Chapter 5: Physical Growth

Question 1

secular trends in physical growth

Answer 1

Changes in body size and rate of growth

from one generation to the next.

Question 2

neurons

Answer 2

Nerve cells that store and transmit information.

Question 3

synapses

Answer 3

The gaps between neurons, across which chemical messages are sent.

Question 4

neurotransmitters

Answer 4

Chemicals released by neurons that cross the synapse to

send messages to other neurons.

Question 5

programmed cell death

Answer 5

Death of many surrounding neurons as neural fibers and their synapses increase rapidly, which makes space for these connective structures.

Question 6

synaptic pruning

Answer 6

Loss of synapses by seldom-stimulated neurons, thereby

returning them to an uncommitted state so they can support future development

Question 7

glial cells

Answer 7

Cells responsible for myelination of neural fibers, which improves the efficiency of message transfer.

Question 8

myelination

Answer 8

The coating of neural fibers with myelin, an insulating fatty
sheath that improves the efficiency of message transfer.

Question 9

cerebral cortex

Answer 9

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.

Question 10

prefrontal cortex

Answer 10

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.

Question 11

lateralization

Answer 11

Specialization of functions in the two hemispheres of the cerebral cortex.

Question 12

brain plasticity

Answer 12

The capacity of various parts of the cerebral cortex to take over functions of damaged regions. Declines as hemispheres of the cerebral cortex lateralize.

Question 13

dominant cerebral hemisphere

Answer 13

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.

Question 14

cerebellum

Answer 14

A structure at the rear and base of the brain that aids in balance and control of body movement.

Question 15

reticular formation

Answer 15

A structure in the brain stem that maintains alertness and consciousness.

Question 16

hippocampus

Answer 16

An inner-brain structure that plays a vital role in memory and in images of space that help us find our way.

Question 17

amygdala

Answer 17

An inner-brain structure that plays a central role in processing emotional information.

Question 18

corpus callosum

Answer 18

The large bundle of fibers connecting the two hemispheres.

Question 19

experience-expectant brain growth

Answer 19

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.

Question 20

experience-dependent brain growth

Answer 20

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.

Question 21

distance curve

Answer 21

A growth curve that plots the average size of a sample of children at each age, indicating typical yearly progress toward maturity. Distinguished from velocity curve.

Question 22

velocity curve

Answer 22

A growth curve that plots the average amount of growth at each yearly interval for a sample of children, revealing the exact timing of growth spurts. Distinguished from distance curve.

Question 23

cephalocuadal trend

Answer 23

An organized pattern of physical growth and motor control in which the head develops ahead of the lower part of the body (“head to tail”). Distinguished from proximodistal trend.

Question 24

proximodistal growth

Answer 24

An organized pattern of physical growth and motor control that proceeds from the center of the body outward. Distinguished from cephalocaudal trend.

Question 25

skeletal age

Answer 25

An estimate of physical maturity based on development of the bones of the body

Question 26

epiphyses

Answer 26

Growth centers at the ends of each of the long bones of the body, where new cartilage cells are produced and gradually harden.

Question 27

pituitary gland

Answer 27

A gland located at the base of the brain that releases hormones affecting physical growth.

Question 28

hypothalamus

Answer 28

A structure located at the base of the brain that initiates and regulates pituitary secretions.

Question 29

growth hormone (GH)

Answer 29

A pituitary hormone that affects the development of all body tissues except the central nervous system and the genitals.

Question 30

thyroid stimulating hormone

Answer 30

A pituitary hormone that stimulates the thyroid gland to release thyroxine, which is necessary for brain development and for growth hormone to have its full impact on body size.

Question 31

estrogens

Answer 31

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.

Question 32

androgens

Answer 32

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.

Question 33

Marasmus

Answer 33

A wasted condition of the body caused by a diet low in all essential nutrients. Usually appears in the first year of life.

Question 34

Kwashiorkor

Answer 34

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.

Question 35

obesity

Answer 35

A greater-than-20-percent increase over healthy body weight, based on body mass index, a ratio of weight to height associated with body fat.

Question 36

growth faltering

Answer 36

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.

Question 37

puberty

Answer 37

Biological changes at adolescence that lead to an adult-sized body and sexual maturity.

Question 38

primary sexual characteristics

Answer 38

Physical features of the reproductive organs—ovaries, uterus, and vagina in females; penis, scrotum, and testes in males. Distinguished from secondary sexual characteristics.

Question 39

secondary sexual characteristics

Answer 39

Features visible on the outside of the body that do not involve the reproductive organs but serve as signs of sexual maturity, including breast development in females and the appearance of underarm and pubic hair in both sexes. Distinguished from primary
sexual characteristics.

Question 40

menarche

Answer 40

First menstruation.

Question 41

spermarche

Answer 41

first ejaculation of seminal fluid

Question 42

body image

Answer 42

Conception of and attitude toward one’s physical appearance

Question 43

anorexia nervosa

Answer 43

An eating disorder in which young people, mainly females, starve themselves because of a compulsive fear of getting fat and an extremely distorted body image.

Question 44

bulimia nervousa

Answer 44

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.