Chapter 28 Flashcards
How long is pregnancy?
Spans from fertilization until birth
Conceptus
Developing offspring
Fertilization to birth
Gestation Period
Last menstrual period until birth ( roughhly 280 days)
Embryo
Conceptus to W8
Fetus
Week 9 to Birth
Fertilization
Sperm chromosomes combine w/ 2nd oocyte to form fertilized egg (zygote)
How long does an oocyte live after ovulation?
12-24 days
How long for spermatoza after ejaculation?
24-48 hours
What is cleaavage?
Mitotic divisions of zygote
When does first clevage occur? What develops?
36 hours - 2 daughter cells (Blastomeres)
When does the embryo first meet the uerus? What stage of development/
3-4 days
Blastocyst
When does implantation occur?
6-7 days after ovulation (trophoblast implants)
What hormone is used to detect early pregnancy? Who produces it?
HCG
Placental Membrane
When is the placenta formed?
Fully formed by end of 3rd month
What does the placenta secrete?
Hormones (human placental lactogen, human chorionic thryotropin, relaxin)
Waste Exchange
What membranes are on the outside of the embryo?
Amnion
Yolk Sak
Allantois
Chorion
What is the amnion?
Transparent sac w/ amniotic fluid for protection
What is the yolk sak?
Sac that hangs from ventral surface of embryo
What fetal organ system does the yolk sak form? Anything else?
digestive tube
- Early blood cells, blood vessels, germ cells
What is the Allantois?
- Small outpocketing at caudal end of yolk sak
- ## Base for the umbillical chord
What does the allantois become?
Urinary bladder
What is the chorion?
Enclosed embryonic body and all other membranes
- Site of gas exchange with maternal circulation
What does the chorion become?
Helps form placenta
What are the placental germ layers?
Ectoderm, mesoderm, endoderm
What does the ectoderm become?
skin and nervous system
What does the mesoderm become?
other tissues not formed by endoderm and ectoderm
What does the endoderm become?
Epithelial linings of GI, respiratory and uriogenital systems
When are organ systems recognizable? What does it signify
at the end of the 8th
- Signals end of embryonic period and beginning of fetal
What are the anatomical effects of a pregnancy on a woman’s body?
- Uterus expands
- Lordosis due to change in center of gravity
- Relaxin causes relaxation of pelvic and pubic ligaments
What does the placenta produces?
- Human placental lactogen
- Human chorionic somatoammotropin
- Human chorionic thyrotropin
What does placental lactogen and human chorionic somatomammotropin causes?
Maturation of breast, fetal growth and glucose sparing
What does human chorionic thyrotropin cause?
Increase maternal metabolism
How does the respiratory system change with pregnancy?
Estrogen causes nasal edema and congestion
increase in tidal volume
dyspena
How does the cardiovascular system change with pregnancy?
Blood volume increases 25-40%
BP and Pulse Rise
Venous return from lower limb impaired
What is parturiton?
Giving birth
What happens during the last few weeks of pregnancy?
Fetus secretes cortisol
What does cortisol stimulate?
Production of oxytocin receptors on myometrium
When do practice contractions happen?
Production of oxytocin antagonize calming effects of progesterone
When the fetus produces surfactant protein A, what happens?
softening of cervix
What does fetal oxytocin cause?
Placental production of prostaglandins
What 2 hormones work together as powerful uterine contraction stimulants?
oxytocin
prostaglandin
Who initiates birth?
fetus
What are the stages of labor?
Dilation
Expulsion
Placental
What is the dilation stage of labor?
Longest period
Contractions start weak and grow stronger
Cervix thins and dilates to 10 cm
Engagement Happens
What is engagement?
Head enters true pelvis
What is the expulsion stage?
Strong contractions every 2-3 minutes, lasting 60 seconds
Urge to push increases
ends with delivery of baby
What is the placental stage?
Contractions continue after birth of baby to detach placenta which is delivered 30 minutes after birth
What is colostrum?
First milk produces, rich in vitamin A, proteins, minerals and IgA antibodies
When does true milk production begin?
2-3 days
What does suckling promote?
positive feeedback response, increased suckling = more milk letdown
What hormone stimulates release of milk?
oxytocin
