Exam 1 Flashcards
When does fertilization occur?
When the nucleus of the sperm and ovum unite
What is the first component of fertilization?
Preparation
How long is sperm viable?
Viable for 48 to 72 hours. Highly viable for 24hr
What is a fertilized egg referred to as?
Zygote
When is the sex of a zygote determined?
At the moment of fertalization
What is the 23rd chromosome?
sex chromosome
First step of Cell multiplication after fertilization
Rapid Mitotic division-cleavage “Me too” carbon copy
Morula
Blastomere grows to a morula-solid ball of 12 to 16 cells
How does the morula divide?
Divides into a solid mass- BLASTOCYST surrounded by outer layer of cells TROPHOBLAST
Trophoblast develops into…
Placenta & Chorion
When does implantation occur?
7 to 10 days
Where does the journey of the fertilized ovum occur?
In the distal 1/3 of the fallopian tube
Women are usually only fertile…
6-24 hours/cycle
How long does it take for the fertilized egg to reach the uterus?
3 to 4 day journey
Where in the uterus does implantation occur?
Upper most posterior of uterus. Endometrium now referred to as decidua
Blastocyst divides into what 2 parts?
Outer-TROPHOBLAST, Inner-EMBRYOBLAST
What does the Embryoblast develop into?
The embryo and Amnion
What does the trophoblast contain?
Chorionic villi that attach to the decidua
T/F…There is direct contact between the blood of the fetus and mother
FALSE-placental barrier
Placental barrier
- Serves as a pass through
- O2 & nutrients
- Carbon dioxide and waste products
- Interchanged through diffusion
- Almost everything ingested passes through-teratogens
Fraternal twins are also referred to as…
dizygotic
Fraternal twins
- Arise from 2 separate ova fertilized by 2 separate spermatozoa
- 2 placentas, 2 chorions, 2 amnions
- Sometimes placentas fuse and appear to be one
- Not similar-like 2 siblings
- May be same or different sex
Identical twins
- Develop froma single fertilized ovum
- Monozygosity
- Same sex; same genotype
- Usually same placenta
Cell Differentiation 10 to 14 days
Blastocyst differentiates into 2 primary germ layers-ectoderm, mesoderm, and endoderm. All body tissues, organs, organ systems are developed from these germ layers
When is amniotic fluid created?
When amnion and chorion grow and connect forming amnitic sac to produce fluid
What does amniotic fluid consist of?
- 98% water
- 2% organic matter
- Fluid from maternal blodd across the amnion and fetal urine
- **Volumes vary-usually 1 liter by term
Functions of amniotic fluid
- Provides protection from trauma
- Symmetrical growth and development
- Constant body temperature
- Decreases umbilical cord compression
- Promotes musculoskeletal growth
Umbilical cord development…
- Develops from amnion.
- Fuses with embryonic portion of placenta.
- Provides a pathway from chorionic villi to embryo
What does the umbilical cord contain?
2 arteries and 1 vein surrounded by Wharton’s Jelly for protection
What is the function of the umbilical cord?
provides circulatory pathway to embryo
When does placental development occur?
- Begins at 3rd week of embryonic development
- Develops from trophoblast
- Trophoblast attaches to uterine wall
Placental function
*Metabolic and nutrient exchange between embryonic and maternal circulations
What are the two parts of the placenta?
- Maternal: “dirty duncan”
2. Fetal: “shiny shultz”
What part of the body assumes the role of the placenta until the placenta is well developed?
Corpus luteum
What does the maternal portion of the placenta consit of?
deciduas basalis and its circulation. Appears red and flesh-like
What does the fetal sid eof the placenta consist of?
chorionic villi and their circulation. Fetal surface is covered by the amnion and appears shiny and gray
Placental functions
- Endocrine: produces hormones
- Nutrition: supplies nutrients
- Respiratory: supplies O2 & removes CO2
- Renal: removes wastes
Fetal Growth and Development:
4 weeks
- Brain formed from anterior neural tube
- Limb buds seen
- Heart beats
- GI system begins
Fetal Growth and Development:
6 weeks
- Respiratory system begins
- Primitive skeletal shape
- Chambers in heart
- Ear formation begins
Fetal Growth and Development:
12 weeks
- Ossification of skeleton begins
- Liver produces red cells
- Thyroid hormone present
- Insuin present in pancreas
- Palate complete in mouth
- skin pink
Fetal Growth and Development:
16 weeks
- Meconium begins to collect in intestines
- Teeth begin to form
- Kidneys assume shape
- Hair present on scalp
Fetal Growth and Development:
20 weeks
- Point of viability*
- Suck and swallow begins
- Lanugo covers body
- Vernix begins to protect the body
- Myelination of spinal cord begins
Fetal Growth and Development:
24 weeks
- Respiration and surfactant production begins
* brain appears mature
Fetal Growth and Development
28 weeks
- eyes are open
- nervous system begins regulation of some functions
- Adipose tissue accumulates
- Nails, eyebrows, and eyelids present
Fetal Growth and Development:
36 weeks
- Few sole creases
* Earlobes soft with little cartilage
Fetal Growth and Development:
40 weeks
- Adequate surfactant
- Earlobes firm
- Vernix in skin folds and lanugo on shoulders
- sex apparent
- Hair on head is coarse and about 1 in long
When is an embryo referred to as a fetus?
9 weeks gestation
Normal Fetal Heart Rate range
120-160
What does an increased hematocrit indicate?
severe dehydration
What is the potassium level?
3.5 to 5.3
