Sexual Reproductive System PDF

Sexual reproduction produces new individuals – Gametes (sperm & egg) formed by testes and ovaries – Fertilization produces one cell (a zygote)with one set of chromosomes from each parent – Creates genetic variation Gonads produce gametes & secrete sex hormones Reproductive systems –...

Sexual reproduction produces new individuals – Gametes (sperm & egg) formed by testes and ovaries – Fertilization produces one cell (a zygote)with one set of chromosomes from each parent – Creates genetic variation Gonads produce gametes & secrete sex hormones Reproductive systems – Gonads, ducts, glands & supporting structures – Gynecology is study of female reproductive system – Urology is study of urinary & male reproductive system  Male Reproductive System Seminal vesicle-semen Ductus deferens-sperm Prostate-semen duct Urethra-urine Penis Epididymis-sperm maturation Scrotum-cools testis Testis-sperm formation Gonads, ducts, sex glands & supporting structures  Scrotum Sac of loose skin, fascia & smooth muscle divided into two pouches by a septum Temperature regulation of testes – Sperm survival requires 2-3 degrees lower temperature than core body temperature – Muscle in scrotum Elevates testes on exposure to cold & during arousal Warmth reverses the process Testes Paired oval glands measuring 2 in. By 1in. Surrounded by dense white capsule – Septa form 200 - 300 compartments called Septum lobules Each is filled with 2 or 3 Lobule seminiferous tubules where sperm are formed Seminiferous tubule Capsule  Seminiferous Tubules Seminiferous tubules contain – Sperm forming cells – Sertoli cells (supporting cells) Interstitial cells in between tubules secrete testosterone  Sperm Morphology Adapted for reaching and fertilizing the egg Head contains DNA and the acrosome with enzymes for penetrating the egg Midpiece contains mitochondria to form ATP for energy Tail is flagellum used for locomotion  Hormonal Control of Male Physiology Hypothalamus Hypothalamus secretes gonadotropin releasing GnRh hormone (GnRH) Anterior pituitary secretes Anterior Pituitary FSH and LH Follicle Stimulating Luteinizing FSH causes Sertoli cells to Hormone Hormone secrete ABP and inhibin LH causes interstitial cells to Sertoli Cells Interstitial Cells secrete testosterone ABP and testosterone Androgen Binding Testosterone Protein stimulate spermatogenesis Spermatogenesis Control is Negative FB by testosterone and inhibin  Male Glands Prostate Secretes 30% of milky, slightly acidic seminal Seminal Vesicles fluid with an Secrete 60% of clear, antibiotic to kill alkaline seminal fluid, with bacteria fructose sugar, ATP and prostaglandins for normal Cowper’s Glands sperm nutrition & function Secrete clear, alkaline Chemicals for coagulation mucus to buffer and of semen lubricate urethra  Semen Mixture of sperms and seminal fluid 60% from seminal vesicles, 30% from prostate Slightly alkaline, milky appearance and sticky Contains nutrients, clotting proteins & an antibiotic to protect the sperms Typical ejaculate is 2.5 to 5 ml in volume Normal sperm count is 50 to 150 millions/mL – Actions of many sperm are needed for one to enter – If less than 20 millions/mL sterile  Erection Sexual stimulation Parasympathetic nervous system reflex Dilation of the arterioles supplying the penis Blood enters the penis compressing the veins so that the blood is trapped Blood sinuses of penis engorge with blood Erection  Emission and Ejaculation Emission – Muscle contractions close sphincter at base of bladder – Fluids propelled through ductus deferens, seminal vesicles, & ejaculatory ducts into bulb of penis – Prostatic fluid secreted into urethra Ejaculation – Sympathetic nervous system reflex – Skeletal muscles squeeze semen out through urethra  Female Reproductive System Ovaries produce eggs (oöcytes) & hormones Uterine tubes transport the eggs Uterine Tube Uterus where fetal development occurs Ovary Vagina or birth canal Uterus External genitalia constitute the vulva Vagina Mammary glands produce milk Vulva  Ovarian Follicles Ovarian Follicles – Contain oöcytes (egg cells) in various stages of development – Secrete estrogens that function for:- Growth and repair of uterine lining Regulation of monthly female cycle Female sexual characteristics Maintenance of bone and muscle – Mature (Graafian) follicle releases an oöcyte each month during ovulation  Ovarian Follicles Oöcytes (egg cells) develop within follicles Stages of follicular development – Primordial follicle Single layer of squamous cells around the oöcyte – Primary follicle Layers of cuboidal granulosa cells around the oöcyte Granulosa cells secrete estrogens  Ovarian Follicles – Secondary follicle Antral cavity forms – Graafian follicle Follicle mature ready to ovulate oöcyte – Ovulation Follicle ruptures releasing oöcyte  Corpus Luteum After ovulation, empty follicle becomes a corpus luteum – Corpus Luteum secretes:- Progesterone – completes the preparation of uterine lining Estrogens – work with progesterone Relaxin – relaxes uterine muscles and pubic symphysis Inhibin – decreases secretion of FSH and LH Corpus albicans is a white scar tissue left after the corpus luteum dies.  Oögenesis – Oögonia to Oöcytes Germ cells from yolk sac migrate to ovary and become potential egg cells called oögonia In fetus, millions of oögonia produced by mitosis but most of them degenerate (atresia) Some develop into immature egg cells called primary oöcytes during fetal development – 200,000 to 2 millions present at birth – 40,000 remain at puberty but only 400 mature during a woman’s reproductive life Each month about 20 primary oöcytes become secondary oöcytes but usually only one survives to be ovulated from Graffian follicle Uterine or Fallopian Tubes Narrow, 4 inch tube that extends from the ovary to uterus – Infundibulum is open, funnel-shaped portion near the ovary – Fimbriae are moving finger-like processes – Ampulla is central region of tube – Isthmus is narrowest portion joins uterus  Uterine or Fallopian Tube Functions -- events occurring in the uterine tube – fimbriae sweep oöcyte into tube – Cilia and peristalsis move it along – Sperm reaches oöcyte in ampulla – Fertilization occurs within 24 hours after ovulation – Zygote reaches uterus about 7 days after ovulation  Anatomy of the Uterus Site of menstruation & development of fetus Description – 3 inches long by 2 in. Wide and 1 in. Thick – Subdivided into fundus, body & cervix – Interiorly contains uterine cavity accessed by cervical canal  Vagina Passageway for birth, menstrual flow and intercourse Description – 4 inch long fibromuscular organ ending at cervix – Lies between urinary bladder and rectum – Orifice partially closed with membrane (hymen)  Mammary Glands Modified sweat glands that produce milk (lactation) – Amount of adipose tissue determines size of breast – Milk-secreting mammary glands alveoli open by lactiferous ducts at the nipple – Areola is pigmented area around nipple – Suspensory (Cooper’s) ligaments suspend breast from deep fascia of pectoral muscles  Physiology of the Breast Milk production and secretion – Estrogens develop the ducts system in the breasts – Progestrone develop the milk-secreting glands which are called alveoli – Prolactin stimulate milk synthesis in the alveoli – Oxytocin stimulate milk ejection from the alveoli Physiology of Mammary Glands Continued Milk ejection (release from glands) – Nursing stimulates the hypothalamus to produce oxytocin – Oxytocin secreted from the posterior pituitary – Oxytocin causes smooth muscles around alveoli to contract and squeeze milk into lactiferous ducts, lactiferous sinuses and into the nipple – Operated by positive feedback  Female Reproductive Cycle Controlled by monthly hormonal cycle from the hypothalamus, anterior pituitary and ovary Monthly cycle of changes in ovary and uterus Ovarian cycle – Changes in ovary during and after maturation of the follicle and oocyte Uterine cycle (menstrual cycle) – Preparation of the uterus to receive fertilized ovum – If implantation does not occur, the functional layer of endometrium is shed during menstruation Hormonal Regulation of Reproductive Cycle Gonadotropin Releasing Hormone (GnRH), secreted by the hypothalamus, controls the female reproductive cycle – Stimulates anterior pituitary to secrete Follicle Stimulating Hormone (FSH) & Luteinizing Hormone (LH) FSH & LH target the ovaries and drive the ovarian cycle (monthly changes in the ovary) Estrogens and progesterone from the ovaries drive the uterine cycle (monthly changes in the uterus)  Phases of Ovarian Cycle Follicular Phase FSH from anterior pituitary stimulates follicle growth Follicles grow into Graafian (mature) follicle Granulosa cells of follicle secrete estrogens and inhibin Increasing levels of estrogens and inhibin inhibit FSH Increasing estrogens also stimulates secretion of LH Ovulation LH stimulates rupture of the Graafian follicle and release of oöcyte from ovary into the pelvic cavity Fimbriae of Fallopian tube picks up the ovulated oöcyte  Phase of Ovarian Cycle Luteal phase (postovulatory phase) – LH stimulates development of Corpus luteum from ovulated or ruptured follicle – Corpus luteum secretes mostly progesterone & some estrogens – Progesterone prepares endometrium for possible pregnancy Follicular Phase Ovulation Luteal Phase  Phases of Uterine Cycle Proliferative phase – Rising estrogen levels from the growing follicle stimulates growth of the functional layer of endometrium to 4-10 mm thickness Secretory phase – Corpus luteum of ovary secretes progesterone – Progesterone stimulates Increased thickening of the functional layer of endometrium to 12-18 mm Increased blood supply into the endometrium Growth of endometrial glands and secretion of uterine milk  Phase of Uterine Cycle Menstruation phase (menses) – Decline in progesterone levels causes functional layer of endometrium to discharge resulting in vaginal bleeding called menstruation – Mark the beginning of the next cycle Summary of Ovarian and Menstrual Cycles