Ch. 6 - Physical Development: The Brain, Body, Motor Skills, and Sexual Development Flashcards
What does growth look like in infants?
Very rapid and uneven
At what age is a child about half of their adult height?
2 years old
What does height/weight growth look like during puberty?
There is often a 2-3 year growth spurt
What is ‘cephalocaudal development’?
A sequence of physical maturation and growth that proceeds from the head (cephalic region) to the tail (or the caudal region).
Which part of the body grows fastest during the first year?
The trunk
Which part of the body grows fastest from one year of age to the adolescent growth spurt?
The legs
During adolescence, which part of the body grows the fastest?
The trunk (but the legs also grow rapidly)
What is ‘proximodistal development’?
A sequence of physical maturation and growth that proceeds from the centre of the body (the proximal region) to the extremities (distal region). However, this centre-outward growth pattern reverses just before puberty, where the hands and feet begin to grow rapidly and become first of body to reach adult proportions.
How does the skeletal structure form?
During the prenatal period, it is initially soft cartilage that will gradually ossify (harden) into bony material
What is one reason that neonates cannot sit up/balance themselves?
Their bones are too small and too flexible
Describe the neonate’s skull?
Consists of several soft bones that can be compressed to allow the child to pass through cervix/birth canal. Bones are separated by six ‘soft spots’/fontanelles that are gradually filled by minerals
What are sutures?
Seams where skull bones join that allow skull to expand as brain grows
What is ‘skeletal age’?
A measure of physical maturation based on the child’s level of skeletal development
What is the order in the body of skeletal maturation/hardening?
Skull and hands first. Leg bones continue to develop until mid to late teens
What are the muscle fibres like in neonates?
Neonates are born with all muscle fibres they will ever have
Which body part(s) grow much faster and are quicker to reach adult proportions?
Brain and head
What did Warren Eaton and Kathryn Ritchot discover about maturational differences?
Maturational differences also predicted the speed with which children would be able to engage in cognitive tasks. Faster processing speed was found in early maturers (especially in boys)
Describe the cultural variations in physical growth?
People from Asia, South America, and Africa tend to be smaller than North Americans, Northern Europeans, and Australians
What is the ‘brain growth spurt’ and when does it occur?
The period between the seventh prenatal month and 2 years of age when more than half of the child’s eventual brain weight is added. This happens through the formation of glia.
When do the vast majority of neurons a human will ever have form?
By the end of the second trimester of pregnancy (before the brain growth spurt has even begun)
What is the error-related negativity (ERN), and how does it change throughout development? Who studied this?
ERN is negative deflection, as measured by an EEG, that occurs after an individual makes an error. ERN gets larger as children mature, which makes sense with the delayed maturation of the frontal lobe.
Dr. Sid Segalowitz
When does synaptogenesis occur?
During the brain growth spurt
What did Austin Riesen and his colleagues find when infant chimpanzees were reared in the dark?
Dark-reared chimps experienced atrophy of the retina and optic nerve. This atrophy was reversible if visual deprivation did not exceed 7 months, but was irreversible (total blindness) if it lasted longer than a year
What did Bryan Kolb and associates find when groups of animals were exposed to complex, stimulating environments?
All groups showed expected increases in dendritic length (quantitative change). Qualitatively, adult and old animals showed an increase in synaptic densities, whereas juveniles showed a decrease in density.
Which brain areas develop first?
Primary motor areas and primary sensory areas
Name two areas which are not fully myelinated until puberty?
Reticular formation and frontal cortex
What is the ‘cerebrum’?
The highest brain centre; includes both hemispheres of the brain and the fibres that connect them
What is the ‘corpus callosum’?
The bundle of neural fibres that connect the two hemispheres of the brain and transmit information from one hemisphere to the other
What is the ‘cerebral cortex’?
The outer layer of the brain’s cerebrum, which is involved in voluntary body movements, perception, and higher intellectual functions such as learning, thinking, and speaking
What is ‘cerebral lateralization’?
The specialization of brain functions in the left and right cerebral hemispheres
When does cerebral lateralization occur?
May originate during the prenatal period and be well under way at birth. Throughout childhood, we come to rely more and more on one particular hemisphere or the other to serve particular functions
When is brain plasticity greatest?
Early in life, before cerebral lateralization is complete
The fact that a newborn’s head is 70% of its adult size and 25% of its body length is best explained by which concept of development?
The cephalocaudal trend
Which of the following body parts overshoots adult levels in childhood then declines to adult levels later in adolescence?
The lymphatic system
The basic unit of the brain and nervous system are the cells that receive and transmit neural impulses. What is the name for these cells?
Neurons
Scientists believe that the human brain has evolved so that the infant brain can be highly responsive to the effects of experience. The brain is thought to produce an excess of neurons and synapses so that it can be responsive to many different kinds of sensory and motor stimulation. This responsiveness also results in synaptic and neural degeneration when the neurons that are not stimulated do not continue to function. What is the term for this aspect of brain development?
Plasticity
Gretchen is having a baby. Based on her understanding of brain lateralization, she predicted the positioning of her fetus when it was examined with ultrasound. If it was like 2/3 of all fetuses, how was her fetus positioned in the womb?
With its right ear facing outward
T or F: At birth, an infant’s bones are very stiff and brittle and easy to break.
False - they are very flexible
T or F: Individual neurons have the potential to serve any neural function, depending on where their migration delivers them
True
T or F: Very few neurons produced early in life die; instead, they are adapted for different functions in the nervous system.
False - during synaptogenesis, if neurons do not make proper connections, they will die. Synaptic pruning occurs throughout life.
T or F: Although the brain is lateralized at birth, lateral preferences continue to become stronger across age through adolescence.
True
What is the first milestone in locomotor development and when does it occur?
Lifting chins while laying flat on their stomach usually occurs by the end of the first month
What does a child’s rate of motor development tell us about future developmental outcomes?
Very little
What is one example that contradicts the cephalocaudal theory of motor development?
Infants are able to coordinate hip movement earlier than shoulder movement
What is the maturational viewpoint of motor development, and what are two pieces of evidence that support it?
Motor development is the unfolding of a genetically programmed sequence of events where the nerves and muscles mature in a downward and outward direction.
Throughout various cultures, children progress through roughly the same steps of motor development. In a twin study, when one twin is denied experience, both seem to display the same levels of motor development.
