BSC 109 1st Edition Lecture 23 Outline of Last Lecture I. Producing concentrated urine: conserving waterII. Urination depends on a reflexIII. Kidneys maintain homeostasisIV. Disorders of the urinary systemChapter 16: Reproduction SystemI. The male reproductive system delivers spermII. Accessory glands help sperm surviveIII. Sperm production requires several cell divisionsIV. Testosterone affects male reproductive capacityV. The female reproductive system produces eggs and supports pregnancyVI. Mammary glands nourish the infantVII. Menstrual cycle consists of ovarian and uterine cyclesVIII. Human sexual response, intercourse, and fertilizationOutline of Current Lecture IX. Fertilization: one sperm penetrates the eggX. Twins may be fraternal or identicalXI. Development: cleavage, morphogenesis, differentiation, and growthXII. Pre-embryonic development: the first two weeksXIII. Embryonic development: weeks three to eightXIV. The placenta and umbilical cordXV. The embryo develops rapidlyXVI. Birth and the early postnatal periodXVII. The transition from fetus to newbornXVIII. Lactation produces milk to nourish the newbornXIX. From birth to adulthoodXX. Death is the final transitionXXI. Birth control methods: controlling fertilityCurrent LectureXXII. Fertilization: one sperm penetrates the eggA. Ejaculate: may contain several hundred million spermB. Sperm may be viable for up to 5 days within the female reproductive tractXXIII. Twins may be fraternal or identicalThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.A. Fraternal twins1. Ovulation of more than one oocyte, each of which is fertilized by differentsperm2. No more similar than two siblings3. May be different gendersB. Identical twins1. One oocyte fertilized2. Split into two pre-embryos before 16-cell stage3. Same gender, look alikeXXIV. Development: cleavage, morphogenesis, differentiation, and growthA. Cleavage1. Series of cell divisions without cell growth2. Produces a ball of identical cells3. Occurs up to about day four after fertilization4. Occurs entirely within the oviductB. Morphogenesis: changes in shape and formC. Differentiation: individual cells take on specialized forms and functionsD. Growth1. Begins significantly at implantation2. Single cell at fertilization to >trillion cells at birth3. Growth in number of cells and size of cells results in increase in overall sizeXXV. Pre-embryonic development: the first two weeksA. Conceptus travels through oviductB. Growth, differentiation, and morphogenesis beginC. Ectopic pregnancy occurs when blastocyst implants in an oviduct prior to reaching the uterusXXVI. Embryonic development: weeks three to eightA. All organs and organ systems established by end of embryonic periodB. Embryonic development: beginning of week three until end of week eightXXVII. The placenta and umbilical cordA. Umbilical cord: two-way life line, connects placenta to embryo’s circulationB. Functions1. Filters nutrients, waste, and antibodies for the fetus without mixing mother and fetal circulations2. Site of nutrient and gas exchange between embryo and mother3. Some toxins or viruses may pass through (alcohol, cocaine, HIV)XXVIII. The embryo develops rapidlyA. Day 151. Embryonic disk elongates along one axis2. Primitive streak appears in embryonic diskB. Days 19-241. Neural tube develops: becomes brain and spinal cord2. Pharyngeal arches develop3. Somites (segments): bone, muscle, skinC. End of week four1. Heart is beginning to develop2. Eye development begins3. Limb buds appearD. Gender development begins at six weeks1. Testes secrete two hormonesa) Testosterone stimulates the further development of male genitaliab) Anti-mullerian hormone suppresses development of female external and internal genitalia2. Absence of Y chromosome results in female developmentE. Months three to four1. Eight weeks: marks the transition from embryonic to fetal development2. Organ development3. Beginnings of organ function (kidneys, liver, spleen)4. Cartilaginous skeleton replaced with bone5. Bone marrow begins producing red blood cells6. Face develops7. Rapid growthF. Months five and six1. Fetal movement begins2. Fetal heartbeat can be heard with stethoscope3. Fetus responds to external sounds4. Lungs produce surfactant- significant for survival outside of mother5. Survival possible outside motherG. End of six months marks end of second trimesterH. Months seven through nine1. Third trimester2. Rapid growth and maturation3. Fetal activity increases4. Fetus prepares for life “on the outside” (lungs and digestive tract ready to function)XXIX. Birth and the early postnatal periodA. Labor initiated by hormones secreted by maturing fetusB. Stages of labor1. Dilation of cervix2. Expulsion of fetus (delivery)3. Afterbirth- expulsion of placentaXXX. The transition from fetus to newbornA. Changes in cardiovascular system1. Umbilical circulation cut off2. Ductus venosus regresses to connective tissue3. Foramen ovale and ductus arteriosus close in days/weeks, cause blood to go through the lungs instead of bypassing them4. All blood from the digestive tract goes to liverXXXI. Lactation produces milk to nourish the newbornA. Endocrine controle of lactiation1. Estrogen and progesterone cause breast enlargement2. Prolactin stimulates milk production3. Oxytocin stimulates smooth muscle contractions that cause ejection of milkB. Colostrum: watery milk produced the first few days after birth, rich in antibodiesXXXII. From birth to adulthoodA. Neonatal period (first month): helpless period- movement by reflex rather than by conscious controlB. Infancy (2 to 15 months)1. Rapid development and maturation of organ systems2. Rapid brain growth, particularly cerebral cortexC. Childhood (16 months to 12 years): continued development and growthD. Adolescence (15 to 20 years): growth spurt, sexual maturationXXXIII. Death is the final transitionA. Failure of critical organ systems leads to rapid death1. Brain2. Respiratory system3. Cardiovascular systemB. Death is a process; defining the moment of death is a challengeC. Legal and medical criteria of death1. Irreversible cessation of circulatory and respiratory functions2. Irreversible cessation of all functions of the entire brain, including the brain stemXXXIV. Birth control methods: controlling fertilityA. Abstinence: not having intercourse, does not always prevent pregnancyB.