Chapter 2 Flashcards
how many chromosomes do people have (those without an abnormality)
46chromosomes
23 from mom and 23 from dad
Three stages of Prenatal Development
first 2 weeks - Germinal stage
weeks 3-8- Embryonic stage
weeks 9-birth- Fetal stage
germinal stage
zygote forms within 36hours; cells divide every 12-15hrs and make way down fallopian tube; cells differentiate into layers; implantation happens when the 100cell blastocyst embeds into the uterine wall; placenta develops
embryonic stage
most fast paced period of development; the circulatory system forms; neural tube develops; by day 26 arm buds develop; legs, rudimentary feet, elbows, wrists, precursors of fingers can be seen; by week 8 all internal organs are in place
fetal stage
development occurs at a more leisurely pace; eyebrows, fingernails, etc.
neurons migrate and begin stages themselves in different areas (the brain doubles in size from month 4to 7); at 6mos hearing and at 7mons sight
age of viability
22-23 weeks
gestational period
38-40weeks
principles of development
Proximodistal (interior to exterior ie: heart before arms)
Cephalocaudal (head to feet ie: crawl before walk)
Mass-to-Specific (larger to complex ie: arms before fingernails)
Down Syndrome
extra chromosome on 21 pair (therefore have 47)
flat facial profile; upward slant to eyes; stocky; enlarged tongue; risk of having heart defects and childhood leukemia
can cause MR and is higher risk for older mothers
Klinefelter syndrome
usually results in a male with an extra X chromosome (XXY); smaller genitalia, enlarged breasts, tall stature and often infertile
Turner syndrome
usually occurs dot to missing X chromosome in females (XO)
small stature, webbed neck, heart defects and often infertile
Teratogens
substances that may cross the placenta and cause harm to the developing embryo or fetus
- most likely to cause major structural damage during the embryonic stage
- can affect the developing brain throughout pregnancy
- have a threshold above which damage occurs
- exert their damage unpredictably, depending on fetal and maternal vulnerabilities
critical period
when a specific organ or system is coming “on line”
Categories of teratogens (there are 5)
Infectious diseases medications recreational drugs environmental toxins Vitamin deficiencies
Thalidomide
given to pregnant women from 1957-1962 in Europe and Japan and more than 12k children had limb malformations and organ system difficulties
Rubella effects on embryos
can cause blindness, deafness, and MR (if mother contracts Rubella later in pregnancy there may be minimal to no side effects)
Tobacco effects on embryos
premature birth, low birth weight, cleft palate and higher risk of miscarriage
Alcohol effects on embyros
most common cause of MR in the united states; causes Fetal Alcohol Spectrum Disorders
ETOH should NEVER be had during pregnancy
Why is gestational diabetes dangerous to a baby
because it can affect neurobehavioral development and cognitive abilities
Can men’s sperm be effected? And if so, what should they avoid
Yes
Lead, tobacco, THC, Cocaine, ETOH, radiation, pesticides and low vitamin C have been linked to teratogens within men. And smoking near a pregnant woman has a greater risk of low birthweight, SIDS, and childhood cancer
