REPRODUCTIVE PHYSIOLOGY Part TwoMale REPRODUCTIVE PHYSIOLOGY Part TwoMale

REPRODUCTIVE PHYSIOLOGY: Part Two—Male

REPRODUCTIVE PHYSIOLOGY: Part Two—Male n n n 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

Why is the pelvis hard “Private parts” don’t uncover except in most intimate setting (or medical setting!) n Not comfortable seeing or talking about (except jokes) n Now serious-many medical issues n Realize and confront, not dehumanize-develop professional manner and language-starts with anatomy n Frolich, Human Anatomy, Reproductive Physiology

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

The pelvic floor (review) MAIN STRUCTURES n Ischial tuberosity n Pubic symphysis n Coccyx n Sacrotuberous ligament n Ischipubic ramus n Perineal body n Anus n External urethral opening n Vaginal opening Frolich, Human Anatomy, Pelvis I MUSCULAR FLOOR AND SPHINCHTERS n transverse perineal m. n Anal triangle and urogentical triangle n Levator ani m. n Urogenital diaphragm EXTERNAL GENITALIA n Clitoris or penis n Ischiocavernosus m. n Bulbospongiosus m. (and labia majorum)

Frolich, Human Anatomy, Pelvis I

n male: • No vaginal opening • Urethra enters into penis • Bulbospongiusus and schiocavernosus surround spongy erectile tissues at base of penis Frolich, Human Anatomy, Pelvis I

Penis anatomy—details n Spony erectile tissues – Paired corpora cavernosa with ischiocavernosus muscle at base – Midline, ventral corpus spongiusum with urethra running down middle and bulbospongiosus at base n Glans penis is head or tip of penis

Male Orgasm

Male Orgasm Arousal Phase: Penis spongy tissue engorge leading to erection; Bulbo-urethral gland secretions lubricate urethra and glans of penis n 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 n 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 n Resolution Phase/Detumescence: Tension release; blood leaves erectile tissue; erection subsides n

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 n Fertilization results in union of female gamete (egg) with male gamete (sperm) n Subsequent embryonic, fetal and embryonic development by mitosis and differentiation of cell types produces new individual n

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 n In walls of tubules, stem cells that give rise to sperm are constantly undergoing meiosis n Sperm are then collected in epididymis n Sperm that are not ejaculated are reabsorbed back into testicular tissue n

Sustentacular cells n n n 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 n Spermatogenic cells within sustentacular cells n Meiosos proceeds as spermatocytes move towards lumen (4 sperm from each spermatocyte) n Seminiferous tubule rete testis head/body/tail epididymis vas deferens (through spermatic cord around bladder) urethra

Vasectomy n Vas deferens is cut n Semen production and ejaculation are as before n Sperm cannot travel through epididymis (in drops of testicular fluid) to join semen n As before, unejaculated sperm are reabsorbed into testicular fluid

Hormonal Control of Sperm Formation and Male Development