feels hard and – Usually treated w/.! • Associated factors: old age, family history, prior history of irregular to fingertips; may be as small as a pea and may be ! STIs, diet high in saturated fats. ! painless or tender to the touch.! • Benign prostatic hyperplasia – Increase in the size of the prostate gland! • Incidence is 70% higher in African American men than • Some other symptoms reported include , dull ache in white men, and survival rate is lower--reasons not known.! , feeling of heaviness in testes, tender and – Increasingly common as men age! .! – Enlarged gland can put pressure on urethra and • Some types of testicular cancer grow more rapidly than other cancers; therefore, very important to catch it early.! decrease urine flow; can be treated w/medication.! • If caught early, survival rate is >90%. !

Prostate Cancer: Symptoms & diagnosis • Symptoms are similar to prostatitis:! – Pelvic and lower , urinary complications! – May be no symptoms in early stages! • Screening and diagnosis! – Physical examination: physician inserts finger into to feel for lumps in prostate gland.! – Blood test: examines levels of PSA (prostate-specific antigen)! • Normal PSA levels are <4 nanograms per ml of blood.! – Detection of prostate cancer is not precise, and there is controversy about whether screening is even beneficial.!