If we look at the cortex starting at the front of the brain and moving over the top (see Figure 3.3), we see first the frontal lobe (behind the forehead), which is responsible primarily for thinking, planning, memory, and judg ment. The cortex is divided into two hemispheres, and each hemisphere is divided into four lobes, each separated by folds known as fissures. Most of the neural activity is occurring in the cortex or the thin outer covering of the brain involved in voluntary activity and thinking. Comparing to adult size, the newborn brain is approximately 33% of adult size at birth, and in just 90 days, it is already at 55% of adult size (Holland et al., 2014). At birth, the brain is about 250 grams (half a pound) and by one year it is already 750 grams (Eliot, 1999). The development of myelin continues into adolescence but is most dramatic during the first several years of life. This enhances the building of neural pathways and improves coordination and control of movement and thought processes. Myelin helps insulate the nerve cell and speed the rate of transmission of impulses from one cell to another. Blooming occurs during the first few years of life, and pruning continues through childhood and into adolescence in various areas of the brain.Īnother major change occurring in the central nervous system is the development of myelin, a coating of fatty tissues around the axon of the neuron (Carlson, 2014). Ultimately, about 40 percent of these connections will be lost (Webb, Monk, and Nelson, 2001). The experience will shape which of these connections are maintained and which of these are lost. It is thought that pruning causes the brain to function more efficiently, allowing for mastery of more complex skills (Kolb & Whishaw, 2011). The blooming period of neural growth is then followed by a period of synaptic pruning, where neural connections are reduced thereby making those that are used much stronger. At birth, the head makes up about 25 percent of our length, and by age 25 it comprises about 20 percent our length. The head initially makes up about 50 percent of our entire length when we are developing in the womb. Body ProportionsĪnother dramatic physical change that takes place in the first several years of life is the change in body proportions. The average length at one year is about 29.5 inches and at two years it is around 34.4 inches (Bloem, 2007). By age 2, the weight has quadrupled, so we can expect that a 2-year-old should weigh between 20 and 40 pounds. By the time an infant is 4 months old, it usually doubles in weight and by one year has tripled the birth weight. This weight loss is temporary, however, and is followed by a rapid period of growth. This often goes unnoticed by most parents but can be cause for concern for those who have a smaller infant. For the first few days of life, infants typically lose about 5 percent of their body weight as they eliminate waste and get used to feeding. The average newborn in the United States weighs about 7.5 pounds (between 5 and 10 pounds) and is about 20 inches in length. Discuss the nutritional concerns of marasmus and kwashiorkor.Explain the merits of breastfeeding and when to introduce more solid foods.Contrast the development of the senses in newborns.Describe the growth in the brain during infancy.Summarize overall physical growth during infancy.All images are property the copyright holder and are displayed here for informational purposes only. Many historical player head shots courtesy of David Davis. Some high school data is courtesy David McWater. Some defensive statistics Copyright © Baseball Info Solutions, 2010-2022. Total Zone Rating and initial framework for Wins above Replacement calculations provided by Sean Smith.įull-year historical Major League statistics provided by Pete Palmer and Gary Gillette of Hidden Game Sports. Win Expectancy, Run Expectancy, and Leverage Index calculations provided by Tom Tango of, and co-author of The Book: Playing the Percentages in Baseball. Much of the play-by-play, game results, and transaction information both shown and used to create certain data sets was obtained free of charge from and is copyrighted by RetroSheet. Use without license or authorization is expressly prohibited. The SPORTS REFERENCE and STATHEAD trademarks are owned exclusively by Sports Reference LLC. Logos were compiled by the amazing .Ĭopyright © 2000-2022 Sports Reference LLC. Our reasoning for presenting offensive logos. We present them here for purely educational purposes. All logos are the trademark & property of their owners and not Sports Reference LLC.
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