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sensory input

when sensory organs send info from the environment to the brain


Central Nervous System, the portion of the vertebrate nervous system consisting of the brain and spinal cord

effector cells

the muscle cells or gland cells that actually carry out the body's responses to stimuli.


Peripheral Nervous System is everything besides the brain and spinal cord


largest part of a typical neuron; contains the nucleus and much of the cytoplasm


long nerve fiber that conducts away from the cell body of the neuron


branching extensions of neuron that receives messages from neighboring neurons

axon hillock

specialized region of the axon, which connects the inital segment of the axon to the cell body

myelin sheath

a layer of fatty tissue segmentally encasing the fibers of many neurons; enables vastly greater transmission speed of neural impulses as the impulse hops from one node to the next

synaptic terminals

Ends of axons that form one side of the synaptic cleft; the location where neurotransmitters are stored.


chemical messengers that traverse the synaptic gaps between neurons


the junction between two neurons (axon-to-dendrite) or between a neuron and a muscle

postsynaptic cell

Cell recieveing the neurotransmitter, so that sodium ions can go in and Action potenital may occur

presynaptic cell

the transmitting cell at a synapse

reflex arc

the neural path of a reflex


an automatic instinctive unlearned reaction to a stimulus

sensory neuron

a neuron conducting impulses inwards to the brain or spinal cord

motor neuron

a neuron conducting impulses outwards from the brain or spinal cord

effector cell

A muscle cell or gland cell that performs the body's responses to stimuli; responds to signals from the brain or other processing center of the nervous system.


clusters of cell bodies in the PNS


clusters of cell bodies in the CNS


sustentacular tissue that surrounds and supports neurons in the central nervous system


largest, most numerous glial cells; maintain blood-brain barrier to isolate CNS from general circulation; provide structural support for CNS; regulate ion and nutrient concentrations; perform repairs to stabilize tissue and prevent further injury

blood brain barrier

Blood vessels (capillaries) that selectively let certain substances enter the brain tissue and keep other substances out


type of neuroglial cell that produces myelin in the CNS

Schwann cells

Supporting cells of the peripheral nervous system responsible for the formation of myelin.

membrane potential

The charge difference between a cell's cytoplasm and the extracellular fluid, due to the differential distribution of ions. Membrane potential affects the activity of excitable cells and the transmembrane movement of all charged substances.

resting potential

electrical charge across the cell membrane of a resting neuron

excitable cells

have the ability to generate changes in their membrane potentials.

chemically gated ion channels

Ion channels that are opened or closed by a neurotransmitter

voltage gated ion channels

A specialized ion channel that opens or closes in response to changes in membrane potential

action potential

the local voltage change across the cell wall as a nerve impulse is transmitted


sodium rushes into neuron through membrane, potassium ruses out; results in a change in charge cell becomes less negative


The movement of the membrane potential of a cell away from rest potential in a more negative direction.

graded potential

a shift in the electrical charge in a tiny area of a neuron

threshold potential

the electrical charge or potential difference at which an action potential will occur

refractory period

(neurology) the time after a neuron fires or a muscle fiber contracts during which a stimulus will not evoke a response

saltatory conduction

Rapid transmission of a nerve impulse along an axon, resulting from the action potential jumping from one node of Ranvier to another, skipping the myelin-sheathed regions of membrane.

synaptic cleft

space between two connecting neurons where neurotransmitters are released

synaptic vesicles

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


transmits nerve impulses across a synapse


Excitatory postsynaptic potential; a slight depolarization of a postsynaptic cell, bringing the membrane potential of that cell closer to the threshold for an action potential.


Inhibitory postsynaptic potential; a slight hyperpolarization of the postysynaptic cell, moving the membrane potential of that cell further from threshold.


(physiology) the process whereby multiple stimuli can produce a response (in a muscle or nerve or other part) that one stimulus alone does not produce


a neurotransmitter that enables learning and memory and also triggers muscle contraction

biogenic amines

Neurotransmitter derived from amino acids, and include catecholamines (dopamine, epinephrine & norepinephrine) & indolamines (histamine & serotonin)ä


adrenaline; activates a sympathetic nervous system by making the heart beat faster, stopping digestion, enlarging pupils, sending sugar into the bloodstream, preparing a blood clot faster


neurotransmitter that is involved in arousal and the fight-or-flight system (also mood, sleep, and learning)


a monoamine neurotransmitter found in the brain and essential for the normal functioning of the central nervous system


a neurotransmitter involved in e.g. sleep and depression and memory


An amino acid; an important inhibitory neurotransmitter in the lower brain stem and spinal cord.


a major excitatory neurotransmitter; involved in memory


an amino acid transmitter that is excitatory at many synapses


gamma-aminobutyric acid, major inhibitory neurotransmitter of the CNS


relatively short chains of amino acids, serve as neurotransmitters.

Substance P

A neurotransmitter that is involved in the transmission of pain messages to the brain.


natural, opiate like neurotransmitters linked to pain control and to pleasure

nerve net

loosely organized network of nerve cells that together allow cnidarians to detect stimuli


concentration of sense organs and nerve cells at the front of an animal's body

nerve cords

a bundle of long extensions of nerve cell bodies, lead away from the brain


the two lower chambers of the heart, and they pump blood out to the lungs and body., series of interconnected cavities within the cerebral hemispheres and brainstem filled with cerebrospinal fluid

central canal

The narrow cavity in the center of the spinal cord that is continuous with the fluid-filled ventricles of the brain.


cerebrospinal fluid, surrounds the brain and spinal cord

white matter

whitish nervous tissue of the CNS consisting of neurons and their myelin sheaths

gray matter

Brain and spinal cord tissue that appears gray with the naked eye; consists mainly of neuronal cell bodies (nuclei) and lacks myelinated axons.

cranial nerves

12 pairs of nerves arising from the brain

spinal nerves

31 pairs of nerves arising from the spinal cord

sensory division

of the PNS of made up of sensory, or afferent, neurons that convey information to the CNS from sensory receptors that monitor the external and internal environment.

motor division

Transmits impulses from the CNS to effector organs

autonomic nervous system

the part of the nervous system of vertebrates that controls involuntary actions of the smooth muscles and heart and glands

sympathetic division

The branch of the autonomic nervous system that mobilizes the body's resources for emergencies.

parasympathetic division

The branch of the autonomic nervous system that generally conserves bodily resources.


top of the brain which includes the thalamus, hypothalamus, and cerebral cortex; responsible for emotional regulation, complex thought, memory aspect of personality


the posterior portion of the brain including cerebellum and brainstem


anterior portion of the brain consisting of two hemispheres

cerebral cortex

the layer of unmyelinated neurons (the gray matter) forming the cortex of the cerebrum

medulla oblongata

lower or hindmost part of the brain


the middle division of brain responsible for hearing and sight; location where pain is registered; includes temporal lobe, occipital lobe, and most of the parietal lobe

reticular formation

a nerve network in the brainstem that plays an important role in controlling arousal


electroencephalogram, a graphical record of electrical activity of the brain


the "little brain" attached to the rear of the brainstem; it helps coordinate voluntary movement and balance


contains the hormone-secreting pineal gland; forms the roof of the diencephalons


the brain's sensory switchboard, 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


a neural structure lying below the thalamus; directs eating, drinking, body temperature; helps govern the endocrine system via the pituitary gland, and is linked to emotion

biologic clock

The theory of aging that suggests that our cells are pre-programmed genetically to divide a specific number of times and then cells lose their ability to repair themselves


suprachaiasmatic nucleus, regulates circadian rhythyms
light=cortisol release (alert)
dark=melatonin (sleep)

cerebral hemispheres

the right and left halves of the cerebrum

basal nuclei

important centers for motor coordination, acting as switches for impulses from other motor systems.


the more recently evolved portions of the cortex of the brain that are involved with higher mental functions and composed of areas that integrate incoming information from different sensory organs.

corpus callosum

a broad transverse nerve tract connecting the two cerebral hemispheres

limbic system

a system of functionally related neural structures in the brain that are involved in emotional behavior

short term memory

activated memory that holds a few items briefly, such as the seven digits of a phone number while dialing, before the information is stored or forgotten

long term memory

the relatively permanent and limitless storehouse of the memory system. Includes knowledge, skills, and experiences


Long term depression, a reduction in the efficiency of a neuronal synapse that can last an hour or more. occurs in cerebellum and is input specific. decreased response in glutamate poss due to internalization of its recpetors


Long Term Potentiation, An increase in a synapse's firing potential after brief, rapid stimulation. Believed to be a neural basis for learning and memory.

growth cone

A distinctive structure at the growing end of most axons. It is the site where new material is added to the axon.

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