| anorexia nervosa | An eating disorder, mainly affecting adolescent girls between the ages of 14 and 18, characterized by a 25 percent to 50 percent loss in body weight through excessive dieting and exercise; usually treated with a combination of hospitalization and family counseling.
|
 |
|
|
| bulimia nervosa | An eating disorder characterized by binge eating followed by vomiting or use of laxatives to purge the body; more common among older teens and young adults. This disorder generally is associated with a distorted body image and an inability to control one's impulses; treatable through family and individual therapy.
|
|
|
|
| cephalocaudal | One of two patterns characterizing growth in infancy; growth begins at the head and proceeds downward.*As a result, the infant's brain, neck, and trunk develop before the legs.
|
|
|
|
| chromosomes | The structures that carry the genes ; composed of long threadlike molecules of deoxyribonucleic acid (DNA).
|
|
|
|
| depression | An affective disorder characterized by disturbances in cognitive and behavioral functioning that last longer than 2 or 3 weeks; symptoms include an inability to concentrate, feelings of hopelessness, weight changes, an inability to have fun, and thoughts of death.
|
|
|
|
| dizygotic twins | Two siblings who come from separate eggs that are released at the same time from an ovary and are fertilized; also known as fraternal twins.
|
|
|
|
| Down syndrome | A genetic disorder of varying degree that is due to the presence of an extra twenty-first chromosome or a piece of one, causes a range of physical and mental handicaps, and occurs in 1 out of 800 live births. Mothers over the age of 35 have an increased risk of conceiving a child with this disorder, because of their longer exposure to environmental substances. The presence of this abnormality can be detected through the genetic screening process amniocentesis in the fourth month of pregnancy.
|
|
|
|
| fine motor skills | Involve small body movements and small muscle coordination and control.
|
|
|
|
| fragile-X syndrome | A genetic disorder more common in male than female offspring due to the presence of an X chromosome that appears to be pinched or very thin in one area and is likely to break during cell division. May cause mild retardation in females; will cause varying degrees of retardation in males and is associated with both physical (cleft palate, eye disorders) and mental (hyperactivity) deficits. This disorder can be detected through genetic screening.
|
|
|
|
| genotype | A person's genetic characteristics as determined by the genes a person inherits from both parents for any particular trait; contrast with phenotype.
|
|
|
|
| gross motor skills | Involve the movement of the head, body, legs, arms, and large muscles.
|
|
|
|
| habituation procedure | A technique researchers use to study infant memory by assessing changes in the intensity of infants' responses to various forms of stimulation over a period of time.
|
|
|
|
| low birth weight | Many premature and some full-term babies who weigh less than 5.5 pounds or 2,500 grams at birth.
|
|
|
|
| menarche | The beginning of a girl's menstrual cycle; generally the last physical change to occur in puberty.
|
|
|
|
| mitosis | The process through which chromosomes produce duplicate copies of themselves and divide into new cells; each new cell has 23 pairs of chromosomes.
|
|
|
|
| monozygotic twins | Two siblings who come from the same fertilized egg and contain the same genetic instructions; also known as identical twins.
|
|
|
|
| myelination | The second of two changes during brain development after birth; the process during which neurons and dendrites become coated with a fatty substance (myelin) to enable neural impulses to travel faster.
|
|
|
|
| neurons | Long thin cells within the central nervous system, different from other cells because they are not closely packed, that are formed during the first 5 months of gestation.
|
|
|
|
| obesity | A greater than 20 percent increase over average body weight for an individual's age, sex, and body build; contributing factors can be heredity, unhealthy diet, lack of exercise, abnormal metabolism, and family trauma.
|
|
|
|
| phenotype | A person's observable physical and behavioral characteristics; when individuals receive a recessive gene from one parent and a dominant gene from another, their genotype will be different from their phenotype.
|
|
|
|
| polygenetic traits | Human characteristics, such as intelligence, skin color, and height, that result from the combination or interaction of two or more genes.
|
|
|
|
| proximal-distal | One of two patterns characterizing growth in infancy;*Development begins in the center and proceeds outward.*As a result, the organs develop before the arms or hands.
|
|
|
|
| puberty | Refers to the period in which a young person becomes capable of sexual reproduction; the average age of onset for girls is 10 to 12 years old and for boys, 12 to 14 years old.
|
|
|
|
| reaction range | A concept used by researchers to understand an individual's unique, genetically determined response to environmental influences. Genes may determine the upper and lower boundaries for development, but the reaction range defines the degree to which the environment can affect development.
|
|
|
|
| resiliency | The capacity of young people to cope with difficult and challenging circumstances in their lives to develop competence.
|
|
|
|
| secular trend | A shift in normative patterns of development exemplified in today's average adult height and the onset of puberty.
|
|
|
|
| teratogen | Any environmental substance or disease (alcohol, caffeine, radiation, caustic chemicals, chicken pox, AIDS) that can have an adverse effect on a fetus during prenatal development.
|
2002 McGraw-Hill Higher Education