Prenatal Development Flashcards
What happens during conception?
When 2 gametes are united/fused
Define gametes
Sex cells/reproductive cells
Contains half the genetic information of a male/female
What are the 2 types of gametes?
Sperm and egg
How are gametes produced?
Cell division (meiosis)
Meiosis involves taking only half of the genetic material of all other normal cells in the body
Where does fertilisation of the egg usually happen?
Fallopian tube
List the 4 steps to conception
1) Egg launches from the ovaries to the fallopian tube
2) As egg moves toward the uterus, it emits a chemical substance to signal sperm to its direction
3) After intercourse, 500 million sperm is ejaculated into the vagina
4) Sperm unifies with egg
What is the term used to describe a fertilised egg?
Zygote
What are the 3 periods of prenatal development?
1) Germinal
2) Embryonic
3) Fetal
When does the germinal period happen?
From conception - 2 weeks
When does the embryonic period happen?
From week 3 to week 8
When does the fetal period happen?
From week 9 to birth
At what prenatal period does the zygote
becomes implanted in the uterine wall?
Germinal period
At what prenatal period does rapid cell division take place?
Germinal period
When does rapid cell division take place during the germinal period?
As early as 12 hours after fertilization
Define mitosis
When the zygote doubles its number of cells roughly twice a day
At what prenatal period does the zygote perform mitosis?
Germinal period
What is the scientific term used to describe twins who are identical?
Mono-zygotic twins
What is the scientific term used to describe twins who are fraternal?
Dizygotic twins
How does the conception of monozygotic twins happen?
- When a single egg is fertilised by a single sperm but later on the zygote splits into 2
- Hence, the twins have the same genetic material as they came from the same cell
How does the conception of dizygotic twins happen?
- When 2 separate eggs are released from the ovaries and are fertilised by 2 separate sperm cells
- Hence, the twins have different genetic material as they came from separate cells
What is the term used to describe the results of the proliferation of cells?
Simply = When zygote keeps doubling (mitosis) until the zygote becomes a newborn with millions of cells
Cell division
What is the term used to describe the movement of cells from point of origin to other locations in embryo?
Cell migration
What is the term used to describe the transformation of stem cells into roughly 350 different types of specialized cell?
Simply = After continuous cell division, the cells start to specialise
Cell differentiation
What term is used to describe the selective death of certain cells (apoptosis)?
Cell death
Define apoptosis
When cells are genetically programmed to die based on a specific timeline
At which prenatal period does major development occur in all the organs and systems of the body?
Embryonic period
At which prenatal period does development take place through the processes of…?
- cell division
- cell migration
- cell differentiation
- cell death
Embryonic period
At which prenatal stage does the zygote turn into an embryo after multiple weeks of mitosis?
Embryonic period
What happens to the inner cell mass and the rest of the cell after the zygote performs multiple weeks of mitosis?
Inner cell mass becomes the embryo
Other parts of the cell become the embryo’s support system
What are the 2 types of support systems the embryo gets?
- Placenta
- Amniotic sac
What is the term used to describe a U-shaped groove formed from the top layer of differentiated cells in the embryo?
The neutral tube
What does the neutral tube eventually become?
It eventually develops into the brain and spinal cord
How does the neural tube become the brain and spinal cord?
One end of the tube will swell to become the brain and the rest of the tube becomes the spinal cord
When does the inner cell mass fold itself into 3 layers?
During the 2nd week
What are the 3 layers of the inner cell mass?
1) Top layer
- Nervous system
- Nails, teeth
- Inner ear
- Eye lens
- Outer skin
2) Middle layer
- Muscles
- Bones
- Circulatory system
- Inner skin
- Internal organs
3) Bottom layer
- Digestive system
- Lungs
- Urinary tract
- Glands
What term is used to describe a semi-permeable tube that allows the exchange
of materials between the bloodstream of the fetus and that of the mother?
Placenta
What is the purpose of the placenta?
It keeps the circulatory systems of the fetus and the mother separate but the semi-permeable membrane permits some material exchange (i.e. oxygen, waste, nutrients and CO2)
What term is used to describe the tube that contains the blood vessels that travel from the placenta to the developing organism and back again?
Simply = The tube that connects the fetus to the placenta
Umbilical cord
At which prenatal development period involves the continued development of physical structures and rapid growth of the body?
Fetal period
At which prenatal development period does the fetus receive antibodies from the mother in last month (particularly) of pregnancy?
Fetal period
At which prenatal development period does the fetus experience increasing levels of behaviour, sensory experience, and learning?
Fetal period
How long is the 1st trimester of pregnancy?
Week 1-Week 12
How long is the 2nd trimester of pregnancy?
Week 13-24
How long is the 3rd trimester of pregnancy?
Week 25-38
What term is used to describe the barrier that blocks against some, but not all toxins and infectious agents?
Placental membrane
What are the 2 components that protect the fetus?
1) Placental membrane
2) Amniotic sac
What term is used to describe a membrane filled with fluid in which the fetus floats, provides a protective buffer for the fetus and regulates temperature?
Amniotic sac
When does the fetus start spontaneously moving during prenatal development (at how many weeks)?
Around 5 weeks
When does the fetus start hiccupping during prenatal development (at how many weeks)?
At 7 weeks
Why does the fetus start hiccupping at 7 weeks?
- To practice a burping reflex (that they’ll use after birth to get rid of excess air)
- Prepares fetus for eventual nursing by removing air from the stomach to make more room for milk