Reproductive Male System PDF

PowerPoint® Lecture Slides prepared by Vince Austin, University of Kentucky The Reproductive System Part A 27 Human Anatomy & Physiology, Sixth Edition Elaine N. Marieb Copyright © 2004 Pearson Education, I...

PowerPoint® Lecture Slides prepared by Vince Austin, University of Kentucky The Reproductive System Part A 27 Human Anatomy & Physiology, Sixth Edition Elaine N. Marieb Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Reproductive System ▪ Primary sex organs (gonads) – testes in males, ovaries in females ▪ Gonads produce sex cells called gametes and secrete sex hormones ▪ Accessory reproductive organs – ducts, glands, and external genitalia ▪ Sex hormones – androgens (males), and estrogens and progesterone (females) Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Reproductive System ▪ Sex hormones play roles in: ▪ The development and function of the reproductive organs ▪ Sexual behavior and drives ▪ The growth and development of many other organs and tissues Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Male Reproductive System ▪ The male gonads (testes) produce sperm and lie within the scrotum ▪ Sperms are delivered to the exterior through a system of ducts: epididymis, ductus deferens, ejaculatory duct, and the urethra ▪ Accessory sex glands: ▪ Empty their secretions into the ducts during ejaculation ▪ Include the seminal vesicles, prostate gland, and bulbourethral glands Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Male Reproductive System Figure 27.1 Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  The Scrotum ▪ Sac of skin and superficial fascia that hangs outside the abdominopelvic cavity at the root of the penis ▪ Contains paired testicles separated by a midline septum ▪ Intrascrotal temperature is kept constant by two sets of muscles: ▪ Cremaster – bands of skeletal muscle that elevate the testes Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  The Scrotum Figure 27.2 Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  The Testes ▪ Septa divide the testis into 250-300 lobules, each containing 1-4 seminiferous tubules Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  The Testes ▪ Seminiferous tubules: ▪ Produce the sperm ▪ Converge to form the tubulus rectus ▪ The straight tubulus rectus conveys sperm to the rete testis Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  The Testes ▪ From the rete testis, the sperm: ▪ Enter the epididymis ▪ Surrounding the seminiferous tubules are interstitial cells that produce androgens Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  The Testes ▪ Testicular arteries branch from the abdominal aorta and supply the testes ▪ Spermatic cord – encloses nerve fibers and blood vessels that supply the testes Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  The Testes Figure 27.3a Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  The Penis ▪ A copulatory organ designed to deliver sperm into the female reproductive tract ▪ Prepuce, or foreskin – cuff of skin covering the distal end of the penis Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  The Penis ▪ Internal penis – the urethra and three cylindrical bodies of erectile tissue ▪ Erectile tissue – spongy network of connective tissue and smooth muscle riddled with vascular spaces Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  The Penis ▪ Erection – during sexual excitement, the erectile tissue fills with blood causing the penis to enlarge and become rigid ▪ Corpus spongiosum – surrounds the urethra and expands to form the glans and bulb of the penis ▪ Corpora cavernosa – paired dorsal erectile bodies Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  The Penis Figure 27.4 Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Epididymis ▪ Nonmotile sperm enter, pass through its tubes and become motile ▪ Upon ejaculation the epididymis contracts, expelling sperm into the ductus deferens Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Ductus Deferens and Ejaculatory Duct ▪ Propels sperm from the epididymis to the urethra ▪ Vasectomy – cutting and ligating the ductus deferens, which is a nearly 100% effective form of birth control Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Urethra ▪ Conveys both urine and semen (at different times) ▪ Consists of three regions ▪ Prostatic – portion surrounded by the prostate ▪ Membranous – lies in the urogenital diaphragm ▪ Spongy, or penile – runs through the penis and opens to the outside at the external urethral orifice Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Accessory Glands: Seminal Vesicles ▪ Lie on the posterior wall of the bladder and secrete 60% of the volume of semen ▪ Join the ductus deferens to form the ejaculatory duct Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Accessory Glands: Prostate Gland ▪ Doughnut-shaped gland that encircles part of the urethra inferior to the bladder ▪ Plays a role in the activation of sperm Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Accessory Glands: Bulbourethral Glands (Cowper’s Glands) ▪ Pea-sized glands inferior to the prostate ▪ Produce thick, clear mucus prior to ejaculation that neutralizes traces of acidic urine in the urethra Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Spermatogenesis ▪ Cells making up the walls of seminiferous tubules are in various stages of cell division ▪ These spermatogenic cells give rise to sperm in a series of events Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Spermiogenesis: Spermatids to Sperm ▪ Late in spermatogenesis, spermatids are haploid but nonmotile ▪ Spermiogenesis – spermatids lose excess cytoplasm and form a tail, becoming sperm ▪ Sperm have three major regions ▪ Head – contains DNA and has a helmetlike acrosome containing hydrolytic enzymes that allow the sperm to penetrate and enter the egg ▪ Midpiece – contains mitochondria spiraled around the tail filaments ▪ Tail – a typical flagellum produced by a centriole Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Spermiogenesis: Spermatids to Sperm Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 27.9a