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The reproductive system and development Ch. 31,32,33 Warm up • Think about what you already know about the reproductive system and write it on your card. Introduction • Purpose: Carry on the human species • Made of a Series of glands and tubes • Produce and nurture sex cells • Transport sex cells to site of fertilization Organs of the male reproductive • Designed to produce sperm and transport sperm to site of fertilization • Sex organs - gonads • Testes – ovoid structures that produce sperm – Suspended by spermatic cord in scrotum – Structure of testes • 250 lobules per teste, separated by connective tissue • Each lobule holds 1-4 highly coiled seminiferous tubules • Seminiferous tubules lined with epithelium – makes sperm • Sperm stays in seminiferous tubule for 1-3 weeks. – Formation of sperm – Spermatogenesis Spermatgenesis sperm • Sperm cell – head contains haploid nucleus, mid-piece containing mitochondria, tail – flagellum • Tip of head – acrosome – contains enzyme that erode tissues surrounding female egg cell Male internal accessory organs • Epididymis – tightly coiled tube near testis, leads to vas deferens – where sperm mature • Vas deferens – muscular tube leads from epididymis into body cavity • Seminal vesicle-saclike structure near base of bladder – secretes alkaline fluid that enhances sperm mobility and neutralizes female reproductive tract acidity • Cowper’s gland – secretes fructose sugar to nourish sperm • Prostate gland-chestnut shaped structure surrounding urethra – secretes thin fluid-neutralizes acidity • Bulbourethral glands – secretes mucus for lubrication • Semen – combination of sperm cells (120 million per milliliter), secretions from accessory glands Male external reproductive organs • Scrotum-pouch of skin and tissue that holds testes suspended from lower abdomen – keeps testes cooler • Penis – specialized erectile tissue designed to convey urine and semen to outside. Hormonal control of male reproductive function • Hypothalamic and pituitary hormones – Gonadotropin releasing hormone – triggers production of other hormones – Luteinizing hormone – promotes development of interstitial cells in testes which secrete male hormone testosterone – Testosterone is responsible for secondary sex characteristics. – Follicle stimulating hormone – stimulates supporting cells of seminiferous tubules for spermatogenesis Reflection 1. What is the purpose of the reproductive system? 2. Describe sperm. 3. How does sperm swim? 4. What controls the reproductive system? Warm up – 4x6 Check wall for missing work 1. In the male reproductive system, the essential organ is called____ 2. List the accessory organs of the male reproductive system. 3. In males, the urethra is involved in both the ______ and ______ systems. 4. Add to notes: 1. Sperm will stay in the epididymis for 1-3 weeks 2. Cowper’s gland secretes fructose to nourish sperm Female reproductive system introduction • Specialized organs that produce and maintain egg cells – Eggs are the sex cells of the female – Eggs contain half the normal chromosome number - haploid • transport cells to site of fertilization • provide favorable environment for developing fetus • give birth • Produce female sex hormones Organs of the female reproductive system • Primary sex organ – gonad ovaries • Ovaries – solid, ovoid structure in lateral pelvic cavity – Subdivisions – medulla/cortex – Cortex contains follicles Female internal accessory organs • Uterine tubes – oviducts –fallopian tube suspended by ligament – lead to uterus – where pregnancy usually takes place – Funnel shaped open ended portion of oviduct called infundibulum with fimbrae to catch egg – Have cilia which beat, drawing egg into tube • Uterus – upper 2/3, body, dome shaped, – Lower 1/3 cervix, extends into vagina • Uterine wall – endometrium, myometrium, perimetrium • Endometrium is sloughed off during menstruation • Does not serve as a passageway for urine • Vagina – muscular tube – extends from uterus to outside – 3 layers Female reproductive system Female sex hormones • Prenatal – primordial follicles (oocyte surrounded by follicular cells) • The process of egg formation is called oogenesis • Oocytes undergo meiosis but process halts and does not resume until puberty. • At about 10, hypothalamus secretes gonadotropic RH, which stimulates production of Lutenizing hormone and follicle stimulating hormone • At puberty FSH initiates follicle maturation • The LH triggers ovulation • Secreted by ovary – Estrogen – responsible for secondary sex characteristic development at puberty – Progesterone – trigger uterine changes during menstrual cycle Ovulation • Release of oocyte from surface of ovary • Egg will travel down the oviduct to the site of fertilization • Triggered by release of LH at day 14 of reproductive cycle • If not fertilized shortly after release, degenerates and get sloughed off during menstruation – shedding of endometrial lining Hormones and the menstrual cycle Mammary glands Accessory organs • Produce and secrete milk – Prolactin – hormone that triggers milk production – Oxytocin – hormone that causes milk to drop into position • Location - Anterior thorax Reflection 1. The process of egg formation is called _____ 2. What are the layers of the uterus? 3. What is the open part of the oviduct? 4. Where does fertilization take place? Warm up • From what you have learned about the female reproductive system, what are some things that could go wrong anatomically or physiologically when a couple would like to conceive a child? Pregnancy – last lesson of the year!! • Presence of developing offspring in uterus • Transport of Sex Cells – Upper one third of uterine tubes – Thin uterine secretions • Fertilization – Sperm erode corona radiata and zona pellucida - one sperm cell penetrates egg membrane – Changes in egg membrane prevent additional sperm from entering Prenatal Period • Early Embryonic Development – Cleavage – Morula – Blastocyst – Embryo Hormonal changes during pregnancy • Human chorionic gonadotropin – Maintains corpus luteum and uterine lining • Aldosterone – Promotes fluid retention • Parathyroid hormone – Maintains high calcium level Embryonic Stage of Development • • • • Weeks 2-8 Placenta development Internal organ development Facial feature development Week 2 • Embryonic disk development – Germ layers • Ectoderm - nervous system and sensory organs, epidermis, linings of mouth and anal canal • Mesoderm - muscle, bone, marrow, blood, lymphatic vessels, reproductive organs, kidneys, linings of cavities • Endoderm - linings of digestive and respiratory tract, urinary bladder and urethra – Yolk sac development - blood cell formation and stem cells – Week 3 - allontois forms - forms blood cells and becomes umbilical arteries and veins Week 4 • • • • Heart beating Head and jaw Limb buds Gas and nutrient exchange through placenta Trophoblast extensions chorionic villi Week 8 • Amnion develops - amniotic fluid • Umbilical cord • Embryo is 30 millimeters in length and all systems are formed Fetal Stage of development • • • • 8th week Growth Bones begin to ossify 5th month - mother feels movement lanugo and sebum cover skin • Final trimester - brain cells and organs mature • 40 weeks - parturition - birth Fetal circulation Birth process Postnatal Period • Production and secretion of milk – First milk – colostrum – rich in nutrients and antibodies – Milk let down – triggered by Oxytocin Neonatal period of development • • • • • Birth - 4 weeks First breath Surfactant Live off fat Changes in fetal circulation Tubal ligation vasectomy Reflection • Describe the embryonic and fetal stages of development and what happens in each.