Fertilization, Pregnancy, Birth
Fertilization, Pregnancy, Birth BIOL 1014
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This 2 page Class Notes was uploaded by Crystal Florman on Saturday April 9, 2016. The Class Notes belongs to BIOL 1014 at University of Northern Iowa taught by Dr. Kurt Pontasch in Spring 2016. Since its upload, it has received 35 views. For similar materials see Life: Continuity and Change in Biology at University of Northern Iowa.
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Date Created: 04/09/16
Fertilization, Pregnancy, and Birth The egg is only viable for one day and the sperm for two days Limited period in which copulation can result in pregnancy Fertilization usually occurs in the fallopian tubes Fertilized egg- zygote- as it travels down the fallopian tube it divides by mitosis into smaller and smaller cells o Solid ball of cells is formed- morula stage o Soon morula becomes hollow- inside is an inner cell mass- blastula stage o At blastula stage embryo is about six days old and ready for implantation At implantation the embryo undergoes gastrulation- forming the gastrulation stage- inner cell mass differentiates into three layers of cells- the three layers differentiate into various structures o Ectoderm- turns into skin, hair, nails, lenses of the eye, lining of the mouth and nose, and forms the nerves o Mesoderm- turns into muscle, connective tissue including blood and bone o Endoderm- forms the lining of digestive tract, lungs, liver, pancreas, etc. Also at implantation three membranes are formed o Goes around inner cell mass- called amnion- filled with water and surrounds embryo o Chorion- goes around the whole thing and fuses with the third membrane o Allantois- Chorion and amnion fuse with the uterine lining to form the placenta (umbilical cord) Blood vessels are in close contact of those of the mother to get nutrition in, waste out, and gas exchange By the end of 8 weeks the embryo is about an inch long, is able to move and is now called a fetus, and is recognizable as human After 14 weeks- fetus is about 3 inches long most physiological systems have been established- tell the sex After about 9 months- hormonal changes cause contractions of the uterus- the amnion bursts releasing the water o Uterine contractions become stronger- then birth Breach birth- when the baby comes out backwards o If the baby is coming out funky or is too big for the birth canal they perform a caesarean section Contraception and Abortion o Contraception is the prevention of fertilization Coitus interruptus- removal of penis from vagina prior to ejaculation Rhythm method- refrain from sex on the days of the month when the secondary oocyte may be present- need a clinical thermometer Spermicidal foams and jellies- make the vagina more acidic and that kills sperm Birth control pill- progesterone inhibits secretion of FSH and LH from the pituitary- thus preventing follicular growth and ovulation Diaphragm- membranous shield placed over the cervix before intercourse- fitted by doctor- uncomfortable for male Condom- membranous shield placed over the penis before intercourse Sterilization- surgical and usually perminant Male- vasectomy- cuts vas deferens- sperm remain in testies and are reabsorbed- ejaculation is normal, but only seminal fluid is present Females- tubal ligation- cuts and ties the fallopian tubes Abortion- termination of the zygote, embryo, or fetus Sensu lato- termination of zygote o IUD- intrauterine device- plastic devices of various shapes that are placed in the uterus by a doctor- move around in the uterus- prevent implantation of the zygote o Morning after pill- plan B Sensu stirictu- 3 methods o Dilation and curettage o Suction o Injection of saline solution into the uterus that kills the fetus or embryo