Development of Human Behavior PDF

Development of Human Behavior Development of Human Behavior Nature and Nurture Developmental psychology is the branch of psychology that studies the patterns of growth and change that occur throughout life. developmental psychologists today agree that bot...

Development of Human Behavior Development of Human Behavior Nature and Nurture Developmental psychology is the branch of psychology that studies the patterns of growth and change that occur throughout life. developmental psychologists today agree that both nature and nurture interact to produce specific developmental patterns and outcomes Nurture – environmental causes of behavior Nature – hereditary causes of behavior Development of Human Behavior Basics of Genetics The one-cell entity established at conception contains 23 pairs of chromosomes, rod-shaped structures that contain all basic hereditary information. Genes smaller units through which genetic information is transmitted Composed of sequences of DNA (deoxyribonucleic acid) equivalent of “software” that programs the future development of all parts of the body’s hardware Humans have 20,000 to 25,000 different genes Development of Human Behavior Earliest Development Germinal Period – first two weeks Zygote – egg becomes familiarized by the sperm, the resulting one-celled entity Embryonic Period – lasts from week 2 through week 8 Embryo – develops through an intricate, programmed process of cell division, developed a rudimentary beating heart, a brain, an intestinal tract, and a number of other organs Fetal Period – week 8 and continuing until birth Fetus – movement become strong enough for the mother to sense them; the major organs begin functioning Development of Human Behavior Genetic Influences on the Fetus 95 to 98 percent of all pregnancies – normal development 2 to 5 percent of cases – born with defects Common Genetic And Chromosomal Difficulties. Phenylketonuria (PKU) – cannot produce an enzyme that is required for normal development; results in an accumulation of poisons that eventually cause profound intellectual disabilities Sickle-cell anemia – abnormally shaped red blood cells; results in pain, yellowish eyes, stunted growth, and vision problems  Development of Human Behavior Genetic Influences on the Fetus Common Genetic And Chromosomal Difficulties. Tay-Sachs disease – usually die by age 3 or 4 because of the body’s inability to break down fat Down syndrome – zygote receives an extra chromosome at the moment of conception; one of the causes of severe mental disabilities Prenatal Environmental Influences Mother’s nutrition Alcohol - fetal alcohol syndrome Mother’s illness disorder (FASD), a condition Mother’s use of drugs resulting in below-average Nicotine intelligence, growth delays, and facial deformities Development of Human Behavior The Structure of a Neuron Dendrites are processes that extend outward Soma or cell body of a neuron Nucleus which is located within the soma, contains genetic information, directs protein synthesis, and supplies the energy Axon is a process that extends far away from the soma and carries an important signal called an action potential to another neuron Development of Human Behavior The Structure of a Neuron Myelin sheath an insulating substance covering the axon of a neuron Terminal Button forms synapses with spines, or protrusions, on the dendrites of neuron at the end of the axon presynaptic terminal button – sending signal postsynaptic membrane – receiving signal Development of Human Behavior The Structure of a Neuron Synaptic Gap/Synaptic Cleft – exists between the presynaptic terminal button and the postsynaptic dendritic spine Synaptic Vesicles – package together groups of chemicals called neurotransmitters Neurotransmitters - released from the presynaptic terminal button, travel across the synaptic gap, and activate ion channels on the postsynaptic spine by binding to receptor sites Development of Human Behavior Types of Cells in the Brain Sensory Neurons – neurons that help us receive information about the world around us Motor Neurons – allow us to initiate movement and behavior, ultimately allowing us to interact with the world around us Interneurons - process the sensory input from our environment into meaningful representations Development of Human Behavior Types of Cells in the Brain Glial Cells- “glue of the nervous system”; provide support for the neurons Oligodendroglia – wrap their dendritic processes around the axons of neurons many times to form the myelin sheath Microglia and Astrocytes - digest debris of dead neurons, carry nutritional support from blood vessels to the neurons, and help to regulate the ionic composition of the extracellular fluid Glial Cells play a vital role in neuronal support, they do not participate in the communication between cells in the same fashion as neurons do. Development of Human Behavior Types of Cells in the Brain Three Main Categories Of Neurons 1. Unipolar neurons are structured in such a way that is ideal for relaying information forward, so they have one neurite (axon) and no dendrites 2. Bipolar neurons are involved in sensory perception such as perception of light in the retina of the eye; one axon and one dendrite which help acquire and pass sensory information to various centers in the brain 3. Multipolar neurons have one axon and many dendrites which allows them to communicate with other neurons. Development of Human Behavior Neuronal Communication Neuron exists in a fluid environment – cytoplasm. Electrical signal that passes through the neuron depends on membrane potential The electrical charge of the fluids is caused by charged molecules (ions) dissolved in the fluid The neuron membrane’s potential is held in a state of readiness – resting potential. Ions in high-concentration areas are ready to move to low- concentration areas, and positive ions are ready to move to areas with a negative charge Development of Human Behavior Neuronal Communication Sodium (Na+) is at higher concentrations outside the cell Potassium (K+) is more concentrated inside the cell The inside of the cell is negatively charged providing force for sodium to move into the cell Development of Human Behavior Neuronal Communication From resting potential state, the neuron receives a signal and its state changes abruptly With this influx of positive ions, the internal charge of the cell becomes more positive reaching a level called threshold of excitation Development of Human Behavior Neuronal Communication At the peak of the spike, the sodium gates close and the potassium gates open. As positively charged potassium ions leave, the cell quickly begins repolarization. It hyperpolarizes, becoming slightly more negative than the resting potential, and then it levels off, returning to the resting potential Development of Human Behavior Neuronal Communication Positive spike constitutes the action potential: the electrical signal that typically moves from the cell body down the axon to the axon terminals The electrical signal moves down the axon with the impulses jumping in a leapfrog fashion between the Nodes of Ranvier – natural gaps in the myelin sheath. Incoming signal from another neuron is either sufficient or insufficient to reach the threshold of excitation Development of Human Behavior Neuronal Communication When the action potential arrives at the terminal button, the synaptic vesicles release their neurotransmitters into the synaptic cleft The neurotransmitters travel across the synapse and bind to receptors on the dendrites of the adjacent neuron, and the process repeats itself in the new neuron Excess neurotransmitters in the synaptic cleft drift away, are broken down into inactive fragments, or are reabsorbed Development of Human Behavior Neuronal Communication Reuptake involves the neurotransmitter being pumped back into the neuron that released it, in order to clear the synapse. Clearing the synapse serves both to provide a clear “on” and “off” state between signals and to regulate the production of neurotransmitter Neuronal communication is often referred to as an electrochemical event. Movement of the action potential down the length of the axon is an electrical event movement of the neurotransmitter across the synaptic space represents the chemical portion of the process NEURON https://youtu.be/zADj0k0waFY