Development 1 Flashcards
What is a congenital disorder?
a structural disorder or functional disorder present at birth due to a problem with genes, chromosomes, intrauterine environment, teratogens or metabolic requirement
What is the frequency of birth defects?
1/33
What is the most common birth defect?
heart defect - 1/200
What is a morula?
A 16 cell ball at around 3 days
What is a blastocyst?
A cell mass with a cavity (blastocoele) at 4 days
What are trophoblasts?
The cells around the outside of the blastocyst that will make up the extra embryonic structures
What is the inner cell mass?
The cells at one pole of the blastocyst that will end up making the embryo
When does the blastocyst implant on the wall of the uterus?
5-10 days
What happens at the two germ layer stage?
The inner cell mass splits into the epiblast and the hypoblast - the epiblast will form the embryo and the hypoblast is extra embryonic
What is the cavity formed by the epiblast?
The amniotic cavity
What is the cavity formed by the hypoblast?
The yolk sac
What happens at the three germ layer stage?
The epiblast forms 3 layers by gastrulation - endoderm, mesoderm and ectoderm
What does the ectoderm give rise to?
The nervous system and the epidermis
What does the mesoderm give rise to?
Blood cells, heart, kidneys, gonads, connective tissue (bone and muscle)
What does the endoderm give rise to?
The epithelial lining of hollow organs (gut, lungs, liver)
What is the notochord?
The first identifiable structure - a stiffened rod that runs down the midline and organises tissues around it