Psych 250 lec 3
Terms
undefined, object
copy deck
- General dynamics of conception
-
ovulation
ovum survives 24-48 hours
sperm cells survive up to 5 or 6 days
brief window - fertilization
- union of sperm and ovum, genetic materials fuse
- zygote
-
fertilized egg.
lasts about 2 weeks, from fertilization to implantation - duration of zygote
- lasts about 2 weeks
- blastocyst
- hollow, fluid-filled ball of cells
- embryonic disk
- cells on inside, and become new organism
- trophblast
- outer layer of cells
- trophoblast develops into 3 life-support systems
-
1. amnion
2. placenta
3. umbilical cord - amnion
- protective covering - encases organism in amniotic fluid, a cushion and temperature regulating
- placenta
- disc-shaped mass of tissue -- partial filter -- permits food and oxygen to reach organism and waste products to be carried away
- umbilical cord
- rope of tissue that connects placenta to developing organism - the anchor
- the period of the zygode ends with
- implantation 7-9 days after fertilization
- the period of the embryo (2-8 weeks)
- rapid change and development -- groundwork for all body structures and internal organs is begun
- embryonic disk folds to form 3 cell layers
-
ectoderm
mesoderm
endoderm - ectoderm
- outermost -- nervous system, skin, sense organs
- mesoderm
- middle -- muscles, skeleton, circulatory system, extretory system
- endoderm
- inner - digestive system, lungs, glands
- neural tube
- primative spinal cord and brain
- developments during 4-8 weeks
- rapid development of body parts and systems
- miscarriages
-
spontaneous abortion.
abou 15-20% of recognized pregnancies. 90% occur by 12 or 13 weeks - Period of the fetus = what time?
- 9th week to birth
- development discussed in terms of _______ for the period of the fetus
- trimesters
- progress at end of first trimester (the 3rd month)
-
- physical structures become more complete
- organs, muscles, nervous system organize and connect
- external genitals well-formed by 12th week
- fetal heartbeat audible with stethescope
- behavioral changes in fetus
- Vernix
- white, cheeselike substance, protects skin from being chapped
- Lanugo
- white, downy hair, helps vernix stick to skin
- second trimester = what time?
- 13-24 weeks
- second trimester includes?
-
fetal growth,
vernix
Lanugo - third trimester time
- 25-38 weeks
- age of viability (22-26 weeks)
- age at which the fetus can 1st survive if born early.