Anatomy Physiology SIXTH EDITION Chapter 28 part 2

Anatomy & Physiology SIXTH EDITION Chapter 28, part 2 The Reproductive System Power. Point® Lecture Slide Presentation prepared by Dr. Kathleen A. Ireland, Biology Instructor, Seabury Hall, Maui, Hawaii Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings Frederic H. Martini Fundamentals of

Spermatogenesis • Seminiferous tubules • Contain spermatogonia • Stem cells involved in spermatogenesis • Contain sustentacular cells • Sustain and promote development of sperm Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Figure 28. 5 The Seminiferous Tubules Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 28. 5 a, b

Figure 28. 5 The Seminiferous Tubules Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 28. 5 c

Figure 28. 6 Chromosomes in Mitosis and Meiosis Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 28. 6

Spermatogenesis • Spermatogenesis involves three processes • Mitosis • Meiosis • Spermiogenesis Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Figure 28. 7 Spermatogenesis Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 28. 7

Anatomy of spermatozoon • Each spermatozoon has: • Head • Nucleus and densely packed chromosomes • Middle piece • Mitochondria that produce the ATP needed to move the tail • The only flagellum in the human body Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Figure 28. 8 Spermiogenesis and Spermatozoon Structure Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 28. 8

Male reproductive tract • Testes produce mature spermatozoa • Sperm enter epididymus • Elongated tubule with head, body and tail regions • Monitors and adjusts fluid in seminiferous tubules • Stores and protects spermatozoa • Facilitates functional maturation of spermatozoa Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Figure 28. 9 The Epididymus Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 28. 9

Ductus deferens AKA vas deferens • Begins at epididymus • Passes through inguinal canal • Enlarges to form ampulla • Ejaculatory duct at base of seminal vesicle and ampulla • Empties into urethra Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Urethra • Urinary bladder to tip of penis • Three regions • Prostatic • Membranous • Penile Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Accessory glands • Seminal vesicles • Active secretory gland • Contributes ~60% total volume of semen • Secretions contain fructose, prostaglandins, fibrinogen Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Accessory glands • Prostate gland • Secretes slightly acidic prostate fluid • Bulbourethral glands • Secrete alkaline mucus with lubricating properties Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Figure 28. 10 The Ductus Deferens and Accessory Glands Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 28. 10 a-e

Contents of Semen • Typical ejaculate = 2 -5 ml fluid • Contains between 20 – 100 million spermatozoa per ml • Seminal fluid • A distinct ionic and nutritive glandular secretion Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

External genitalia • Male external genitalia consist of the scrotum and the penis • Skin overlying penis resembles scrotum • Penis • Contains three masses of erectile tissue • 2 corpora cavernosa beneath fascia • 1 corpus spongiosum surrounding urethra • Dilation of erectile tissue produces erection Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Figure 28. 11 The Penis Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 28. 11

Hormones and male reproductive function • FSH (Follicle stimulating hormone) • Targets sustentacular cells to promote spermatogenesis • LH (leutinizing hormone) • Causes secretion of testosterone and other androgens • Gn. RH (Gonadotropin releasing hormone) • Testosterone • Most important androgen PLAY Animation: Male Reprroductive System Flythrough Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Figure 28. 12 Hormonal Feedback and the Regulation of the Male Reproductive Function Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 28. 12