Chapter 24 (Reproductive system) PDF

CHAPTER 25 The Reproductive System Human Anatomy Copyright Copyright©©2011 2011Pearson PearsonEducation, Educatio, Inc. Inc. The Male Reproductive System The scrotum – skin and superficial fascia surrounding the testes Positioning provides an environment 3˚ cooler than body temperature Dartos muscle...

CHAPTER 25 The Reproductive System Human Anatomy Copyright Copyright©©2011 2011Pearson PearsonEducation, Educatio, Inc. Inc. The Male Reproductive System The scrotum – skin and superficial fascia surrounding the testes Positioning provides an environment 3˚ cooler than body temperature Dartos muscle – layer of smooth muscle Cremaster muscle – bands of skeletal muscle surrounding the testes Elevates the testes The Male Reproductive System Urinary bladder Prostatic urethra Seminal vesicle Ampulla of ductus deferens Ejaculatory duct Membranous urethra Urogenital diaphragm Corpus cavernosum Corpus spongiosum Spongy urethra Prostate Bulbourethral gland Bulb of penis Ductus (vas) deferens Epididymis Testis Scrotum Glans penis Prepuce External urethral orifice The Scrotum – Containing the Testes and Spermatic Cord Urinary bladder Superficial inguinal ring (end of inguinal canal) Spermatic cord Testicular artery Penis Autonomic nerve fibers Middle septum of scrotum Cremaster muscle External spermatic fascia Superficial fascia dartos Scrotum containing muscle Skin Ductus (vas) deferens Pampiniform venous plexus Epididymis Tunica vaginalis (from peritoneum) Tunica albuginea of testis Internal spermatic fascia The Testes Are enclosed in a serous sac – the tunica vaginalis Tunica albuginea – fibrous capsule of the testes Divides each testis into 250-300 lobules Lobules contain 1-4 coiled seminiferous tubules The Seminiferous Tubules and Spermatogenesis Seminiferous tubules Separated by areolar connective tissue Epithelium consists of Spermatogenic cells – sperm-forming cells Columnar sustentacular cells – support cells Spermatogenesis Cells Spermatogenesis – sperm formation Begins at puberty – 400 million sperm per day Cells differentiate and move toward the lumen Stage 1 – formation of spermatocytes Stage 2 – meiosis Stage 3 – spermiogenesis Spermatids differentiate into spermatozoa Cells Sustentacular cells Surround spermatogenic cells Extend from basal lamina to the lumen Tight junctions between cells Blood-testis barrier Myoid cells – surround seminiferous tubules Interstitial cells (Leydig cells) – secrete testosterone The Epididymis Duct of the epididymis is 6m long (when uncoiled) Dominated by pseudostratified columnar epithelium Bears tufts of stereocilia – immotile, long microvilli 20-day journey for sperm to move through Gain the ability to swim and to fertilize an egg The Epididymis Spermatic cord Blood vessels and nerves Ductus (vas) deferens Head of epididymis Efferent ductule Rete testis Straight tubule Body of epididymis Testis Seminiferous tubule Lobule Septum Tunica albuginea Tunica vaginalis Duct of epididymis Tail of epididymis (a) Cavity of tunica vaginalis The Ductus Deferens The Spermatic Cord Urinary bladder Superficial inguinal ring (end of inguinal canal) Spermatic cord Testicular artery Penis Autonomic nerve fibers Middle septum of scrotum Cremaster muscle External spermatic fascia Superficial fascia dartos Scrotum containing muscle Skin Ductus (vas) deferens Pampiniform venous plexus Epididymis Tunica vaginalis (from peritoneum) Tunica albuginea of testis Internal spermatic fascia The Urethra Accessory Glands The seminal vesicles Lie on the posterior surface of the urinary bladder Secretes about 60% of the volume of semen Fluid contains Fructose to nourish sperm Other substances to enhance fertilization To stimulate uterus contraction Suppress immune response Enhance sperm motility To clot semen and then liquefy for sperm to leave semen Accessory Glands The prostate gland Encircles the prostatic urethra Consists of 20-30 compound tubuloalveolar glands Secretes about 25-30% of seminal fluid Contains substances that enhance sperm motility clot and liquefy semen Accessory Glands Bladder Pubic symphysis Rectum Prostate Anterior Submucosal glands Main glands Connective tissue capsule Fibromuscular stroma Mucosal glands Urethra Accessory Glands The bulbourethral glands Pea-sized glands inferior to the prostate gland Produce a mucus Mucus enters spongy urethra prior to ejaculation Cleanses and lubricates urethra and enhances pH for fertilization The Penis The Female Reproductive System Produces gametes (ova) Prepares to support a developing embryo Undergoes changes according to the menstrual cycle The Female Reproductive System Female Internal Reproductive Organs Uterosacral ligament Perimetrium Posterior fornix Cervix Anterior fornix Vagina Greater vestibular (Bartholin’s) gland Suspensory ligament of ovary Infundibulum Uterine tube Ovary Fimbriae Uterus Round ligament Mons pubis Clitoris Hymen Labium minus Labium majus The Ovaries Small, almond-shaped organs Held in place by ligaments and mesenteries Broad ligament Suspensory ligament Ovarian ligament Ovarian arteries – arterial supply Structure of the Ovary Tunica albuginea Cortex Oocyte Degenerating corpus luteum (corpus albicans) Germinal epithelium Granulosa cells Antral follicle Mesovarium and blood vessels Mature ovarian (Graafian) follicle Antrum Oocyte Primary follicles Ovarian ligament Zona pellucida Theca folliculi Ovulated oocyte Medulla Corpus luteum Developing corpus luteum Corona radiata The Ovarian Cycle The Ovarian Cycle Ovulation – occurs about halfway through each ovarian cycle Oocyte exits from one ovary Enters the peritoneal cavity Is swept into the uterine tube Luteal Phase – occurs after ovulation Remaining follicle becomes a corpus luteum Secretes progesterone Acts to prepare for implantation of an embryo Oogenesis Includes chromosomal reduction division of meiosis Takes many years to complete The Uterine Tubes The Uterus The Uterine Wall Lumen of uterus Lumen of uterus Epithelium Epithelium Capillaries Uterine glands Uterine glands Functional layer of the endometrium Venous sinusoids Lamina propria of connective tissue Lamina propria of connective tissue Spiral (coiled) artery Straight artery Basal layer of the endometrium Portion of the (a) myometrium Endometrial vein Smooth muscle fibers Radial artery Smooth muscle fibers Radial artery Arcuate artery Uterine artery (b) The Uterine Cycle Series of cyclic phases of the endometrium Phases coordinate with the ovarian cycle Endometrial phases directed by FSH and LH Phases of uterine cycle Menstrual phase – days 1-5 Stratum functionalis is shed Proliferative phase – days 6-14 Secretory phase – days 15-28 The Menstrual Cycle Days Plasma hormone level Plasma hormone level Structural and hormonal changes LH FSH Estrogens Progesterone Days 1 1 5 Menstrual phase 10 Proliferative phase 15 20 Secretory phase 25 (a) Fluctuation of gonadotropin levels: Fluctuating levels of pituitary gonadotropins (follicle-stimulating hormone and luteinizing hormone) in the blood regulate the events of the ovarian cycle. 28 5 10 15 20 25 28 Menstrual Proliferative Secretory phase phase phase (c) Fluctuation of ovarian hormone levels: Fluctuating levels of ovarian hormones (estrogens and progesterone) cause the endometrial changes of the uterine cycle. The high estrogen levels are also responsible for the LH/FSH surge in (a). The Menstrual Cycle Blood vessels Endometrial glands Menstrual flow Functional layer Basal layer Days 1 5 Menstrual phase 10 Proliferative phase 15 20 Secretory phase 25 (d) The three phases of the uterine cycle Menstrual: Shedding of the functional layer of the endometrium. Proliferative: Rebuilding of the functional layer of the endometrium. Secretory: Begins immediately after ovulation. Enrichment of the blood supply and glandular secretion of nutrients prepare the endometrium to receive an embryo. Vesicular Corpus Primary follicle follicle luteum Secondary Ovulation Degenerating corpus luteum follicle Follicular phase Days 1 5 Menstrual phase Ovulation (Day 14) 10 Proliferative phase 15 Both the menstrual and proliferative phases occur before ovulation, and together they correspond to the follicular phase of the ovarian cycle. The secretory phase corresponds in time to the luteal phase of the ovarian cycle. Luteal phase 20 Secretory phase 25 (b) Ovarian cycle: Structural changes in the ovarian follicles during the ovarian cycle are correlated with (d) changes in the endometrium of the uterus during the uterine cycle. 28 28 The Vagina The Vagina Peritoneum Uterosacral ligament Perimetrium Rectouterine pouch Rectum Posterior fornix Cervix Anterior fornix Vagina Anus Urogenital diaphragm Greater vestibular (Bartholin’s) gland Suspensory ligament of ovary Infundibulum Uterine tube Ovary Fimbriae Uterus Round ligament Vesicouterine pouch Urinary bladder Pubic symphysis Mons pubis Urethra Clitoris External urethral orifice Hymen Labium minus Labium majus The Mammary Glands Breasts – modified sweat glands Glandular structure – undeveloped in non-pregnant women Milk production – starts after childbirth The Mammary Glands First rib Skin (cut) Pectoralis major muscle Suspensory ligament Adipose tissue Lobe Areola Nipple Opening of lactiferous duct Lactiferous sinus Lactiferous duct Lobule containing alveoli Hypodermis (superficial fascia) Intercostal muscles (a) (b) Pregnancy Events leading to fertilization Sperm binds to the zona pellucida Undergoes the acrosomal reaction Fusion of oocyte and sperm plasma membranes Cortical reaction Enzymes prevent any other sperm from binding to the egg Fertilization – chromosomes of male and female gametes join Events Leading to Fertilization Sperm Corona radiata Zona pellucida First polar body Oocyte in second meiotic division (b) Sperm nucleus Acrosome Acrosomal reaction Granulosa cells of corona radiata Zona pellucida Extracellular space (a) Oocyte plasma membrane Cortical granule Oocyte cytoplasm Cortical Fusion of oocyte reaction and sperm plasma membranes Sperm nucleus engulfed by oocyte cytoplasm Implantation Implantation Formation of the Placenta Decidua basalis Maternal blood Chorionic villus Umbilical blood vessels in umbilical cord Amnion Amniotic cavity Yolk sac Extraembryonic coelom Lumen of uterus Chorion Decidua capsularis (d) 41/2 -week embryo. The decidua capsularis, decidua basalis, are well formed. The chorionic villi lie in blood-filled intervillous spaces within the endometrium. The embryo is now receiving its nutrition via the umbilical vessels that connect it (through the umbilical cord) to the placenta. Anatomy of the Placenta Exchanges across the chorionic villi between maternal and fetal blood Provide fetus with nutrients and oxygen Dispose of its wastes Allow hormonal signals to be sent to the mother By week 13 the placenta is fully formed Anatomy of the Placenta Placenta Chorionic villi Decidua basalis Maternal arteries Maternal veins Myometrium Umbilical cord Decidua capsularis Uterus Lumen of uterus Chorionic villus containing fetal capillaries Maternal blood in lacuna (intervillous space) Fetal arteriole Fetal venule Amnion Umbilical cord Stratum basalis of endometrium Maternal portion of placenta (decidua basalis) Fetal portion of placenta (chorion) Umbilical arteries Umbilical vein Connection to yolk sac Anatomy of the Placenta Placental barrier consists of All three layer of the chorionic villi Sugars, fats, and oxygen diffuse from mother to fetus Urea and carbon dioxide diffuse from fetus to mother Syncytiotrophoblast – secretes substances that regulate events of pregnancy Suppress mother’s T lymphocytes Hormones Childbirth Parturition—266 days after fertilization Labor—events that expel the infant from the uterus Umbilical cord Placenta Uterus Pubic symphysis Cervix Vagina (a) Dilation (early) Sacrum (b) Dilation (late) Figure 25.27a, b Childbirth Perineum (c) Expulsion Uterus Placenta (detaching) Umbilical cord (d) Placental Figure 25.27c, d Reproductive System Cancers in Males Testicular cancer Affects 1 of 50,000 males Commonly from early-stage spermatogenic cells Increase of 50% from 1974 – 1990 Cured in 95% of cases Reproductive System Cancers in Males Prostate cancer Slow-growing – arises from peripheral glands Risk factors Fatty diet Genetic predisposition Reproductive System Cancers in Females Ovarian cancer arises from cells in the germinal epithelium Endometrial cancer arises from the endometrium of the uterus Cervical cancer slow-growing, arises from epithelium at the tip of the cervix Reproductive System Cancers in Females Breast cancer Second most common cause of cancer deaths in women 97% occurs in women over 50 Treatment Surgical removal of the mass (lumpectomy) Radiation therapy Administration of selected hormones Chemotherapy Menopause Female reproductive peak – late 20s Around age 35 – rate of follicle degeneration increases Ovulation and menstruation cease – age 46-54 Ovaries stop secreting estrogen Reproductive organs and breasts begin to atrophy