Psych chapter 3

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 (CNS)

the brain and spinal cord.

peripheral nervous system

(PNS)

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 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 that

communicate internally and

intervene 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 [aw-tuh-NAHM￾ik] nervous system (ANS)

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 in

stressful situations.

parasympathetic nervous

system

the 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.

endocrine

system

the body’s “slow” chemical

communication system; a set of

glands that secrete hormones into

the 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

the endocrine

system’s most influential gland.

Under the influence of the

hypothalamus, the pituitary

regulates growth and controls other

endocrine glands.

lesion

tissue

destruction. A brain lesion is a

naturally or experimentally caused

destruction of brain tissue.

electroencephalogram (EEG)

an amplified recording of the waves

of electrical activity sweeping

across the brain’s surface. These

waves are measured by electrodes

placed on the scalp.

CT (computed tomography)

scan

a series of X-ray photographs

taken from different angles and

combined by 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.

fMRI scans show brain function as

well as its structure.

brainstem

the oldest part and

central core of the brain, beginning

where the spinal cord swells as it

enters the skull; the brainstem is

responsible for automatic survival

functions.

medulla

the base

of the brainstem; controls heartbeat

and breathing.

thalamus

the brain’s sensory control center,

located on top of the brainstem;

it directs messages to the sensory

receiving areas in the cortex and

transmits replies to the cerebellum

and medulla.

reticular formation

a nerve

network that travels through the

brainstem and thalamus and plays

an important role in controlling

arousal.

cerebellum

the “little brain” at the

rear of the brainstem; functions

include processing sensory input,

coordinating movement output and

balance, and enabling nonverbal

learning and memory.

limbic system

neural system

(including the hippocampus,

amygdala, and hypothalamus)

located below the cerebral

hemispheres; associated with

emotions and drives.

amygdala

two

lima-bean-sized neural clusters in

the limbic system; linked to emotion.

hypothalamus

a neural structure lying below

(hypo) 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.

cerebral cortex

the intricate fabric of interconnected

neural cells covering the cerebral

hemispheres; the body’s ultimate

control and information-processing

center.

glial cells (glia)

cells in the

nervous system that support,

nourish, and protect neurons; they

may also play a role in learning and

thinking.

frontal lobes

portion of the

cerebral cortex lying just behind the

forehead; involved in speaking and

muscle movements and in making

plans and judgments.

parietal lobes

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 lobes

portion of the cerebral cortex lying

at the back of the head; includes

areas that receive information from

the visual fields.

temporal lobes

portion of the

cerebral cortex lying roughly above

the ears; includes the auditory

areas, each receiving information

primarily from the opposite ear.

motor cortex

an area at the rear

of the frontal lobes that controls

voluntary movements.

somatosensory cortex

area at

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 brain’s ability

to change, especially during

childhood, by reorganizing after

damage or by building new

pathways based on experience.

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

a condition resulting

from surgery that isolates the brain’s

two hemispheres by cutting the

fibers (mainly those of the corpus

callosum) connecting them.

consciousness

our awareness

of ourselves and our environment.

ognitive neuroscience

the

interdisciplinary study of the brain

activity linked with cognition

(including perception, thinking,

memory, and language).

dual processing

the principle

that information is often

simultaneously processed on

separate conscious and unconscious

tracks.

behavior genetics

the study

of the relative power and limits

of genetic and environmental

influences on behavior.

environment

every external

influence, from prenatal nutrition to

the people and things around us.

chromosomes

threadlike

structures made of DNA molecules

that contain the genes.

DNA

a

complex molecule containing the

genetic information that makes up

the chromosomes.

genes

the biochemical units

of heredity that make up the

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 twins (monozygotic

twins)

twins who develop from

a single fertilized egg that splits

in two, creating two genetically

identical organisms.

fraternal twins (dizygotic twins)

twins who develop from separate

fertilized eggs. They are genetically

no closer than brothers and sisters,

but they share a fetal environment.

molecular genetics

the subfield

of biology that studies the

molecular structure and function

of genes

heritability

the proportion of

variation among individuals that we

can attribute to genes. The heritability

of a trait may vary, depending

on the range of populations and

environments studied.

interaction

the interplay that

occurs when the effect of one factor

(such as environment) depends on

another factor (such as heredity

epigenetics

the study of

environmental influences on gene

expression that occur without a

DNA change.

evolutionary psychology

the

study of the evolution of behavior

and the mind, using principles of

natural selection.

natural selection

the principle

that, among the range of inherited

trait variations, those contributing

to reproduction and survival

will most likely be passed on to

succeeding generations.

mutation

a random error in gene

replication that leads to a change.

biological psychology

the scientific study of the links

between biological (genetic, neural,

hormonal) and psychological

processes. (Some biological

psychologists call themselves

behavioral neuroscientists,

neuropsychologists, behavior

geneticists, physiological psychologists,

or biopsychologists.)

neuron

a nerve cell; the basic

building block of the nervous

system.

dendrites

a neuron’s bushy,

branching extensions that receive

messages and conduct impulses

toward the cell body

axon

the 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; enables

vastly greater transmission speed

as neural impulses hop from one

sausage-like node to the next.

action potential

a neural impulse;

a brief electrical charge that travels

down an axon.

refractory period

a period of

inactivity after a neuron has fired.

threshold

the level of stimulation

required to trigger a neural impulse

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,

neurotransmitters 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,

opiate-like neurotransmitters linked

to pain control and to pleasure

agonist

a molecule that, by

binding to a receptor site, stimulates

a response.

antagonist

a molecule that, by

binding to a receptor site, inhibits

or blocks a response