DNA
a long, complex molecule that encodes genetic characteristics
gene
segment of a chromosome that encodes the directions for the inherited physical and mental characteristics of an organism; the functional units of chromosomes
neuron
cell specialized to receive and transmit information to other cells in the body; also called nerve cell
nerves
bundles of many neurons
sensory neuron
nerve cell that carries messages from sense receptors toward the central nervous system; also called an afferent neuron
motor neuron
nerve cell that carries messages away from the central nervous system toward the muscles and glands; also called an efferent neuron
interneuron
a nerve cell that relays messages between nerve cells, especially in the brain and the spinal cord
dendrite
a branched fiber that extends outward from the main cell body and carries information into the neuron
soma
the part of a cell (such as a neuron) containing the nucleus, which includes the chromosomes; also called the cell body
axon
in a nerve cell, an extended fiber that conducts information from the soma to the terminal buttons; information travels along the axon in the form of an electric charge called the action potential
resting potential
the electrical charge of the action in its inactive state, when the neuron is ready to "fire"
action potential
the nerve impulse caused by a change in the electrical charge across the cell membrane of the axon; when the neuron "fires," this charge travels down the axon and causes neurotransmitters to be released by the terminal buttons
all-or-none principle
refers to the fact that all the action potential in the axon occurs either full-blown or not at all
synapse
the microscopic gap that serves as a communications link between neurons; also occur between neurons and the muscles or glands they serve
terminal buttons
tiny bulb-like structures at the end of the axon, which contain neurotransmitters that carry the neuron's message into the synapse
synaptic transmission
the relaying of information across the synapse by means of chemical neurotransmitters
dopamine
produces sensations of pleasure and reward; used by CNS neurons in voluntary movement; problems can cause schizophrenia and Parkinson's disease
serotonin
regulates sleep and dreaming, mood, pain, aggression, appetite, and sexual behavior; problems can cause depression, certain anxiety disorders, and OCD
norepinephrine
controls heart rate, sleep, sexual responsiveness, stress, vigilance and appetite; problems can cause high blood pressure and depression
acetylcholine
primary transmitter used by neurons carrying messages from CNS; involved in some kinds of learning and memory; problems can cause certain muscular disorders, and Alzheimer's disease
GABA
most prevalent inhibitory neurotransmitter in neurons of CNS; problems can cause anxiety and epilepsy
glutamate
primary excitatory neurotransmitter in CNS; involved in learning and memory; problems can cause brain damage after stroke
endorphins
control pleasurable sensations and control of pain; lowered levels resulting from opiate addiction
hindbrain
oldest part of the brain; responsible for basic life functions, including breathing, respiration, and sleeping
midbrain
second oldest brain structure; includes the reticular activating system/RAS and several neural centers that act as lower-level control centers for some limited motor, auditory, and visual functions
forebrain
newest part of brain; contains cerebral cortex, thalamus, basal ganglia, and hippothalamus
medulla
portion of brain stem associated with basic life functions, such as heartbeat and respiration
pons
portion for brain stem that is involved in coordinating muscular action and facial expression
cerebellum
portion of hindbrain that helps to control posture, balance, and muscle coordination
limbic system
group of brain structures involved with emotions, the autonomic nervous system, and olfactory processing
thalamus
portion of brain whose primary function is to relay information from sensory systems to the cerebral cortex
hippothalamus
region of hindbrain involved in regulating hunger, thirst, sex drive, body temperature, and more; secretes hormone that triggers pituitary gland
hippocampus
part of limbic system involved in long-term memory
amygdala
portion of limbic system linked to emotions and forming long-term memories
cerebral cortex
outer layer of nerve cells covering cerebrum that is responsible for most higher cognitive function
corpus callosum
bundle of nerve fibers that connects the left and right hemispheres of the brain
central fissure
long, deep groove on the lateral surface of the cerebral cortex
threshold
the level of stimulation required to trigger a neural impulse
reuptake
a neurotransmitter's reabsorption by the sending neuron
somatic nervous system
the division of the peripheral nervous system that controls the body's skeletal muscles
autonomic nervous system
the 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 in stressful situations
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, such as the knee-jerk response
nervous system
the body's speedy electrochemical communication network consisting of all the nerves of the peripheral and central nervous systems
central nervous system
the brain and the spinal cord
peripheral nervous system
the sensory and motor neurons that connect the CNS to the rest of the body
lateral fissure
fissure that separates the different lobes of the cerebrum
EEG
record the brain-wave pattern of electrical activity in different parts of the brain; can detect the activity of a single neuron
CAT
a series of x-rays that, when combined, show a composite representation of horizontal slices of the brain
MRI
displays high-resolution pictures of structures and different types of soft tissues deep inside the brain
PET
provides color coded map of areas showing high activity in the brain
pituitary gland
gland located at the base of the brain producing hormones that control other glands and affect metabolism, bone growth, and sexual maturity
thyroid
an endocrine gland located in the necks of people and other vertebrates that secretes the hormones that control metabolism and growth
pancreas
a gland situated near the stomach that secretes a digestive fluid into the intestine and produces the hormone insulin
adrenal glands
small glands that produce steroid hormones, adrenaline, and noradrenaline, which help control heart rate, blood pressure, and other important bodily functions; there are two, one located on top of each kidney
epinephrine
a hormone secreted by the adrenal medulla that is stimulated by the CNS in response to stress or fear; increases heart rate, blood pressure, cardiac output, and carbohydrate metabolism
norepinephrine
hormone secreted by the adrenaline gland that increases blood pressure and rate and the depth of breathing, raises the level of blood sugar, and decreases activity in the intestines; main neurotransmitter of sympathetic nerve endings supplying the major organs and skin
thymus
an organ, located at the base of the neck, that is involved in the development of cells of the immune system, particularly T cells
gonads
sex organs in a male or female animal that make the cells needed to produce babies
ovaries
pair of organs in a female's body that produce eggs
testes
pair of male reproductive glands that produce sperm and are contained in the scrotum in most mammals
chromosomes
structures made of DNA that contain genes; located in cell nucleus; humans normally have 23 pairs, or 46 total
temperament
a person's characteristic emotional reactivity and intensity
behavior genetics
the study of the relative power and limits of genetic and environmental influences on behavior
genome
the complete instructions for making an organism consisting of all the genetic material in that organism's chromosomes
heretability
the proportion of variation among individuals that we can attribute to genes; may vary on particular traits, depending on the range of populations/environments studied
interaction
the interplay that occurs when the effect of one factor (such as environment) depends on another factor (such as heredity)
molecular genetics
the subfield of biology that studies the molecular structure and function of genes
mutation
a random error in gene replication that leads to a change
individualism
giving priority to one's own goals and defining one's identity in terms of personal attributes rather than group identifications
collectivism
giving priority to goals of one's group (often one's extended family or work group) and defining one's identity accordingly
absolute threshold
the lowest amount of stimulation needed to detect a particular stimulus 50 percent of the time
accommodation
the process in which the lens of the eye changes shape in response to external conditions so that an object remains in focus
adaptation
the process by which the eye adjusts to varying levels of light or color
amplitude
the height of the sound waves developed by an auditory stimulus
binocular cues
a visual depth cue that requires the use of both eyes
blind spot
an area or direction in which a person's vision is obscured because no receptor cells are located there
cochlea
the snail shaped, fluid filled organ in the inner ear that contains the basilar membrane
conduction deafness
hearing loss related to problems with the ossicles, the bones of the inner ear
cones
receptors in the retina that allow us to see color, but do not function as well in low light conditions
confabulation
an imagined but plausible memory that fills in the gaps of what a person actually remembers
convergence
a binocular cue that perceives depth; the eyes converge inwards when looking at an object
cornea
the clear part of the eye that lies in front of the retina and is part of the eye's protective covering
depth perception
the ability to visually perceive the world and understand spacial relationships in order to gauge the distance between objects
eardrum
another term for the tympanic membrane
feature detection cells
cells in the cortex of the brain that respond to different characteristics of a visual stimulus
feature detection theory
an explanation for pattern recognition; the theory that we process images in terms of their constituent parts and then match the features of a pattern to those features stored in memory
figure and ground
an aspect of perception where the perceived is separated into at least two parts, with different attributes, but influencing one another
fovea
a depression near the center of the retina that is densely packed with cones; vision is most accurate here
gate control theory
theory of pain perception that there is a spinal "gate" that can be closed by the brain; closed gate would prevent brain from feeling bodily pain
frequency theory
a theory that sound is heard when pulses travel up the auditory nerve and carry the information to the brain for processing, and that the rate of this pulse exactly matches the frequency of whatever tone is heard
gustation
sense of taste
induced motion
an optical illusion in which a stationary object appears to be moving in one direction because of the movement of objects on either side in the opposite direction
iris
the colored portion of the eye that controls how much light enters through the pupil
kinesthetics
the sense of body position; also known as proprioception
law of effect
proposed by Edward Thorndike; states that a behavior is more likely to be repeated if it maximizes pleasure and/or minimizes pain
lens
the portion of the eye that changes shape to focus the visual image on the retina
light adaptation
the changes that occur in the eye to permit vision when moving from darkness to light
monocular cue
a visual depth cue that makes use of only one eye