Chapter 5 Body, Brain, and Health
The Endocrine System the body’s “slow” chemical communication system a set of glands that secrete hormones into the bloodstream
Hormonal Influences on Growth and Development
Neural Communication
The Brain and Nervous System Neurons Dendrite, cell body, and axon
Principles of Growth Cephalocaudal principle Growth occurs in a head-to-tail direction Proximodistal principle Growth and development of muscles from the center outward to the extremities Orthogenetic principle Development starts globally and undifferentiated Moves toward increasing differentiation and hierarchical integration
The Infant Synaptogenesis Growth of synapses, during childhood Synaptic pruning Removal of unnecessary synapses Developing brain has plasticity Responsive to the individual’s experiences and can develop in a variety of ways
Figure 5-2
Plasticity Responsiveness to experiences Can be negative Vulnerable to damage Environmental deprivation Can be positive Aids in recovery from from injury Can compensate for each other Can benefit from stimulation Allows for adaptability
Emotional Content of Language Visual-spatial Emotional Content of Language Psychology 7e in Modules
Brain Lateralization Figure 5.7 The brain consists of two hemispheres that specialize in different functions
Our Divided Brain large band of neural fibers Corpus callosum large band of neural fibers connects the two brain hemispheres
Brain Development Never truly complete Changes occur across lifespan Growth spurts in infancy, childhood and adolescence Full adult weight by about age 16 Processing speed increases in adolescence Myelination continues into adulthood
The Changing Brain Brain development is never truly complete Neurogenesis Process of generating new neurons Elderly adults may end up with 5–30% fewer neurons than early adulthood Neuron loss greater in areas that control sensory and motor activities Increased activity in the prefrontal cortex
Brain Development The Aging Brain Gradual and mild degeneration Elderly adults 5-30% fewer neurons than younger adult Greater loss in sensory-motor areas Plasticity still possible Main result of age is slower processing
Programmed theories of aging Maximum life span (species specific) Hayflick Limit – cells from embryos divide a limited amount 50 ± 10; for adult cells even less telomeres
Random error theories of aging Free radicals – toxic by-products of the metabolism of O2 damage cells and their functioning (also damage DNA) Interaction of the two – or more