REPRODUCTIVE PHYSIOLOGY: Part Two—Male

Introduction--why is pelvis so hard? Review—Male Reproductive Organs Male Orgasm Making a new human—what it’s all

about Sperm Production Hormonal Control of Male

Development, Sex Drive and Sperm Production

REPRODUCTIVE PHYSIOLOGY: Part Two—Male

Frolich, Human Anatomy, Reproductive Physiology

Why is the pelvis hard “Private parts” don’t

uncover except in most intimate setting (or medical setting!)

Not comfortable seeing or talking about (except jokes)

Now serious-many medical issues

Realize and confront, not dehumanize--develop professional manner and language--starts with anatomy

Frolich, Human Anatomy, Pelvis I

Male reproductive organs

Sperm produced in testes (left, right) Carried by vas deferens (left, right) up into abdominal cavity (millions of sperm in a

few drops of testicular fluid) Join with urethra at base of penis Semen made by prostrate and seminal glands at base of penis Ejaculation—sperm travel from testes, joined by semen, expelled through erect penis

Frolich, Human Anatomy, Pelvis I

The pelvic floor (review)MAIN STRUCTURES Ischial tuberosity Pubic symphysis Coccyx Sacrotuberous ligament Ischipubic ramus Perineal body Anus External urethral opening Vaginal opening

MUSCULAR FLOOR AND SPHINCHTERS

transverse perineal m. Anal triangle and

urogentical triangle Levator ani m. Urogenital diaphragm

EXTERNAL GENITALIA Clitoris or penis Ischiocavernosus m. Bulbospongiosus m.

(and labia majorum)

Frolich, Human Anatomy, Pelvis I

Frolich, Human Anatomy, Pelvis I

In male:• No vaginal opening• Urethra enters into penis• Bulbospongiusus and ischiocavernosus surround spongy erectile tissues at base of penis

Penis anatomy—details

Spony erectile tissues– Paired corpora cavernosa with ischiocavernosus muscle at

base– Midline, ventral corpus spongiusum with urethra running

down middle and bulbospongiosus at base Glans penis is head or tip of penis

Male Orgasm

Arousal Phase: Penis spongy tissue engorge leading to erection; Bulbo-urethral gland secretions lubricate urethra and glans of penis

Emission Phase: Testicular fluid moves through vas deferens; Seminal vessicles and prostate gland begin rhythmic contractions of ducts; Bladder and internal urethral sphinchter contract so that semen does not enter bladder

Ejaculation/Orgasm Phase: Ischiocavernosus (stiffens penis) and Bulbospongiosus (moves semen towards end of urethra) muscles contract in pelvic floor; elevanted heart rate and blood pressure; intense pleasure sensations

Resolution Phase/Detumescence: Tension release; blood leaves erectile tissue; erection subsides

Male Orgasm

Starting a new person—the end game: How are genetic traits combined and passed on from parent to offspring (Basic Bio review)

Meiosis produces gametes or sex cells (eggs and sperm) with just one member of each chromosome pair

Fertilization results in union of female gamete (egg) with male gamete (sperm)

Subsequent embryonic, fetal and embryonic development by mitosis and differentiation of cell types produces new individual

Meiosis (Basic Bio Review)

• Two nuclear divisions occur to make 4 haploid cells (cells with just one member of each chromosome pair)

• Meiosis results in gametes (egg and sperm)

• Has 8 phases (4 in each meiosis I & II)

So where does meiosis happen? Tissue of testes is

full of seminiferous tubules

In walls of tubules, stem cells that give rise to sperm are constantly undergoing meiosis

Sperm are then collected in epididymis

Sperm that are not ejaculated are reabsorbed back into testicular tissue

Sustentacular cells Form thick epithelial lining of seminiferous tubules

Tight junctiones between keep sperm proteins from entering bood

Produce testicular fluid which helps move sperm

Concentrate testosterone to stimulate sperm production

Produce inhibin which slows sperm production

Spermatogenesis Sperms form in walls of

seminiferous tubules Spermatogenic cells within

sustentacular cells Meiosos proceeds as

spermatocytes move towards lumen (4 sperm from each spermatocyte)

Seminiferous tubulerete testis head/body/tail epididymis vas deferens (through spermatic cord around bladder) urethra

Vasectomy

Vas deferens is cut Semen production and

ejaculation are as before

Sperm cannot travel through epididymis (in drops of testicular fluid) to join semen

As before, unejaculated sperm are reabsorbed into testicular fluid

Hormonal Control of Sperm Formation and Male Development