Chapter 19 Reproductive System PDF

Because learning changes everything. ® Chapter 19 Lecture Outline Essentials of Anatomy and Physiology Third Edition Kenneth S. Saladin, Robin K. McFarland © 2022 McGraw Hill, LLC. All rights reserved. Authorized only for instructor use in the classroom. No...

Because learning changes everything. ® Chapter 19 Lecture Outline Essentials of Anatomy and Physiology Third Edition Kenneth S. Saladin, Robin K. McFarland © 2022 McGraw Hill, LLC. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior written consent of McGraw Hill, LLC.  Essentials of Sexual Reproduction 1 Learning Outcomes: Explain why sexual reproduction in humans requires two different types of gametes Enumerate the functions of the male and female reproductive systems Distinguish between the gonads of the two sexes, and between the internal and external genitalia © McGraw Hill, LLC 2  Essentials of Sexual Reproduction 2 Gametes Sperm – small, motile sex cell Egg (ovum) – full of nutrients for the embryo Zygote – fertilized egg The reproductive systems Produce and unite the gametes Harbor the fetus Give birth Nourish the infant © McGraw Hill, LLC 3  Gonads Gonads (primary sex organs) Organs that produce the gametes Testes of the male Ovaries of the female Produce sex hormones that have widespread effects in the body Secondary sex organs Other organs necessary to reproduction For example, penis, uterus, mammary glands, etc. © McGraw Hill, LLC 4  Genitalia External genitalia Located in the perineum between the thighs Most are externally visible or superficial beneath the skin Internal genitalia Most are located in the pelvic cavity Except for the testes and some scrotal ducts © McGraw Hill, LLC 5  The Male Reproduction System Learning Outcomes: Describe the anatomy of the male reproductive tract Trace the pathway taken by a sperm cell from its formation to ejaculation, naming all the passages that it travels Describe the structure, locations, and functions of the male accessory glands, scrotum, and penis Discuss male sexual development from puberty through andropause © McGraw Hill, LLC 6  Anatomy 1 Testes (testicles) Produce sex hormones and sperm Each is covered with a fibrous capsule with extensions (septa) that divide it into lobules Each lobule contains 1-3 seminiferous tubules Slender ducts in which sperm are produced Interstitial endocrine cells Located in clusters between the seminiferous tubules Produce testosterone © McGraw Hill, LLC 7 Figure 16.2a Male reproductive organs. Ureter Urinary bladder Seminal vesicle Prostatic urethra Ampulla of Pubis ductus deferens Membranous urethra Ejaculatory duct Urogenital diaphragm Rectum Erectile tissue Prostate of the penis Bulbo-urethral gland Spongy urethra Shaft of the penis Ductus (vas) deferens Epididymis Glans penis Testis Prepuce Scrotum External urethral (a) orifice © 2018 Pearson Education, Inc. © McGraw Hill, LLC  The Male Reproductive System a) Sagittal section Access the text alternative for slide images. © McGraw Hill, LLC 9  Anatomy 2 Seminiferous tubule epithelium Has germ cells in process of becoming sperm Smaller number of nurse cells (supporting cells, sustentocytes) Support and protect germ cells, promote their development Secrete inhibin – a hormone that regulates sperm production © McGraw Hill, LLC 10 Figure 16.1 Sagittal section of the testis and associated epididymis. Spermatic cord Blood vessels and nerves Seminiferous tubule Rete testis Ductus (vas) deferens Lobule Septum Tunica Epididymis albuginea © 2018 Pearson Education, Inc. © McGraw Hill, LLC  Seminiferous Tubule c: © Steve Gschmeissner/Science Source; d: © Ed Reschke Access the text alternative for slide images. © McGraw Hill, LLC 12  The Epididymis and Ductus Deferens 1 Epididymis Site of sperm maturation and storage Adheres to the posterior side of testis Sperm from the seminiferous tubules exit through ducts into the epididymis Will stay here and remain fertile for 40 to 60 days, but will then be reabsorbed © McGraw Hill, LLC 13 Figure 16.2a Male reproductive organs. Ureter Urinary bladder Seminal vesicle Prostatic urethra Ampulla of Pubis ductus deferens Membranous urethra Ejaculatory duct Urogenital diaphragm Rectum Erectile tissue Prostate of the penis Bulbo-urethral gland Spongy urethra Shaft of the penis Ductus (vas) deferens Epididymis Glans penis Testis Prepuce Scrotum External urethral (a) orifice © 2018 Pearson Education, Inc. © McGraw Hill, LLC  The Testis and Associated Structures a: © Dennis Strete/McGraw-Hill Education; © McGraw Hill, LLC 15  Anatomy of the Testis, Epididymis, and Spermatic Cord Access the text alternative for slide images. © McGraw Hill, LLC 16  The Epididymis and Ductus Deferens 2 Ductus (vas) deferens Tube with a thick wall of smooth muscle that is important for ejaculation Also called the vas deferens, which led to the term vasectomy – surgical cutting for contraception Travels upward through the inguinal canal, where it enters the pelvic cavity © McGraw Hill, LLC 17 Figure 16.2a Male reproductive organs. Ureter Urinary bladder Seminal vesicle Prostatic urethra Ampulla of Pubis ductus deferens Membranous urethra Ejaculatory duct Urogenital diaphragm Rectum Erectile tissue Prostate of the penis Bulbo-urethral gland Spongy urethra Shaft of the penis Ductus (vas) deferens Epididymis Glans penis Testis Prepuce Scrotum External urethral (a) orifice © 2018 Pearson Education, Inc. © McGraw Hill, LLC  The Male Reproductive System b) Posterior view Access the text alternative for slide images. © McGraw Hill, LLC 19  The Epididymis and Ductus Deferens 3 Ductus (vas) deferens, continued Unites with the duct of the seminal vesicle behind the urinary bladder The two become a short ejaculatory duct, which passes through the prostate gland and empties into the urethra © McGraw Hill, LLC 20  The Male Urethra Shared by reproductive and urinary systems Three regions: Prostatic urethra in the prostate gland Membranous urethra passes through the pelvic floor Spongy (penile) urethra passes through the penis © McGraw Hill, LLC 21 Figure 16.2a Male reproductive organs. Ureter Urinary bladder Seminal vesicle Prostatic urethra Ampulla of Pubis ductus deferens Membranous urethra Ejaculatory duct Urogenital diaphragm Rectum Erectile tissue Prostate of the penis Bulbo-urethral gland Spongy urethra Shaft of the penis Ductus (vas) deferens Epididymis Glans penis Testis Prepuce Scrotum External urethral (a) orifice © 2018 Pearson Education, Inc. © McGraw Hill, LLC  The Male Reproductive System b) Posterior view Access the text alternative for slide images. © McGraw Hill, LLC 23  The Scrotum Pouch of skin, muscle, and fibrous connective tissue that contains the testes, epididymis and spermatic cord The left testis is usually suspended lower than the right Divided into right and left compartments by a median septum © McGraw Hill, LLC 24 Figure 16.2a Male reproductive organs. Ureter Urinary bladder Seminal vesicle Prostatic urethra Ampulla of Pubis ductus deferens Membranous urethra Ejaculatory duct Urogenital diaphragm Rectum Erectile tissue Prostate of the penis Bulbo-urethral gland Spongy urethra Shaft of the penis Ductus (vas) deferens Epididymis Glans penis Testis Prepuce Scrotum External urethral (a) orifice © 2018 Pearson Education, Inc. © McGraw Hill, LLC  The Scrotum and Spermatic Cord Access the text alternative for slide images. © McGraw Hill, LLC 26  The Spermatic Cord Fibrous bundle that contains the ductus deferens, blood and lymphatic vessels, nerves Passes anterior to the pubis and into the inguinal canal © McGraw Hill, LLC 27 Figure 16.1 Sagittal section of the testis and associated epididymis. Spermatic cord Blood vessels and nerves Seminiferous tubule Rete testis Ductus (vas) deferens Lobule Septum Tunica Epididymis albuginea © 2018 Pearson Education, Inc. © McGraw Hill, LLC  Controlling Testicular Temperature 1 Sperm production requires a temperature 2°C cooler than the pelvic cavity; 3 mechanisms to control testicular temperature: Cremaster – muscle of the spermatic cord; draws the testes closer to the body in response to cold Dartos fascia - layer of smooth muscle that contracts and tautens the scrotum if it’s cold When warm, both relax to suspend the testes farther from the body © McGraw Hill, LLC 29  The Scrotum and Spermatic Cord Access the text alternative for slide images. © McGraw Hill, LLC 30  Controlling Testicular Temperature 2 Pampiniform plexus Network of veins in the spermatic cord Carries heat away from the testes © McGraw Hill, LLC 31  Seminal Vesicles Pair of glands on the posterior side of the urinary bladder Produce 60% of semen Produce a thick, yellowish secretion that contains: Fructose, Vitamin C Nourish and activate sperm Contributes to sperm motility and viability Secrete viscous, alkaline fluid that neutralizes acidic vagina ​ Helps semen coagulate for better delivery © McGraw Hill, LLC 32  The Prostate Surrounds urethra and ejaculatory duct immediately inferior to the urinary bladder Produces a milky secretion that makes up 30% of semen Secretes into the prostatic urethra by pores in the urethral wall Secretes a slightly acidic, milky fluid Helps to activate sperm Coagulates sperm into semen Helps break down semen after delivery © McGraw Hill, LLC 33 Figure 16.2a Male reproductive organs. Ureter Urinary bladder Seminal vesicle Prostatic urethra Ampulla of Pubis ductus deferens Membranous urethra Ejaculatory duct Urogenital diaphragm Rectum Erectile tissue Prostate of the penis Bulbo-urethral gland Spongy urethra Shaft of the penis Ductus (vas) deferens Epididymis Glans penis Testis Prepuce Scrotum External urethral (a) orifice © 2018 Pearson Education, Inc. © McGraw Hill, LLC  Clinical Application 19.1: Prostate Diseases 1 The prostate starts to slowly enlarge at about 45 years old By age 70, 90% of men experience benign prostatic hyperplasia (BPH) Can compress the urethra, making it hard to empty the bladder © McGraw Hill, LLC 35  Clinical Application 19.1: Prostate Diseases 2 Prostate cancer Approximately 11.6% of men will be diagnosed with prostate cancer at some point in their life. Tumors If caught before it metastasizes, it’s highly curable Grows slowly, so often caught before it metastasizes Can be detected by: Digital rectal examination (DRE) – palpation through the rectal wall Prostate-specific antigen (PSA) blood test © McGraw Hill, LLC 36  The Bulbourethral Glands Have short ducts leading to the urethra at the root of the penis During sexual arousal, produce a clear fluid that provides lubrication for intercourse and neutralizes the acidity of the urethra Urine leaves the urethra with an acidic pH that could harm sperm if not neutralized © McGraw Hill, LLC 37 Figure 16.2a Male reproductive organs. Ureter Urinary bladder Seminal vesicle Prostatic urethra Ampulla of Pubis ductus deferens Membranous urethra Ejaculatory duct Urogenital diaphragm Rectum Erectile tissue Prostate of the penis Bulbo-urethral gland Spongy urethra Shaft of the penis Ductus (vas) deferens Epididymis Glans penis Testis Prepuce Scrotum External urethral (a) orifice © 2018 Pearson Education, Inc. © McGraw Hill, LLC  The Penis 1 Functions to deposit semen into the vagina Externally visible portions, the shaft and glans, make up half of its length Glans – the expanded head at the distal end Has an external urethral orifice at tip © McGraw Hill, LLC 39 Figure 16.2a Male reproductive organs. Ureter Urinary bladder Seminal vesicle Prostatic urethra Ampulla of Pubis ductus deferens Membranous urethra Ejaculatory duct Urogenital diaphragm Rectum Erectile tissue Prostate of the penis Bulbo-urethral gland Spongy urethra Shaft of the penis Ductus (vas) deferens Epididymis Glans penis Testis Prepuce Scrotum External urethral (a) orifice © 2018 Pearson Education, Inc. © McGraw Hill, LLC  Anatomy of the Penis Access the text alternative for slide images. © McGraw Hill, LLC 41  The Penis 2 Skin of the shaft continues over the glans as the prepuce (foreskin) In adults, the frenulum anchors the prepuce to the glans The prepuce is the most sensitive part of the penis Circumcision – surgical removal of the prepuce © McGraw Hill, LLC 42 Figure 16.2a Male reproductive organs. Ureter Urinary bladder Seminal vesicle Prostatic urethra Ampulla of Pubis ductus deferens Membranous urethra Ejaculatory duct Urogenital diaphragm Rectum Erectile tissue Prostate of the penis Bulbo-urethral gland Spongy urethra Shaft of the penis Ductus (vas) deferens Epididymis Glans penis Testis Prepuce Scrotum External urethral (a) orifice © 2018 Pearson Education, Inc. © McGraw Hill, LLC  Erectile Tissues of the Penis 1 Three cylindrical bodies that fill with blood during sexual arousal Accounts for enlargement and erection Corpus spongiosum Passes along the ventral side of the penis Encloses the urethra, fills the glans © McGraw Hill, LLC 44  Anatomy of the Penis Access the text alternative for slide images. © McGraw Hill, LLC 45  Erectile Tissues of the Penis 2 Corpus cavernosa (sing., cavernosum) Two on the dorsal side of the penis Extend as far as the margin of the glans Separated by a median septum and sheathed in fibrous tunics All three contain tiny blood sinuses called lacunae Partitions between the lacunae are called trabeculae © McGraw Hill, LLC 46  Internal Portions of the Penis The root is not exposed The corpus spongiosum ends internally as the bulb, which is ensheathed in the bulbospongiosus muscle © McGraw Hill, LLC 47 Figure 16.2a Male reproductive organs. Ureter Urinary bladder Seminal vesicle Prostatic urethra Ampulla of Pubis ductus deferens Membranous urethra Ejaculatory duct Urogenital diaphragm Rectum Erectile tissue Prostate of the penis Bulbo-urethral gland Spongy urethra Shaft of the penis Ductus (vas) deferens Epididymis Glans penis Testis Prepuce Scrotum External urethral (a) orifice © 2018 Pearson Education, Inc. © McGraw Hill, LLC  From Puberty to Andropause 1 Surge of pituitary gonadotropins awakens the reproductive system Age 10 to 12 for boys; 8 to 10 for girls Begins preparing the system for adult reproductive functions Adolescence From the onset of gonadotropin secretion to attainment of adult height (late teens to early twenties) © McGraw Hill, LLC 49  From Puberty to Andropause 2 Puberty – first few years of adolescence Until the first menstrual period in girls Until the first ejaculation of viable sperm in boys Around the age of 12 in girls, 14 in boys in U.S. © McGraw Hill, LLC 50  Gonadotropin-Releasing Hormone (GnRH) Secreted by the hypothalamus Stimulates the anterior pituitary gland to secrete two gonadotropins: Follicle-stimulating hormone (FSH) Luteinizing hormone (LH) © McGraw Hill, LLC 51  Gonadotropins FSH – named for its function in females; makes seminiferous tubules sensitive to testosterone LH – also named for its function in females; stimulates interstitial endocrine cells of the testes to secrete testosterone © McGraw Hill, LLC 52  Effects of Testosterone 1 Growth of sex organs and sperm production First the testes and scrotum, later the penis and internal ducts and glands Burst of general body growth Elongation of limb bones Increasing muscle mass Enlargement of the larynx and deepening of the voice Elevated metabolic rate and appetite © McGraw Hill, LLC 53  Effects of Testosterone 2 Hair and sweat glands Appearance of pubic, axillary, then facial hair Apocrine glands become active Awakening of libido Frequent erections and spontaneous ejaculations, especially in sleep (nocturnal emissions) Throughout adulthood, sustains male reproductive tract, sperm production, and libido © McGraw Hill, LLC 54  Effects of Testosterone 3 Nurse cells also secrete inhibin, which inhibits FSH but not LH Testosterone levels peak at age 20, decline throughout adulthood After age 50, rising FSH and LH produces andropause (male climacteric) Little effect in most men, but sometimes causes mood changes, hot flashes Sperm is produced through the end of life © McGraw Hill, LLC 55  The Female Reproductive System Learning Outcomes: Describe the anatomy and histology of the ovaries Describe the gross anatomy and histology of the female reproductive tract Describe the structure and function of the glands and other accessory organs of the female reproductive system Discuss female sexual development from puberty through menopause © McGraw Hill, LLC 56  The Ovaries and Reproductive Tract 1 Ovaries Produce eggs cells (ova) and sex hormones Located in depressions in the posterior pelvic wall Held in place by ligaments Enclosed in fibrous capsules Medulla – the central core of connective tissue and vessels Outer cortex – where eggs develop © McGraw Hill, LLC 57  Structure of the Ovary Access the text alternative for slide images. © McGraw Hill, LLC 58  The Ovaries and Reproductive Tract 2 Egg follicles Eggs develop within follicles inside the ovary Released when follicle bursts (ovulation) Follicles bulge off the ovary surface Wall of each follicle made up of: An inner layer of granulosa cells Outer layer called a theca These layers produce the female sex hormones, estrogen and progesterone © McGraw Hill, LLC 59  The Uterine (fallopian) Tubes Muscular canal that extends from the ovary to the uterus Flares into the infundibulum at its distal end Has feathery projections called fimbriae that catch an ovulated egg Lined with ciliated epithelium The cilia beat to help move the egg toward the uterus © McGraw Hill, LLC 60 Figure 16.8b The human female reproductive organs. Suspensory Uterine (fallopian) tube ligament of ovary Fundus Lumen (cavity) Ovarian of uterus of uterus blood vessels Ovary Broad Infundibulum Uterine ligament Fimbriae tube Ovarian ligament Round ligament of uterus Body of Endometrium uterus Wall of Myometrium Perimetrium uterus Ureter Uterine blood Cervical canal vessels Uterosacral ligament Vagina Cervix (b) © 2018 Pearson Education, Inc. © McGraw Hill, LLC  The Female Pelvic Cavity and Reproductive Organs Access the text alternative for slide images. © McGraw Hill, LLC 62  The Uterus 1 Tilts forward over the urinary bladder Harbors the fetus, provides nutrition, and expels it Fundus – the broad superior curvature Body – midportion Cervix – cylindrical inferior end © McGraw Hill, LLC 63 Figure 16.8b The human female reproductive organs. Suspensory Uterine (fallopian) tube ligament of ovary Fundus Lumen (cavity) Ovarian of uterus of uterus blood vessels Ovary Broad Infundibulum Uterine ligament Fimbriae tube Ovarian ligament Round ligament of uterus Body of Endometrium uterus Wall of Myometrium Perimetrium uterus Ureter Uterine blood Cervical canal vessels Uterosacral ligament Vagina Cervix (b) © 2018 Pearson Education, Inc. © McGraw Hill, LLC  The Uterus 2 Upper corners open into the uterine tubes Lower end communicates with the vagina through a narrow passage through the cervix called the cervical canal Contains glands that secrete mucus © McGraw Hill, LLC 65  The Female Reproductive Tract Access the text alternative for slide images. © McGraw Hill, LLC 66  Uterine Wall 1 Perimetrium Thin external serosa Myometrium Thick middle layer of smooth muscle Responsible for labor contractions © McGraw Hill, LLC 67  Uterine Wall 2 Endometrium Inner mucosa of simple columnar epithelium Deep glandular pits with spiral arteries Functional layer is shed during each menstrual period Basal layer regenerates a new functional layer Site of attachment of the embryo Forms part of the placenta, which nourishes the fetus © McGraw Hill, LLC 68 Figure 16.8b The human female reproductive organs. Suspensory Uterine (fallopian) tube ligament of ovary Fundus Lumen (cavity) Ovarian of uterus of uterus blood vessels Ovary Broad Infundibulum Uterine ligament Fimbriae tube Ovarian ligament Round ligament of uterus Body of Endometrium uterus Wall of Myometrium Perimetrium uterus Ureter Uterine blood Cervical canal vessels Uterosacral ligament Vagina Cervix (b) © 2018 Pearson Education, Inc. © McGraw Hill, LLC  Clinical Application: Cervical Cancer 1 Cervical cancer usually occurs in women aged 30 to 50, who smoke, began sexual activity at an early age or have histories of frequent sexually transmitted diseases Usually caused by the human papilloma virus (HPV) Called invasive if it spreads to the subepithelial connective tissue © McGraw Hill, LLC 70  Pap Smears a: © SPL/Science Source; b: © Parviz M. Pour/Science Source © McGraw Hill, LLC 71  Clinical Application 19.2: Cervical Cancer 2 Pap smear – scraping of the cervix Examine cells for dysplasia (abnormal development) and carcinoma (cancer) © McGraw Hill, LLC 72  The Vagina 1 Tube allowing for: Discharge of menstrual fluid Receipt of penis and semen Birth of baby Walls are thin but distensible Lubricated by serous fluid seeping through wall and by mucus draining from cervix Epithelium is nonkeratinized stratified squamous (resistance to abrasion) © McGraw Hill, LLC 73  The Vagina 2 Cells are rich in glycogen Fermented to lactic acid by bacteria; produces a low pH, inhibiting pathogen growth Hymen – membrane stretching across the vaginal opening Has one or more openings for menstrual fluid Often torn during childhood or adolescence by physical activity, use of tampons, or medical examinations may tear at the first act of sexual intercourse. © McGraw Hill, LLC 74  External Genitalia 1 Vulva External genitalia of female Includes: Mons pubis, labia majora and minora Clitoris, vaginal orifice Accessory glands and erectile tissues © McGraw Hill, LLC 75 Figure 16.9 External genitalia of the human female. Mons pubis Labia majora Prepuce of clitoris Clitoris Vestibule Urethral orifice Vaginal orifice Opening of duct of greater vestibular gland Labia minora Perineum Anus © 2018 Pearson Education, Inc. © McGraw Hill, LLC  The Female Perineum: Surface Anatomy Access the text alternative for slide images. © McGraw Hill, LLC 77  External Genitalia 2 Mons pubis Anterior mound of adipose tissue and skin Overlies pubic symphysis Covered in pubic hair Labia majora (sing., labium majus) Pair of thick folds of skin and adipose tissue Forms lateral borders of vulva Bears pubic hair © McGraw Hill, LLC 78  External Genitalia 3 Labia minora (sing., labium) Medial to the labia majora; thinner, hairless Form a hood like prepuce over the clitoris Vestibule Area enclosed by labia minora and labia majora Contains urinary and vaginal orifices © McGraw Hill, LLC 79  The Clitoris Consists of a pair of corpora cavernosa Only the glans is external Crus anchors it to the pelvic girdle Sensory function in sexual stimulation © McGraw Hill, LLC 80  Vestibular Bulbs Pair of subcutaneous erectile tissues just deep to the labia majora Become congested with blood during sexual excitement Cause vagina to tighten around the penis © McGraw Hill, LLC 81  Vaginal Glands Greater vestibular glands (Bartholin glands) Found on each side of vagina Moisten vulva during sexual excitement Provide most of the lubrication for intercourse Lesser vestibular glands also lubricate Paraurethral glands open into the vestibule near external urethral orifice Eject fluid during orgasm Arise from same embryonic structure as prostate © McGraw Hill, LLC 82  Breasts 1 Mounds of tissue overlying pectoralis major Enlarge markedly at puberty Mammary gland Develops within the breast during pregnancy Atrophies when woman ceases breastfeeding © McGraw Hill, LLC 83  The Breast: Lactating Breast a) Anterior view Access the text alternative for slide images. © McGraw Hill, LLC 84  The Breast: Lactating Breast d: © Dr. Donald Fawcett/Science Source Access the text alternative for slide images. © McGraw Hill, LLC 85  Breasts 2 Regions of the breast Conical body with the nipple at the apex Nipple is surrounded by a circular, colored zone called the areola Sensitive and deeper in color Sparse hair and areolar glands (small visible bumps) Axillary tail – the extension toward the armpit © McGraw Hill, LLC 86  Breasts 3 The nonlactating internal breast is mostly adipose and collagenous tissue Size differences are based on differences in adipose tissue Lactiferous ducts lead to the nipple Develop during pregnancy Dilated to form a lactiferous sinus before opening on the nipple © McGraw Hill, LLC 87  The Breast: Nonlactating Breast b: © The University of Toledo/McGraw-Hill Education; b) Cadaver breast, nonlactating © McGraw Hill, LLC 88  From Puberty To Menopause Female puberty Begins around age 9 to 10 Rising levels of GnRH stimulate the anterior pituitary to secrete FSH and LH Elevations in FSH stimulate the development of ovarian follicles, which secrete estrogens, progesterone, inhibin, and a small amount of androgen Estrogens – feminizing hormones with widespread effects © McGraw Hill, LLC 89  Puberty Breast development is the earliest noticeable sign of puberty Begins with the formation of breast buds – small elevations of the areolas Lobules and ducts develop under the influence of estrogens and progesterone, followed by the growth of adipose and fibrous tissue Is complete around age 20 © McGraw Hill, LLC 90  Other Changes of Puberty 1 Appearance of: Pubic and axillary hair Sebaceous glands and axillary glands Menarche The first menstrual period Occurs around age 12 in U.S. First few cycles are usually anovulatory – no egg is ovulated © McGraw Hill, LLC 91  Other Changes of Puberty 2 Estrogen stimulates growth of ovaries and secondary sex organs Also stimulates the secretion of growth hormone Rapid increase in height Widening of pelvis Fat deposition in the breasts and hips Inhibin is secreted, which regulates the development of eggs and follicles © McGraw Hill, LLC 92  Midlife Changes 1 Climacteric Midlife change in hormone secretion Accompanied by menopause – cessation of menstruation Begins when only about 1,000 follicles left; they secrete less estrogen and progesterone Causes atrophy in the uterus, vagina, breasts, skin, and bones © McGraw Hill, LLC 93  Midlife Changes 2 Climacteric, continued Hot flashes Constriction and dilation of vessels from hormone imbalances Spreading sense of heat, sweating © McGraw Hill, LLC 94  End for today © McGraw Hill, LLC 95  The Production and Union of Sex Cells 1 Learning Outcomes: Explain the relevance of meiosis to sexual reproduction, state the stages of meiosis, and describe how it differs from mitosis Describe the stages in the production of sperm and eggs, how these stages relate to meiosis, and the major differences between sperm and egg production Give a functional description of the major components of semen and sperm cells © McGraw Hill, LLC 96  The Production and Union of Sex Cells 2 Learning Outcomes, continued: Relate the process of egg production to the cyclic changes in the ovary and uterus Describe the production of eggs and how it is correlated with cyclic changes in the ovaries and uterus Describe the physiological processes that occur in the male and female during sexual intercourse © McGraw Hill, LLC 97  Meiosis and Gametogenesis 1 Meiosis – cell division with a reduction of chromosome number by half There are 23 chromosome pairs in most cells One chromosome from mother, one from father Pairs 1-22 plus one pair of sex chromosomes, which are X, Y in male, X, X in female Homologous chromosomes look identical All chromosome pairs are homologous except the X and Y in males © McGraw Hill, LLC 98  Meiosis and Gametogenesis 2 n number Diploid – any cell with 23 chromosome pairs Symbolized 2n Haploid – any cell with 23 unpaired chromosomes Symbolized n Germ cells (egg, sperm) are haploid Chromosome number is reduced from diploid to haploid during meiosis (reduction division) © McGraw Hill, LLC 99  Differences Between Mitosis and Meiosis Mitosis Meiosis Used for growth, tissue Used only for the repair production of gametes Constant number of Reduces chromosome chromosomes number to haploid Chromosomes unchanged Chromosomes exchange genetically portions of DNA Two daughter cells Four daughter cells Four sperm; in females, three tiny nonviable cells and one large egg © McGraw Hill, LLC 100  Meiosis I Meiosis I – the first division of meiosis produces two haploid daughter cells Two homologous chromosomes exchange segments of DNA, then migrate to separate daughter cells Each chromosome is double-stranded: two chromatids joined at the centromere © McGraw Hill, LLC 101  Meiosis Access the text alternative for slide images. © McGraw Hill, LLC 102  Meiosis II Meiosis II – the second division of meiosis Each centromere divides Four daughter cells, each with 23 single-stranded chromosomes © McGraw Hill, LLC 103  Spermatogenesis, Sperm, and Semen Spermatogenesis 400 million sperm are made per day in young men Spermatogonia (sing., spermatogonium) – stem cells in the testes at birth Activated by testosterone during adolescence © McGraw Hill, LLC 104  Spermatogenesis 1 Stages of spermatogenesis Spermatogonia divide by mitosis One daughter cell remains as a stem cell Second daughter cell becomes a primary spermatocyte © McGraw Hill, LLC 105  Spermatogenesis 2 Stages of spermatogenesis, continued Primary spermatocyte undergoes meiosis I; divides into two haploid secondary spermatocytes Are genetically unique Secondary spermatocyte undergoes meiosis II Divides into two spermatids (four total for each spermatogonium) © McGraw Hill, LLC 106  Spermatogenesis 3 Stages of spermatogenesis, continued Spermiogenesis – spermatid transforms into a single sperm cell The spermatid sprouts a tail (flagellum), sheds excess cytoplasm © McGraw Hill, LLC 107  Spermatogenesis Access the text alternative for slide images. © McGraw Hill, LLC 108  Sperm 1 Spermatozoon (sperm cell) has two parts: head and tail Head contains: The nucleus with haploid chromosomes Acrosome – a lysosome that forms a thin cap covering the nucleus Contains enzymes used to penetrate the egg © McGraw Hill, LLC 109  The Mature Spermatozoon a: © BSIP SA/Alamy Stock Photo Access the text alternative for slide images. © McGraw Hill, LLC 110  Sperm 2 Spermatozoon, continued Tail – divided into three parts: Midpiece – thickest part with large mitochondria Make ATP needed for sperm movement Principal piece – most of tail Consists of axoneme (core of the flagellum) and supportive fibers Provides most of the propulsion Endpiece Axoneme only © McGraw Hill, LLC 111  Semen 1 Semen (seminal fluid) Fluid expelled in orgasm 2 to 5 mL Sperm count usually 50 to 120 million/mL Infertility (sterility) – inability to fertilize an egg If less than 20 million sperm/mL © McGraw Hill, LLC 112  Semen 2 Prostate contributes a thin, milky fluid with calcium, a protein- clotting enzyme and serine protease (prostate-specific antigen, PSA) Seminal vesicles secrete a fluid containing: Fructose and other carbohydrates that provide nourishment for the sperm Prostaglandins © McGraw Hill, LLC 113  Semen 3 Contains semenogelin – a fibrinlike protein that entangles sperm and makes semen sticky so it doesn’t drain out of the vagina 30 minutes after ejaculation, the serine protease breaks down semenogelin and liquefies semen Sperm then become very active; fuel is supplied by fructose in semen © McGraw Hill, LLC 114  Oogenesis and the Ovarian-Menstrual Cycle Women have two monthly cycles controlled by shifting patterns of hormones: Ovarian cycle (events in the ovary) Oogenesis – production of eggs Folliculogenesis – the parallel developments in follicles Menstrual cycle (events in the uterus) © McGraw Hill, LLC 115  Oogenesis 1 Produces one haploid gamete per month by meiosis Stages of oogenesis: Stem cells called oogonia (sing., oogonium) multiply by mitosis in the ovaries of a female fetus Oogonia transform into primary oocytes, which proceed to early meiosis I and stay there until puberty No oogonia remain after birth © McGraw Hill, LLC 116  Oogenesis and Corresponding Development of the Follicle 1–2: © Ed Reschke; 3: © Alvin Telser/McGraw-Hill Education; 4: © Ed Reschke/Getty Images; 5: © Petit Format/Science Source; 6: © Alvin Telser/McGraw-Hill Education Access the text alternative for slide images. © McGraw Hill, LLC 117  Oogenesis 2 Oogenesis resumes in adolescence FSH stimulates about two dozen oocytes to complete meiosis I each month Each primary oocyte divides into two haploid cells of unequal size Produces one large daughter cell, a secondary oocyte The smaller one, the first polar body, disintegrates © McGraw Hill, LLC 118  Oogenesis 3 Secondary oocyte proceeds as far as metaphase II, where it arrests until after ovulation If not fertilized, it dies If fertilized, it completes meiosis II and casts off a second polar body © McGraw Hill, LLC 119  Folliculogenesis 1 Stages of folliculogenesis Primordial follicles Consist of a primary oocyte surrounded by a single layer of squamous follicular cells Primary follicles Single layer of cuboidal follicular cells surround the primary oocyte © McGraw Hill, LLC 120 Figure 16.7 Sagittal section of a human ovary showing the developmental stages of an ovarian follicle. Primary follicle Growing follicles Degenerating corpus luteum Blood vessels Antrum Corona radiata Mature vesicular (Graafian) follicle Germinal epithelium Corpus luteum Developing Ruptured Ovulation Secondary oocyte corpus luteum follicle © 2018 Pearson Education, Inc. © McGraw Hill, LLC  Folliculogenesis 2 Stages of folliculogenesis, continued Secondary follicles Follicular cells are now in multiple layers and are called granulosa cells Granulosa cells secrete a layer of gel around the oocyte called the zona pellucida Connective tissue around the follicle is called the theca © McGraw Hill, LLC 122  Folliculogenesis 3 Stages of folliculogenesis, continued Tertiary follicles Contain a fluid-filled cavity called the antrum Theca absorbs cholesterol, converts it to androgens Androgens move into granulosa cells, which convert them to estrogen Mature (graafian) follicles Only one follicle/month becomes a mature follicle; it ovulates while the rest degenerate © McGraw Hill, LLC 123  The Ovarian Cycle 1 Averages 28 days Hypothalamic hormones regulate the pituitary gland; pituitary hormones regulate the ovaries Ovarian hormones regulate the uterus, but also exert feedback control over the hypothalamus and pituitary © McGraw Hill, LLC 124  The Ovarian Cycle 2 Follicular phase (days 1 to 13) FSH causes the growth of a group of follicles As they grow, they secrete an estrogen called estradiol The dominant follicle is selected to ovulate; others degenerate Estradiol and inhibin suppress FSH secretion © McGraw Hill, LLC 125  The Ovarian Cycle Access the text alternative for slide images. © McGraw Hill, LLC 126  The Ovarian Cycle 3 Ovulation (day 14) A sharp spike in LH causes the rupture of a mature follicle and the release of its egg Also induces the completion of meiosis I Oocyte is swept into uterine tube by fimbriae © McGraw Hill, LLC 127  More Ovarian Cycle Luteal (postovulatory) phase (days 15 to 28) LH causes the ruptured follicle to become a corpus luteum, which secretes progesterone and estrogen Prepare the uterus for pregnancy In the absence of pregnancy, it involutes (shrinks) and becomes a corpus albicans (inactive scar tissue) The pituitary is no longer inhibited, so increasing levels of FSH cause new follicles to develop for the next cycle © McGraw Hill, LLC 128  Menstrual Cycle 1 Proliferative phase (days 5 to 14) Uterus rebuilds tissue lost in menstruation After menstruation, only a thin basal layer is present in the endometrium Estrogen stimulates mitosis in the basal layer and blood vessel growth; this forms the functional layer of the endometrium (which is later shed during menstruation) Also stimulates the production of progesterone receptors © McGraw Hill, LLC 129  The Menstrual Cycle Access the text alternative for slide images. © McGraw Hill, LLC 130  Menstrual Cycle 2 Secretory phase (days 15 to 26) Endometrium thickens more, but from secretions vs. from mitosis Progesterone from the corpus luteum stimulates endometrial cells to secrete glycogen © McGraw Hill, LLC 131  Menstrual Cycle 3 Premenstrual phase (days 27 to 28) If no pregnancy, the dying corpus luteum secretes less progesterone; this triggers contractions of the spiral arteries of endometrium Causes tissue necrosis and menstrual cramps Pieces of dying endometrium mix with blood and serous fluid, producing menstrual fluid All of the functional layer is lost; only the basal layer remains © McGraw Hill, LLC 132  Endometrial Changes Through the Menstrual Cycle Access the text alternative for slide images. © McGraw Hill, LLC 133  More Menstrual Cycle Menstrual phase (menses) Accumulated fluid is discharged from the vagina First day = day 1 of the menstrual cycle Lasts about 5 days © McGraw Hill, LLC 134  Uniting the Gametes 1 Blood supply to the genitals Penile artery Branches off the internal iliac artery Enters the root of the penis and divides into the dorsal artery and the deep artery Dorsal artery travels dorsally along the penis Deep artery Travels through the corpus cavernosum and gives off smaller arteries that empty into the lacunae When dilates, the penis becomes erect © McGraw Hill, LLC 135  Uniting the Gametes 2 Blood supply to the genitals, continued Blood drains from the penis through the deep dorsal vein Blood supply to the female clitoris is essentially the same © McGraw Hill, LLC 136  Nerve Supply of the Genitals Dorsal nerves Collect information from penis and clitoris Autonomic and somatic fibers carry signals from the spinal cord to the genitalia Sympathetic fibers from T12 to L2 and parasympathetic fibers from S2 to S4 are involved in an autonomic reflex that causes erection in response to stimulation of genitalia © McGraw Hill, LLC 137  Sexual Response Sexual arousal At the onset of arousal, the genitals swell with blood Increased muscle tension throughout the body Increased heart rate, BP, and respiratory rate Secretion of fluids to provide lubrication for intercourse: From the bulbourethral glands in male, greater vestibular glands in female © McGraw Hill, LLC 138  Erection of the Penis Erection An autonomic reflex via parasympathetic fibers dilate the deep arteries Lacunae near the deep arteries fill with blood and compress the veins that drain the penis Tactile and pressure sensations during intercourse enhance the reflex Clitoris also becomes engorged and erect © McGraw Hill, LLC 139  Orgasm 1 Orgasm (climax) Occurs with discharge of semen in males, vaginal and uterine contraction in females Stages of ejaculation: emission and expulsion Emission Sympathetic nervous system induces peristalsis in the ductus deferens; sperm is propelled from the epididymis to the prostatic urethra Prostate gland and seminal vesicles expel fluid into urethra © McGraw Hill, LLC 140  Orgasm 2 Expulsion Triggered by semen in urethra; involves somatic and sympathetic reflexes Constriction of internal urethral sphincter prevents urine from entering the urethra Bulbospongiosus muscle ensheaths the penis root; compresses the urethra and expels semen © McGraw Hill, LLC 141  Orgasm 3 In female orgasm, the vagina and uterus strongly contract Following orgasm, blood flow is reduced to the penis and clitoris Refractory period in men prevents erection or orgasm for a period of time after orgasm Only occurs in men © McGraw Hill, LLC 142 © McGraw Hill, LLC 143  Pregnancy Pregnancy (gestation) Average of 266 days from conception (fertilization of the egg) to childbirth Measured from the first day of woman’s last menstrual period 280 days after last menstrual period (LMP) Term (duration) described in 3-month intervals called trimesters © McGraw Hill, LLC 144  Effects of Pregnancy on Women 1 Effects on the integumentary system Skin growth to accommodate expansion of abdomen and breasts Tearing of the connective tissue of the dermis results in stretch marks (striae) More melanin in the areolas, so they darken © McGraw Hill, LLC 145  Effects of Pregnancy on Women 2 Effects on the circulatory system Gains 1 to 2 L of blood Pressure on pelvic blood vessels from the growing uterus interferes with venous return Can result in hemorrhoids, varicose veins, and edema of the feet © McGraw Hill, LLC 146  Effects of Pregnancy on Women 3 Effects on the respiratory system Pressure on diaphragm from below makes breathing more labored Effects on the urinary system Urine output slightly elevated Compression of bladder by uterus makes urination more frequent © McGraw Hill, LLC 147  More Effects of Pregnancy on Women Effects on the digestive system Morning sickness Nausea, especially rising from bed in the first few months of gestation Effects on metabolism and nutritional needs Raised metabolic rate stimulates appetite Need extra 300 kcal/day in the last trimester Need supplemental iron, vitamin D, and vitamin K Extra folic acid, if taken prior to pregnancy, reduces risk of spina bifida © McGraw Hill, LLC 148  Childbirth 1 Relatively weak Braxton Hicks contractions occur throughout pregnancy Labor contractions are more powerful Mark the onset of parturition (giving birth) Directly stimulated by oxytocin (OT) and stretching of the uterus Intermittent so uterus can relax to restore blood flow Push the fetus downward © McGraw Hill, LLC 149  Childbirth 2 Positive feedback theory of labor Contractions are induced by stretching of the cervix, which triggers a reflex contraction of the uterus Pushes fetus downward, stretching the cervix more, triggering a reflex through the spinal cord, hypothalamus, pituitary Pituitary gland releases oxytocin, which stimulates uterine muscle to contract Self-amplifying cycle © McGraw Hill, LLC 150  Stages of Labor 1 Dilation stage Dilation (widening) of cervical canal to about 10 cm Effacement (thinning) of cervix Rupture of fetal membranes, discharging amniotic fluid Takes 8 to 24 hours if women primapara (first birth), as little as a few minutes if multipara (later birth) © McGraw Hill, LLC 151  Stages of Childbirth (Figure 19.17) Top: Petit Format/Science Source bottom: © Medicshots/Alamy Stock Photo Access the text alternative for slide images. © McGraw Hill, LLC 152  Stages of Labor 2 Expulsion (second) stage 30 to 60 minutes in primapara, as little as 1 minute in multipara Begins when baby’s head enters vagina, lasts until baby is expelled Delivery of the head is the most difficult part © McGraw Hill, LLC 153  Stages of Labor 3 Placental (third) stage Uterus continues to contact after expulsion Placenta and fetal membranes (afterbirth) are expelled by uterine contractions Can cause excessive bleeding if not completely expelled © McGraw Hill, LLC 154  Postpartum Changes Postpartum (after birth) Shrinkage of uterus (involution) Self-digestion of uterine cells by their own enzymes produces vaginal discharge called lochia Hastened by breast-feeding © McGraw Hill, LLC 155  Lactation Synthesis and ejection of milk from mammary glands Can continue for many years if breast is stimulated © McGraw Hill, LLC 156  Development of the Mammary Glands in Pregnancy Estrogen and other hormones induce growth and branching of ducts of the mammary glands Progesterone stimulates budding and development of acini at the ends of the ducts Acini are organized into clusters called lobules within lobes of the breast © McGraw Hill, LLC 157  Colostrum and Milk Synthesis Colostrum Contains less fat than breast milk Contains antibodies that protect infant © McGraw Hill, LLC 158  Milk Production Prolactin is synthesized early in pregnancy but milk synthesis is inhibited by placental steroids When placenta is discharged, inhibition is removed With feeding, there is a prolactin spike Stimulates milk production for the next feeding If don’t breastfeed, stop lactating within a week © McGraw Hill, LLC 159  Milk Ejection Milk ejection – milk flow into ducts Milk is continually secreted into mammary acini Controlled by a neuroendocrine reflex Suckling stimulates nerves in nipple that signal the hypothalamus and pituitary to release oxytocin Oxytocin stimulates contractile myoepithelial cells around the acini; they squeeze milk down into the ducts and lactiferous sinuses © McGraw Hill, LLC 160  Breast Milk 1.5 L/day produced Places high demand on mother for nutrients Cow’s milk is a poor substitute for colostrum and breast milk © McGraw Hill, LLC 161  End of Main Content Because learning changes everything. ® www.mheducation.com © 2022 McGraw Hill, LLC. 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