Prenatal Development Notes PDF

Quiz will be averaged out as many people were unable to complete it. Prenatal Development Egg cell is 85000 times the size of a single sperm Sperm releases an enzyme that makes the egg penetrable and once one has entered the egg becomes impenetrable so no more can get in The egg and sperm fuse i...

Quiz will be averaged out as many people were unable to complete it. Prenatal Development Egg cell is 85000 times the size of a single sperm Sperm releases an enzyme that makes the egg penetrable and once one has entered the egg becomes impenetrable so no more can get in The egg and sperm fuse into a single cell The germinal period -- starts when ovum is released into the fallopian tube, fertilization of the egg by the sperm usually happens within 24 hr -- fertilized in fallopian tube -- at 36 hr the cells begin to divide -- the cell is travelling down the fallopian tube toward the uterus -- in about 2 days the zygote (fertilized egg) has travelled down the fallopian tube -- Blastocyst is a cluster of divided cells made by the fertilized egg -- implants to side of uterus -- the side of uterus is tissue and blood and full of nutrients and during period that is what is expelled -a zygote is a fertilized egg with 100 cells and becomes increasingly diverse -- at about 14 days turns into embryo -fewer than half of all fertilized eggs make it through two weeks, after about 10 days the zygote implants and the inside cells become embryo -the amniotic sac surrounds the developing embryo to protect against -the chorion develops into the placenta -placenta is an organ -- formed from the lining of the uterus and chorion and provides respiration, nourishment and removal of waste -umbilical cord is a soft tube containing blood vessels connecting embryo to placenta Period of the embryo -- 3-8 weeks growth of the head takes precedence over growth of the body -- central axis coincides with the spinal cord -- 3 cell layers develop rapidly (ectoderm become nervous system, skin, hair, nails, teeth, outer layer of skin, hair) 2 ridges appear and close up and wrap around the developing nerves spina bifida is where it hasn't closed properly) nm becomes muscles bones and circulatory system and excretory systema and reproductive organs, Endoderm - digestive system, lungs, urinary tract and other vital organs -in the second month the ears are formed, around end of month limb buds form, brain begins to develop, upper arm and legs develop first but by the second month the limbs are elongated and separated -- webbing of the fingers is gone -- facial features become distinct and its only about an inch long but brain is starting to fire, kidneys are functioning and red blood cells are being developed, gonads begin to appear but male or female distinguishing factors don't appear until about 7 weeks Fetus -- 9 weeks -- last 7 months of pregnancy -- everything has been formed and now growing and developing -- in third 3 fetus begins to kick, turn and tumble but rarely felt, digestive and excretory systems are working together, can swallow and excrete -- testosterone is present and results in male genitalia and about 3 " long -- 2^nd^ trimester 4-6 month fetus is 7-8" 20-25 cm and weighs about 8 oz -- more refined motor actions and kicking may be strong enough to be felt by mother -- heart beat can be heard with stethoscope and at this point mothers feel reassured -- skeleton is hardening and can be seen on ultrasound, eyebrows, eyelashes and head hair develops and fetus is covered with vernix which is white and cheesy and lanugo which are fine hairs that fall away -- 3^rd^ trimester -- organ system is mature, weight gain continues, age of viability outside of the body begins between 22 and 28 weeks, people born in that time period may develop delays of deficiencies -- baby is moving kicking and thumb sucking -- moves to head down position in 9^th^ month, tones uterine muscles, cervix starts to widen and head positions into the pelvic bone gap -- vernix is there because they are in a water filled chamber and it protects the skin During this time there are environmental influences that can impact the development of the fetus -- Teratogens -- agents like drugs, chemicals, viruses, radiation that can harm the fetus however 95% of fetuses are born without issue -- the higher does and more exposure can impact and each organ has a time period of development that is most sensitive Maternal characteristics -- nutrition, emotional well-being, age Effects of Teratogens -- each developing structure is most susceptible to damage during sensitive period and rapid growth period Maternal Disease -- Rubella -- most dangerous in 1^st^ trimester and 60-85% of babies whose mothers had rubella in 1^st^ trimester have birth defects -- blindness, deafness, cardiac abnormalities, mental issues, liver and spleen damage -- Toxoplasmosis -- a parasite in cat feces or uncooked meat -- Thalidomide -- used for morning sickness, hyperemesis is hyper vomiting, had been tested on rats with no side effects, Canada banned the drug in early 60s many babies were born with deformed ears, eyes, hearts and a condition where hands or feet were attached to body(like flippers), parts of limbs were missing but some had no side effects Drugs FAS -- fetal alcohol syndrome -caused by heavy drinking - small head, thin upper lip, flat philtrum (above lip), small eye openings, underbite look, cardiovascular disorders, shortened eyelids, flattened nose FAE -- fetal alcohol effects Cigarette smoking -- affects size, low birth weight, higher risk of post-natal death, may have cognitive deficits \*\*\*this day is on test and lots of this info is not in the book Childbirth Stage 1 -Dilation state -- cervix thins and opens (dilates) to approx. 10 cm Stage 2 -- uterus begins to contract and gets ready to push the baby out, along with mother pushing the baby is expelled Stage 3 -- delivery of the placenta -- can take up to an hour or even longer Infancy and Childhood Physical Development 3-6 months rapid development Neurons from newborn to 15-month growth is significant