Psych 350 1st Edition Lecture 17 Outline of Last Lecture I Discriminating faces II The other face effect III Perceptual tuning IV threshold screening Outline of Current Lecture II Physical growth III Diet IV Brain development Current Lecture Physical Growth Diet Motor and Brain Development pages 137 152 159 181 Patterns of physical growth in childhood changes in body size growth curve for various organ systems sharp increase in height over infancy followed by slow growth over middle childhood ending with a growth spurt during the teen years the brain and head grow rapidly over preschool years continuing the rapid rate of growth of the prenatal period changes in reproductive growth show no change over childhood and then rapid maturing beginning around 12 or 13 changes in the lymphoid system These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute thymus and lymph glands develop quickly over childhood greatly exceeding adult dimensions until 12 when it just as quickly declines to adulthood difference in growth sex girls reach maturity earlier than boys girls achieve 50 of their adult height 1 75 to 2 year earlier than boys they enter puberty sooner stop growing sooner prenatal period girls growth faster too girls skeletons are three weeks more advanced midway though fetal period girls will have 4 6 week advantage in skeletal development by birth by puberty this changes to around 2 years girls develop permanent teeth first they have more mature organ systems at birth Cephalocaudal and proximodistal growth Cephalocaudal head grows before the tail grows infant 20 length of child head embryonic developemt spreads from head to foot this process continues postnatally at 2 months the head is 50 of the body birth the head is 20 of the body by adulthood head is 12 large heads relative to body size need to develop early and continue to develop for an extended period to promote survival Proximodistal things closer to trunk develop before things far away develop arm and legs grow first and then the hands and the fingers growth from center to periphery beginning during the prenatal period development is most rapid toward the center of the body salutatory growth shown in infancy saltatory conduction jump from place to place down the nerve measure the baby everyday and he would grow a centimeter and ahaf each time he grows the bumps and growth were occurring when they were a sleep Bone growth the skeleton starts at cartilage bone tissue begins to replace cartilage beginning about the 6th week of prenatal development ossification the replacement of bone tissue with cartilage development does not continue forever it tends to stop in early adulthood this is mediated by the growth plates these plates produce cartilage which separates the growing part of the bone from the rigid part these growth plates increase in size over childhood and eventually thin out and disappear as cartilage is replaced by bone skull is not solid as the brain increases the skull increases new areas of bone will be added between the connective tissue between the bones know it is the end of skeletal growth if there is no growth plate break or fracture in growth plate can stunt growth Sexual differentiation girls develop ovaries boys develop testis girl develop faster than boys they have 4 6 weeks advantage of skeletal growth by birth they are developed 2 full years before boys by the beginning of puberty endocrine system collection of glands that produce hormones human growth hormone stimulates the replication of most body cells affecting growth ovaries produce estrogen and progesterone testes produce testosterone menarche first menstrual period this occurs relatively late In puberty usually between 12 8 and 13 2 years Sensitivity of pubertal timing to rearing environment Primary and secondary sexual characteristics Primary sexual characteristics those associated directly with reproduction maturing of the gonads and the anatomy of the genitals Secondary sexual characteristics those not directly related to reproduction pubic hair breasts change in voice and body shape Tanner stages Secular trend in age of menarche Effects of early menarche child who are bigger or more mature looking for there age may get treated like they are older than they actually are by adults and vice versa average age is 13 years old Malnutrition marasmus Kwashiorkor malnutrition delays growth associated with lower levels of intelligence because of brain development kwashiorkor children receive just enough calories to survive usually from starch but do not receive enough protein development of extended bellies lose of hair and become listless and irritable marasmus body waste away when infants receive a diet low in ass essential nutrients often because their mothers are too malnourished to provide adequate breast milk malnutrition and intellectual development malnutrition is associated with lower levels of intelligence their brain will growth slower poor nutrition has an effect by reducing activity level less exploration less play less social interaction that could cause a delay in intelligence Developmental milestones when the primary and secondary characteristics develop in a child they can vary from person to person male initial testicular growth 11 75 year early growth of pubic hair 12 year enlargement of penis 13 temporary breast development 13