AP PSYCH UNIT 1 PART 1 : Biological Bases of Behavior

nature-nurture issue

he longstanding controversy over the relative contributions that genes and experience make to the development of psychological traits and behaviors.

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 split 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 share a prenatal environment.

interaction

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

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

the brain and spinal cord.

peripheral nervous system

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

nerves

bundled axons that form neural cables connecting the central nervous system with muscles, glands, and sensory 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 the 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

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 calms the body, conserving its energy.

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 integrate 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 neural impulses hop from one node to the next.

glial cells

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 neural impulse; a brief electrical charge that travels down an axon.

threshold

the level of stimulation required to trigger a neural impulse.

refractory period

in neural 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 gaps between neurons. When released by the sending neuron, ______ 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

agonist

a molecule that increases a neurotransmitter’s action.

antagonist

a molecule that inhibits or blocks a neurotransmitter’s action.

endocrine system

the body’s “slow” chemical communication system; a set of glands and fat tissue that secrete hormones into the bloodstream.