CHAPTER 19 PRENATAL DEVELOPMENT AND BIRTH LESSON 1
CHAPTER 19 PRENATAL DEVELOPMENT AND BIRTH LESSON 1 -THE BEGINNING OF THE LIFE CYCLE ØIn this Chapter we will discuss events from fertilization to birth ØDescribe Prenatal care ØIndentify Prenatal risks
PRENATAL DEVELOPMENT We begin life from a single cell During the 9 -month period, the cell will divide millions of times It will form tissues, organs, body systems, & characteristics of the person it will become
CONCEPTION AND IMPLANTATION Fertilization: ü ü Union of egg cell(female) and the sperm cell (male) Also known as conception Zygote: Fertilized egg cell ü Takes about 4 days to reach the uterus Once formed, a protective membrane surrounds it to prevent more sperm from entering the ovum Divides many times (mitosis-cell division) to form a cluster of cells with a hollow space in the middle After 5 days, the zygote reaches the uterus & is called Blastocyst ü ü ü Implantation: the zygote attaches to the uterine wall ü Takes about 10 days to implant The endometrium tissue protects & nourish the egg ü
A CLOSER LOOK!
EMBRYONIC GROWTH Embryo: A cluster of cells following implantation ü Called an embryo for about 8 weeks 3 layers of tissue formed as cell continues dividing: Respiratory & digestive system Muscles, bones, blood vessels, & skin Nervous system, sense organs, mouth ü ü ü
EMBRYONIC STAGES
EMBRYONIC GROWTH Amniotic Sac: Thin membrane formed to surround the developing embryo Amniotic Fluid: Fluid in the amniotic sac Acts as a shock absorber Insulates from temperature changes Allows fetal movement Permits proper lung development Constantly circulated by the baby swallowing & inhaling existing fluid & replacing it through exhalation & urination. ü ü ü
EMBRYONIC GROWTH ü ü Placenta: Provides nutrition, excretion, & immunity Blood rich tissue made by embryonic cells & the tissue from the mother Umbilical Cord: Tube which nutrients & oxygen pass from the mother’s blood to the embryo Carries waste products from embryo to diffuse into the mother’s blood
FETAL DEVELOPMENT Conception to birth is usually about 9 months Divided into (3) 3 -month periods called Trimesters First Trimester: 0 -14 weeks Second Trimester: 15 -28 weeks Third Trimester: 29 weeks to birth Let’s look at pages 488 -489 to see what’s going on in these stages of fetal development!
STAGES OF BIRTH The last few weeks of pregnancy, the baby’s head moves to the lower part of the uterus 95% of the time it rests on the cervix Dilation: ü Cervix stretches because of mild contractions (Labor) Contractions break the amniotic sac (water breaks) Cervix dilated about 3 cm Contractions are about 5 -20 minutes apart ü ü ü
STAGES OF BIRTH ü ü ü q ü ü Birth: Contractions are 1 -3 minutes apart (active labor) Cervix 8 to 10 cm Stage lasts minutes to hours Baby passes through the birth canal Cries to clear lungs and amniotic fluid Umbilical cord cut Apgar Test: Routine diagnostic test to determine the physical condition of the baby Appearance Reflex Activity Pulse and respiration
AFTERBIRTH CONTRACTIONS CONTINUE TO PUSH OUT THE PLACENTA 15 -30 MINUTES LATER Umbilical Cord Placenta
HOW ARE TWINS BORN? Identical Fraternal Single egg fertilized by single sperm that divides to form 2 embryos Ovaries release 2 eggs Separate sperm fertilize each egg Same genetic info Different genetic makeup Same gender May or may not be the same gender
1 OUT OF 87 BIRTHS RESULT IN TWINS (1/3 BEING IDENTICAL) 1 OUT OF 7570 ARE TRIPLETS 1 OUT OF 658, 00 ARE QUADRUPLETS 1 OUT OF 57, 290, 000 AREQUINTUPLETS 1 IN 50, 000 ARE BORN CONJOINED
PAIN RELIEF DURING PREGNANCY ü ü ü Anesthetic: Local-numbs the vagina Regional-eases the pain of contractions Spinal: Injection into the spine (works immediately) ü Epidural: Tube inserted into the back for medicine to be released throughout labor General: Puts patient to sleep (used mainly in C-sections) Birthing Tube: ü ü Warm soak Reduces anxiety Lamaze: Used since the 1950’s ü Started mainly with breathing exercises Goal is to increase the mother’s confidence in their ability to give birth ü ü Promotes deep relaxation Relieves pain
COMPLICATIONS DURING PREGNANCY Miscarriage: ü Spontaneous expulsion of the fetus before the 20 th week Still Birth: ü Death of a fetus after week 20 of pregnancy Ectopic Pregnancy: ü ü Zygote implants in the fallopian tube, abdomen, ovary, or cervix Egg cannot get to the uterus because of inflammation or scar tissue resulting from a STD Stone baby Preclampsia: Toxemia prevents the placenta from getting ü High Blood pressure and high protein in the urine Bed rest, meds, or hospitilization ü ü enough blood
PROBLEMS WITH PREGNANCIES Ectopic pregnancy Breech position
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