Presentation on theme: "Aim: How does an embryo develop inside the uterus? Do Now: Explain the difference between internal and external fertilization and development. Which one."— Presentation transcript:
Aim: How does an embryo develop inside the uterus? Do Now: Explain the difference between internal and external fertilization and development. Which one would produce more offspring? Explain.
How long are humans pregnant? Females are pregnant for nine months or 40 weeks During this time, the mother and baby undergo many changes.
Embryonic Development :(Review) + SpermEgg Fertilization Zygote Mitosis Embryo- the stage in human development from the first division of the zygote until about eight weeks after fertilization.
Cleavage (Review) The term used to describe the early cell division associated with embryonic development. During this time period, the number of cells increase tremendously.
The result of cleavage is an embryo that is ….. A solid ball of cells which moves towards the uterus Morula
Mitosis continues & the embryo becomes…… A hollow ball of cells Blastocyst
What happens after fertilization? The embryo travels to the uterus and implants itself in the uterus lining
EARLY DEVELOPMENT Cleavage occurs by mitosis 4 days the embryo = 50 cells 6-7 days = 100 cells and Attaches to the uterine wall (IMPLANTATION)
Cell division continues & the embryo starts to …. Gastrula Fold inwardly
Gastrulation Three layers Each layer will eventually form the different organ systems Ectoderm (skin & CNS) Endoderm (GI Tract & lungs) Mesoderm (muscle, bone, blood)
CELLULAR DIFFERENTIATION Due to gene expression, cells undergo cellular differentiation, in which the cells become increasingly specialized in structure & function.
Embryo vs. Fetus Embryo Fetus (Fertilization-8 weeks) (8 weeks-Birth) Once the embryo becomes a fetus, all the major organs have begun to form.
In the uterus - womb Surrounded by an amniotic sac & fluid for protection from shock Where does the embryo develop?
Why is the fetus floating in a fluid? The fetus is surrounded by amniotic fluid and it helps absorb shock
What does a developing embryo need? 1. Nutrients for ATP & to build its own body parts 2. Oxygen for ATP
Fetal Blood Supply The blood from the mom and the embryo NEVER mix. Materials diffuse between the mother’s blood & the baby’s blood.
Umbilical Cord The umbilical cord is responsible for carrying nutrients and oxygen to the developing fetus, and waste away.
Placenta The placenta is the organ that allows for the exchange of nutrients and wastes (DIFFUSION OF NUTRIENTS)
STRUCTURES BY 3rd WEEK Placenta Nervous and endocrine system (starting) Vital organs forming Heart is beating
FIRST TRIMESTER (3months) Most major organs formed Umbilical cord formed Muscular system developed Reflexes Amnion formed
SECOND TRIMESTER Tissues become specialized Skeleton forms Strong fetal heartbeat At ~6 months the baby can live outside the mom with life support
3rd Trimester Fetus doubles in size Lungs are forming Sleeps 90-95% of the time Dreams Premature if born before 8 months
What happens at around 9 months? The fetus has developed all its organs and is ready to live in the outside world The uterine muscles begin to contract and the baby is forced out of the mother. This process is called:Labor
Prenatal care Good nutrition Moderate exercise No smoking No drugs, prescription or illegal No alcohol
Don’t get morning sickness: Thalidomide (1950)
Fetal Alcohol Syndrome (FAS) Consuming alcohol during development can cause FAS which has disastrous affects on the CNS. Includes: Low birth weight Small cranium Organ dysfunction Failure to thrive Developmental delays
What trimester is the most dangerous? The first trimester, because all the organs are forming at this time. Dangerous chemicals can affect cell division.