Unit 3: Biological Bases

neuron: a nerve cell; the basic building block of the cell

cell body: part of the neuron that contains the nucleus; the cell's life-support system

dendrites: the neurons bushy, branching extensions that receive and integrate messages, conducting impulses towards the cell body

axon: neuron extension that passes messages through its branches to other neurons or to muscles or glands

myelin sheath: fatty tissue layer segmentally encasing the axon of some neurons; enables vastly greater transmission speed as neural impulses hop from one node to the next

glial glands (glia): cells in the nervous system that support, nourish, and protect neurons; they 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 the junction is called the synapse gap/synaptic cleft

neurotransmitters: chemical messengers that cross the synaptic gap between neurons, thereby influencing whether that neuron will generate a neural impulse

reuptake: a neurotransmitters reabsorption by the sending neuron

endorphins: natural, opiate-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

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 to the rest of the body

nerves: bundles axons that form neural cables connecting the central nervous system with muscles, glands, and sense organs

sensory (afferent) neurons: neurons that carry incoming information from the 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: part of the peripheral nervous system that controls the glands and the muscles of the internal organs

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

parasympathetic nervous system: division of the autonomic nervous system that calms the body, conserving its energy

reflex: a simple, automatic response to a sensory stimulus (ie knee jerk reaction)

endocrine system: the body's 'slow' chemical communication system; a set of glands that secrete hormones into bloodstream

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

adrenal glands: a pair of endocrine glands that sit just above the kidneys and secrete hormones (epinephrine and norepinephrine) that help arouse the body in times of stress.

pituitary gland: under influence of the hypothalamus; regulates growth and controls other endocrine glands; the endocrine systems most influential gland

lesion: tissue destruction; brain lesions are naturally/experimentally caused

EEG (electroencephalogram): an amplified recording of the waves of electrical activity that sweep across the brain's surface; waves are measured by electrodes placed on the scalp.

MEG (megnetoencephalography): a brain imaging technique that measures magnetic fields from the brains natural electrical activity

CT (computed tomography) scan: a series of x-ray photographs taken from different angles and combined by a computer into a composite representation of a slice of the brain's structure (also called CAT scan)

PET (positron emission tomography) scan: a visual display of brain activity that detects where a radioactive form of glucose goes while the brain performs a given task

MRI (magnetic resonance imaging): a technique that uses magnetic fields and radio waves to produce computer-generated images of soft tissue; MRI scans show brain anatomy

fMRI (functional MRI): a technique for revealing bloodflow and therefore brain activity by comparing successive MRI scans; shows brain function and structure

brainstem: the oldest part and central core of the brain, beginning where the spinal cord swells as it enters the skull; the brain stem is responsible for automatic survival functions

medulla: the base of the brain stem; controls heartbeat and breathing

thalamus: the brain's sensory control center, located at the top of the brain stem; it directs messages to the sensory receiving areas in the cortex and transmits to the medulla and cerebellum

reticular formation: a nerve network that travels through the brain stem into the thalamus and plays an important role in controlling arousal

cerebellum: the "little brain" at the rear of the brain stem; functions include processing sensory input, coordinating movement output and balance, and enabling nonverbal learning and memory

limbic system: neural system located below the cerebral hemispheres; associated with emotions and drives; includes amygdala, hypothalamus, and hippocampus

amygdala: two lima bean-sized neural clusters in the limbic system; linked to emotion.

hypothalamus: a neural structure lying below the thalamus; it directs several maintenance activities (eating, drinking, body temperature), helps govern the endocrine system via the pituitary gland, and is linked to emotion and reward.

hippocampus: neural center located in the limbic system that helps process explicit memories for storage

cerebral cortex: the intricate fabric of interconnected neural cells covering the central hemispheres; the body's ultimate control and information-processing center

frontal lobe: the portion of the cerebral cortex lying just behind the forehead; involved in speaking and muscle movements and in making plans and judgement

parietal lobe: the portion of the cerebral cortex lying at the top of the head and toward the rear; receives sensory input for touch and body position

occipital lobe: the portion of the cerebral cortex lying at the back of the head; includes areas that receive information from visual fields

temporal lobe: the portion of the cerebral cortex lying roughly above the ears; includes the auditory areas, each receiving primarily from the opposite ear

motor cortex: the area at the rear of the frontal lobes that controls voluntary movement

somatosensory cortex: an area in the front of the parietal lobes that registers and processes body touch and movement sensations

association areas: areas of the cerebral cortex that are not involved in primary motor or sensory functions; rather they are involved in higher mental functions such as learning, remembering, thinking, and speaking

plasticity: the brains ability to change, especially during childhood, by reorganizing after damage or by building new pathways based on experiences

neurogenesis: the formation of new neurons

corpus callosum: the large band of neural fibers connecting the two brain hemispheres and carrying messages between them

split brain: the condition resulting from surgery that isolates the brains two hemispheres by cutting the fibers (the corpus callosum) connecting them

cognitive neuroscience: the interdisciplinary study of the brain activity linked with cognition; includes perception, thinking, memory, and language

dual processing: the principle that information is often simultaneously processed on separate conscious and unconscious tracks

blindsight: a condition in which a person can respond to a visual stimulus without consciously experiencing it

parallel processing: processing many aspects of a problem simultaneously; generally used to process well-learned information or to solve easy problems

sequentially processing: processing one aspect of a problem at a time; generally used to process new information or solve difficult problems

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

heredity: the genetic transfer of characteristics from parents to offspring

chromosome: threadlike structures made of DNA molecules that contain the genes

DNA: a complex molecule containing the genetic information that makes up the chromosomes

genes: biochemical units of heredity that make up chromosomes; segments of DNA capable of synthesizing proteins

genome: the complete instructions for making an organism, consisting of all the genetic material in that organism's chromosomes

identical (monozygotic) twins: develop from a single fertilized egg that splits in two, creating two genetically identical organisms

fraternal (dizygotic) twins: develop from separate fertilized eggs; genetically no closer than ordinary siblings, but share a prenatal environment

heritability: the proportion of variation among individuals in a group that we can attribute to genes

molecular genetics: subfield of biology that studies the molecular structure and functions of genes

molecular behavior genetics: study of how structure and function of genes interact with our environment to influence behavior

epigenetics: the study of environmental influences on gene expression that occur without a DNA change

evolutionary psychology: study of the evolution of behavior and the mind, using principles of natural selection

natural selection: the principle that inherited traits that better enable an organism to survive and reproduce in a particular environment will most likely be passed on to succeeding generations

social script: a culturally modeled guide for how to act in various situations