Flashcards in Conception And Fetal Development Deck (56):
Union of eggs and sperm and marks the beginning of pregnancy.
Conception occurs in the...
Ampulla of the Fallopian tubes (not uterus)
Ovum comes from....
The grafting follicle at ovulation
Two protective layers of the ovum
Thick shapeless membrane that covers the ovum
Outer ring composed of elongated cells that are held together by hyaluronic acid
What chance of conception is there with a healthy cycle and good variables?
Length of time it takes sperm to reach ovum and how long they are viable for
What is capacitation
When the sperm is exposed to the reproductive tract and it's protective coating on the acrosome (head) comes off. Enzymes escape and the enzymes are necessary for sperm to penetrate the egg
What is the Zona Reaction ?
When an egg is penetrated by one sperm, another will not be able to fertilize it and the egg will degenerate if it happens
What is a pronuclei?
When the nucleus of the spermatozoa and ovum become distinct bodies of chromatin (chromosomes)
What is the name of the structure with 46 chromosomes
What are the three main events of the pre embryonic period?
Divisions of cells
Development of fetal membranes
How many times does the zygote divide?
Until 64 cells are produced
At what number cell stage does the zygote enter the uterus?
16 cells stage (morula)
What is a morula?
A 16 cell stage surrounded by a Zona Pellucida
What has to happen before a zygote embeds?
Divide into a blastocyst
What happens during implantation?
The Zona Pellucida degenerates
Structural changes occur
Fluid in the center pushes cells to the outside border
The inner cell mass (blastocyst) becomes the embryo and embryonic membranes
What is the outer cell mass of the embryo called and what is its principle function?
Trophoblast- eventually become the chorion
To secure food for the embryo and embed the ovum
Where is the ovum usually implanted
Upper part of uterine wall
What are chronic villi
Finger like projections that develop out of trophoblasts into the endometrium
Why are chronic villi important
They contain blood vessels that get O2 and nutrients from moms blood and dispose of waste
They also secrete Hgc hormone
What is the corpus luteum
Secretes progesterone until the placenta is formed
What is HGC?
Human chorionic gonadatropin
A hormone that maintains progesterone production by the corpus luteum
What does progesterone do?
Supports to product of conception- holds off the period
What does the endometrium change to once fertilization and implantation takes place?
What is a decidua?
A structure that loses its structure after 40 weeks... In this case a gestation term instead of monthly (uterus)
What is a decidua basalis?
The part directly under the embedded ovum that forms the placenta
What is the decidua calsularis?
The portion that overlies the ovum and separates it from the rest of the uterine cavity
What is the decidua Vera?
The remaining portion that is not in immediate contact with the fertilized ovum
What is the chorion?
The outermost embryonic membrane that is furthest from the embryo and closest to the mother. It covers the fetal side of the placenta
What is the chorion developed from?
What is the amnion?
It is generated from fluid filled space around the embryo called the amniotic cavity. It's lined with a glistening smooth membrane. It encases the fetus with fluid and is closest to the fetus
Characteristics of Amniotic fluid
Fetus floats in it, maintains temperature, provides cushion against injury, clear yellow to straw, fetus drinks and voids into it
What does amniotic fluid contain?
Lanugo, albumin, urea, epithelial cells, vernix
What is lanugo
What is vernix
Cheese like substance that coats baby
When does the heart start beating
What is the shiny vs dirty side of the placenta
Shiny side- fetal side
Dirty side- mothers side
When is the embryonic period and when are organs fully functionable?
3-8 weeks, at 8 weeks organs are formed and functioning
What is organogenesis
Organ system development
What is the function of the placenta
To connect the fetus to the uterine wall via umbilical cord to provide nutrients, respiration, and excretory functions
When is the placenta functional and what stood in its place until it was developed?
12 weeks, chorion
What does the placenta act as
Lungs, kidneys, endocrine, digestive system, liver and immune system
What viruses can cross to baby?
Hep b and HIV
Characteristics of placenta
Maternal side is rough, bloody, 22 irregularly shaped lobes, round, 8-10 inches
Fetal side is smooth and shiny
What hormones does the placenta produce
Progesterone, estrogen, relaxin, hpl (human placental lactogen for breast milk production)
What are the germ layers?
Function and structure of umbilical cord
Connects fetus to placenta to mother
Has 2 arteries and 1 vein
Arteries carry deoxygenated blood
Vein carries oxygenated blood
18-22 inches long
What is whartons jelly
Jelly like substance in umbilical cord that is 90% water
What are the 2 blood circulations
Bypasses fetal lung
Oxygenation occurs in placenta
What does blood bypass while going through the umbilical vein?
Ductus venosus then to inferior vena cava
What does the foremen ovale do
Shunts blood to body
What must the foremen ovale do once born?
Snap shut because it is critical to respirations
What do the ductus arteriosus and ductus venosus do once born?
Atrophy and become ligaments