Fetal Development/Genetics Flashcards
What must happen with the female for conception to occur?
A healthy ovum is released from the ovary, passes into an open fallopian tube, and starts its journey downward
What is the area where fertilization takes place?
Sperm from the male is deposited into the vagina and swims approximately 7 inches upward to meet the ovum at the outer most portion of the fallopian tube
How long does it take for the ovum to reach the cervix?
an hour
How long does the process of fertilization typically take?
5 hours
Pre-embryonic Stage
fertilization through the second week
What are the 3 stages of fetal development during pregnancy?
- Pre-embryonic
- Embryonic
- Fetal
When does fertilization typically occur?
around 2 weeks after the last normal menstrual cycle
Morula
16 cells appearing as a solid ball of cells
“little mulberry”
Reaches the uterine cavity about 72 hours after fertilization
Blastocyst
appears within the morula as an off-centered, fluid filled space, transforming into a hollow ball of cells
-inner surface will form the embryo and amnion
Trophoblast
outer layer of cells surrounding the blastocyst cavity
What will the trophoblast develop into?
one of the embryonic membranes, the chorion, and helps to form the placenta
What will the inner surface of the blastocyst develop into?
Will form the embryo and amnion
What will attach its self to the endometrium for implantation?
trophoblast
Where does implantation typically occur?
Fundus
What are the 3 embryonic layers of cells formed?
Ectoderm
Mesoderm
Endoderm
Ectoderm
forms the central nervous system (CNS), special senses, skin, and glands
Mesoderm
forms the skeletal, urinary, circulatory, and reproductive systems
Endoderm
forms the respiratory system, liver, pancreas, and digestive system
What two fetal membranes form the fluid-filled amniotic sac?
Amnion and chorion
How much fluid can the amniotic sac hold at full term?
1 L
What is amniotic fluid derived from?
Maternal blood and fetal urine
Embryonic Stage
begins at day 15 after conception and continues through week 8
Week 3 Gestation
Beginning development of brain, spinal-cord, heart, and GI tract
-Leg and arm buds appear and grow
Week 4
Brain differentiates
Stomach, pancreas, and liver begin to form
Week 5
Heart beat has regular rhythm
Beginning structures of eyes and ears
Some cranial nerves visible
Muscles innervated
Week 6
Beginning of lungs Fetal circulation Liver produces RBC's Primitive skeleton forms CNS forms Brain waves detectable
Week 7
Straightening of trunk Nipples and hair follicles form Elbows and toes visible Arms and legs move Diaphragm formed Heart beat can be heard Mouth with lips and early tooth buds
Week 8
Rotation of intestines
Facial features develop
Heart development complete
Resembles a human being
Weeks 9-12
Sexual differentiation continues Buds for all 20 temporary teeth formed Digestive system shows activity Head comprises is nearly half the fetus size Face and neck are well formed Urogenital tract complete Red blood cells produced in liver Urine is produced and excreted Fetal gender can be determined Limbs long and thin; digits formed
Weeks 13-16
Lanugo hair Fetal skin is almost transparent Bones become harder Sucking motions Amniotic fluid is swallowed Fingernails/toenails Weight quadruples Mom can feel movement
Weeks 17-20
Rapid brain growth Fetal heart tones heard w/ stethoscope Vernix ceseosa covers the fetus Eyebrows and head hair Sebaceous glands Brown fat Muscles well developed
Weeks 21-24
Eyebrows and eyelashes Grasp and startle reflex Alveoli forming in lungs Skin is translucent and red Lungs begin to produce surfactant
Weeks 25-28
Fetus reaches length of 15 inches Rapid brain development Eyelids open and close Nervous system controls some functions Fingerprints are set Blood formation shifts from spleen to bone marrow Usually assumes head-down position
Week 29-32
Rapid increase in body fat Increased CNS control Rhythmic breathing movements occur Lungs are not fully mature Stores iron, calcium, phosphorus
Week 33-38
Testes are in scrotum of male fetus Lanugo begins to disappear Increase body fat Small breast buds present Mother supplies fetus w/ antibodies Considered full term at 38 wks Fills uterus
Oligohydramnios
too little amniotic fluid (< 500 mL)
What can happen due to oligohydraminos?
uteroplacental insufficiency, fetal renal abnormalities, higher risk of surgical births, and low birth weight
