PREGNANCY & DEVELOPMENT

P & A

IX. PREGNANCY A. Def: condition resulting in union of

sperm and egg and a fetus developing in the uterus

B. How occur?1. semen containing sperm is deposited in

vagina2. sperm travels up through uterus &

uterine tubes A. able to move b/c of tails and sugary energy B. estrogen is high in first part of menstrual

cycle- causes uterus and cervix to create a watery

secretion that aids in sperm transport C. second part of cycle progesterone is high

- secretion prevents good sperm travel

3. when sperm penetrates egg membrane, nuclei of the two combine = 46 chromosomes A. first cell of life = ZYGOTE B. after 32 hrs = zygote starts dividing = mitosis C. zygote now called EMBRYO D. after 3 days, embryo arrives to uterus E. after 1 week – embryo attached in uterine wall

Endometrium F. after 8 weeks – now called FETUS

Body is recognizable as human G. outer embryo/fetus cells and endometrium form

the placenta Def: bloody sac that exchanges nutrients, gases,

and wastes between mother and baby Also acts as a barrier to some toxins

C. HORMONAL CHANGES IN PREGNANCY 1. human chorionic gonadotropin (HCG)

A. def: hormone that prevents normal decline in estrogen and progesterone that causes uterine lining to shed away (menstruation) Hormone that a pregnancy test detects

B. if this hormone fails or there is not enough = miscarriage will result

2. placental estrogenA. def: hormone secreted by placenta that

maintains thick uterine wall 1. also causes relaxation of pelvic joints – helps

in birthing process

3. placental lactogenA. hormone secreted by the placenta that

allows for breast development and milk production

X. EMBRYONIC DEV (2ND-8TH WEEK) A. germ layers

1. def: layers of cells in an embryo that arise to form body structures A. ectoderm: nervous system, hair, nails, skin, mouth,

anal canal B. mesoderm: muscle, bone, blood, lymph,

reproductive organs C. endoderm: digestive, respiratory, and urinary

tracts

B. pre-natal nourishment1. amnion

A. membrane around embryo B. filled with fluid = amniotic fluid

Contains same cells as baby = samples used for genetic testing

C. umbilical cord forms1. provides a pathway for nutrients from

placenta to embryo

C. By the end of the 8th weekBaby length = 30 mmBaby weight = less than 5 g.** THESE FIRST FEW MONTHS ARE VERY

CRITICAL IN BABIES’ DEVELOPMENT - mother should immediately see Dr. when

suspect pregnant - nutrition is very important!

XI. FETAL DEVELOPMENT – 9TH WEEK - BIRTH ** Lunar month = 28 days A. 3rd lunar month

1. body length grows greatly2. head growth slows3. ossification centers develop4. by end of 12th week, reproductive organs

visible B. 4th lunar month

1. body grows to 13-17 cm2. skeleton ossifies

C. 5th lunar month 1. growth supresses 2. skeletal muscles active = mother feels

movement 3. hair develops

D. 6th lunar month 1. large weight gain 2. eyebrows and eyelashes appear

E. 7th lunar month 1. fat deposited = smooths out skin 2. eyelids open 3. approx 37 cm in length

F. 8th lunar month 1. testes of male descend

* sometimes this doesn’t happen and surgery is needed

G. 9th lunar month 1. body chubby b/c of fat deposits 2. skin pink

H. 10th lunar month 1. full term 2. skin sebum coated 3. scalp has hair 4. skull bones ossified 5. nails developed 6. head positioned to cervix

XII. FETAL CIRCULATION A. blood in the pulmonary artery

bypasses the lungs by entering DUCTUS ARTERIOSUS - which brings blood back to aorta

XIII. LABOR A. uterine & vaginal stretching in

late pregnancy1. initiates hypothalamus to signal

posterior pituitary gland2. PPG releases oxytocin

- stimulates uterine contractions3. rhythmic contractions send uterine

contents to cervix - signals stronger contractions = POSITIVE

FEEDBACK4. fetus forced outside5. 10-15 minutes after birth, placenta

separates from uterine wall & is delivered