MindMap Gallery PREGNANCY AND DEVELOPMENT
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PREGNANCY AND DEVELOPMENT
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Edited at 2020-09-27 13:42:48
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PREGNANCY & DEVELOPMENT
ACROSOMAL REACTION & SPERM PENETRATION- sperm must penetrate oocyte covering - corona radiata & zona pellucida- sperm binds to zona p. & undergoes acrosomal reaction - enzymes are released to digest holes in zona pellucida- sperm head approaches oocyte- oocyte & sperm membranes fuse- only one sperm is allowed to penetrate oocyte (monospermy)
HORMONAL CHANGES DURING PREGNANCYhuman chorionic gonadotrophin (hCG)- secreted by trophoblast cells, later chorion- prompts corpus luteum to continue secretion of progesterone & estrogen- hCG levels rise until end of second month, then decline as placenta begins to secrete progesterone & estrogen
PREGNANCYevents that occur from fertilization until the infant is born
CONCEPTUSdeveloping offspring
GESTATION PERIODtime from last menstrual period until birth (280 Days)
EMBYROconceptus from fertilization through week 8
FETUSconceptus from week 9 through birth
FERTILIZATIONsperms chromosomes combine w/ those of secondary oocyte to form a fertilized egg (zygote
FROM EGG TO ZYGOTE- oocyte is viable 12-24 hours- sperm is viable 24-48 hours after ejaculation- for fertilization to occur, coitus must occur no more than -2 days b4 ovulation -24 hrs after ovulation
EMBYRONIC DEVELOPMENTblastocyst: fluid filled hollow spheresTrophoblast cells - display factors that are immunosuppressive- participate in placenta formation Inner cell mass- becomes embryonic disc (embryo & 3 of embryonic membranes)
CLEAVAGE-mitotic divisions of zygote- 1st cleavage @ 36 hrs = 2 daughter cells (blastomeres)- @ 72 hours = morula (16 or + cells)- @ day 3-4, embryo of ~100 cells (blastocyst( has reached uterus
IMPLANTATIONBlastocyst floats for 2-3 days unattachedImplantation beings 6-7 days after ovulation- trophoblast adheres to site w/ proper receptors & chemical signals- inflammatory-like response occurs in endometriumImplanted blastocyst is covered over by endometrial cellsImplantation is completed by 12 day after ovulation
TROPHOBLASTSproliferate & form 2 distinct layers
1. CYTOBLASTS (cellular trophoblast)inner layer of cells
2. SYNCYTIOTROPHOBLASTcells in outer layer lose thier plasma membranes, invade & digest endometrium
PLACENTATIONformation of placenta from embyronic & maternal tissues
1. EMBRYONIC TISSUES- mesoderm cells develop from inner cell mass & line trophoblast- together these form chorion & chorionic villi
2. MATERNAL TISSUES- decidua basalis (stratum functionalis between chorionic villi stratum basalis of endometrium) develops blood-filled lacunae
GASTRULATION - occurs in week 3, embryonic disc becomes a 3-layered embryo w/ ectoderm, mesoderm, & endoderm- begins w/ appearance of primitive streak, a raised dorsal groove that establishes longitudinal axis of embryo
ORGANOGENESISgastrulation sets stage for organogenesisformation of body organs & systems@ 8 weeks- all organ systems are recognizable - end of embryonic period
PRIMARY GERM LAYERSprimitive tissues from which all body organs derive- endoderm & ectoderm are considered epithelia
ECTODERMnervous system & skin epidermis
ENDODERMepithelial linings of digestive respiratory, & urogenital systems
MESODERMforms all other tissues
PATURITION giving birth to the babylabor events that expel infant from uterus
STAGES OF LABOR
DILATION STAGElongest stage of labor: 6-12 hrs or +initial week contractions:- 15-20 mins apart, 10-30 sec long- become more vigorous & rapidcervix effaces & dilates fully to 10 cmamnion ruptures, releasing amniotic fluidengagement occurs: head enters true pelvis
EXPULSION STAGEstrong contractions every 2-3 mins, about 1 min longurge to push increases (- local anesthesia)crowning occurs when largest dimension of head disterids vulvadelivery of infant
PLACENTAL STAGESstrong contractions continue, causing detachment of placenta & compression of uterine BVsdelivery of afterbirth (placenta & membranes) occurs ~30 min. after birthall placenta fragments must be removed to prevent postpartum bleeding
ADJUSTMENTS OF INFANT TO EXTRAUTERINE LIFENeonatal period: 4 week period immediately after birthPhysical status is assessed 1-5 mins after birth
APGAR SCORE0-2 points each for:HR, RR, color, muscle tone & reflexes- score: 8-10 (healthy)
LACTATIONproduction of milk by mammary glandstoward end of pregnancy- placental estrogens, progesterone, & lactogen stimulate hypothalamus to release prolactin-releasing factors (PRFs)- anterior pituitary releases prolactinColostrum:- yellowish secretion rich in vitamin A, protein, minerals, & IgA antibodies- released first 2-3 days- followed by true milk productionsuckling initiates a (+) feedback mechanismoxytocin causes letdown reflex
FIRST BREATHincreased CO2 = central acidosis= stimulates respiratory centers to trigger first inspiration- requires tremendous effort: airways are tiny & lungs are collapsed- surfactant in alveolar fluid helps reduce surface tensionrespiratory rate: ~45 per min for first 2 weeks, then declines