Module 2 - From Conception to Birth Flashcards
Chapter 2 and 3
define epigenesis
the emergence of new structures and function during development
define gametes
reproductive cells, egg and sperm, that contain only half the genetic material of all other cells in the body
define meiosis
gametes are produced by a form of cell division in which the eggs and sperm receive only one member from each of the 23 chromosomes pairs contained in all the other cells. the reduction is necessary as it matters for the union of the egg and sperm
define conception
the union of an egg and sperm in the women;s uterus. once union occurs, a chemical is released in the women to prevent other spemr from entering
define zyote
a fertilized egg cell that is composed of human genetic material
What are the 4 main developmental processes that create a fetus?
- cell divison
- cell migration
- cell differentiation
- death
what is the difference between an emryo and a fetus?
an embryo is a developping organsim from the 3rd to 8th week and fetus is from the 9th week onward to 40
define cell division
also known as mitosis, the zygote will divide into 2 equal parts, contained proper amount fo genetic material. then they conitue to divide into 4, 8, 16 and so on. This will continue to occur for the whole 38 weeks to create a fetus
define migration
this is the movement of newly formed cells away from the point of origin (ex. neurons)
define cell differentiation
here, the cells are referred to as embryonic stem cells as they can become any different kind of cell in the body. Cells will become specialised parts of the body from location and their communication with neighbouring cells.
define death as the final stage in the developmental process
this is known as apoptosis, which is genetically programmed cell death. and this follows a specific timeline that are programmed into the cells.
at what stage will indentifcal twins orginate?
also called monozygotic, it will happen when they cells have created the inner cell mass. This will split in half, creating 2 cells with the same genetic makeup.
how are monozygotic and dizygotic twins different?
monozygotic occurs when the 1 created cell then goes to divide into 2, to create two cells of the same genetic material. where for dizygotic, to eggs are fertilized in the fallopian tubes, giving them different genetic material.
What happens in the 1st week if all goes well?
the zygote will embed itselfs into the uterine lining and become dependent on the mother for sustenance. cells will start to differentiate and create a support system with the amnitic sac and the placenta.
define neural tube
a groove formed in the top layer of differentiated cells in the embryo that eventually become the brain and spinal cord
how do the amniotic sac and placenta support the embryo?
the amniotic sac is a fluid-filled sac where the fetus will float to act as a protective buffer, maintaining the fetus at the same temperature and cushioning it. the placenta is a temporary support organ with a semipermeable membrane that permits the exchange of materials to the fetus from the mom.
define umbilical cord
a tube containing blood vessels connecting the fetus and placenta
define cephalocaudal development
the pattern of growth in which areas near the head develop earlier than areas farther
head-to-tail development
what week does the heart began to appear and beat?
after 4 weeks
what are the main milestones reached at the weeks during development
look at table in one note
what is the first movement that a fetus does?
around 5-6 weeks, the fetus will hiccup
what does sucking your thumb in the whomb have to do with you outside of the womb?
most fetuses who suck their right thumb are more likely to become right-handed and vice versa