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psychobiology

the area of psychology that focusses on the biological foundations of behavior and mental processes

neuroscience

the study of the brain and the nervous system

neurons

individual cells that are the smallest units of the nervous system

dendrites

short fibers that branch out fromt he cell body and pick up incoming messages

axon

single long fiber extending from the cell body; it carries outgoing messages

nerve (tract)

group of axons bundled together

myelin sheath

white fatty covering found on some axons

sensory neurons

neurons that carry messages from sense organs to the spinal cord or brain

motor neurons

neurons that carry messages from the spinal cord or brain to the muscles and glands

interneurons

neurons that carry messages from one neuron to another

glial cells

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 into the brain

ions

electrically charged particles found both inside and outside the neuron

resting potential

electrical charge across a neuron membrane due to excess positive ions concentrated on the outside and excess negative ions on the inside

polarization

the condition of a neuron when the inside is negatively charged relative to the outside; for example, when the neuron is at rest

neural impulse

the firing of a nerve cell

graded potential

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

all-or-none law

principle that the action potential in a neuron does not vary in strength; the neuron either fires at full strength or it 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 whena neuron is returning to its normal polarized state and will fire again only if the incoming message is much stronger than usual

synaptic space

tiny gap between the axon terminal of one neuron and the dendrites or cell body of the next neuron

terminal button

structure at the end of an axon terminal branch

synapse

area composed of the axon terminal of one neuron, the synaptic space and the dendrite or cell body of the next neuron

synaptic vesicle

tiny sacs in a terminal button that release chemicals into the synapse

neurotransmitters

chemicals released by the synaptic vesicles that travel across the synaptic space and affect adjacent neurons

receptor site

a location on a receptor neuron into which a specific neurotransmistter fits like a key into a lock

neural plasticity

the ability of the brain to change in response to experience

neurogenesis

the growth of new neurons

central nervous system

division of the nervous system that consists of the brain and spinal cord

peripheral nervous system

division of the nervous system that connects the central nervous system to the rest of the body

hindbrain

area containing the medulla, pons, and cerebellum

cerebellum

structure in the hindbrain that controls certain refleces and coordinates the body's movements

midbrain

region between the hindbrain and the forebrain; it is important for hearing and sight, and it is one of the several places in the brain wehre pain is registered

thalamus

forebrain region that relays and translates incoming messages from the sense receptors, except those for smell

hypothalamus

forebrain region that governs motivation and emotional responses

reticular formation (RF)

network of neurons in the hindbrain, the midbrain, and part of the forebrain whose primary function is to alert and arouse the higher parts of the brain

limbic system

ring of structures that play a role in learning and emotional behavior

cerebral cortex

the outer surface of the two cerebral hemispheres that regulates most complex behavior

association areas

areas of the cerebral cortex where incoming messages from the separate senses are combined into meaningful impressions and outgoing messages fromt he motor areas are integrated

occipital lobe

part of the cerebral hemisphere that recieves and interprets visual information

temporal lobe

part of the cerebral hemisphere that helps regulate hearing, balance and equilibrium, and certain emotions and motivations

parietal lobe

part of the cerebral cortex that receives sensory information from throughout the body

primary somatosensory cortex

area of the parietal lobe where messages from the sense receptors are registered

frontal lobe

part of the cerebral cortex that is responsible for voluntary movement; it is also important for attention, goal-directed behavior, and appropriate emotional experiences

primary motor cortex

the section of the frontal lobe responsible for voluntary movement

corpus collosum

a think band of nerve fibers connecting the left and right cerebral cortex

spinal cord

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

sympathetic division

branch of the autonomic nervous system; it prepares the body for quick action in an emergency

parasympathetic division

branch of the autonomic nervous system; it calms and relaxes the body

endocrine glands

glands of the endocrine system that release hormones into the blood stream

hormones

chemical substances released by the endocrine glands; they help regulate bodily activities

thyroid gland

endocrine gland located below the voice box; it produces the hormone thyroxin

parathyroids

four tiny glands embeded in the thyroid; they secrete parathormone

pineal gland

a gland located roughly in the center of the brain that appears to regulate activity levels over the course of the day

pancreas

organ lying between the stomach and the small intestine; it secretes insulin and glucagon to regulate blood-sugar levels

pituitary gland

gland located on the underside of the brain; it produces the largest number of the body's hormones

gonads

the reproductive glands, testes in males and ovaries in females

adrenal glands

two endocrine glands located just above the kidneys

behavioral genetics

study of the relationships between heredity and behavior

evolutionary psychology

a subfield of psychology concerned with the origins of behaviors and mental processes, their adaptive value, and the purposes they continue to serve

genetics

study of how traits are transmitted from one generation to the next

genes

elements that control the transmission of traits; they are found in the chromosomes

chromosomes

pairs of threadlike bodies with the cell nucleus that contain the genes

deoxyribonucleic acid (DNA)

complex molecule in a double-helix configuration that is the main ingredient of chromosomes and genes and forms the code for all genetic information

human genome

the full complement of genes with a human cell

dominant gene

member of a gene pair that controls the appearance of a certain trait

recessive gene

member of a gene pair that can control the appearance of a certain trait only if it is paired with another recessive gene

polygenic inheritance

process by which several genes interact to produce a certain trait; responsible for our most important traits

strain studies

studies of the heritability of behavioral traits using animals that have been inbred to produce strains that are genetically similar to one another

selection studies

studies that estimate the heritability of a trait by breeding animals with other animals that have the same trait

family studies

studies of heritability in humas based on the assumption that if genes influence a certain trait, close relationships should be more similar on that trait that distant relatives

twin studies

studies of identical and fraternal twins to determine the relative influence of heredity and environment on human behavior

identical twins

twins developed from a single fertilized ovum and therefore identical in genetic makeup at the time of conception

fraternal twins

twins developed from two separate ova and therefore different in genetic makeup

adoption studies

research carried out on children, adopted at birth by parents not related to them, to determine the relative influence of heredity and environment on human behavior

natural selection

the mechanism proposed by Darwin in his theory of evolution, which states that organisms best adapted to their environment tend to survive, transmitting their genetic characteristics to succeeding generations, whereas organisms with less adaptive characteristics tend to vanish from the earth

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