the five major stages of lifespan development
prenatal (conception to birth)
infancy (birth to 2 years old)
Prenatal Development Stages
1) germinal period (first 14 days and it is fertilization and implantation)
-fertilization→first cleavage→two-cell stage→morula→blastocyst→ early stage of implantation
2) Embryonic Period (Weeks 3-8)
-morphological development occurs
-embryonic disk forms (ectoderm, mesoderm, endoderm)
-Trophoblast develops into nurturing and protective organs.
3)Fetal Period (weeks 9 till birth)
-developing organism is called a fetus
-major body parts formed previously now grow rapidly and become
refined in structure
-By week 13, fetus is 3 inches long
age of viability?
By 21 to 22 weeks after fertilization, the lungs gain some ability to breathe air. survival outside the womb becomes possible for some fetuses.
What are the distinctions between the zygote, morula, and blastocyst?
A zygote is the initial cell formed after a sperm and egg have joined.
Morula is the process where the zygote begins to divide and multiply into many cells. A blastocyst begins at day 5 in mammals after fertilization.This all occurs during the first week of being conceived.
What is morphological development?
The formation and structure of an organism.
Define the term teratogen
agents, such as chemicals and viruses, that can reach the embryo or fetus during prenatal development and cause harm.
List and describe several examples of teratrogens.
Drugs (legal, illegal, common medications)
What are the signs and symptoms of fetal alcohol syndrome?
Birth Defects (including small eyes, an exceptionally thin upper lip, a short, upturned nose, and a smooth skin surface between the nose and upper lip)
How might teratogens affect a father-to-be?
Whatever they are exposed to affects the baby's genes because half of the father's genes are a part of the baby. (ex. Marijuana, alcohol, age, exposure to chemicals, exposure to radiation, and smoking)
This reflex begins when the corner of the baby's mouth is stroked or touched. The baby will turn his/her head and open his/her mouth to follow and "root" in the direction of the stroking. This helps the baby find the breast or bottle to begin feeding.
Rooting helps the baby become ready to suck. When the roof of the baby's mouth is touched, the baby will begin to suck. This reflex does not begin until about the 32nd week of pregnancy and is not fully developed until about 36 weeks. Premature babies may have a weak or immature sucking ability because of this. Babies also have a hand-to-mouth reflex that goes with rooting and sucking and may suck on fingers or hands.
The Moro reflex is often called a startle reflex because it usually occurs when a baby is startled by a loud sound or movement. In response to the sound, the baby throws back his/her head, extends out the arms and legs, cries, then pulls the arms and legs back in. A baby's own cry can startle him/her and begin this reflex. This reflex lasts about five to six months.
Stroking the palm of a baby's hand causes the baby to close his/her fingers in a grasp. The grasp reflex lasts only a couple of months and is stronger in premature babies.
(Birth to age 2) the child learns about himself and his environment through motor and reflex actions. Thought derives from sensation and movement. The child learns that he is separate from his environment and the aspects of his environment—his parents or favorite toy—continue to exist even though they may be outside the reach of his senses.