Psych Unit 1.1-1.4

Nature-nuture issue

The longstanding controversy over the relative contributions that genes and experience make to development of psychological traits and behaviors. Today’s science views traits and behaviors as arising from the interaction of nature and nurture

Natural Selection

The principle that the inherited traits enabling an organism to survive and reproduce in a particular environment will (in competition with other trait variations) most likely be passed on to succeeding generations

Evolutionary Psychology

The study of the evolution of behavior and the mind, using principles of natural selection

Behavior Genetics

The study of the relative power and limits of genetic and environmental influences on behavior

Mutation

A random error in gene replication that leads to a change

Environment

Every nongenetic influence, from prenatal nutrition to our experiences of the people and things around us

Heredity

The genetic transfer of characteristics from parents to offspring

Genes

The biochemical units of heredity

Genome

The complete instructions for making an organism

Identical (monozygotic) Twins

Individuals who developed from a single fertilized egg that slit in two, creating two genetically identical organisms

Fraternal (dizygotic) Twins

Individuals who developed from separate fertilized eggs. They are genetically no closer than ordinary siblings, but they shared a prenatal enironment

Interaction

The interplay that occurs when the effect of one factor (such as environment) depends on another factor (such as heredity)

Epigenetics

“Above” or “in addition to” (epi) genetics; the study of the molecular mechanisms by which environments can influence genetic expression (without a DNA change)

Nervous System

The body’s speedy, electrochemical communication network, consisting of all the nerve cells of the peripheral and central nervous systems

Central Nervous System (CNS)

The brain and spinal cord

Peripheral Nervous System (PNS)

The sensory and motor neurons that connect the central nervous system (CNS) to the rest of the body

Nerves

Bundled axons that form neutral cables connecting the central nervous system with muscles, glands, and sensory and organs

Sensory (afferent) neurons

Neurons that carry incoming information from the body’s tissues and sensory receptors to the brain and spinal cord

Motor (efferent) neurons

Neurons that carry outgoing information from the brain and spinal cord to the muscles and glands

Interneurons

Neurons within the brain and spinal cord; they communicate internally and process information between and sensory inputs and motor outputs

Somatic Nervous System

The division of the peripheral nervous system that controls the body’s skeletal muscles. Also called the skeletal nervous system

Autonomic Nervous System (ANS)

The part of the peripheral nervous system that controls the glands and the muscles of the internal organs (such as the heart). Its sympathetic division arouses; its parasympathetic division calms

Sympathetic Nervous System

The division of the autonomic nervous system that arouses the body, mobilizing its energy

Parasympathetic Nervous System

The division of the autonomic nervous system that clams the body, conserving its energy

Reflex

A simple, automatic response to a sensory stimulus, such as the knee-jerk reflex

Neuron

A nerve cell; the basic building block of the nervous system

Cell Body

The part of a neuron that contains the nucleus; the cell’s life-support center

Dendrites

A neuron’s often bushy, branching extensions that receive and inter-grate messages, conducting impulses toward the cell body

Axon

The segmented neuron extension that passes messages through its branches to other neurons or to muscles or glands

Myelin Sheath

A fatty tissue layer segmentally encasing the axons of some neurons; it enables vastly greater transmission speed as neutral impulses hop from one node to the next

Glial cells (glia)

Cells in the nervous system that support, nourish, and protect neurons; they may also play a role in learning, thinking, and memory

Action Potential

A neutral impulse; a brief electrical charge that travels down an axon

Threshold

The level of stimulation required to trigger a neutral impulse

Refractory Period

In neutral processing, a brief resting pause that occurs after a neuron has fired; subsequent action potentials cannot occur until the axon returns to its resting state

All-or-none Response

A neuron’s reaction of either firing (with a full-strength response) or not firing

Synapse

The junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron. The tiny gap at this junction is called the synaptic gap or synaptic cleft

Neurotransmitters

Chemical messengers that cross the synaptic gap between neurons. When released by the sending neuron, neurotransmitters travel across the synapse and bind to receptor sites on the receiving neuron, thereby influencing whether that neuron will generate a neural impulse

Reuptake

A neurotransmitter’s reabsorption by the sending neuron

Endorphins

“Morphine within”; natural, opioid-like neurotransmitters linked to pain control and to pleasure

Hormones

Chemical messengers that are manufactured by the endocrine glands, travel through the bloodstream, and affect other tissues