Week 3

Neuron

nerve cell; the basic unit of the nervous system, each composed of receptive extensions called dendrites, an integrating cell body, a conducting axon, and a transmitting axon terminal

Glial cells

nonneuronal brain cells that provide structural, nutritional, and other types of support to the brain

Synapse

cellular location at which information is transmitted from a neuron to another cell

Cajal

established the neuron doctrine

Neuron Doctrine

. 1. Neurons and other cells of the brain are structurally, metabolically, and functionally independent 2. Information is transmitted from neuron to neuron across tiny gaps

Genes

encoded in DNA inside a cell nucleus

Mitochondria

produces energy to power cellular operations

Ribosomes

translate genetic instructions into specialized proteins essential for the structure and functioning of the neuron

Input zone

the part of a neuron that receives information from other neurons or from specialized sensory structures

Dendritic spines

small projections from the surface of the dendrite that add additional space for synapses

Dendrite

an extension of the cell body that receives information from other neurons

Integration zone

the part of a neuron that initiates neural electrical activity

Cell body

soma; the region of a neuron that is defined by the presence of the cell nucleus

Conduction zone

the part of a neuron (typically the axon) over which the action potential is actively propagated

Axon

nerve fiber; a single extension from the nerve cell that carries action potentials from the cell body toward the axon terminals

Axon collateral

a branch of an axon

Output zone

the part of a neuron at which the cell sends information to another cell

Axon terminal

synaptic bouton; the end of an axon or axon collateral which forms a synapse onto a neuron or other target cell and thus serves as the output zone

Motor neuron

transmits neural messages to muscles or glands; large with long axons

Sensory neuron

nerve cell that is directly affected by changes in the environment such as light, odor, or touch

Interneuron

nerve cell that is neither a sensory neuron nor a motor neuron; interneurons receive input from and send output to other neurons; analyze information gathered from one set of neurons and communicate with others

Larger neurons

tend to have more complex inputs and outputs, cover greater distances, or convey information more rapidly

Multipolar neuron

a nerve cell that has many dendrites and a single axon

Bipolar neuron

nerve cell that has a single dendrite at one end and a single axon at the other; common in sensory systems

Unipolar neurons

monopolar neuron; nerve cell with a single branch that leaves the cell body and then extends in two directions; one end is the input zone, and the other end is the output zone; transmit touch information from the body to the spinal cord

Presynaptic

referring to the transmitting side of a synapse

Postsynaptic

referring to the region of the synapse that receives and responds to neurotransmitter

Synaptic cleft

the space between the presynaptic and postsynaptic neurons at a synapse

Synaptic vesicle

a small, spherical structure that contains molecules of neurotransmitter; 20-40 nm

Neurotransmitter

chemical released from the presynaptic axon terminal that serves as the basis of communication between neurons; generally do not enter the postsynaptic neuron

Neurotransmitter receptor

specialized protein that selectively senses and reacts to molecules of a corresponding neurotransmitter or hormone

Neuroplasticity

ability of the nervous system to change in response to experience or the environment

Axon hillock

cone-shaped area on the cell body from which the axon originates

Innervate

provide neural input to

Arbors

dendritic trees

Electrical activity

in axon causes synaptic vesicles to fuse to the presynaptic membrane and then rupture, releasing their payload of neurotransmitter molecules into the synaptic cleft

Axonal transport

the transportation of materials from the neuronal cell body toward the axon terminals and from the axon terminals back toward the cell body

Axon

hollow tube that conveys enzymes and structural proteins through the interior of the axon from the cell body where they are produced to the axon terminals where they are used

Anterograde transport

moves used materials back to the cell body for recycling

Retrograde transport

moves used materials back to the cell body for recycling

Axon functions

rapid transmission of electrical signals along the outer membrane and slower transportation of substances within the axon to and from the axonal terminals

Glial cells

affect neuronal processes by providing neurons with raw materials, chemical signals, and specialized structural components

Oligodendrocyte

a type of glial cell that forms myelin in the central nervous system

Schwann cell

a type of glial cell that forms myelin in the peripheral nervous system

Myelin

the fatty insulation around an axon, formed by glial cells; boosts the speed at which nerve impulses are conducted

Node of Ranvier

a gap between successive segments of the myelin sheath where the axon membrane is exposed

Astrocyte

star shaped glial cell with numerous processes that run in all directions; control local blood flow to increase the amount of blood reaching more active brain regions and form touch outer membranes that swaddle the brain; excrete chemical signals that affect synaptic transmission and the formation of synapses

Microglial cells

Extremely small motile glial cells that remove cellular debris from injured or dead cells

Gross neuroanatomy

anatomical features of the nervous system that are apparent to the naked eye

Central nervous system

the portion of the nervous system that includes the brain and the spinal cord

Peripheral nervous system

The portion of the nervous system that includes all the nerves and neurons outside the brain and spinal cord

Nerve

a collection of axons bundled together outside the central nervous system

Motor nerve

a nerve that transmits information from the central nervous system to the muscles and gland

Reductionism

the scientific strategy of breaking a system down into increasingly smaller parts in order to understand it

Level of analysis

the scope of an experimental approach, a scientist may try to understand behaviour by monitoring molecules, nerve cells, brain regions, or social environments or using some combination of these levels of analysis

Molecular, synaptic, cellular, circuit, brain region, neural systems, organ, social

levels of analysis

Neurophysiology

the study of the life processes of neurons

Action potential

rapid electrical signal along the axons

Ion

an atom or molecule that has acquired an electrical charge by gaining or losing one or more electrons

Anion

a negatively charged ion, such as a protein or a chloride ion

Cation

a positively charged ion, such as a potassium or sodium ion

Intracellular fluid

also called cytoplasm, the watery solution found within cells

Extracellular fluid

interstitial fluid; the fluid in the spaces between cells

Cell membrane

the lipid bilayer that encloses a cell

Microelectrode

an especially small electrode used to record electrical potentials inside living cells

Polarized

neurons are more negative inside than outside

Resting potential

the difference in electrical potential across the membrane of a nerve cell at rest; -50 to -80 mV

Millivolt

a thousandth of a volt

Ion channel

a pore in the cell membrane that permits the passage of certain ions through the membrane when the channel is open

Cell membrane

double layer of fatty molecules with specialized proteins

Selective permeability

the property of a membrane that allows some substances to pass through but not others

Diffusion

the spontaneous spread of molecules from an area of high concentration too an area of low concentration

Electrostatic pressure

the propensity of charged molecules or ions to move toward areas with the opposite charge

Sodium-potassium pump

the energetically expensive mechanism that pushes 3 sodium ions out of a cell and 2 potassium ions in

Diffusion and electrostatic pressure

balance sets resting membrane potential

Equilibrium potential

the point at which the movement of ions across the cell membrane is balances, as the electrostatic pressure pulling ions in one direction is offset by the diffusion force pushing them in the opposite direction

Hyperpolarization

An increase in membrane potential (interior of the neuron becomes even more negative)

Depolarization

A decrease in membrane potential (the interior of the neuron becomes less negative)