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The Reproductive System Reproduction Primary function: to produce offspring genetic material passed from generation to generation Sharing intimate feelings with another person Some terms to know Gonads: the organs in the body that produce the sex cells (GAMETES) Male = testes --> Sperm Female = ovaries --> Ova or Egg cells Ducts: transport and secrete Glands: secrete Testes Paired organs located inside the scrotum Located outside the body to ensure proper temp for sperm production Function of the testes Produce and mature sperm maturation of sperm takes approximately 74 days Protect sperm and sperm development-Sertoli cells Produce testosterone: Leydig cells Functions of Testosterone the principle male hormone produced by Cells of Leydig responsible for the male secondary sexual characteristics: growth and development maintenance of sex organs bone growth influences sexual behavior influences final maturation of sperm cells Seminiferous Tubules tightly coiled tubules in testes Spermatogenesis occurs Spermatogonia = immature Sperm Cell Spermatozoa = mature Sperm Cell Interstitial Cells (Cells of Leydig) = endocrine cells produce and secrete testosterone Epididymis • • • • 7 m long Head - superior, receives spermatozoa Body Tail - leads to ductus deferens Epididymis • • Functions: 1) Monitors and adjusts tubular fluid • 2) Recycles damaged spermatozoa • 3) Stores sperm and facilitates maturation Ductus (Vas) Deferens long duct (18 inches) passageway for sperm from epididymis to urethra enters the body through the pelvic floor called the Inguinal Canal Ejaculatory Ducts union of seminal vesicles and the ductus (vas)deferens eject sperm into the prostatic urethra prior to ejaculation Urethra passageway for sperm and urine to the external environment measures about 8 inches in length 4 sections of the Urethra Urethra 1. prostatic 1 urethra 2. Membranous 2 urethra 3 3. spongy urethra Urethra 4 4. external urethral orifice Accessory Male Sex Glands secrete most of the liquid portion of Semen provides a liquid, nutrious medium for the support of sperm cells Seminal Vesicles Paired, on posterior wall of urinary bladder Tubular (~ 15 cm) Produce 60% of semen, hormones, fructose, etc. Activate sperm (leading to motility) Prostate Gland about the size of a chestnut located inferior to the urinary bladder - surrounds the urethra secretes a fluid rich in citric acid, prostatic acid, phosphatase, and prostaglandins makes up about 13% of the semen often site of cancerous growth in males Bulbourethral Glands (Cowper’s Glands) • Pea size, paired, at base of penis • Produce about 10% of semen • Alkaline mucus neutralize acidic nature of female vagina Semen (Seminal Fluid) mixture of sperm and secretions of accessory glands 2.5 - 5.0 ml of semen per ejaculation (1/2 tsp) 300-500 million sperm per ejaculation if less than 100 million sperm-- male is considered infertile MALE: EXTERNAL GENITALIA SCROTUM supports and protects testes continuation of abdominal wall skin Separated by a structure called the raphe SCROTUM Cremaster muscle Dartos muscle in dermis Cremaster muscle - continuous with abdominal wall muscles Involuntary contraction in response to TEMP changes Temp must be 2-3o Lower than body temp Penis used to introduce sperm into the female vagina during intercourse Voids urine (urination) cylindrical in shape Three parts of penis Body : 3 cylindrical masses of tissue Corpora Cavernosa Penis ( 2) Corpus Spongiosum Penis Made of erectile tissue filled with blood sinuses Penis (cont) Root--portion attached to pubic area Bulb--attached to abdominal wall Crus--Attached to muscles that aid in erection Glans penis Slightly enlarged portion of the corpus spongiosum Separated from body by corona Contains many nerve endings Uncircumcised glans contains prepuce or foreskin Penis erection With sexual stimulation, arteries dilate, veins constrict, large quantities of blood enter sinuses and an erection occurs Erections occur also to maintain health of penis End of male REPRODUCTIVE System QUESTIONS? FEMALE REPRODUCTIVE SYSTEM Ovaries the female gonads oogenesis occurs females are born with all egg cells as they will ever have (500,000) Oogenesis Maturing of an oocyte (egg) Begins with primary follicles, ends with secondary ooctye other primary follicles donate material to developing egg Ovarian follicles each month about 20 primary oocytes are stimulated to undergo meiosis usually only one of these 20 completes the process of oogenesis & develops into a secondary oocyte Graffian Follicle Oocyte continues to mature before released by ovary during ovulation Contains two parts Antrum and oocyte Secretes estrogen Ovulation Process where secondary oocyte is released from ovary About day 14 of cycle Corpus Luteum and Corpus Albicans Glandular body that develops after release of egg Secretes progesterone, estrogen, relaxin, inhibin Becomes corpus albicans if egg is NOT fertilized Stays in tact during pregnancy Uterine (Fallopian) Tubes ducts transport ova from site of ovulation to uterus Infundibulum = funnel shaped, open distal end – Fimbriae = “little fingers” on distal end Uterine (Fallopian) Tubes Ampulla = widest, longest portion of the uterine tubes – fertilization usually occurs in this region Isthmus = narrow, constricted, proximal end where the tubes attach to the uterus Uterus serves as the site of menstruation, implantation of a fertilized ovum, and development and maintenance of fetus during pregnancy inverted pear shaped muscular organ has 3 sections or areas – Fundus – Body – Cervix Tissue Layers of the Uterus 3 tissue layers Perimetrium = outermost layer Myometrium = middle, muscular layer – majority of the uterus – consists of three layers of smooth muscle Endometrium = innermost layer of the uterus Made of stratum functionalis and stratum basalis Vagina tubular fibromuscular organ lined with mucous membrane passageway for sperm & menstrual flow receptacle for penis during sexual intercourse lower portion of birth canal FEMALE: EXTERNAL GENITALIA Female External Genitalia Vulva = term used to describe female external genitalia Mons Pubis = adipose tissue above the pubic symphysis, covered by skin and coarse pubic hair Labia Majora = an area of longitudinal folds of tissue Labia Minora = medial longitudinal folds of tissue Female External Genitalia (cont) Vestibule: the space between the Labia Minora Bulb of vestibule contain: Greater Vestibular Glands (Bartholin’s) produce mucoid substance Provide lubrication for sexual intercourse Female External Genitalia (cont) Clitoris: small cylyndrical mass of nervous and erectile tissue Prepuce: layer of skin from labia minora covers clitoris Hymen: thin membrane partially covering the vagina Mammary Glands (Breasts) modified sudoriferous glands (Sweat Glands) each gland contains 15 - 20 lobes or compartments separated by adipose tissue amount of adipose tissue between lobes determines breast size breast size is not related to milk production Mammary Glands (Breasts) each lobe has compartments called lobules Inside lobules are milk secreting cells Nipple = the raised area on the breast that an infant suckles to receive milk and stimulate lactation Areola = the dark, circular, pigmented area that encircles the nipple Lactation the process of milk production, secretion, and ejection Menstrual and Ovarian Cycles Ovarian Cycle = maturation and ovulation of an ovum Menstrual Cycle = changes of the endometrial lining of the uterus – preparation for implantation of a fertilized ovum correlated with each other and are under the influence of hormones Endocrine influence Hypothalamus stimulates pituitary FSH and LH FSH : ovarian follicles LH: ovulation-stimulates production of estrogen, progesterone and relaxin Ovaries produce estrogen and progesterone Estrogen 6 different types development and maintenance of the female reproductive system helps control fluid and electrolyte balance Keeps heart strong Keeps bones strong Progesterone hormone of maturation prepares the endometrial lining for implantation stimulates milk production and secretion Drop in progesterone starts menstrual cycle Relaxin and Inhibin Relaxin = produced by the corpus luteum during pregnancy Relaxin = most prominent during the final trimester of pregnancy relaxes the pubic symphysis and helps dilate the cervix Inhibin = is the negative feedback hormone for estrogen and progesterone DEVELOPMENT and INHERITANCE HUMAN DEVLOPMENT The continuous process of body changes Begins at fertilization Continues until death Two periods Prenatal: Conception until birth Postnatal: birth until death Spermatogenesis vs. Oogenesis Spermatogenesis: production & maturation of sperm Oogenesis: production & maturation of egg Prenatal Development changes that occur prior to Birth Divided into Two Periods The Embryonic Period – fertilization until eight weeks The Fetal Period – eight weeks until birth Fertilization also called “Conception” union of sperm & oocyte one sperm cell penetrates layers of the egg aided by enzyme on head of sperm oocyte cell membrane changes biochemically The Embryonic Period first 8 weeks of life fertilized egg called Zygote first cell divisions of Zygote are called: CLEAVAGE --result in ball of cells called Morula Morula turns into a large mass of cells called Blastocyst Blastocyst Stages of Development Implantation = attachment of the Blastocyst to the endometrium about 6 days after fertilization Blastocyst differentiates into primary Germ Layers (Endoderm, Mesoderm, Ectoderm) Trophoblast Development and Implantation Becomes Trophoblast-layers form (Chorion, Amnion, and Yolk Sac) begin to form around the embryo Called pregnancy when implanted Embryonic Period 5 weeks after conception Bones begin to form, major blood vessels form other systems form Heart forms & starts to beat Nervous system forms Embryonic Development Development of Body Form – weeks three to eight – the embryo resembles a human like figure Development of Organs – most major organs appear during the first eight weeks of development Embryonic Period 8 weeks Resembles a human and is called a FETUS—Latin word for OFFSPRING Fetal Development 18 weeks Face looks human Joints form Bones ossify Rapid development of body organs Fetal Development Can recognize sounds Urine forms Fetal Development 18 weeks Rapid development of body organs Fetal Development • • • • 20 weeks Lanugo appearsprotects fetus from waste in amniotic fluid Fetal movements felt by mother Hair appears on head Fetal Development 20 weeks Fetal Development 24 weeks Sense of taste develops, lungs are ready to produce surfactant Substantial weight gain Eyelids separate Eyelashs form Can survive outside womb (viable) Fetal Development 30 weeks Head and body more proportionate In male, testes descend Fetus assumes upside down position Subcutaneous fat deposited Fetal Development 40 weeks Additional subcutaneous fat accumulates Lungs secrete oxytocin Lanugo is shed Fetus is full term Is ready at 38 weeks Fetal Development Labor movement of the fetus through birth canal in response to uterine contractions Three Stages of Labor Stage One = dilation & effacement contractions push fetus against cervix amniotic sac ruptures cervix dilates Once cervix dilates to 10 cm Stage Two begins Fetal Development Stage Two = delivery and birth Stage Three = expulsion of the placenta Stages of Physical Development Neonate - “newborn” Infancy Toddlerhood Childhood Adolescence – puberty Adulthood Middle Age Advanced Age