Pre-natal Biological Development

Question 1

Phylogenetic development proposes that…

Answer 1

humans have same origin with other animals and plants

Question 2

Describe how human brains are similar and different with other animals (mammals)

Answer 2

similar:
-> cognitive development and physiology are the same
difference:
-> size is way bigger

Question 3

where are ovum produced and how they travel?

Answer 3

produces at the ova -> travels along the fallopian tub to the uterus

Question 4

Describe meiosis and the outcome

Answer 4

-> Parent cell (46 chromosomes) replicate its own chromosomes
-> Homologous chromosomes pair up and cross over information on content randomly (genetic variation)
-> Go to the middle and splitted into two gametes.
-> Same process for the second time (results in four gametes with 23 chromosomes including x or y) (only male has y chromosomes in gametes, therefore defining the sex of the infant)
-> four sperms and one egg.

Question 5

Describe what happens after sperm enters the ovum and when does the brain start to develop

Answer 5

-> one sperm enter the ovum, the tail of the sperm loses
-> the nuclei of the sperm interacts with the nuclei of the ovum
-> forms the zygote.
-> 12 hrs later the zygote starts to reproduce through the process of mitosis (the process of the parent cell reproducing into two identical daughter cells)
-> 2-3 weeks after conception

Question 6

What happens after the mitosis

Answer 6

Around 4 days after conception:
-> Blastocyst is formed
-> Blastocyst is attached to the wall of the uterus
-> Around 75% fails during the process

Question 7

After Blastocyst and the four main support systems

Answer 7

-> the embryo is formed through cell differentiation
-> Inner cell mass = embryo, others = amniotic sac and placenta
-> the four main support systems:
1. Amnion = provides the weightless and suitable environment for the baby
2. Chorion = the outer layer of the amnion and later becomes the placenta
3. Allantois = umbilical cord

Question 8

3 layers of the inner cell mass

Answer 8

ectoderm: becomes the nervous system, nails teeth
mesoderm: skin, bones, muscles
endoderm: internal organs (lungs and glands)

Question 9

The neural tube develops into…

Answer 9

the brain and the spinal cord

Question 10

How are identical twins and fraternal twins differ?

Answer 10

Same zygote splits into two vs two totally separated zygote

Question 11

Describe the sensations and learning of the baby in the embryo and when does the CNS capable enough to support fetal learning

Answer 11

-> babies can move by the end of week 12 (degree of movement correlates with post-birth activeness)
-> they can taste, smell and hear
-> learning: more reactive to sound they’ve heard in the embryo, smell they’ve been exposed etc.

last 3 months of pregnancy

Question 12

What are teratogens?

Answer 12

-> external environmental agents that harms or even lead to the death of the embryo.
-> e.g., alcohol leads to fetal alcohol syndrome (lower IQ, hindered physical growth, smaller head, malformations of the heart and other organs etc)
-> Thalidomide (drug taking)
-> Mothers with diseases (e.g., german measles). Sensitive period: 8 weeks

Question 13

what are the three periods of pregnancy?

Answer 13

zygote (0-14 days)
embryo (3-8 weeks)
fetus (9 weeks till birth)

Question 14

what are the characteristics of teratogens

Answer 14

> parts of the fetus/embryo are only damaged if they are exposed to the teratogens during the sensitive periods
The same teratogen can cause multiple effects (Thalidomide)
The first trimester of pregnancy (0-12 weeks) is the most critical period

Question 15

Describe alcohol as a teratogen

Answer 15

Alcohol can does not have a specific sensitive period, which means that alcohol can affect the fetus/embryo throughout the entire pregnancy