DEP3103 Exam 2 Study Guide Chapter 5 Physical Growth Know the main factors that affect physical growth focus on nutrition 1 Heredity Genes influence growth by controlling the body s production of and sensitivity to hormones a process that can be disrupted by mutations Identical twins are more alike in body size than fraternal twins 2 Nutrition Especially crucial during the first 2 yrs infants need extra calories to keep their rapidly developing organs functioning properly during a time of rapid brain and body growth Children who grow tallest usually live in developed countries where food is plentiful and infectious diseases are largely controlled Physically small children tend to live in less developed regions where poverty hunger and disease are common An infants energy needs are twice those of an adult babies need breast milk over bottle food to get the correct nutrients advised exclusive breastfeeding for the first 6 mos and inclusion of breast milk in the baby s diet until at least 1 yr Breast milk boosts children s immune system Easier transition to solid food when began with breastfeeding Around 1 year infant s diets should contain all the basic food groups By age 2 the appetite becomes unpredictable needs high quality diet Trying new foods at home might be easier than trying new foods at someone else s house environment has influence Which practice will most likely increase a child s acceptance of broccoli repeatedly serving broccoli with dinner without pressuring the child to eat it Malnutrition is typically seen in high poverty countries 1 Marasmus a wasted condition of the body caused by a diet low in all essential nutrients usually appears in 1st year when mother is malnourished to produce breast milk and bottled feeding is inadequate 2 Kwashiorkor is caused by an unbalanced diet very low in protein usually occurs between 1 and 3 yrs children have large stomachs that stick out severly common in regions where children get calories from starches but little protein 3 Iron deficiency anemia is caused by an unbalanced diet with low iron causes CNS issues lack of attention withdrawal listlessness inability to be soothed Overweight in adults characterized by having a BMI of 25 to 29 in children being above the 85th percentile About 25 of North American children and adolescents are overweight Research on body weight shows that adult onset diabetes is rising rapidly among overweight children Obesity in adults characterized by having a BMI of 30 or more in children being above the 95th percentile Causes overweight parents low SES less nightly sleep family eating habits response to food cues low physical activity television cultural dietary conditions A follow up of more than 2 000 U S 3 to 12 year olds revealed that children who got less nightly sleep were more likely to be overweight five years later than their well rested peers Compared to their normal weight age mates obese children are less responsive to internal hunger cues 3 Infectious Diseases Especially when children are poorly fed ordinary childhood illnesses interact with malnutrition in a vicious spiral 4 Emotional Well Being Extreme emotional deprivation can interfere with Growth Hormone GH production leading to psychosocial dwarfism a growth disorder What gender differences similarities exist in relation to physical growth 1 Body Size During infancy and childhood the two sexes are similar in height vs age with the typical girl slightly shorter and lighter than the typical boy Around age 10 to 11 the typical girl becomes taller and heavier for a time because her pubertal growth spurt takes place two years earlier than the boys At age 14 the typical boy begins his growth spurt and surpasses the typical girl who is almost finished with her growth spurt Growth in height is complete for moth girls by age 16 and boys by age 17 2 Body Proportions In infancy and childhood girls and boys have similar body proportions During adolescence large differences appear between boys and girls caused by the action of sex hormones on the skeleton boy s shoulders broaden relative to the hips whereas girl s hips broaden relative to the shoulders and waist Boys end up considerably larger than girls and their legs are longer in relation to the rest of the body because they have two extra years of preadolescent growth than girls 3 Muscle Fat Makeup Body fat increases prenatally and also after birth reaching a peak at about 9 mos of age At birth girls have slightly more body fat than boys a difference that persists into the early school years and then magnifies Around age 8 girls start to add more fat on their arms legs and trunk and continue to do so throughout puberty while the arm and leg fat of adolescent boys decreases Muscle accumulates slowly throughout infancy and childhood with a dramatic rise at adolescence Both sexes gain muscle at puberty but the increase in 150 greater in boys who develop larger skeletal muscles hearts and lung capacity Also the number of red blood cells increases in boys but not in girls giving boys the ability to carry more oxygen from the lungs to the muscles contributing to their superior athletic performance during the teenage years 4 Skeletal Growth African American children tend to be slightly ahead of Caucasian American children in skeletal age Girls are considerably ahead of boys a gap of about 4 6 wks at birth which widens over infancy and childhood Girls are advanced in development of other organs as well may contribute to girls greater resistance to harmful environmental influences Girls experience fewer developmental problems than boys and have lower infant and childhood mortality rates 5 Gross Motor Skills During childhood there are little differences between boys and girls During adolescence boys develop more strength speed and endurance Size and strength contribute to boy s superior athletic performance in adolescence but the social environment plays a more prominent role in their advantage more athletic pressure on boys may lead to more practice Understand the basics of brain neuron growth as well as related terms i e the different lobes lateralization pruning etc 1 Neurons are nerve cells that store and transmit information Between neurons are synapses which are tiny gaps where fibers from different neurons come close together but do not touch where nerve impulses pass Neurons send messages to one another by releasing chemicals called neurotransmitters which cross synapses In the prenatal
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