Chapter 23 Flashcards
What is the first to develop in a fetus
Morula
the morula is the early ball of cells that will become the blastocyst
Name a fact about blastomeres
Blastomere is an early cell type that divides by cleavage
Three facts about implantation
Involves a blastocyst the preembryo which implants
Has cells that produce HCG
Occurs by the sixth day
In the process of in vitro fertilization, the woman is given ? To induce follicle development
Human menopausal gonadotropin
HMG or related compounds will stimulate the ovary to produce follicles; HCG is then used to induce ovulation
The main factor that may NOT allow a 24 week fetus to survive independently is the
Surfactant
Surfactant is the lipid in the lungs that prevents collapse and allows the fetus to breathe; premature infants often lack this ability and must be sustained artificially until their surfactant is sufficient
The ductus venosus transports blood to the ?
Vena cava
The umbilical vein becomes the ductus venosus
The foramen ovale allows blood from the right atrium to enter the
Left atrium
Large amounts of blood do NOT enter r fetal lungs because their
Resistance is high
The resistance to blood flow in the fetal lungs is higher than the right ventricle blood flow pressure which cannot overcome the resistance to any great extent
The ductus arteriosclerosis allows blood to flow from the pulmonary trunk to the
Aorta
The ductus arteriosus is a shunt lung bypass between the pulmonary trunk and the aorta
What vessel transports blood rich in oxygen and nutrients to the fetus
Umbilical vein
The umbilical vain travels toward the heart of the fetus and is thus a vein; however it is coming from the placenta where it picked up oxygen and nutrients.
With in the fetus, much of the circulating blood bypasses the lungs and flow through the
Ductus arteriosus
The arteriosus shunts blood from the pulmonary trunk to the aorta
The period immediately after birth to four weeks of age is called the ? Period
Neonatal
The first month of extrauterine life in the neonatal period
Many changes occur in the newborn infant as it adapts to a life apart from its mother. What happens to the umbilical vein?
It closes off to become the ligamentum teres.
The umbilical vein remains as a ligament attached to the liver
What is the biological definition of human adulthood
Adolescence to old age
An adolescent is reproductively mature, and therefore is considered an adult
In which process do the cells become progressively smaller
Cleavage
Cell division takes place so rapidly during cleavage that the cells do not grow between divisions
When is a developing individual most susceptible to genetic birth defects from smoking
First trimester
The first trimester is the most critical time period in all of development
When is it possible to distinguish the sex of the fetus
Third month
The sex of the fetus begins differentiation around week 8 or 9
When does bone start to replace cartilage
Third month
Endochondral ossification and intramembranous ossification begin around week 10
The embryonic period lasts from the second week through ? Week
Eighth
The embryonic period begins when two distinct cell layers form and proceeds until around the eighth week when differentiation ends
Name 3 things that arise from the mesoderm
Muscle
Kidney
Blood
What prevents the maternal and embryonic blood cells from mixing
Placental membrane
The placental membrane is a layer of epithelial cells that separate the villi from the maternal endometrium
When will the embryo take on a human appearance
Eighth week
Human structures become evident and differentiated by the eighth week, prior to this time the embryo passes through. Stages that seem to resemble other mammals
Name 3 fetal component
Chlorion
Amnion
Umbilical cord
Of every 100 secondary oocytes that are exposed to sperm, how many infants are actually born alive
About 31
When does the amnion first appear
Second week
The rudimentary amnion appears in the second week and becomes fluid filled
What is the origin of fetal blood cells
Yolk sac
The yolk sac appears in the second week and is the origin of the fetal blood cells and gametes that will migrate into the fetus
What is the major cell process in the fetus
Mitosis
Differentiation has ended with the onset of the fetus and all growth processes are mitotic in nature
When can the male and female organs be distinguished first
Twelfth week
By the twelfth week the external genitalia are distinguishable
Name 3 things true at full term
Fingernail are present
Vertex position is evident
Fetus is 50 cm long
The testes begin to descend around the eight month but may not be completed until after birth
The umbilical arteries are branches of the
Internal iliac arteries
What has the greatest oxygen content in a fetus
Umbilical vein
Umbilical Arteries are traveling to the placenta to gain oxygen from the mother
What system function is most critical in the neonate
Respiratory
During the first month of life, the exchange of gasses is critical, the liver is one of the last organs to mature
Name 3 factors that causes the first breath of life
Blood pH
Carbon dioxide
Low blood oxygen
The initiation of breathing occurs from stimulation of the brain stem, epinephrine is produced and rises because of the stress of delivery and is important for increasing the ability of the lungs to expand
In the first days of life, what is the primary source of energy
Lipid
The superior vesical arteries are remnants of the
Umbilical arteries
A portion of the umbilical arteries persist in the neonate as the superior vesical arteries that supply blood to the bladder