Chapter 5: Physical GrowthVocabulary: Amygdala: an inner brain structure that plays a central role in processing emotional information.Androgens: hormones released chiefly by boys’ testes, and in smaller amounts by the adrenal glands, that influence the pubertal growth spurt and stimulate muscle growth, body and facial hair, and male sex characteristics.Anorexia nervosa: an eating disorder in which young people, mainly females, starve themselves because of compulsive fear of getting fat and an extremely distorted body image.Body image: conception of and attitude toward one’s physical appearance.Brain plasticity: the capacity of various parts of the cerebral cortex to take over functions of damaged regions. Declines as hemispheres of the cerebral cortex lateralize.Bulimia nervosa: an eating disorder in which individuals, mainly girls but also including some gay and bisexual boys, engage in strict dieting and excessive exercise accompanied by binge eating, often followed by deliberate vomiting and purging with laxatives. Cephalocaudal trend: an organized pattern of physical growth and motor control in whichthe head develops ahead of the lower part of the body. Distinguished from proximodistal trend.Cerebellum: a structure at the rear and base of the brain that aids in balance and control of body movement.Cerebral cortex: the largest, most complex structure of the human brain, containing the greatest number of neurons and synapses, which accounts for the highly developed intelligence of the human species.Corpus Callosum: the large bundle of fibers connecting the two cerebral hemispheres.Distance Curve: a growth curve that plots the average sixe of a sample of children at eachage, indicating typical yearly progress toward maturity. Distinguished from velocity curve.Dominant cerebral hemisphere: the hemisphere of the cerebral cortex with greater capacity to carry out skilled motor action and where other important abilities (language) generally are located. In right handed individuals, the left hemisphere is dominant; in left handed individuals, language is often shared between the hemispheres.Epiphyses: growth centers at the ends of each of the long bones of the body, where new cartilage cells are produced and gradually harden.Estrogens: hormones released by girls’ ovaries that cause the breasts, uterus, and vagina to mature, the body to take on feminine proportions, and fat to accumulate. Estrogens also contribute to regulation of the menstrual cycle.Experience-dependent brain growth: growth and refinement of established brain structures as a result of specific learning experiences that vary widely across individuals and cultures. Distinguished from experience-expectant brain growth.Experience-expectant brain growth: the young brain’s rapidly developing organization, which depends on ordinary experiences—opportunities to interact with people, hear language and other sounds, see and touch objects, and move about and explore the environment. Distinguished from experience-dependent brain growth.Glial cells: cells responsible for myelination of neural fibers, which improves the efficiency of message transfer.Growth faltering: failure of an infant to grow normally, characterized by weight, height, and head circumference substantially below age-related growth norms and by withdrawn,apathetic behavior. A disturbed parent-infant relationship is often a contributing factor.Growth hormone: a pituitary hormone that affects the development of all body tissues except the central nervous system and the genitals.Hippocampus: an inner-brain structure that plays a vital role in memory and in images of space that help us find our way.Hypothalamus: a structure located at the base of the brain that initiates and regulates pituitary secretions.Kwashiorkor: a disease caused by an unbalanced diet very low in protein, which usually strikes after weaning, between 1 and 3 years of age. Symptoms include an enlarged belly, swollen feet, hair loss, skin rash and irritable, listless behavior.Lateralization: specialization of functions in the two hemispheres of the cerebral cortex.Marasmus:a wasted condition of the body caused by a diet low in all essential nutrients. Usually appears in the first year of life. Menarche: first menstruationMyelination: the coasting of neural fibers with myelin, an insulating fatty sheath that improves the efficiency of message transfer.Neurons: nerve cells that store and transmit informationNeurotransmitters: chemicals released by neurons that cross the synapse to send messages to other neuronsObesity: a greater-than-20-percent increase over healthy body weight, based on body mass index, a ration of weight to height associated with body fat.Pituitary Gland: a gland located at the base of the brain that releases hormones affecting physical growth. Prefrontal Cortex: the region of the cerebral cortex, lying in front of areas controlling body movement, that is responsible for thought- in particular, for consciousness, attention, inhibition of impulses, integration of information, and use of memory, reasoning, planning, and problem-solving strategies. Primary Sexual Characteristics: physical features of the reproductive organs- ovaries, uterus and vagina in females; penis, scrotum, and testes in males. Distinguished from secondary sexual characteristics.Programmed cell death: death of many surrounding neurons as neural fibers and their synapses increase rapidly, which makes space for these connective structures. Proximodistal Trend: an organized pattern of physical growth and motor control that proceeds from the center of the body outward. Distinguished from cephalocaudal trend.Psychosocial Dwarfism: a growth disorder, usually appearing between 2 and 15 years of age, caused by extreme emotional deprivation. Typical characteristics include decreased growth hormone secretion, very short stature, immature skeletal age, and serious adjustment problems, which help distinguish it from typical shortness.Puberty: biological changes at adolescence that lead to an adult-sized body and sexual maturity.Reticular Formation: a structure in the brain stem that maintains alertness and conciousness.Secondary Sexual Characteristics: features visible on the outside of the body that do not involve the reproductive organs but serve as signs of sexual maturity, including bread development in females and the appearance of underarm and pubic hair in both sexes. Distinguished from primary sexual