pregnancy Flashcards
pregnancy
state of carrying a developing conceptus
Gestation period
time from last menstrual period until birth
~280 days/40 weeks
embryo
conceptus from fertiliation through week 8
fetus
conceptus from week 9 through birth
when oocye is viable, when sperm is viable, and when coitus muct occur
Fertilization
- oocyte viable for 12-24 hours
- sperm is viable 24-48 hours after ejactualtion
- coitus must occur no more than 2 days before and no more than 24 hours after ovulation
fate of sperm
- some leak out after deposition
- some are destoryed by acidic vaginal enviornment
- some fail to make it though the cervix
- some are dispersed in uterine cavity or destroyed by phagocytes
- only a few thouseand out of million reach the fallopian tubes
Capcitated
when the acrosome of the sperm is broken down so the chromosomes in the head of the sperm can be deposited into the ovum
Sperm have… to reach the egg
sperm have olfactory receptors that can follow the chemical trail released by an egg or surrounding cells
Cleavage
rapid mitotic divisions
-first after 36 hours
-after 72 hours morula forms
Blastocyst Formation
-days 4-5 (100 cells) in uterus
-nourished by uterie secretions
-day 8-10 implant into endometrium
implantation
as the endometrium erodeds, the blastocyst burrows into lining and surrounds itself by pool of leaked blood
then enomertial cells cover and seal off implanted blastocyst
if implantation fails, the uterus becomes non-receptive again
-about 2/3 of all zygotes formed fail to implant by end of first week or spontaneously abort
Human Chorionic Gonadotropin (hCG)
-prevents menstration(is secreted by embryo)
-prompts corpus luteum to continue secreation of progesterone and estrogen
-promotes placental development
-declines as placenta begins to secrete progesterone and estrogen
Placenta
-tempoaray organ that originates from both embryonic and maternal tissues
-fully formed and function by end of 3rd month
–provied nutritive, respiratory, excretory, and endocrine functions
what are they, and what do they do?
Germ Layers
endoderm (inner)
-digestive, respiratory systems
mesoderm (middle)
-cardiovascular, musculoskeletal system
ectoderm (external)
-integumentary, nervous system
1st trimester
conception to 12th week
organogensis
building of organs - weeks 5-7
week 5
- formation of the Neural Tube (gives rise to brain and spinal cord)
- first major even of organogensis
- two vessels forming heart have fused
- heart beats 110 bpm
Week 7
- bones begins to replace cartilage
- gonads begin to form
- resembles tadpole or seahorse
- size of a blueberry
Week 8
- enbryo is 1 inch long
- all organ systems are recognizable
- size of a black bean
Week 9
- now referred to as “Fetus”
- beomes more human - looking
Week 11
- Fetus can open/close fists & mouth
Week 12
- End of 1st trimester
- risk of miscarriage decreased
- mom feels better
- 2.5-3 in. size of lime