PRENATAL DEVELOPMENT Flashcards
19TH CENTUARY:
Found the embryonic developmental process was not a single process
WHAT IS SCALA NATURAE
A great chain of being, species are placed in a hierarchy, humans are at the top
WHO CREATED THE TERM SCALA NATURAE
Aristotle
RECAPITULATION THEORY:
The hypothesis that the embryo goes through different stages before reaching its final form of a human (e.g turtle and fish)
3 STAGES OF PRENATAL DEVELOPMENT
- Germinal Period (Conception - Implantation)
- The Period of the Embryo (Implantation - 2 months)
- The Period of the Fetus (2 months - Birth)
DESCRIBE THE PROCESS OF CONCEPTION
Conception happens when the sperm fertilises the egg in the Fallopian tube. The zygote travels down the Fallopian tube to the uterus. The zygote continues to multiply. The mass of cells develops of centre cavity at DAY 5, this is the first form of differentiation. The zygote is now known as the Blastocyst.
WHAT 3 CELL DIFFERENTIATION LAYERS ARE FORMED AT 2 WEEKS
- Ectoderm - Organs
- Mesoderm: Muscles, bones and circulatory system
- Endoderm - nervous system
WHAT CAN CAUSE VARIATIONS FROM NORMAL DEVELOPMENT
- Genetics - cystic fibrosis, sickle cell
- Env Toxins - Alcohol, Radiation and Pesticides
- Env Nutrition - Folic Acid
MITOSIS
Parent cell turns into 2 daughter cells, 46 chromosomes in each cell
MEIOSIS
Parent cell turns into 4 daughter cells, gametes contain 23 chromosomes, half from mother half from father
WHAT IS ANEUPLOIDY
Having more or less than 46 chromosomes
WHAT IS THE TERM FOR HAVING MORE OR LESS CHROMOSOMES
Aneuploidy
WHAT ARE 3 CLASSES OF ANEUPLOIDY?
- Down syndrome Karyotype
- Edwards Syndrome Karyotype
- Patau Syndrome Karyotype
WHAT CAN VARIATIONS IN SEX CHROMOSOMES LEAD TO?
Ambiguous genitalia at birth
WHAT ARE TERATOGENS
Substances that cause birth defects. The CNS is vulnerable to chemical insult. Different parts of the body are vulnerable at different times.