olds’ maternal-newborn nursing & women’s health across the lifespan, ninth edition michele...

Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth EditionMichele Davidson • Marcia London • Patricia Ladewig

CONCEPTION AND BIOPHYSICAL CHANGES


THE PROCESS OF FERTILIZATION

Sperm and ovum unite to form a zygote

Ova are fertile for 12 to 24 hours

Sperm are fertile for 72 hours

Takes place in the ampulla of fallopian tube


CONCEPTION

Necessary functional componentsa. uterusb. fallopian tubesc. ovaries (eggs)d. hormonese. sperm


PREPARATION FOR FERTILIZATION

Estrogen levels increase peristalsis in fallopian tubes

Fertilization usually takes place in ampulla

Single ejaculation – 200 to 500 million spermatozoa

Prostaglandins in semen help transport sperm


FERTILIZATION & IMPLANTATIONa. process over time Ovum Fertilized Ovum Zygote (Pronuclei Stage) 1st Mitotic Division 2-Cell Zygote (1 1/2 days later) 16-Cell Morula (3 days) 58-Cell Blastocyst (4 days) 107-Cell Unilaminar Blastocyst (4 1/2 days) Several Days Pass Until Bilaminar Blastocyst Implants (6 days)


FIGURE 11-4 A. SPERM PENETRATION OF AN OVUM. THE SEQUENTIAL STEPS OF OOCYTE PENETRATION BY A SPERM ARE DEPICTED MOVING FROM TOP TO BOTTOM.


FIGURE 11-4 B. SPERM PENETRATION OF AN OVUM. SCANNING ELECTRON MICROGRAPH OF HUMAN SPERM SURROUNDING A HUMAN OOCYTE (750 ). THE SMALLER SPHERICAL CELLS ARE GRANULOSA CELLS OF THE CORONA RADIATA. SOURCE: USED WITH PERMISSION FROM NILSSON, L. (1990). A CHILD IS BORN. NEW YORK, NY: DELL PUBLISHING.


PREEMBRYONIC STAGE

First 14 days of human development

Cleavage

Blastomeres form morula

BlastocystDevelops into embryonic disc and amnion

Trophoblast Develops into chorion


IMPLANTATION

Occurs 7 to 10 days after fertilization

Blastocyst burrows into endometrium

Endometrium is now called decidua


CELLULAR DIFFERENTIATION (CONT’D)Embryonic membranes begin to formChorion(outerm membrane contribues to placental development)

Amnion (inner most membranous sac)

Amniotic fluidFunctions –protects against physical force, maintains temperature, allows fetal movement

Characteristics-clear, slightly yellow, 700-1000cc by 3rd trimester,

Abnormal variations-

Yolk sac-provides early nourshment


CELLULAR DIFFERENTIATION (CONT’D)

Umbilical cordBody stalk fuses with embryonic portion of placenta

Provides circulatory pathway from chorionic villi to embryoOne vein, two arteriesWharton’s jelly

Delivers oxygenated blood to fetusTwo arteries


PLACENTA

Metabolic and nutrient exchangeMaternal portionDecidua basalis and circulationFetal portionCovered by amnion (chorionic villi)Fetal surface covered by amnion


PLACENTAL DEVELOPMENTChorionic villi form spaces in

decidua basalisSpaces fill with maternal bloodChorionic villi (provide blood

supply to the embryo)Syncytium: outer layerCytotrophoblast: inner layerAnchoring villi form septa


FIGURE 11-13 LONGITUDINAL SECTION OF PLACENTAL VILLUS. SPACES FORMED IN THE MATERNAL DECIDUA ARE FILLED WITH MATERNAL BLOOD; CHORIONIC VILLI PROLIFERATE INTO THESE MATERNAL BLOOD-FILLED SPACES AND DIFFERENTIATE INTO A SYNCYTIUM LAYER AND A CYTOTROPHOBLAST LAYER.


PLACENTAL CIRCULATION

After implantation cells differentiate

Trophoblast invades endometriumOpens uterine capillariesCompletion of maternal-placental-

fetal circulationAbout 17 days after conception


FIGURE 11-14 VASCULAR ARRANGEMENT OF THE PLACENTA. ARROWS INDICATE THE DIRECTION OF BLOOD FLOW. MATERNAL BLOOD FLOWS THROUGH THE UTERINE ARTERIES TO THE INTERVILLOUS SPACES OF THE PLACENTA AND RETURNS THROUGH THE UTERINE VEINS TO MATERNAL CIRCULATION. FETAL BLOOD FLOWS THROUGH THE UMBILICAL ARTERIES INTO THE VILLOUS CAPILLARIES OF THE PLACENTA AND RETURNS THROUGH THE UMBILICAL VEIN TO THE FETAL CIRCULATION.


PLACENTAL FACTS

• Size of 8-inch dinner plate• Consists of 15-20 cotyledons,

chorionic villi branch out from it• Structure is complete at the end of

12th week gestation• Grows till 20th week gestation,

covers ½ of uterine surface


PLACENTAL FUNCTIONS

Transfers nutrients Diffuses oxygen and carbon dioxide functioning as fetal

lungs Production of 4hormones

hCG Progesterone Estrogens hCS/hPL

Facilitates transfer of metabolic wastes from the fetus to the maternal ciruclation

Transfers heat from mother to fetus.


DEVELOPMENT OF THE FETAL CIRCULATORY SYSTEMMaintains blood flow to placenta

Provides fetus with oxygen and nutrients

Removes carbon dioxide and waste products

Blood flows through umbilical vein into abdominal wall of fetus


FIGURE 11-15 FETAL CIRCULATION. BLOOD LEAVES THE PLACENTA AND ENTERS THE FETUS THROUGH THE UMBILICAL VEIN. AFTER CIRCULATING THROUGH THE FETUS, THE BLOOD RETURNS TO THE PLACENTA THROUGH THE UMBILICAL ARTERIES. THE DUCTUS VENOSUS, THE FORAMEN OVALE, AND THE DUCTUS ARTERIOSUS ALLOW THE BLOOD TO BYPASS THE FETAL LIVER AND LUNGS.


TABLE 11-4 EMBRYONIC AND FETAL DEVELOPMENT: WHAT PARENTS WANT TO KNOW


http://www.ehd.org/resources_bpd_illustrated.php

The endowment for Human Development


FACTORS INFLUENCING DEVELOPMENT

Quality of sperm or ovum

Genetic code

Adequacy of intrauterine environment

Teratogens (any agent that interfere with a developing embryo)

Organs formed primarily during embryonic development


SIGNS AND SYMPTOMS OF PREGNANCY—THIS IS IMPORTANT TO KNOWPresumptive signs of pregnancy

(subjective)• menstrual suppression (amenorrhea, menstruation may occur after conception)

• nausea, vomiting, and "morning sickness" (due to increased HCG levels)

• frequency of micturition (uterus stretches base of bladder)

• tenderness and fullness of the breasts, breast pigmentation, and discharge (due to increased progesterone, estrogen)

• "quickening" (usually 18-20 wks. may be 16 wks. in multigravida)

• fatigue


PROBABLE SIGNS (OBJECTIVE)

• Dark blue discoloration of the vaginal mucous membrane known as CHADWICK'S SIgn

• pigmentation of the skin and abdominal striae (may also occur in breasts, buttocks, and thighs)

• changes in the size, shape, and consistency of the uterus - HEGAR'S SIGN (lower part of the body of uterus much softer than cervix)

• fetal outline, distinguished by abdominal palpation and detection of a fetal part vaginally by BALLOTTEMENT (sudden tap on presenting part makes it rise in amniotic fluid)

• changes in the cervix (GOODELL'S SIGN - cervix softens due to increased vascularity edema)

• BRAXTON HICKS contractions (painless, cause of false labor)• positive pregnancy test (increased Hcg levels, blood/serum 8-9

days after ovulation and fertilization and urine test within 2 wks of gestation)


POSITIVE SIGNS (DIAGNOSTIC)

• fetal heart sounds (audible with Doppler 8-10 weeks gestation, or ultrasound)

• fetal movements felt by examiner• x-ray- outline of fetal skeleton• ultrasonic demonstration of the

presence of a conceptus (6-8 wks. yields most information)

• fetal movements visible

olds’ maternal-newborn nursing & women’s health across the lifespan, ninth edition michele...

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