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This 7 page One Day of Notes was uploaded by Baylee Owen on Thursday September 18, 2014. The One Day of Notes belongs to PSYC 333 at a university taught by a professor in Fall. Since its upload, it has received 343 views.
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Date Created: 09/18/14
Chapter 5 Physical Development The Brain Body Motor Skills and Sexual Development An Overview of Maturation and Growth Changes in Height and Weight Babjesgroyvveryrapidy during the first 2 years often doubling their birth weight by 4 to 6 months of age and tripling it by the end of the 1 year 3rgyvthisyeryunevenini1fancy Babies may remain the same length for days or weeks at a time before showing spurts of growth By age 2 toddlers are already half their eventual adult height and have quadrupled their birth weight From age 2 until puberty children gain about 2 to 3 inches in height and 6 to 7 pounds in weight each year During middle childhood children may seem to grow very little gaining 2 inches and around 6 pounds However physical growth and development are once again obvious at puberty when adolescents enter a 2 to 3 year growth spurt during which they may post an annual gain of 10 to 15 pounds and 2 to 4 inches in height After this there are typically small increases in height until full adult stature is attained in the midto late teens Changes in Body Proportions 0 Cephalocaudal development a sequence of physical maturation and growth that proceeds from the head cephalic region to the tail caudal region o Head downward direction 0 Proximodistal development a sequence of physical maturation and growth that proceeds from the center of the body the proximal region to the extremities distal region o Center outward direction Skeletal Development The skeletal structures that form during the prenatal period are initially soft cartilage that will eventually ossify harden into bony material 0 Fontanelles soft spots that separate the skull bones in neonate s o Gradually filled in by minerals to form a single skull with pliable points at the seams where skull bones join I Sutures the seams which allow the skull to expand as the brain grows larger 0 Skeletal age a measure of physical maturation based on the child39s level of skeletal development Not all parts of the skeleton grow and harden at the same rate The skull and hands mature first whereas the leg bones continue to develop until the mid to late teens Skeletal development is complete by age 18 Muscular Development Newborns are born with all the muscle fibers they will ever have At birth muscle tissue is 35 percent water however muscle fibers soon begin to grow as the cellular fluid in the muscle tissue is bolstered by the addition of protein and salts Muscular development proceeds in cephalocaudal and proximodistal directions with muscles in the head and neck maturing before those in the trunk and limbs The maturation of muscle tissue occurs very gradually over childhood and then accelerates during early adolescence Variations in Physical Development Physical development is an uneven process in which different bodily systems display unique growth patterns Individual Variations There are sizable individual variations in the rates at which children grow Cultural Variations People from Asia South America and Africa tend to be smaller than those from North America Northern Europe and Australia There are also cultural differences in the rate of physical growth Asian American and African American children tend to mature faster than European American and European children Asynchronies in the maturation of different body systems are built into our species heredity along with environmental factors and emotional climate which produce significant variations in the rate at which children grow and the statures they attain Development of the Brain The brain grows at an astounding rate early in life 0 Brain growth spurt the period between the 7 prenatal month and 2 years of age when more than half of the child39s eventual brain weight is gained o More than half of one s adult brain weight is gained at this time Neural Development and Plasticity 0 Synapse the connective space juncture between one nerve cell neuron and another 0 Neurons nerve cells that receive and transmit neural impulses o Produced in the neural tube of the developing embryo The vast majority of the neurons a person will ever have have already formed by the end of the second trimester of pregnancy 0 Gia nerve cells that nourish neurons and encase them in insulating sheathes of myelin o Accounts for the brain growth spurt 0 Myelin waxy substance insulating sheaths Neural Development Cell Differentiation and Synaptogenesis Individual neurons have the potential to serve any neural function and the function each serves depend on where it ends up 0 Synaptogenesis formation of connections synapses among neurons o Proceeds rapidly during the brain growth spurt Infants have more neurons and neural connections that adults do Neural Plasticity The Role of Experience The brain produces and excess of neurons and synapses in preparation for receiving any and all kinds of sensory and motor stimulation that a human being could conceivably experience 0 Plasticity capacity for change a developmental state that has the potential to be shaped by expe ence 0 Synaptic pruning surviving neurons that are stimulated less therefore losing their synapses o Stand in reserve to compensate for brain injuries or to support new skills Neurons that are not properly stimulated with degenerate Brain Differentiation and Growth Not all parts of the brain develop at the same time At birth the most highly developed areas are the lower stJbccrtica brain centers which control states of consciousness inborn reflexes and vital biological functions such as digestion respiration and elimination Surrounding the subcortical brain centers are the cerebrurn and cerebralcortex the area39s most directly implicated in voluntary bodily movements perception and higher intellectual activities such as learning thinking and language The first areas of the cerebrum to mature are the prirr1aryrnctorareas which control sensory ties such as waving the arms and the prirr1arysensgryareas hearing smelling tasting Myelinization 0 Myelinization the process by which neurons are enclosed in waxy myelin sheaths that will facilitate the transmission of neural impulses o Enhances the efficiency between the more primitive emotive subcortal areas of the brain and the more regulatory prefrontal cortical areas of the rain ability to process and respond to socially important emotional input I A child s ability to monitor his or her own emotional reactions increases o Myelin sheath acts as an insulator to speed up the transmission of neural impulses allowing the brain to communicate more efficiently with different parts of the body Reticuarfgrmation and the1 rg1taccrtegtlt allow us to concentrate on a subject from lengthy periods 0 Not fully myelinated at puberty Cerebral Lateralization 0 Cerebrum the highest brain center includes both hemispheres of the brain and the fibers that connect them 0 Corpus caosum the bundle of neural fibers that connects the two hemispheres of the brain and transmits information from one hemisphere to the other o Left hemisphere controls the right side of the body and contains centers for speech hearing verbal memory decision making language processing and expression of positive emotions o Right hemisphere controls the left side of the body and contains centers for processing visualspatial information nonlinguistic sounds such as music tactile touch sensations and expressing negative emotion 0 Cerebral cortex the outer layer of the brain39s cerebrum that is involved in voluntary body movements perception and higher intellectual functions such as learning thinking and speaking 0 Cerebral laterization the specialization of brain functions in the left and the right cerebral hemispheres o Involves a preference for using one hand or one side of the body more than the other Development of the Brain during Adolescence Pubertal reorganizations may involve synaptic pruning 0 Prefrontal cortex involved in higherlevel cognitive activities Motor Development An infant lifting their chins while lying flat on their stomachs is the first milestone in locomotor development Basic Trends in Locomotor Development Motor development proceeds in a cephalocaudal direction The kicking movements displayed by infants during the first few months present a problem for the cephalocaudal perspective and are usually dismissed as unintentional movements generated by the central nervous system The Maturational Viewpoint Describes motor development as he unfolding of a genetically programmed sequence of events in which the nerves and muscles mature in a downward and outward direction As a result children gain more control over the lower and peripheral parts of their bodies Maturation underlies motor development and practice allows a child to perfect the skills that maturation has made possible The Experiential or practice Hypothesis Maturation is necessary but not sufficient for the development of motor skills Motor Skills as Dynamic GoalDirected Systems 0 Dynamical systems theory a theory that views motor skills as active reorganizations of previously mastered capabilities that are undertaken to find more effective ways of exploring the environment or satisfying other objectives Infants hope to acquire and perfect new motor skills that will help them to get to interesting objects they hope to explore or to accomplish other goals they have in mind Crawling represents an active and intricate reorganization of existing capabilities that is undertaken by a curious infant that has a goal in mind Fine Motor Development Development of Manipulatory Skills Grasping objects with both hands 0 Ulnar grasp an early manipulatory skill in which an infant grasps objects by pressing the fingers against the palm 0 Pincer grasp a grasp in which the thumb is used in opposition to the fingers enabling an infant to become more dexterous at lifting and fondling objects Psychological Implications of Early Motor Development Achieving various motor milestones may foster perceptual development 0 Optic flow the perceived movement of objects in the visual field as well as the perceived movements of the foreground and background in which the objects are embedded o Allow the infant to improve posture and crawl or walk more efficiently Human development is a holistic enterprise changes in motor skills have clear implications for other aspects of development Beyond Infancy Motor Development in Childhood and Adolescence Boys and girls are nearly equal in physical abilities until puberty when boys continue to improve on tests of arge musce activities This is attributable to biology 0 Physically active play moderate to vigorous play activities such as running jumping climbing play fighting or game playing that raise a child s metabolic rate far above resting levels Puberty The Physical Transition from Child to Adult 0 Adolescent growth spurt the rapid increase in physical growth that marks the beginning of adolescence 0 Puberty the point at which a person reaches sexual maturity and is physically capable of fathering or conceiving a child The Adolescent Growth Spurt Girls enter growth spurt at age 105 reach a peak growth rate by 12 and return to a slower rate of growth by age 13 to 135 Boys enter growth spurt at age 13 peak at age 14 and return to a more gradual rate of growth by age 16 Sexual Maturation Maturation of the reproductive system occurs at roughly the same time as the adolescent growth spurt and follows a predictable sequence for boys and girls Sexual Development in Girls Sexual maturation begins at about age 911 as fatty tissue accumulates around the nipples forming small quotbreast buds Full breast development finishes around age 14 0 Menarche the first occurrence of menstruation o Around age 12 o May be unable to reproduce for 12 to 18 months after menarche Sexual Development in Boys Sexual maturation begins at about 1013 with an enlargement of the testes and scrotum which thins and darkens and descends to its pendulous adult position Meanwhile the penis lengthens and widens At about age 13 145 sperm production begins Lowering of the voice Secular Trends Are We Maturing Earlier 0 Secular trend a trend in industrialized societies toward early maturation and greater body size now than in the past 0 Due to better nutrition and advances in medical care Causes and Correlates of Physical Development Physical development results from a complex and continuous interplay between the forces of nature and nurture Biological Mechanisms Hormonal Influences The Endocrinology of Growth Endocrine hormone producing gland 0 Pituitary a quotmaster gland located at the base of the brain that regulates the endocrine glands and produces growth hormone 0 Growth hormone GH a pituitary hormone that stimulates the rapid growth and development of body cells primarily responsible for the adolescent growth spurt o Influenced by the hypothalamus 0 Estrogen female sex hormone produced by the ovaries that is responsible for female sexual maturation 0 Testosterone male sex hormone produced by the testes that is responsible for male sexual maturation Environmental Influences Nutrition Diet is the most important environmental influence on human growth and development Problems of Undernutrition 0 Catchup growth a period of accelerated growth in which children who have experienced growth deficits grow very rapidly to catch up to the growth trajectory that they are genetically programmed to follow 0 Marasmus a growth retarding disease affecting infants who receive insufficient protein and too few calories 0 Kwashiorkor a growth retarding disease affecting children who receive enough calories but very little protein 0 Vitamin and mineral deficiency a form of malnutrition in which the diet provides sufficient protein and calories but is lacking in one or more substances that promote normal growth 0 Iron deficiency anemia a listlessness caused by too little iron in the diet that makes children inattentive and may retard physical and intellectual development Problems of Overnutrition 0 Obese medical term describing individuals who are at least 20 percent above the ideal weight for their height age and sex Illnesses Common childhood illnesses such as measles chicken pox or even pneumonia have little effect on physical growth and development Diseases are likely to permanently stunt the growth of children who are moderately to severely undernourished Emotional Stress and Lack of Affection 0 Nonorganic failure to thrive an infant growth disorder caused by lack of attention and affection that causes growth to slow dramatically or stop 0 Deprivation dwarfism a childhood growth disorder that is triggered by emotional deprivation and characterized by decreased production of GH slow growth and small stature
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