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M6 13-005

Exam 9: Labor & Delivery

Gametogenesis the development of ova in the woman and sperm in the man.
Gametes Oogenesis Spermatogenesis Meiosis
Oogenesis formation of female gamete
Spermatogenesis formation of male gamete
Meiosis the process in which cells divide to form gametes
Conception human fertilization occurs when the sperm penetrates an ovum and unites with it.
Release of the Ovum Ovulation occurs approx. 14 days before a woman's next menstrual cycle would begin. Estimated to survive no longer than 24 hrs after its release at ovulation.
Ovum Transportation Mature ovum (released on surface of ovary then picked up by fallopian tube). Fertilization occurs in the distal 3rd of the fallopian tube. Fertilized or not, ovum enters uterus approx 3 day after release.
Ejaculation MOST sperm survive no longer than 24 hrs in the female reproductive tract. A few may remain fertile for up to 80 hours.
Sperm transportation in the female reproductive tract Only sperm enters the cervix (seminal remains in the vagina). Most are lost along the way. Fewer than 50-150 reach the fallopian tube.
Prep of sperm for fertilization Sperm undergo changes that enable one of them to penetrate the protective layers surrounding the ovum (Capacitation)
Fertilization When one spermatozoon enters the ovum and the two nuclei containing the parents' chromosomes merge.
Fusion of the nuclei of sperm and ovum 23 chromosomes for sperm unite with 23 form ovum restoring the total # to 46.
Fertilization is complete and cell division can begin when The nuclei of the sperm and ovum unit.
What is conception? Human fertilization occurs when the sperm penetrates an ovum and unites with it.
Pre-embryonic Period First 2 weeks after conception. Around the 4th day after conception, zygote (fertilized ovum) enters the uterus.
Cell division (Initiation) Zygote divides until it reaches 16 cells (morula). Outer cells of the morula secrete fluid (blastocyst a sac of cells). Inner cell mass develops in the fetus. Outer layer of cells develops as placenta & fetal membranes.
Zygote into the uterus (Entry) Blastocyst contains approx 100 cells, enters the uterus. It lingers in uterus another 2-4 days before implantation. Endometrium (decidua), secretes rich fluids to nourish the zygote before placental circulation is established.
Implantation in the Decidua Proper time and location in the uterus is critical for cont. development. Occurs between 6th and 10th days after conception.
Maintaining the Decidua Survival of the zygote (requires continuing supply of E&P to maintain decidua in secreatory phase). Zygote secretes HCG (signals body that pregnancy has begun). HCG causes the corpus luteum continuing secretion E&P until placenta takes over.
Location of Implantation Location is important because that is where placenta develops. Normally in the upper uterus (slightly more often on the POSTERIOR wall)
Mechanism of implantation Chorionic villi form & nourish zygote by diffusion b/c circulatory system not established. Villi eventually forms fetal side of placenta, decidua basalis forms the maternal side of the placenta.
Zygote is fully embedded within the uterus by 10 days
Implantation Spotting As it implants, usually near the time of the next menstrual period, a small amount of bleeding may be confused with the normal period
what is the pre-embryotic period? The first 2 weeks after conception.
Zygote Cell formed by union of sperm and ovum.
Embryo 3rd week to 8th week of development
Fetus 9th week until birth
Embryonic Period Extends from the beginning of the 3rd week through the 8th week after conception
All major organ systems in place by End of 8th week
Why are structures vulnerable to damage from teratogens? because they are developing rapidly.
Teratogens agents that cause congenital malformations and developmental abnormalities if introduced during gestation (ie; Drugs, Viruses, Radiation, Infectious Agents).
Weekly Embryonic Development Pattern Cephalocaudal. Central-to-peripheral direction. Simple-to-complex. General-to-specific.
Cephalocaudal pertaining to the long axis of the body, or the relationship between the head and the base of the spine
3 germ layers that in turn give rise to major organ systems of the body Ectoderm. Mesoderm. Endoderm.
Teratogenic can do this to an embryo seriously harm
Prenatal Development: Week 2 Most growth occurs in the outer cells of the trophoblast. An inner cell mass becomes flattened into the embryonic disc (where 3 primary cell layers meet)
Prenatal Development: Week 3 First body segments appear: Neural tube forms. Primitive brain. Primitive Spinal Cord. Primitive or tubular heart begins beating at 22-23 days.
Prenatal Development: Week 4 Embryo is now 1/5th inch long; head is a third of its total length.
Week 4: Embryo Embryos shape changes resembling a "C" shape. Neural tube closes. Face & upper respiratory tract begin. Ears & eyes apparent. Upper extremities appear as buds. Partitioning of the heart into 4 chambers begins. Esophagus & trachea separate.
Prenatal Development: Week 5 Heart beating & continuing to develop 4 chambers. Limbs continue to form. Head is large d/t rapid brain growth.
Prenatal Development: Week 6 4 chambers of the heart are complete. Facial development begins with: -eyes -ears -nasal pits
Prenatal Development: Week 7 Development is proceeding rapidly: -Face is more human looking -Eyelids begin to form -Fast intestinal growth
Prenatal Development: Week 8 Embryo is now a little more than 1" long. Fingers & toes are stubby but well formed. External genitalia begin to differentiate. Heartbeat can be heard with an amplified stethoscope.
Fetal Period Longest part of prenatal development. Begins 9 weeks after conception & ends with birth. All major system are present in their basic form. Teratogens may damage already formed structures but are LESS LIKELY to cause major structural alterations.
Prenatal Development: Weeks 9 through 12 Head i 1/2 the total length of the fetus at the start of this period. 1st fetal movements begin but are too slight for the mother to detect. Eyes close at 9 weeks & reopen at 26 weeks. Urine production begins. End of 12th week, gender can be determine
Prenatal Development: Weeks 13 through 16 Grows rapidly in length. Quickening (fetal movement) occurs
Prenatal Development: Weeks 17 through 20 Vernix covers skin. Lanugo is present. Eyebrows & head hair appear. Brown fat is deposited. (Special heat-producing fat that helps newborn maintain temperature stability at birth)
Prenatal Development: Weeks 21 through 24 Fetus appears thin d/t minimal fat. Skin is translucent & red Lungs begin to produce surfactant although alveoli capillary network immature. Most systems still extremely immature & fetal survival is not likely.
Prenatal Development: Weeks 25 through 28 Fetus more likely to survive if born and lungs & CNS have matured. Subcutaneous is deposited under skin. Fetus assumes head down position.
Prenatal Development: Weeks 29 through 32 Toenails & fingernails are present. Subcutaneous fat increases. Skin is pigmented and smooth.
Prenatal Development: Weeks 33 through 38 Rate of growth slows; mainly gaining weight.
What is formed by the union of the sperm and ovum? Zygote
What are examples of teratogenic agents? Any drugs, virus or irradiation that the mother is exposed to. (Example; virus: Rubella)
What is the definition of the embryonic period? Extends from the beginning of the 3rd week through the 8th week after conception.
Placenta Thick dick-like organ. Made up of about 15-20 segments (cotyledons) that are present only during pregnancy. Site of exchange of nutrients, oxygen & waste products. After birth, it is expelled because it has no use.
Placenta: Hormones Produced Progesterone Estrogen HCG HPL
Placenta: Maternal side "beefy" rough appearance where it attaches to the uterus. "Dirty Duncan" Meternal and fetal blood low does not mix.
Placenta: Amniotic Fetal Membrane Grayish, shiny appearance. "Shiny Schultz"
Placenta: Fetal Component Chorionic villus supplied by a tiny fetal artery carrying deoxygenated blood & waste products from the fetus. Vein of the chorionic villus returns oxygenated blood & nutrients to the embryo and fetus. Arteries and veins converge in umbilical cord.
Placental Functions: Metabolic Produces some nutrients needed by the fetus -glycogen, cholesterol, and fatty acids are synthesized
Placental Functions: Transfer Exchange of oxygen, nutrients & waste products across the chorionic villi
Placental Functions: Endocrine Produces several hormones necessary for normal pregnancy.
Fetal Membranes (2) Amnion Chorion *So close together that they seem to be one membrane (the "bag of waters"), but can cen be separated.
Fetal Membrane: Amnion Inner membrane
Fetal Membrane: Chorion Outer membrane
Amniotic Sac A sac made up of the chorion and the amnion that contains the fetus and amniotic fluid.
Amniotic Fluid Clear, yellowish fluid that surrounds and protects the fetus in the uterus.
Amniotic Fluid: Function Protects the growing fetus & promotes normal prenatal development. -Cushions impact -Maintain Temperature -Symmetric development, major body towards midline. -Prevents developing fetal parts adhering to membranes. -Room & buoyancy for fetal movement.
Amniotic Fluid: Derivative (2) Fetal urine. Fluid transported from maternal blood across the amnion.
Amniotic Fluid: Around baby Castoff fetal epithelial cells & vernix are suspended in the amniotic fluid. Fetus swallows amniotic fluid & absorbs it in the digestive tract.
Amniotic Fluid: Volume Increases during pregnancy & is approximately 700-800 ml at 40 weeks.
Amniotic Fluid: Oligohydramnios An abnormally small amount. <400ml
Amniotic Fluid: Hydramnios an abnormally large amount. >2000ml
Amniotic Fluid: Contains Albumin. Vernix. Fat. Urea. Lanugo. Bilirubin. Castoff fetal cells. Fructose
Umbilical Cord Is the lifeline between the fetus & placenta. Contains 2 arteries and one vein. Protected from compression by Wharton's Jelly. Has no pain receptors.
Umbilical Cord: Vein Carries freshly OXYGENTATED & nutrient-laden blood to the fetus
Umbilical Cord: Arteries Carry DEOXYGENATED blood back & waste products away from the fetus to the placenta.
What is the amniotic sac? A sac made up of the chorion and the amnion that contains the fetus and amniotic fluid.
Identify 3 parts of the umbilical cord Two arteries, one vein, and Wharton's Jelly.
Fetal Circulatory Circuit because the fetus does not breathe air, several alternations of the postnatal circulatory route are needed. Also, the fetal liver does not have the metabolic functions that it will have after birth, because the mother’s body performs these functions.
Three shunts in the fetal circulatory system allow blood with the highest oxygen content to be sent to the ear and brain: Ductus venosus Foramen ovale Ductus arteriossus
Fetal Circulation: Dispursion OXYGENATED blood is brought to the fetus by thew umbilical vein: -2/3 blood: enters the fetal liver (portal sinus) -1/3 blood: bypasses the liver via the 1st shunt (ductus venosus)
Fetal Circulation: Process Blood enters the right atrium & joins deoxygenated blood from the body & head. Most blood passes directly into the left atrium through the 2nd shunt (foramen ovale) where it mixes with the small amount of blood returning from lungs.
Fetal Circulation: Blood Nourishment Blood ejected from LV into aorta to nourish body. Small amount of blood from RV is circulated to lungs to nourish lung tissue. Rest of blood from RV joins oxygenated blood in the aorta through the 3rd shunt (ductus arteriosus).
Which portion of the fetus receive the greatest amount of oxygenated blood? The head and upper body
Circulation changes at birth Fetal circulation shunts are not needed after birth: -infant oxygenates blood in the lungs & is not circulating blood to the placenta
Circulation Changes at Birth: Infant breathes & Lungs Expand Blood flow to the lungs increases. Pressure in the right side of the heart falls. Foramen ovale closes.
Circulation changes at Birth: Ducts Ductus arteriosus constricts when flow of blood from the umbilical cord stops. Transition to the postnatal circulatory pattern is gradual.
Which fetal circulatory structure is responsible for blood entering the heart from the vena cava & directed across the right atrium to the left atrium? The foramen ovale
Multi-Fetal Pregnancy: 2 Types Identical Twins (Monozygotic) Fraternal Twins (Dizygotic)
Mutli-Fetal Preganancy: Stats Incidence increasing in the U.S. Increase is a result of a rise in: -Maternal Age -Infertility Treatments Twinning is the most common form
Monozygotic twins The twins carry the same genetic code, same sex. May have two amnions (inner membranes) or a single chorion (outer membrane) or may have two amnions and two chorions. They share a placenta, or have two placentas that may fuse and appear as one at birth.
Dizygotic twins Same or different gender May not have similar physical traits These twins have a separate placenta, and the sex and genetic makeup can vary Membranes and placentas are separate but may fuse if close Women who conceive after age 40 increased
Multifetal Pregnancy Complications Spontaneous abortions Uterine over distension that can cause preterm Maternal anemia Gestational Hypertension Placenta Previa Abruptio Placentae Hydramnios Congenital anomalies Problems with entangled cords. Growth problems (twin to twin transf
Which twins originate with one fertilized ovum? Monozygotic twins
What are some possible complications from a multigestational pregnancy? Spontaneous abortions, prematurity, uterine over distention, birth defects and maternal anemia.
Created by: jtzuetrong