The area of psychology that focuses on the biological foundations of behavior and mental processes.
The study of the brain and nervous system.
Individual cells that are the smallest units of the nervous system.
Short fibers that branch out from the cell body and pick up incoming messages.
Single, long fiber extending from the cell body; it carries outgoing messages.
Group of axons bundled together
White fatty covering found on some axons.
Sensory (afferent) neurons
Neurons that carry messages from sense organs to the spinal chord or brain.
Motor (efferent) neurons
Neurons that carry messages from the spinal chord or brain to the muscles and glands.
Interneurons (association neurons)
Neurons that carry messages from one neuron to another.
Cells that form the myelin sheath; they insulate and support neurons by holding them together, removing waste products, and preventing harmful substances from passing from the bloodstream to the brain.
Electrically charged particles found both inside and outside the neuron.
Electrical charge across a neuron membrane due to excess positive ions concentrated on the outside and excess negative ions on the inside.
The condition of a neuron when the inside is negatively charged related to the outside; for example, when the neuron is at rest
Neural impulse (action potential)
The firing of a nerve cell.
A shift in the electrical charge in a tiny area of a neuron.
Threshold of excitation
The level an impulse must exceed to cause a neuron to fire.
Principle that states the action potential in a neuron does not vary in strength; the neuron either fires at full strength or does not fire at all.
Absolute refractory period
A period after firing when a neuron will not fire again no matter how strong the incoming messages may be.
Relative refractory period
A period after firing when a neuron is returning to its normal polarized state and will fire again only if the incoming message is much stronger than usual.
Synaptic space (synaptic cleft)
The gap between the axon terminal of one neuron and the dendrites or cell body of the next neuron.
Terminal Button (synaptic knob)
Structure at the end of the axon terminal branch.
Area composed of the axon terminal of one neuron, the synaptic space, and the dendrite or cell body of the next neuron.
Tiny sacs in a terminal button that release chemicals into the synapse
Chemicals released by the synaptic vesicles that travel across the synaptic space and affect adjacent neurons.
A location of a receptor neuron into which a specific neurotransmitter fits like a key into a lock.
The ability of the brain to change in response to the environment.
The growth of new neurons.
Central nervous system
Division of the nervous system that consists of the brain and spinal chord.
Peripheral nervous system
Division of the nervous system that connects the central nervous system to the rest of the body.
Area containing the medulla, pons, and cerebellum.
Structure in the hindbrain that controls certain reflexes and coordinates the body's movements.
Region between hindbrain and forebrain; it is important for hearing and sight, and it is one of several places in the brain where pain is registered.
Forebrain region that relays and translates incoming messages from the sense receptors, except those for smell.
Forebrain region that governs motivation and emotional responses.
Network of neurons in the hindbrain, the midbrain, and part of the forebrain whose primary function is to alert and arouse higher parts of the brain.
Ring of structures that play a role in learning and emotional behavior.
The outer surface of the two cerebral hemispheres that regulates the most complex behaviors.
Areas of the cerebral cortex where incoming messages from the separate senses are combined into meaningful impressions and outgoing messages from the motor areas are integrated.
Part of the cerebral hemisphere that receives and interprets visual information.
Part of the cerebral hemisphere that helps regulate hearing, balance, and equilibrium, and certain emotions and motivations.
Part of the cerebral cortex that receives sensory information from throughout that body.
Primary somatosensory cortex
Area of the parietal lobe where messages from the sense receptors are registered.
Part of cerebral cortex responsible for voluntary movement; it is also important for attention, goal-directed behavior, and appropriate mental experiences.
Primary motor cortex
The section of the frontal lobe responsible for voluntary movement.
A thick band of nerve fibers connecting the left and right cerebral cortex.
Complex cable of neurons that runs down the spine, connecting the brain to most of the rest of the body.
Somatic nervous system
The part of the peripheral nervous system that carries messages from the senses to the central nervous system and between the central nervous system and the skeletal muscles.
Autonomic nervous system
The part of the peripheral nervous system that carries messages between the central nervous system and the internal organs.
Branch of the autonomic nervous system; it prepares the body for quick action in an emergency.
Branch of the autonomic nervous system; it calms and relaxes the body.
Glands of the endocrine system that release hormones into the bloodstream.
Chemical substances released by the endocrine glands; they help regulate bodily activities.
Endocrine gland located below the voice box; it produces the hormone thyroxin.
Four tiny glands embedded in the thyroid; they secrete parathormone.
A gland located roughly in the center of the brain that appears to regulate activity levels over the course of the day.
Organ lying between the stomach and small intestine; it regulates insulin and glucagon to regulate blood-sugar levels.
Gland located on the underside of the brain; it produces the largest number of the body's hormones.
The reproductive glands, testes in males and ovaries in females.
Two endocrine glands located just above the kidneys.
Study of the relationship between heredity and behavior.
A subfield of psychology concerned with the origins of behaviors and mental processes, their adaptive value, and the purposes they continue to serve.
Study of how traits are transmitted from one generation to the next.
Elements that control the transmission of traits; they are found on the chromosomes.
Pairs of threadlike bodies within the cell nucleus that contain the genes.
Complex molecule in a double helix configuration that is the main ingredient of chromosomes and genes and forms the code for all genetic information.
The full complement of genes within a human cell.
Member of a gene pair that controls the appearance of a certain trait.
Member of a gene pair that can control the appearance of a certain trait only if it is paired with another recessive gene.
Process by which several genes interact to produce a certain trait; responsible for our most important traits.
Studies of the heritability of behavioral traits using animals that have been inbred to produce strains that are genetically similar to one another.
Studies that estimate the heritability of a trait by breeding animals with other animals that have the same trait.
Studies of heritability in humans based on the assumption that if genes influence a certain trait, close relatives should be more similar on that trait than distant relatives.
Studies of identical and fraternal twins to determine the relative influence of heredity and environment on behavior.
Research carried out on children, adopted at birth by parents not related to them, to determine the relative influence of heredity and environment on behavior.