Unit 2

Prenatal Reproductive Development
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-mother ovum carries single X chromosome; each of the father's sperm carries either an X or Y chromosome->depends on offspring's genetic sex
-during the 7th week, differences b/t males and females appear in the internal structures; exterior appear in 9th week; differentiation of external sex organs complete at 12 weeks (if critical part of Y chromosomes is absent a female will develop from XY genetic makeup)
-secretions of the hypothalamus, anterior pituitary, and gonads all play a part
-hypothalamus secretes gonadotropin-releasing hormone (GnRH) to initiate puberty (significant amounts during late childhood)
-GnHR ^ until reaching adequate levels to stimulate the anterior pituitary to ^ it's production of follicle-stimulating hormone (FSH) and luteinizing hormone (LH). ovaries/testes ^ production of sex hormones and begin producing gametes in response to ^ levels of FSH and LH
-anterior pituitary gland secretes ^ amounts of FSH and LH in response to hypothalamic secretion of GnRH. these pituitary hormones stimulate secretion of estrogens and progesterone by the ovary=maturation of reproductive organs/breasts & secondary (axillary/ pubic hair)
-Breasts (earliest of all; nipple enlarges/protrudes; areola surrounding nipple enlarges and protrudes; growth of glandular & ductal tissue; fat deposited in breasts-may develop at dif rates resulting in temp lopsided appearances)
-Body Contours (pelvis widens, assumes rounded basin-like shape; fat selectively deposited in hips, rounder appearance)
-Body Hair (pubic hair; axillary hair near menarche (menstrual onset))
-Skeletal (girls grow taller for several years during puberty; growth spurt approx 1 yr after breast; cause epiphyses (growth areas of the bone) to unite shaft of bones)
-Reproductive Organs (genitalia enlarges as fat deposits mons pubis, labia. vagina, uterus, fallopian tubes, ovaries grow larger. mucosa changes to prepare for sex)
-Menarche (primary amenorrhea-delayed onset; amenorrhea-abesence of menstruation (1 yr after mom/sisters onset); secondary amenorrhea-for at least 3 cycles after regular cycles have been established)
-secretion of GnRH by hypothalamus begins ^, stimulating secretion of LF and FSH from anterior pituitary. LH/FSH stimulates secretion of testosterone and eventually spermatogenesis (formed male gametes=sperm)
-Testes/Penis (first=growth of testes; circumference and lengthening of penis after approx 1 yr of testes growth begins; scrotum thins/darkens)
-Nocturnal Emissions ("wet dreams")
-Body Hair (begins at base of penis; hair coarsens/spreads upward and in midline of abdomen; 2 yrs later axillary hair appears; facial hair, chest, upper backs
-Body Comp (testosterone causes males to develop more muscle mass than females; exceeds womans by 50%)
-Skeletal (undergo rapid height growth spurt, approx 1 yr later than girls and lasts longer->greater height at maturity; causes <union of epiphysis w/ shaft of long bones; shoulders broaden, pelvis assumes upright position w/ narrower diameter/heavier structure)
-Voice (hypertrophy of laryngeal mucosa/enlargement of larynx causes males voice to deepen)
-Vagina (muscular/membranous tissue approx 8-10 cm long b/t bladder anteriorly and rectum posteriorly; connects uterus above w/ vestibule below; coitus -to receive male penis, allow passage from fetus to uterus)
-Uterus (upside-down pear that houses fetus til birth, contracts during labor to expel fetus; anteverted (rotated forward) slightly anteflexed (flexed forward)) Corpus; Isthmus; Cervix)
-Fallopian Tubes (aka oviducts; ovum travels from the ovary to the uterus through the fallopian tubes (interstitial; isthmus; ampulla; infundibulum)
-Ovaries (produce sex hormones; develop ovum to maturity during each productive cycle) (ovaries secrete estrogen and progesterone in varying amounts)
Spinnbarkeitelasticity of cervical mucusGametogenesisto develop ova in females and spermatozoa in males, gametogenesis (creation of reproductive cells) requires a special reduction division called meiosis. unlike mitosis, in which the diploid # of chromosomes (46) is retained in each new cell, meiosis halves the # of chromosomes (haploid #). only one of each chromosome in a pair is directed to the gamete, yielding 22 autosomes and 1 sex chromosome. when the sperm and ovum unite at conception, the "halves" form a new cell and restore the chromosome number to 46Oogenesisformation of ova or female gametes -begins during prenatal life when primitive ova (oogonia) multiply by mitosisSpermatogenesisformation of sperm -primitive sperm cells (spermatogonia) develop during fetal life and begin multiplying by mitosis during pubertyFemale Preparation for Conception-oocytes begin to mature d/t FSH and LH. each maturing oocyte contained in a sac w/in ovary called the Graafian follicle->produces estrogen and progesterone to prepare endometrium for pregnancy. -ovulation, release of ovum (approx 14 day before next period). follicle develops thin spot, ruptures, releasing mature ovum w/ cells on surface of cell of ovary. follicles become corpus luteum maintaining high estrogen/progesterone -Ovum Transport (mature ovum picked up by fimbriated (fringed) ends of fallopian tube near surface of ovary. fertilization occurs in distal 3rd of fallopian tube. ovum enters uterus approx 3 days after release of ovaryOvulatory Phase of Ovarian Cycle (2nd Phase)near 28 day reproductive cycle, approx 2 days before ovulation, LH secretes rises; secretion of FSH also rises, but less than LH. surges in LH and FSH cause a slight fall in follicular estrogen production and a rise in progesterone secretion, stimulating final maturation of a single follicle and release mature ovum. Ovulation marks beginning of luteal phase of the female reproductive cycle and occurs approx 14 days before next menstrual cycleLuteal Phase of Ovarian Cycle (3rd phase)after ovulation and under the influence of LH, the remaining cells of the old follicle persist for approx 12 days as a corpus luteum. the corpus luteum secretes estrogen and large amounts of progesterone to prepare for a fertilized ovum. Levels of FSH and LH decrease during this phase in response to higher levels of estrogen/progesterone. if ovum is fertilized, it secretes hCG causing corpus luteum to maintain early pregnancy. if ovum not fertilized FSH and LF fall to low levels the corpus luteum regresses- uterine lining breaks down. loss of proge/estrogen from corpus luteum at end of cycle stimulates anterior pituitary to ^ secrete FSH and LH initiating new cycle. old corpus luteum is replaced by fibrous tissue called corpus albicansEndometrial Cycleuterine endometrium responds to ovarian hormone stimulation w/ cyclic changes. 3 phases mark the changes in the endometrium: proliferative phase, secretory phase, menstrual phaseProliferative Phasetakes place as the ovum matures and is released during the first half of the ovarian cycle. after completion of a menstrual period, the endometrium is very thin, w/ only the basal layer of cell remainingSecretory Phaseoccurs during the second half of the ovarian cycle as the uterus is prepared to recieve a fertilized ovum. the endometrium continues to thicken under the influence of estrogen/progesterone from the corpus luteum, reaching its maximum thickness of 5-6mm. the blood vessels and endometrial glands become twisted and dilated.Ejaculation35-200 million sperm are deposited in the upper vagina and over the cervixPreparation of Sperm for Fertilizationsperm are not immediately ready to fertilize the ovum when they are ejaculated. while making the trip to the ovum, the sperm undergo changes (capacitation) that enable one to penetrate the protective layers surrounding the ovum. the sperm that reach the ovum release an enzyme (hyaluronidase) to digest a pathway through the corona radiata and zona pellucida. their tails beat harder to propel them toward the center of the ovum. eventually, one spermatozoon penetrates the ovumProcess of Fertilization1. sperm enters the ovum 2. the 23 chromosomes from the sperm mingle with the 23 chromosomes from the ovum, restoring the diploid number to 46 3. the fertilized ovum, now called a zygote, is ready for the mitotic cell divisionPre-Embryonic Periodfirst 2 weeks after conception. -when conceptus (fertilized ovum) is a solid ball of 12 to 16 cells, it is called a morula b/c it resembles a mulberry. the outer cells of the morula secrete fluid, creating a sac of cells (the blastocyst) that has an inner cell mass within the sac. the inner cell mass of the blastocyst cells develops into the placenta and fetal membranes -when it contains approx 100 cells. it lingers in the uterus another 2-4 days before beginning implantation. the endometrium now called the decidua, is in the secretory phase of the reproductive cycle, 1.5 weeks before the woman would begin her menstruation -conceptus carries a small supply of nutrients for early cell division, but implantation (nidation) at the proper time/ location in the uterus is crucial for cont. development. complete implantation a gradual process that occurs b/t 6 and 10 days. embryonic structures cont developing implantation. -zygote secretes hCG to signal that a pregnancy has begun. with continued hCG production by the conceptus, the corpus luteum continues to secrete estrogen/ progesterone rather than regressingLocation of Implantation (Pre-Embryonic Period)-right place at right time for implantation to occur -site of implantation is the place that the placenta develops. normal implantation occurs in upper uterus (fundus). its the best area b/c: its richly supplied w/ blood for optimal fetal gas exchange and nutrition uterine lining is thick preventing the placenta from attaching so deeply that it does not easily detach after birth limits blood loss after birth b/c strong interlacing muscle fibers in this area compress open vessels after the placenta detachesMechanism of Implantation (Pre-Embryonic Period)enzymes produced by the conceptus erode the decidua, tapping maternal sources of nutrition. primary chorionic villi are tiny projections on the surface of conceptus. they extend into decidua basalis that lies b/t conceptus and wall of uterus. nutritive fluid passes to the embryo by diffusion b/c no circulatory system is established yet. by 10 days the conceptus is fully embedded w/in the mother's uterine decidua as conceptus implants, usually time of next expected period, small amount of bleeding may occur at siteEmbryonic Period (cells become specialized)extends from the beginning of the 3rd week through the 8th week after conception -week 3 (neural plate becomes brain and spinal cord) -week 4 (eye, ear, limbs bud) -week 6 (eye, ear, limbs, CRL 13 mm) -week 8 (CRL 30mm - crown-rump length -human form) -week 12 (sex determination) -week 16 (quickening -butterflies) -week 21-24 (lungs develop -baby may survive at this period)Fetal Perioddramatic growth and refinement in the structure and function of all organ systems occur. teratogens may damage already formed structures but are less likely to cause major structural alterations. CNS is vulnerable to damaging agents throughout the entire pregnancyPlacentathick, disk-shaped organ. major functions: metabolic, transfer of substances b/t mother and fetus, endocrine. fetal side is smooth w/ branching vessels covering the mebrane-covered surface. maternal side is rough where it attaches to uterus. umbilical cord is normally inserted on the fetal side of the placenta, near the center. it may insert off-center or even out on the fetal membranes. it is larger than embryo or fetus during early pregnancy and low lying. fetus grows faster than placenta so that placenta is approx 1/6 the weight of the fetus at end of term pregnancy and implanted in upper uterusVelamentous Insertion of Umbilical Cordcord vessels branch far out on membranes. when membranes rupture, fetal umbilical vessels may be torn, and the fetus can hemorrage -amnion (inner membrane -chorion (outer membrane)Amniotic Fluidprotects the growing fetus and promotes normal prenatal development by: -cushion against impact -stable temperature -allowing symmetric development of the fetus as body surfaces fold toward midline -keeping membranes from adhering to developing fetal parts -providing room and buoyancy for fetal movement >fetal urine and fluid transported from maternal blood across the amnion. cast off fetal epithelial cells and vernix are suspended in amniotic fluid -at term, 500 to 1000 ml -hydramnios (excessive 2,000 ml; may occur fetus has sever malformation of CNS or GI tract prevents normal ingestion of amniotic fluid)Umbilical Cordtwo arteries (carries blood w/ co2; deoxygenated from fetus to placenta then to mother's circulation for elimination) and one vein (oxygenated; nutrient rich blood back to fetus) -coiled w/in cord to allow them to stretch and prevent obstruction of blood flow through them. entire cord is cushioned by soft substance called Wharton's jelly to prevent obstruction by pressureFetal Circulatory SystemThis system has three shunts that divert most circulating blood from the lungs and liver -oxygenated blood from the placenta enters the fetal body through the umbilical vein. approx half the oxygenated blood goes through the liver during early pregnancy and the rest bypasses the liver and enters the inferior vena cava through the first shunt 1) Ductus Venosus: Connects the umbilical vein to the inferior vena cava, bypassing the liver (right atrium) 2) Foramen Ovale: Connects the right atrium to the left atrium, bypassing the lungs (mixing small amount of blood returning from lungs. blood pumped from left ventricle into aorta to nourish body. small amount of blood from right ventricle is circulated into lungs to nourish lung tissue. rest of blood from right ventricle joins oxygenated blood in aorta through 3) Ductus arteriosus: Connects the pulmonary artery to the aorta, bypassing the lungs **head/upper body receives greatest amount of oxygenated blood. late pregnancy liver recieves 75-80% of oxygenated venous blood** **resistance to blood flow through uninflated lungs is high, causing right ventricle to work harder/ have thicker wall than left. breathing established, resistance to pulmonary blood flow falls and systemic resistance rises causing right ventricle wall to thin and left thicken**Changes in Blood Circulation After Birth-fetal circulatory shunts are not needed after birth because the infant oxygenates blood in the lungs, and metabolizes/filters substances in the liver, and stops circulating blood to the placenta -as the infant breathes, blood flow to the lung increases, pressure in the right heart falls, and the foramen ovale closes -Pressure in the aorta rises as pressure in the pulmonary artery falls -> causes the direction of blood flow through the ductus arteriosus to REVERSE from the aorta into the pulmonary artery. -The ductus arteriosus constricts -> closes when blood flow from the umbilical cord stops -The foramen ovale and ductus venosus permanently close as tissue proliferates in these structures -the ductus venosus and ductus arteriosus become ligaments, as do the umbilical vein and arteriesMonozygotic Twinningconceived by the union of a SINGLE OVUM and SPERMATOZOON, with later division if the conceptus into two -IDENTICAL GENETIC COMPLEMENTS and are of the same sex and are often called "identical" -a single conceptus divides early in gestation -in most cases -> formed blastocyst has two inner cell masses instead of one -> two amnions (inner membranes) but a single chorion (outer membrane) -If the conceptus divides EARLIER -> two separate but identical blastocysts develop and implant SEPARATELY -placentas may develop separately and may fuse together -their chorions also may fuse during prenatal development -> placenta membranes cannot always distinguish from monozygotic and dizygotic twins -LATE separation of the inner cell mass -> may result in twins with a SINGLE amnion and SINGLE chorion -> INCREASED risk of twin death because umbilical cords get tangled -Incomplete separation of the inner cell mass -> conjoined twinsDizygotic Twinningarise from two ova that are fertilized by different sperm -twins do not look alike -> "fraternal" -may be the same or different sex, they may or may not have similar physical traits -Infertility therapy + advancing maternal age -> INCREASED risk of dizygotic twin births -may be HEREDITARY (increased tendency to release MORE THAN ONE OVUM per cycle) -The membranes and placentas of dizygotic twins are separated because they arise from two separate zygotes -The membranes, placentas, or both may fuse during development IF they implant closely -NOT CONJOINED because they do NOT INVOLVE division of a single cell mass into twoUterus Growth during Pregnancy-uterine growth occurs as result of of hyperplasia and hypertrophy (during first trimester=growth cause by stimulation from estrogen/growth factors) -before conception weighs 70 g (2.5 oz) holds 10 ml (1/3 oz) -full term weighs 1100-1200 g (2.4-2.6 lb) and holds 5000 ml -12 wks of gestation, the fundus (top of uterus) can be palpated above symphysis pubis -16 wks, fundus reaches midway b/t symphysis pubis and umbilicus. -reaches highest level at xiphoid process at 36 wks, pushing against diaphragm -by 40 wks fetal head descends into pelvic cavity and uterus sinks to lower levelCervix Changes during Pregnancy-hyperemia (congestion with blood) results in bluish-purple color extending into vagina and labia referred as Chadwick's sign (earliest sign of pregnancy) -collagens fibers in connective tissues decrease, causing cervix to soften (tip of nose->earlobe) known as Goodell's sign) -cervical glands proliferate resembling honeycomb filled with mucus. Mucus plugs cervical canal and blocks ascent of bacteria from vagina into uterus during pregnancyOvary Changes during Pregnancyafter conception, major function of ovaries is to secrete progesterone from corpus luteum for first 6-7 wks of pregnancy until placenta is developed. once developed, placenta produces progesterone throughout pregnancy -ovulation ceases during pregnancy b/c circulating levels of estrogen and progesterone are high, stopping LH and FSH needed for ovulationBreast Changes during Pregnancyestrogen stimulates the growth of mammary ductal tissue, and progesterone promotes the growth of lobes, lobules, and alveoliCardiovascular Changes during Pregnancy- Cardiac changes are relatively minor and reverse after childbirth - Myocardium increases in size slightly due to the increased workload - A systolic murmur is heard in 95% of pregnant women - Blood pressure - First time pregnancies are more susceptible to gestational HTN - Blood volume is increased by as much as 45% - Cardiac output rises up to 50% with half of that rise occurring in the first 8w - Increases in various clotting factorsBlood Flow During Pregnancy-altered to include the uteroplacental unit -more blood must circulate through materna kidneys to remove increased metabolic wastes generated by mother and fetus -woman's skin requires increased circulation to dissipate the heat generated by increased metabolism -blood flow to breasts increases resulting in engorgement and dilated veins w/ feeling of heat and tingling -weight of expanding uterus on inferior vena cava and iliac veins partially obstructs blood return from veins in the legs, causing stasis of veins of the lower legs may result in varicose veins of legs, vulva, or rectum (hemorrhoids) -iron/ iron-binding product increaseRespiratory Changes during Pregnancy-Oxygen consumption increases by about 20 -oxygen is used by uterus, fetus, and placenta -rest is used by breast tissue, increased cardiac renal and respiratory maternal demands -to compensate, woman hyperventilates breathing more deeply although rate remains unchanged (promotes transfer of carbon dioxide from fetal to maternal circulation **renal excretion of bicarbonate from the kidneys compensates for the resulting respiratory alkalosisProgesterone Hormonal Factorsrelaxes smooth muscles (respiratory tract)Estrogencauses increased vascularity of mucous membranes of upper respiratory tract causing congestionGI Changes During Pregnancy-^ estrogen causes hyperemia (built up blood) -ptyalism (excessive salivation) -relaxed esophageal sphincter causes acid reflux and heartburn (pyrosis) -decreased emptying time (constipation -gallbladder hypotonic leaving gallstonesGU Changes During Pregnancy-Bladder (progesterone^relaxes muscle; change in glomerular filtration rate; ^ volume; ^ blood flow; walls become hypertrophrophied -Kidneys/ureters (change in shape/size d/t dilation from progesterone; ureters become elongated and distensible, compression of ureters b/t enlarging uterus & bony pelvic brim; renal blood flow ^ by 50%-80% by mid pregnancy, then decreases as pregnancy progresses to term; rise in plasma volume and cardiac output; GFR ^ by 50% 2nd trimester **glycosuria is common during pregnancy ^ UTI; mild proteinuria is common**Integumentary Changes During Pregnancy-pregnant women feel warmer and sweat more (^ circulation to the skin) especially during 3rd trimester -^ hyperpigmentation d/t estrogen, progesterone, melanocyte-stimulating hormone (brownish patches=melasma, chloasma, or mask of pregnancy) (linea alba=line that marks the longitudinal division of midline of abdomen darkens to become linea negra) -blood vessels dilate/proliferate (estrogen) surface blood vessels are obvious; spider angiomas and palmar erythema -striae gravidarum (stretch marks) -hair falls out 2-4 mnths postpartum; hair growth normal 6-12 after deliveryMusculoskeletal Changes During Pregnancy-absorption of calcium from intestines ^ first trimester to meet later needs of fetus (small) -2nd trimester ^ mobility of the pelvic ligaments to facilitate passage of fetus through pelvis. 28-30 wks pelvic symphysis separates; relaxed pelvic joints creates instability->wide stance and waddling gate; 3rd trimester creates progressive lordosis leading to backache -3rd trimester abdominal muscles stretch, rectus abdominis muscles separate (diastasis recti), varies from slight to severeEndocrine Changes During Pregnancy-prolactin from anterior pituitary gland ^ to prepare breasts to produce milk; FSH and LH stopped; posterior pituitary produces oxytocin stimulating milk-ejection reflex after childbirth and contractions to prevent excessive bleeding; during childbirth progesterone relaxes smooth muscle fibers of uterus -second half of pregnancy, maternal tissue sensitivity to insulin declines d/t effects of hCS, prolactin, progesterone, estrogen, cortisol. mom uses fat to meet energy needs; ^ BG for fetus energy needs producing ^ insulin **inadequate insulin results in gestational diabetes** -early pregnancy, hCG is produced by trophoblastic cells that surround developing embryo, stimulating corpus luteum to produce progesterone/estrogen until placenta developed approx 10-12 wks after conception **this causes positive pregnancy test** -Progesterone (maintain endometrium layer for implantation of fertilized ovum); (prevent spontaneous abortion by relaxing smooth muscle of uterus); (prevent tissue rejection of fetus); (stimulate development of lobes/lobules in breast to prepare for lactation) -normal pregnancy weight (25-35 lbs) fetus, placenta, amniotic fluid, make up > half the weight gain. rest is d/t ^ size of uterus, breasts, ^ blood volume, interstitial fluid, subcut fat -body water increases 6.8-8.5 L -b/c of hemodilution, a slight decrease occurs in colloid osmotic pressure causing edema -fluid retention-> carpal tunnel syndromeSensory Organ Changes During Pregnancy-eyes (corneal edema causes thickening) -ear (changes in mucous membranes of eustachian tube brought about by estrogen causes blocked ears/ mild temporary hearing loss -immune system altered d/t foreign tissue developing; autoimmune disorders improveEstimated Date of Delivery (EDD) from LNMP-subtract 3 months from the first day of the LNMP (last normal menstrual period), adding 7 days, and correcting the year if needed ex: LNMP: October 30, 2022 subtract 3 months: July 30, 2022 add 7 days and correct the year: August 6, 2023Fundal heightnot palpable until 12 weeks, 2nd and 3rd trimesters week gestation 20-22 cm so at the navel is 20 weeks -measure from from upper border of symphysis pubis to the top of fundusMaternal Responses of Pregnancy-First Trimester (uncertainty; self as primary focus; ambivalence-conflicting feelings) -Second Trimester (physical evidence of pregnancy; fetus as primary focus; narcissism and introversion; body image; changes in sexuality) -Third Trimester (vulnerability; preparation for birth;Calculate G/PGravida- pregnant woman; Nullipara- never given birth G/P (formula uses to record gravidity and parity -gravidity (# of pregnancies) -parity (# of births carried to viability -@ least 20 wks/doesn't matter if the fetus is born alive or not)