User:Atcovi/Developmental Psychology/Chapter 2 (Birth)

=2.1 (Genes and Chromosomes)= All living beings are made out of cells, to which each cell contains DNA. Every molecule of DNA is stored in a chromsome. Almost all humans have 46 chromosomes.

Every chromosome contains a gene (contains molecules of DNA/RNA). Every cell in the human body contains a copy of that human being's chromosomes (in pairs) except for its reproductive cell (the gamete). Each gamete (sperm for man and ovum for woman) contains only 23 chromosomes.

During conception, the genes on the 23 chromosomes from the sperm link up with the genes on the 23 chromosomes from the ovum. This creates a zygote.

Remember the order is: Genome, Chromosome, Gene, Nucleotide.

Variations in People

 * Homozygous - Two identical alleles for a gene.
 * Heterozygous - Two different alleles for a gene.

How unique are you?

 * More than 8 million versions of the mother and father's chromosomes are all possibilities for the zygote. Every zygote forms from 8 million possibilities from the man and the woman.
 * The DNA code on those chromosomes contain over a billion base pairs of chemicals boiled down into triplets (three pairs). Each dictates production of a possible 20 amino acids.
 * Copy number variations (mutations, repetitions) in the triplets cause significant changes in the build-up of a person.
 * Methylation - Alters genes, made up of other DNA/RNA molecules.

Genetic Expression
Almost every trait emerges from a combination of genes, each depending on epigenetic factors on whether they're expressed or not.

Microbiome
The microbes of the human body are all the bacteria, viruses, fungi, archaea and yeasts that live within the human body. Although most people try to kill these "germs", most of them are actually helpful for us. They have their own DNA.

After a study finding that mice change body size when a microbe of another mice with an opposite body size is implanted in them, we're able to figure out that the microbiome affects genetic expression.

Siblings
Although contrary to what one may think, siblings are not alike whatsoever! They each have their own unique zygote. Copy variations account for many differences, although majority are significant, some may be a step away from certain health conditions.

Genotype and Phenotype

 * Genotype - Collection of a person's genes [beginning of diversity]
 *  Phenotype - Person's appearance and behavior [manifestation of diversity (result of “multiple interactions among numerous genetic and environmental factors”)]

Shared and Divergent Genes

 * Genome - Full set of genes that are the instructions to constructing an individual member.
 * Human Genome Project - Scientific project to determine the base pairs of human DNA and displaying all genes of the human genome.

Male and Female
One chromosome on the 23rd pairing of chromosomes is crucial for sex makeup. XY is for males, and XX is for girls. The Y chromosome contains a gene, the SRY gene, which entails the fetus to create male organs. Gender of the fetus is determined by which sperm penetrates the ovum, the Y or the X.

Sex ratio is worth noting here: during conception, the males outweigh the females. (XY:XX 120:100). But since male embryos are more sensitive than female embryos (more Y genes?), they are less likely to survive the pre-natal stage. At birth its somewhat evens, with males:females 104:100. Nurture is playing its role here: males are more likely to die at birth (if the woman lacks pre-natal care and proper nutrition) and women are more likely to live older than 85 compared to men.

Twins
In the cases of twins/triplets, the zygotes duplicates and (1/250 human conceptions) splits into two - creating genetically identical zygotes. An example of this are monozygotic (MZ) twins (twins who come from one zygote that split early in development; same-sex) from one zygote. An incomplete split results in '''conjoined twins. Dizygotic (DZ) twins''' are where "twins who are formed when two separate ova are fertilized by two separate sperm at roughly the same time (same/different sex)". They are born 3x compared to monozygotic twins.

Genetic Interactions

 * Additive genes - They "add" up to create the phenotype (skin color and height, combination of both rather than one or the other).
 * Nonadditive genes - Genes that do not contribute in equal proportions. An example of this is alleles interacting in a dominant-recessive manner. For each gene from their parent, one is dominant and one is recessive. The dominant is the influential gene while the recessive gene is carried on his/her genotype.
 * X-linked traits - A recessive X-linked gene, for recessive genes like color blindness, they will show since the X gene is critical. This is because the X-linked recessive genes do not have a dominant gene since the Y is a lot smaller than the X. Girls are protected by their other X gene, but boys do not have this luxury as they have a small Y. Males with inherited X-linked genetic diseases inherit it from their mother since girls are protected by the other X gene (the dominant gene).

= 2.2 From Zygote to Newborn =

First 2 weeks
This period is known as the germinal period (2 weeks after conception). Here, the single cell germinates into an embryo. Hours after conception, the zygote begins splitting up and duplicating.


 * 1) The 23 pairs of chromosomes duplicate, forming two sets of the genes.
 * 2) These two new cells duplicate and divide, turning into 4.
 * 3) These four new cells duplicate and divide, turning into 8.

Then differentiation begins. Here the cells take different forms and reproduce at different rates. After a week, the multiplying cells separate themselves into two masses.

The outer cells first task is to form a special kind of "wall" to protect the embryo, known as the placenta. This must nourish the future embryo during the prenatal time. Afterwards, implantation takes place - the developing life attaches itself to the mother's uterus, thereby creating the interdependence relationship between the two.

Embryo (3rd --> 8th Week)

 * Embryo - Developing human life from 3rd-8th week.

End of 2nd Week

 * Primitive Streak - Thin line in the middle of cell mass which creates the neural tube 22 days after conception. This turns into the central nervous system and the body parts begin to emerge (eyes, ears, mouth, nose, etc.).

5th Week

 * Buds (future arms and legs) emerge.
 * Heart is formed
 * Forearms and webbed fingers emerge.
 * Legs, knees, feet, and webbed toes grow (in this order).
 * 52-54 days after conception, the fingers and toes separate.

End of 8th Week

 * Weighs 1 gram and about 1 inch long.
 * Has all body parts of a human being.

In the early stages, the embryo contains an intersex gonad with both male and female private parts. At the end of this period, hormonal/genetic influences cause one or the other to decrease in size and then either private part grows from that point onwards.

Fetus (9th Week --> Birth)

 * Fetus - Developing human organism from the 9th week till birth.

3rd Month

 * Weighs about 3 ounces, about 3 inches long.

4th, 5th and 6th Month

 * Greatest brain growth, now with hemispheres and many neurons and synapses are formed.
 * About the 5th month (22 weeks after conception), the brain's maturity may allow the fetus to be taken care of WITHOUT the mother's care (this is known as the age of viability).

Last Trimester (months 7, 8 or 9)

 * Organs are fully formed, weight is significantly gained (doubled), fetus is prepared for outside life.
 * Heart beating is fastest its ever been during this period

Chromosomal Anomalies
Most sperm and ova actually do not have exactly 23 chromosomes. The zygotes with an erroneous number of chromosomes are usually reduced before conception takes place.


 * Mosaicism - One person has cells with various genetic makeup.
 * Syndrome - Series of symptoms that are associated with a particular condition.
 * Trisomy - Three chromosomes in a certain location rather than the normal two (causing serious medical conditions).

Difference between the insignificant mosaicism and a syndrome? An entire chromosome!

 List of Syndromes 

 List of Diseases 
 * 1) Down Syndrome - 3 chromosomes at the 21st location. Symptoms include thick tongue, slanted eyes, round face, physical abnormalities, etc.
 * 2) Sex Chromosomes Syndromes - An embryo is unable to develop without 44 autosomes and one X chromosome.  1/300 infant(s) is born with either only an X or with three or more chromsomes. These include XXY (Klinefelter syndrome: learning disablities, puberty is disrupted including voice not deepening), XYY (Jacob's syndrome: poor language skills, extremely tall), XXX (Triple X syndrome: for females, mentally challenged) and XO (Turner syndrome: for females, short with webbed necks, puberty is disrupted).


 * 1) Huntington's Disease - A fatal central nervous system illness that shows up in adulthood. This is caused by 35+ repetitions of a certain set of 3-base pairs (copy number variations).

Gene Disorders
All of us carry dozens of alleles that have the potential to showcase detrimental diseases. So, what are the factors that prevent these?

Most recessive diseases are on the autosomes (non-sex chromosome) and is not X-linked, meaning either parent could be a carrier. Albiet, a few are X-linked. An example is fragile X syndrome, which is caused by an insane amount of repititions of one gene. Since it is X-linked, boys are more affected by this than girls since the latter have only one X.
 * 1) If the inherited gene is dominant
 * 2) If the zygote receives the same recessive gene from both parents (see "Recessive genetic conditions")
 * 3) If the number of additive genes add up and cause major issues.

Spontaneous Mutations

 * Spontaneous Mutations - Not present in the parents' genes, unlikely to show up in future embryos. This is more likely to show up if the parents have been exposed to pollutants/radiations, affecting the zygote or the sperm/ovum. Also, the older the parents, the more likely the mutations to occur.

Nature usually aborts embryos early during the pregnancy stages if the embryo has a major abnormality.

Teratogen
A teratogen is a substance in the prenatal environment that can affect a healthy embryo. An example is alcohol.

Birthweight
 Definitions 
 * Low birthweight - <2500 grams
 * Very low birthweight - <1500 grams
 * Extremely low birthweight - <1000 grams
 * Preterm - 2 or more weeks earlier than ideal time (full 38 weeks)
 * Small for gestational age (SGA) [small for dates]- A baby who's weight is significantly lower than what was expected, accounting for appropriate time after conception. This may be because of a teratogen or poor nutrition.

Causes of Low Birthweight

 * 1) Preterm Labor
 * 2) Teratogens
 * 3) Poor Nutrition

Consequences of Low Birthweight

 * 1) Cry often, disobedient
 * 2) Neurological disruptions
 * 3) Develop diabetes/cardiovascular diseases, depression [adulthood]

Remember that plasticity may have a say in these situations, thereby reducing any impairments.

Prevention of Low Birthweight

 * 1) Eating enough and having good nutrition
 * 2) Increase intake of folic acid (prevents spina bifida).
 * 3) Starting pre-natal care early on.
 * 4) Watching over what type of medications you take during pregnancy.

Father's Impact
Everyone, including the woman's spouse, has a significant affect on the fetus' health (stressing the mother, for example). This has been proven in the:


 * Immigrant Paradox - Immigrants being more successful than the non-immigrants in several outcomes, including health of a newborn. In this specific situation, this is thought to be the case because immigrant fathers and the culture they bring entail a strictness in care of the mother.

2.4 (A Baby!)

 * Timeline: 36 weeks after conception

Labor begins with the fetus' brain releasing oxytocins to begin labor. The baby is born normally after 12 hours (if first birth) and following births about 7 hours.

Normal Birth Timeline


 * 1) 1st stage of labor: Cervix dilates, allowing a pathway for the baby's head
 * 2) Baby starts moving through the birth canal (the vagina)
 * 3) 2nd stage of labor: Baby moves through the pathway and comes out of the mother completely
 * 4) 3rd stage of labor: Expulsion of placenta


 * Apgar Scale (Appearance, Pulse, Grimace, Activity, and Respiration) - Measurement of a baby's health. <6 = emergency, >7 = good.

Natural Birth
The following is an opininated piece supporting the use of natural birth Birth is the emergence of an offspring from its parent and is, thereby, the start of a new life. The birth of a child can be considered a natural occurrence (since this is how humans have been repopulating on Earth for centuries) or a medical emergency (such as unplanned childbirth and in cases where the mother is on the verge of death due to significant blood loss). Naturally, people may raise the question: Which method of childbirth is better? Which method would I prefer for me and my partner? After some extensive research and reading, I've come to the conclusion that vaginal birth (natural birth) is the best option.

I would choose this method because this has been the most used method throughout history. It's the most natural process and the woman's body is constructed in a way to ensure that the process is safe and manageable. This method also requires little to no medical intervention (which most women would prefer not to have medical intervention), saving the risk of a doctor acting way too fast during the procedure. I believe that we would only need a different way of birth (c-section or epidural) in a case where my partner cannot physically accomplish a vaginal delivery (such as if my partner's uterus is too small or the baby's head is not in the right position for it to leave its mother's body). Finally, this method also gives a feeling of immense satisfaction to the woman, who has single-handedly brought a new life to this Earth.

Although I personally believe the advantages outweigh the disadvantages, the latter still requires some mentioning. The pain can be unbearable and not a pleasant experience for the woman and could possibly take away the experience of childbirth. Also, a series of complications may arise (such as a huge amount of blood loss), which may prove disastrous if there is no medical intervention. Finally, women who are older, have a history of medical conditions (such as diabetes), and have previously used a C-section are recommended NOT to conceive a child through vaginal birth.  Sources 
 * 1) Hersh, Erica. “Natural Child Birth: What to Expect, Benefits, Risks, Recovery & More.” Healthline, Healthline Media, 29 May 2019, www.healthline.com/health/pregnancy/natural-birth (Links to an external site.).
 * 2) Lothian, J A. “Why Natural Childbirth?” The Journal of Perinatal Education, U.S. National Library of Medicine, 2000, www.ncbi.nlm.nih.gov/pmc/articles/PMC1595040/.

C-section
A cesarean section (or c-section) is a method of birth where the abdomen and uterus of the mother is cut open to retrieve the baby (and thereby avoid a vaginal birth). Once a very rare practice, it is very common and has increased in usage in the US. Countries with low rates of C-section have higher infant mortality, but the opposite is not necessarily true either.

Reasons for a c-section include:


 * Multiple births
 * Fetus head is not straight down
 * C-sections in the past
 * Long labor (24hrs+)
 * Medical conditions (diabetes)

Advantages

 * Better to schedule
 * Birth is quick

Disadvantages

 * More expensive for women
 * Less likely to breastfeed, develop medical conditions afterwards
 * Children born this way are more likely to develop asthma or become obese (this is thought to be because the microbiomes of a c-section baby do not contain beneficial bacteria vs. a baby born naturally).

Epidural
An epidural is the injection in to the back of the mother to alleviate the pain of birth. This may be good to relieve pain, but it may cause complications for the baby (less newborn suckling). Induced labor is another method of birth where the birth is sped up by a drug. This may be essential for the lives of the baby and mother, but may cause complications.

Home Birth
A home birth is self-explanatory. A home birth is very risky since in the case of a medical emergency, a trained profession isn't nearby to assist the mother. This is why newborn death is high in countries where home births are very common.

Some people may want doulas when a home birth is taking place (a person trained to support a birthing woman). Doulas have shown to be very useful for immigrants who are scared of doctors. They help out the mothers by showing them efficient breathing techniques, give good massages and a sense of calmness. After the birth, the doula can provide care advice, such as breastfeeding, and can increase bonding between the infant and the mother.

New Family Member!
In the first day or so of the newborn, the NBAS test may be applied which records certain reflexes and behaviour patterns.

Although the entrance of a new family member is surely an exciting and welcoming feature, a lot of pain can be brought onto the mother after birth. This includes general healing, sore nipples and urination issues. After the "honeymoon phase" is over (after birth), 1/7 mothers fall into a postpartum depression, a feeling of sadness after the birth.

Fathers also play a pivotal role in the birthing process. They create a sense of calmness and courage in the mother during the whole birthing process (including before, during and after labor). A study found that an absence of a father figure resulted in longer complications and longer labor. A couvade is a father's symptoms after a birth, which may include depression as well.