Term | Definition |
Indeterminate cleavage | Indeterminate cleavage results in cells that can still develop into complete organisms. These create humans. |
Cleavage | A zygote undergoes rapid mitotic cell divisions |
Determinate cleavage | Determinate cleavage results in cells that are committed to differentiating into a certain type of cell. |
Blastula | Blastulas are characterized by the presence of a hollow, fluid-filled inner cavity known as a blastocoel. It consists of a "trophoblast" and "inner cell mass" |
Trophoblast | Trophoblast cells surround the blastocoel and give rise to the chorion and later the placenta |
Inner cell mass | The inner cell mass protrudes into the blastocoel and gives rise to the organism itself. |
Implantation | Planting an embryo into the endometrium, progesterone provides the fertile soil by promoting proliferation. |
Gastrulation | The generation of three distinct cell layers |
Archenteron | The cavity created by the deep invagination, which later develops into the gut |
Blastopore | The opening of the archenteron. In deuterostomes, such as humans, the blastopore develops into the anus. In protostomes, it develops into the mouth. |
Ectoderm | Attract-oderm:
Integument (including the epidermis, hair, nails, epithelium of the nose, mouth, and anal canal), lens of the eye, and the nervous system. Adrenal MEDULLA |
Mesoderm | Means-oderm (get from place to place):
Musculoskeletal system, circulatory system, excretory system, gonads, muscular and connective tissue coats of the digestive and respiratory systems. Adrenal CORTEX |
Endoderm | End-dernal (mouth ---> anus and lungs):
Epithelial linings of digestive and respiratory tracts and parts of the liver, pancreas, thyroid, bladder, and distal urinary and reproductive tracts. |
Neurulation | Development of the nervous system. |
Placenta | The organ where nutrient, gas, and waste exchanges occur. |
Amniotic Fluid | A shock absorber during pregnancy and labor (similar to a car's airbags) |
Yolk sac | The site of early blood vessel development |
Chorionic villi | Grow into the placenta and support maternal-fetal gas exchange |
Foramen ovale | Connects the right atrium to the left atria |
Ductus arteriosus | Connects the pulmonary artery to the aorta to shunt leftover blood that doesn't go through the foramen ovale |
Ductus venosus | shunts most of the left umbilical vein blood flow directly to the inferior vena cava. Thus, it allows oxygenated blood from the placenta to bypass the liver. |
Umbilical arteries | (Away from the fetus)
Carry deoxygenated blood away from the fetus |
Umbilical vein | (To the fetus)
Carry oxygenated blood to the fetus |
First Trimester | Most of the organs have formed, the brain is fairly developed, and the embryo is referred to as a fetus |
Second Trimester | The fetus grows. It begins to move around in the amniotic fluid, its face appears, and its toes and fingers elongate |
Third Trimester | Continued rapid growth and further brain development. Antibodies are transported by highly selective active transport from the mother to the fetus. |