Title: Exploring Lifespan Development
1Exploring Lifespan Development
- Chapter 2
- Prenatal Development
- (Part 2)
2Quick Quiz
- What is the purpose of a menstrual cycle?
- T/F Women are born with all the eggs they will
ever have. - Conception happens where in a womans body?
- T/F A woman is pregnant for 10 months.
- The most dramatic changes in our development
occur when? - T/F All embryos start out as girls.
3Prenatal Development is Divided into 3 Periods
- Period of the Zygote (1-2 weeks) (Germinal stage)
- Period of the Embryo (3-8 weeks) (Embryonic
stage) - Period of the Fetus (9 weeks to birth)
- (stages of pregnancy/fetal development are also
referred to as trimesters, or 2 month increments)
41. Period of the Zygote
- Conception Cells Zygote travels
Implantation - Occurs ? Divide ? to uterus ? into
uterine wall - 0 hours 36 hrs 3-4 days 1 week
5From Conception to Implantation
6Internal Female Organs
Uterus
Fallopian Tube
Fallopian Tube
Ovary
Ovary
(Via Laparoscopic Surgery)
7Know
- The final step in the period of the zygote is
Implantation to the uterine wall. - Why?
8Implantation Facts (the answer to Why?)
- The dividing cell or blastocyst will not develop
if it is not implanted, for it needs nourishment
from the mother. - Implantation takes about 1 week to complete.
- Implantation triggers hormonal changes that tell
the womans body not to menstruate. - Once a Zygote is firmly implanted it is now
called an Embryo.
9 Cell Division Implantation (what it looks
like)
Blastocyst hatching out of the hard outer shell
before it can begin to implant
Implantation! On to the next phase
Blastocyst
102. Period of the Embryo
- The embryos body structures and internal organs
develop. - Leg, arm buds appear, sensory systems and the
brain and nervous system have begun to develop. - The embryo can sense its world, respond to touch
and is moving. (mom cant feel it yet!) - Amniotic fluid cradles the embryo and the
umbilical cord nourishes it and connects it to
the mothers blood supply. - Growth of the head takes precedence over growth
of the lower parts of the body
11Period of the Embryo, cont.
- The heart begins to beat at 6 weeks of pregnancy.
- The placenta permits the embryo to exchange
nutrients with mother - Placenta filters oxygen/nutrients which pass from
mother to embryo and permits carbon dioxide/waste
products to pass to the mother from the embryo. - Mother and embryo have separate circulatory
systems
12The Placenta (In Pictures!)
13Guess What Guys?
- You all started out as a female during the embryo
stage of development! - At 9 weeks of pregnancy your Y chromosome kicked
in and here you are, the vagina turned into a
penis.
14 Which Embie is A Human?
Dolphin
Water Buffalo
Komodo Dragon
Whale
Mouse
Human
15 Embryo Development
3 ½ wks Neuronal development begins 8 wks
Neurons begin to fire!
6 wks My heart beats!
1 inch long and ½ oz.
163. Period of the Fetus
- The longest prenatal period.
- Further maturation of fetal organ
systems/dramatic gains in size. - Gender can be determined via ultrasound.
- Significant increase in brain maturity means new
behavioral capacities ability to regulate its
own basic body functions.
179-12 Weeks of Fetal Development
- The brain signals the fetus to kick, curl its
toes, open its mouth, and suck its thumb. - Fingernails, toenails, tooth buds and eyelids
that open and close are formed. -
- 3 inches, lt 1 oz.
9 weeks
12 weeks
1813-24 Weeks of Fetal Development
22 wks
16 wks
20 wks
24-25 wks
1913-24 Weeks of Fetal Development
- Skin thickens and is covered with Vernix-which
protects it. A soft downy hair develops called
Lanugo which helps the vernix stick. - Movements are now strong enough for mom to feel.
- Alternates between periods of sleep/waking.
- Fingers/toes completely formed
- Fetus develops a temperament/activity level
- Fetal hiccoughs common
- Eyebrows, eyelashes and scalp hair emerge.
- 12 inches, 1.8 lbs.
20What is the Age of Viability?
- The point at which a fetus can survive outside
the womb. - Usually between
- 23-24 weeks of pregnancy.
22 weeks
2125-38 Weeks of Fetal Development
- Fetus practices breathing by breathing and
swallowing amniotic fluid - Heart/lungs capable of sustaining independent
life. - Layer of fat is added to aid in temperature
regulation - Fetus assumes head down position.
- 19-20 inches, 7.5 lbs.
22Question
- True or false
- Prenatal fetal movement can predict infant
activity levels after birth. -
23Critical Periods in Prenatal Development
- There are specific times during prenatal
development when certain organs are developing
rapidly. - If there is exposure to a Teratogen during these
Critical Periods there can be harm done to the
developing embryo/fetus.
24Critical Periods in Prenatal Development
25Teratogens
-
- Environmental agents that can harm the developing
embryo or fetus. - STDs
- HIV/AIDS
- Rubella
- Toxemia
- Rh Incompatibility
26Teratogens, cont.
- Drugs taken by the parents
- Heroin/Methadone
- Marijuana
- Cocaine
- Alcohol
- Cigarettes
27Teratogens, cont.
- Environmental hazards
- Parental age
28Know
- The embryo is generally more vulnerable to
exposure to teratogens than the fetus.