21.3

Study Notes

Genes from both biological parents influence a person's traits
Chromosomes from each parent carry genetic material that determines characteristics
22 pairs of chromosomes possess similar genetic material, which influences traits such as eye color, hair color, and risk of diseases
Multiple genes influence many characteristics, with some genes being dominant and others being recessive

Humans reproduce through sexual intercourse, where sperm enter the vagina and swim to the fallopian tube to fertilize an egg
The moment of sperm and egg combination is called conception
A single sperm fertilizes an egg, and a barrier forms to prevent additional sperm from entering

A technology developed to help couples conceive, involving hormone stimulation, egg fertilization, and embryo insertion into the uterus
IVF can help people conceive children, passing on genes from the mitochondria

Human gestation is approximately 9 months, with most babies born 36-40 weeks after fertilization
Pregnancy can be divided into stages, and a person's behaviors during pregnancy influence the health of the developing baby

Germinal Stage: Lasts about 2 weeks, from conception to implantation, where the zygote divides rapidly into many cells
Embryonic Stage: Lasts about 6 weeks, where the embryo develops tissues and organs, and systems take shape
Fetal Stage: Begins at the 9th week, where the fetus grows and develops, lasting until birth

Ectopic Pregnancy: A serious condition where the embryo attaches and develops inside the fallopian tube, requiring urgent medical attention
Miscarriage: A pregnancy that ends before the 20th week, often caused by genetic abnormalities, infections, or diseases
Preeclampsia: High blood pressure during pregnancy, which can develop into eclampsia, a life-threatening condition
Gestational Diabetes Mellitus: A condition where the body cannot produce enough insulin during pregnancy, usually caused by hormone levels and weight gain
Premature Birth: The birth of a baby more than 3 weeks before the estimated due date, which can lead to health complications
Stillbirth: The death of a baby after the 20th week of pregnancy, but before birth

Eating well and gaining 25-35 pounds promotes personal and fetal health
Regular physical activity, such as walking and swimming, helps maintain circulation and blood sugar levels
Avoiding certain substances, such as alcohol, nicotine, and drugs, is crucial for fetal health and development

Labor pushes the baby out of the pregnant person's body and into the world
There are three stages of labor:
1. First Stage: Contractions cause the cervix to thin and stretch, opening the cervix for the baby to pass through
2. Second Stage: Uterine and abdominal muscles push the baby into the vagina and out of the body
3. Third Stage: The placenta is delivered
The Apgar test is used to evaluate the baby's health, responsiveness, and vital signs immediately after birth

Regular visits to an obstetrician/gynecologist (OB/GYN) are essential for the developing baby and pregnant person's health
Prenatal care involves monitoring the pregnancy, estimating the due date, and performing lab tests and physical exams
Doctors may prescribe vitamins, such as folic acid, to support fetal development