DEP3103 Study Guide for Exam 2 Chapter 5 Physical Growth Know the main factors that affect physical growth Factors that Affect Physical Growth development is affected by the interaction of genes and environment Many factors act together to affect growth and development o Heredity Genes influence growth by controlling the body s production of and sensitivity to hormones a process that can be disrupted by mutations o Nutrition is especially crucial during the first two years when infants need extra calories to keep their rapidly developing organs functioning properly during a time of rapid brain and body growth There are many health advantages to breast feeding an infant Breast milk is the best milk It provides the correct balance of fat and protein it ensures nutritional completeness it protects against many diseases it helps ensure healthy physical growth it protects against faulty jaw development and tooth decay it ensures digestibility and it soothes the transition to solid foods Additionally the child is less likely to get sick because breast milk provides antibodies against any diseases to which the mother is immune Around 1 year a child s diet should include all the basic food groups And as children approach age 2 their appetites become unpredictable Malnutrition can cause Marasmus and Kwashiorkor Marasmus a wasted condition of the body cause by a diet low in all essential nutrients Kwashiorkor caused by an unbalanced diet very low in protein The body responds by breaking down its own protein reserves The effects of this can be seen through an enlarged belly swollen feet loss of hair and rashes Obesity can also become a problem with children not getting proper nutrition About 25 of North American children and adolescents are overweight Health risks for children with obesity include diabetes blood pressure and cholesterol problems respiratory problems sleep and digestive disorders and cancer Correlates of Obesity Overweight parents low SES less nightly sleep family eating habits response to food cues low physical activity television and cultural dietary conditions o Infectious Disease especially when children are poorly fed Ordinary childhood illnesses interact with malnutrition in a vicious spiral o Emotional Well Being Extreme emotional deprivation can interfere with the production of GH growth hormones This can lead to growth disorders such as psychosocial dwarfism What gender differences and similarities exist in relation to physical growth During early growth there is not much difference between how males and females develop They generally grow at the same over time However females tend to go through their pubescent growth spurt before males As a result in middle school many males are shorter than females that are their same age Fortunately males hit their growth spurt and continue to typically grow taller than most women Body fat and muscle is another aspect of physical growth that differs in males and females Females are born with more fat than males Over time females add more fat to their body while males lose fat and add more muscle Understand the basics of brain neuron growth as well as related terms Brain Development o A newborn s brain is disproportionately large at birth the brain is 25 the size of an adult brain while the body is typically less than 5 of the adult weight By age 2 the brain is almost 75 of the adult brain weight and the child s total body weight is only about 20 of its adult weight o Frontal Lobes responsible for thought in particular consciousness attention inhibition of impulses integration of information and regulation of behavior through planning o Cerebral Cortex Largest most complex structure in the human brain it accounts for 85 of brain s weight It makes possible the unique intelligence of our species It contains greatest number of neurons and synapses and is the last brain structure to stop growing It is sensitive to environmental influences for longer than any other part of the brain o Lateralization the brain is made up of two hemispheres The left hemisphere sensory information and control over the right side of the body is largely responsible for verbal activities and positive emotions while the right hemisphere sensory information and control over the left side of the body is largely responsible for spatial abilities and negative emotions This might be reversed in left handed people But it is true for most of us This specialization of the two hemispheres is called lateralization Brain Plasticity Infants and young children have parts of their brains that are not yet specialized Before lateralization if one part of the cortex is damaged then other areas can take over o Corpus Callosum large bundle of fibers that connects the two cortical hemispheres This is the bridge through which the two hemispheres communicate Interesting things happen when the corpus callosum is severed https www youtube com watch v lfGwsAdS9Dc Neurons store and transmit information They are different than other cells in our body because they are not jam packed together instead there are gaps between them called synapses o Neurons receive information through the dendrites Nerve impulses travel through the cell body Soma to the axons The axons are covered in the myelin sheath This allows for information to travel fast through the neuron The impulses then are transferred to another neuron the synapse the junction between neurons through which nerve impulses pass Neurons send messages to one another by releasing chemicals called neurotransmitters o Programmed cell death occurs because neurons require space As synapses form many surrounding neurons die 20 80 o Synaptic pruning when neurons that are seldom stimulated loose their synapses This helps support future development What is the difference between experience expectant and experience dependent brain growth Experience Expectant Brain Growth refers to the young brain s rapidly developing organization which depends on ordinary experiences opportunities to see and touch objects to hear language and other sounds and to move around and explore the environment Evolutionary development has prepared the brains of infants and young children to encounter these experiences and to grow normally as a result Experience Dependent Brain Growth extends throughout our lives It is a lifelong process consists of additional growth and refinement of established brain structures as a result of specific learning experiences that vary
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