[PHYSIO LEC MIDTERMS] TO2

Central Nervous System (CNS)

Division of the nervous system consisting of the brain and spinal cord

Peripheral Nervous System (PNS)

Division of the nervous system consisting of the cranial and spinal nerves

Neuron

Cell type responsible for responding to stimuli, conducting electrochemical impulses, and releasing chemical regulators

Glial Cells

Supporting cells of neurons that are more abundant than neurons and are capable of mitosis

Neuroglia

Another term for glial cells that function as supporting cells of neurons

Neurogenesis

Process by which neural stem cells generate new neurons

Cell Body

Part of the neuron containing the nucleus and serving as a nutritional center

Nucleus

Structure within the cell body containing the neuron's genetic material

Nissl Bodies

Structures containing endoplasmic reticulum in the neuron cell body and dendrites that support protein synthesis

Nuclei

Clusters of neuron cell bodies found in the CNS

Ganglion

Cluster of neuron cell bodies found in the PNS

Dendrites

Extensions of the cell body cytoplasm that receive electrochemical impulses

Axon

Neuron process that conducts impulses away from the cell body

Axon Hillock

Starting point of the axon and site where the action potential starts

Axon Terminal

End region of the axon where it communicates with another cell

Schwann Cells

PNS supporting cells that form myelin sheaths around peripheral axons

Neurolemmocytes

Another name for Schwann cells

Satellite Cells

PNS supporting cells that support neuron cell bodies within PNS ganglia

Ganglionic Gliocytes

Another name for satellite cells

Oligodendrocytes

CNS supporting cells that form myelin sheaths around CNS axons

Microglia

CNS immune defense cells that phagocytose foreign or degenerated material

Astrocytes

CNS supporting cells that regulate the external extracellular environment of CNS neurons

Ependymal Cells

CNS supporting cells that line the brain ventricles and spinal cord central canal and maintain CSF

Myelin Sheath

Lipid-rich insulating layer surrounding an axon that allows rapid signal transmission

Neurilemma

Sheath associated with axons in the PNS formed by Schwann cells/other term for schwann cells

Node of Ranvier

Unmyelinated gap along a myelinated axon

Saltatory Conduction

Process in which the action potential jumps from one node of Ranvier to another, allowing faster transmission

Axon Regeneration

Process of regrowing an injured axon that is more successful in the PNS than in the CNS

Regeneration Tube

Structure formed by Schwann cells at a site of PNS injury that helps guide growing axons

Nogo Receptor

Receptor to which inhibitory proteins produced by oligodendrocytes bind and inhibit axon growth

Glial Scar

Physical barrier formed by astrocytes around CNS injury that limits axon growth

Axonal Transport

Energy-dependent transport of proteins, vesicles, and cytoskeleton materials along the axon

Anterograde Transport

Movement of cargo from the cell body toward the axon terminals

Kinesin

Motor protein that moves cargo during anterograde transport

Retrograde Transport

Movement of cargo from the axon terminal toward the cell body

Dynein

Motor protein that moves cargo during retrograde transport

Lysosome

Structure involved in breaking down damaged organelles and materials transported back to the cell body

Unipolar Neuron

Neuron whose process branches into dendrites and an axon and is found predominantly in invertebrates

Bipolar Neuron

Neuron with two processes consisting of one axon and one dendrite and associated with sensory functions

Pseudounipolar Neuron

Neuron with one short process that splits into two branches and functions primarily in sensory transmission

Multipolar Neuron

Neuron with a single axon and multiple dendrites

Sensory Neuron

Neuron that transmits sensory input from receptors toward the CNS

Somatic Motor Neuron

Neuron that stimulates voluntary effectors such as skeletal muscles

Autonomic Motor Neuron

Neuron that regulates involuntary effectors such as smooth and cardiac muscle

Interneuron

Neuron located within the CNS that integrates and processes signals between sensory and motor neurons

Membrane Potential

Electrical voltage difference between the inside and outside of a cell

Resting Membrane Potential (RMP)

Membrane voltage of a neuron when it is at rest, approximately -70 mV

Na/K Pump

Membrane pump that maintains ion gradients by moving 3 Na+ out of the cell and 2 K+ into the cell

Leakage Channel

Ion channel that is normally open, especially for K+

Gated Channel

Ion channel that opens or closes in response to a stimulus

Voltage-Gated Channel

Channel that responds to changes in membrane voltage

Ligand-Gated Channel

Channel that opens when a specific ligand such as a neurotransmitter binds to its receptor

Ligand

Molecule such as a neurotransmitter that binds to a receptor and produces a cellular response

Action Potential

Rapid and temporary change in electrical voltage across the axon membrane that causes communication and neurotransmitter release

Depolarization

State in which the inside of the cell becomes less negative, commonly due to positive ion entry

Threshold

Membrane voltage that must be reached to trigger an action potential, commonly around -55 mV

Repolarization

Process in which the membrane returns toward its resting negative state

Hyperpolarization

State in which the inside of the cell becomes more negative than the resting potential

Refractory Period

Period when a neuron becomes temporarily unresponsive to stimuli and another action potential cannot readily be triggered

Na+

ion that is concentrated outside the neuron and enters during depolarization

K+

Ion that is concentrated inside the neuron and leaks outward during repolarization

Cl-

Negative ion whose entry into a postsynaptic cell can produce hyperpolarization and an inhibitory response

Synapse

Functional connection between a neuron and a second cell located toward the axon terminal

Presynaptic Neuron

Neuron that sends a signal toward the synapse

Postsynaptic Neuron

Neuron that receives the signal from the presynaptic neuron

Synaptic Transmission

Process of transmitting information across a synapse that is usually one-way

Electrical Synapse

Type of synapse in which ions are the main form of communication and cells are joined by gap junctions

Gap Junction

Water-filled channel connecting cells that allows ions and small molecules to pass directly between them

Connexin

Protein subunits that form gap junctions, with six present in each plasma membrane according to the notes

Chemical Synapse

Type of synapse that communicates through neurotransmitters

Terminal Bouton

Button-like structure at the presynaptic axon terminal involved in neurotransmitter release

Synaptic Cleft

Space between the presynaptic terminal bouton and postsynaptic cell at a chemical synapse

Cellular Adhesion

Molecules present on both presynaptic and postsynaptic cells that contribute to synaptic connection

Synaptotagmin

Protein in the presynaptic bouton that binds calcium and participates in vesicle fusion

Exocytosis

Process by which synaptic vesicles fuse with the membrane and release neurotransmitters

Neurotransmitter

Chemical messenger released by a neuron into a synapse and considered a ligand

Graded Potential

Localized change in membrane potential produced when a neurotransmitter binds to a receptor

Excitatory Postsynaptic Potential (EPSP)

Postsynaptic potential produced by ligand-gated channel opening and inward Na+ diffusion that can trigger an action potential if threshold is reached

Inhibitory Postsynaptic Potential (IPSP)

Postsynaptic potential associated with Cl- entry and hyperpolarization that produces an inhibitory response

EPSP

Abbreviation for excitatory postsynaptic potential

IPSP

Abbreviation for inhibitory postsynaptic potential

Excitatory Response

Response in which depolarization may reach threshold and trigger an action potential

Inhibitory Response

Response in which hyperpolarization makes the neuron less likely to produce an action potential

Voltage Summation

Process in which graded potentials combine and may help a neuron reach threshold

Nicotinic ACh Receptor

Ligand-gated acetylcholine receptor in which ACh binding opens an ion channel and allows Na+ to enter

Acetylcholine (ACh)

Excitatory neurotransmitter used by some CNS neurons and somatic motor neurons

Muscarinic ACh Receptor

G-protein-coupled acetylcholine receptor involved in regulation of cardiac and smooth muscle

G-Protein Coupled Channel

Channel system in which a neurotransmitter binds a receptor and activates G-proteins that influence ion channels

G-Protein Coupled Receptor (GPCR)

Receptor involved in signaling pathways where G-protein subunits dissociate after ligand binding

Alpha Subunit

G-protein subunit that dissociates from the other two subunits after ACh binds to a muscarinic receptor

Beta-Gamma Complex

G-protein components that can open or close an ion channel after activation of a muscarinic receptor

Monoamines

Neurotransmitters including serotonin, dopamine, and norepinephrine that bind G-protein-coupled receptors

Serotonin, dopamine, norepinephrine

Monoamine neurotransmitters listed in the notes as one of the major monoamines

Adenylate Cyclase

Enzyme activated by GPCR signaling that converts ATP into cyclic AMP

cAMP

Cyclic molecule produced from ATP by adenylate cyclase that activates protein kinase

Protein Kinase

Enzyme activated by cAMP that phosphorylates target proteins

Phosphorylation

Process in which protein kinase adds a phosphate group to target proteins

Voltage-Gated Ca2+ Channel

Channel that opens during an action potential and allows Ca2+ to enter the presynaptic terminal

Synaptic Vesicle

Vesicle containing neurotransmitters that fuses with the presynaptic membrane during exocytosis

Reuptake

Process in which the presynaptic cell takes neurotransmitters back up to prevent excess action potentials