Download conception and biophysical changes

CONCEPTION AND
BIOPHYSICAL CHANGES
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
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
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
CONCEPTION
Necessary functional components
a. uterus
b. fallopian tubes
c.
ovaries (eggs)
d. hormones
e. sperm
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
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
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
FERTILIZATION
& IMPLANTATION
a.
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)
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
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.
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
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.
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
PREEMBRYONIC STAGE
First 14 days of human development
Cleavage
Blastomeres form morula
Blastocyst
Develops into embryonic disc and amnion
Trophoblast
Develops into chorion
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
IMPLANTATION
Occurs 7 to 10 days after fertilization
Blastocyst burrows into endometrium
Endometrium is now called decidua
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
CELLULAR DIFFERENTIATION (CONT’D)
Embryonic membranes begin to form
Chorion(outerm membrane contribues to
placental development)
Amnion (inner most membranous sac)
Amniotic fluid
Functions –protects against physical force,
maintains temperature, allows fetal movement
Characteristics-clear, slightly yellow, 7001000cc by 3rd trimester,
Abnormal variationsYolk sac-provides early nourshment
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
CELLULAR DIFFERENTIATION (CONT’D)
Umbilical cord
 Body stalk fuses with embryonic portion of placenta
 Provides circulatory pathway from chorionic villi to
embryo
One vein, two arteries
Wharton’s jelly
Delivers oxygenated blood to fetus
 Two arteries
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
PLACENTA
Metabolic and nutrient exchange
Maternal portion
Decidua basalis and circulation
Fetal portion
Covered by amnion (chorionic villi)
Fetal surface covered by amnion
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
PLACENTAL DEVELOPMENT
Chorionic villi form spaces in decidua
basalis
Spaces fill with maternal blood
Chorionic villi (provide blood supply to the
embryo)
Syncytium: outer layer
Cytotrophoblast: inner layer
Anchoring villi form septa
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
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.
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
PLACENTAL CIRCULATION
After implantation cells differentiate
Trophoblast invades endometrium
Opens uterine capillaries
Completion of maternal-placentalfetal circulation
About 17 days after conception
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
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.
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
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
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
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.
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
DEVELOPMENT OF THE FETAL
CIRCULATORY SYSTEM
Maintains 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
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
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.
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
TABLE 11-4 EMBRYONIC AND
FETAL DEVELOPMENT: WHAT
PARENTS WANT TO KNOW
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
http://www.ehd.org/resources_bpd_illustrated.php
The endowment for Human Development
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
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
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
SIGNS AND SYMPTOMS OF PREGNANCY—THIS
IS IMPORTANT TO KNOW
Presumptive 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
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
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)
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
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 Davidson • Marcia London • Patricia Ladewig