Chapter 26: The Nervous System

acetylcholine

neurotransmitter released by neurons in the central nervous system and peripheral nervous system

action potential

self-propagating momentary change in the electrical potential of a neuron (or muscle) membrane

Alzheimer’s disease

neurodegenerative disorder characterized by problems with memory and thinking

amygdala

structure within the limbic system that processes fear

arachnoid mater

spiderweb-like middle layer of the meninges that cover the central nervous system

astrocyte

glial cell in the central nervous system that provide nutrients, extracellular buffering, and structural support for neurons; also makes up the blood-brain barrier

attention deficit hyperactivity disorder (ADHD)

neurodevelopmental disorder characterized by difficulty maintaining attention and controlling impulses

autism spectrum disorder (ASD)

neurodevelopmental disorder characterized by impaired social interaction and communication abilities

autonomic nervous system

part of the peripheral nervous system that controls bodily functions

axon

tube-like structure that propagates a signal from a neuron’s cell body to axon terminals

axon hillock

electrically sensitive structure on the cell body of a neuron that integrates signals from multiple neuronal connections

axon terminal

structure on the end of an axon that can form a synapse with another neuron

basal ganglia

interconnected collections of cells in the brain that are involved in movement and motivation; also known as basal nuclei

basal nuclei

basal nuclei

brainstem

portion of the brain that connects with the spinal cord; controls basic nervous system functions like breathing, heart rate, and swallowing

cerebellum

brain structure involved in posture, motor coordination, and learning new motor actions

cerebral cortex

outermost sheet of brain tissue; involved in many higher-order functions

cerebrospinal fluid (CSF)

clear liquid that surrounds the brain and spinal cord and fills the ventricles and central canal; acts as a shock absorber and circulates material throughout the brain and spinal cord.

choroid plexus

spongy tissue within ventricles that produces cerebrospinal fluid

cingulate gyrus

helps regulate emotions and pain; thought to directly drive the body’s conscious response to unpleasant experiences

corpus callosum

thick fiber bundle that connects the cerebral hemispheres

cranial nerve

sensory and/or motor nerve that emanates from the brain

dendrite

structure that extends away from the cell body to receive messages from other neurons

depolarization

change in the membrane potential to a less negative value

dura mater

tough outermost layer that covers the central nervous system

ependymal

cell that lines fluid-filled ventricles of the brain and the central canal of the spinal cord; involved in production of cerebrospinal fluid

epilepsy

neurological disorder characterized by recurrent seizures

excitatory postsynaptic potential (EPSP)

depolarization of a postsynaptic membrane caused by neurotransmitter molecules released from a presynaptic cell

frontal lobe

part of the cerebral cortex that contains the motor cortex and areas involved in planning, attention, and language

glia

(also, glial cells) cells that provide support functions for neurons

gyrus

(plural: gyri) ridged protrusions in the cortex

hippocampus

brain structure in the temporal lobe involved in processing memories

hyperpolarization

change in the membrane potential to a more negative value

hypothalamus

brain structure that controls hormone release and body homeostasis

inhibitory postsynaptic potential (IPSP)

hyperpolarization of a postsynaptic membrane caused by neurotransmitter molecules released from a presynaptic cell

limbic system

connected brain areas that process emotion and motivation

long-term depression (LTD)

prolonged decrease in synaptic coupling between a pre- and postsynaptic cell

long-term potentiation (LTP)

prolonged increase in synaptic coupling between a pre-and postsynaptic cell

major depression

mental illness characterized by prolonged periods of sadness

membrane potential

difference in electrical potential between the inside and outside of a cell

meninge

membrane that covers and protects the central nervous system

microglia

glia that scavenge and degrade dead cells and protect the brain from invading microorganisms

myelin

fatty substance produced by glia that insulates axons

neurodegenerative disorder

nervous system disorder characterized by the progressive loss of neurological functioning, usually caused by neuron death

neuron

specialized cell that can receive and transmit electrical and chemical signals

nodes of Ranvier

gaps in the myelin sheath where the signal is recharged

norepinephrine

neurotransmitter and hormone released by activation of the sympathetic nervous system

occipital lobe

part of the cerebral cortex that contains visual cortex and processes visual stimuli

oligodendrocyte

glial cell that myelinates central nervous system neuron axons

parasympathetic nervous system

division of autonomic nervous system that regulates visceral functions during rest and digestion

parietal lobe

part of the cerebral cortex involved in processing touch and the sense of the body in space

Parkinson’s disease

neurodegenerative disorder that affects the control of movemen

pia mater

thin membrane layer directly covering the brain and spinal cord

proprioception

sense about how parts of the body are oriented in space

radial glia

glia that serve as scaffolds for developing neurons as they migrate to their final destinations

refractory period

period after an action potential when it is more difficult or impossible for an action potential to be fired; caused by inactivation of sodium channels and activation of additional potassium channels of the membrane

saltatory conduction

“jumping” of an action potential along an axon from one node of Ranvier to the next

satellite glia

glial cell that provides nutrients and structural support for neurons in the peripheral nervous system

schizophrenia

mental disorder characterized by the inability to accurately perceive reality; patients often have difficulty thinking clearly and can suffer from delusions

Schwann cell

glial cell that creates myelin sheath around a peripheral nervous system neuron axon

sensory-somatic nervous system

system of sensory and motor nerves

somatosensation

sense of touch

spinal cord

thick fiber bundle that connects the brain with peripheral nerves; transmits sensory and motor information; contains neurons that control motor reflexes

spinal nerve

nerve projecting between skin or muscle and spinal cord

sulcus

(plural: sulci) indents or “valleys” in the cortex

summation

process of multiple presynaptic inputs creating EPSPs around the same time for the postsynaptic neuron to be sufficiently depolarized to fire an action potential

sympathetic nervous system

division of autonomic nervous system activated during stressful “fight or flight” situations

synapse

junction between two neurons where neuronal signals are communicated

synaptic cleft

space between the presynaptic and postsynaptic membranes

synaptic vesicle

spherical structure that contains a neurotransmitter

temporal lobe

part of the cerebral cortex that processes auditory input; parts of the temporal lobe are involved in speech, memory, and emotion processing

thalamus

brain area that relays sensory information to the cortex

threshold of excitation

level of depolarization needed for an action potential to fire

ventricle

cavity within brain that contains cerebrospinal fluid