Fundamentals of the nervous system and nervous tissues
Terms in this set (22)
List the functions of the nervous system.
Sensory, Integration, Motor
Explain the structural and functional divisions of the nervous system.
CNS - Brain and spinal cord (12 cranial nerves)(31 spinal nerves)
PNS - Outer regions of body
Somatic Afferents - from skin, skeletal muscles and joints
Visceral afferents - from guts
Somatic motor - voluntary nervous system
Autonomic nervous system - involuntary
Sympathetic - fight or flight
Parasympathetic - Rest and digest (SalivationLacrimationUrinationDefecation) SLUD
List the types of neuroglia and cite their functions
Astrocytes - regulate the chemical environment (K+ and NT) helps to form the BBB
Microglia - CNS cells that monitor health and preform immune functions
Ependymal Cells - CNS glial cells of CNS produce and circulate cerebrospinal fluid (CSF)
Oliodendrocytes - CNS glial cells that wrap around neurons forming myelin sheaths (MS is loss of this)
Satellite cells - PNS located, function unknown
Schwann Cells - PNS Forms myelin sheath in
Describe five distinguishing features common to all neurons.
Excitability, Conductivity, Secretion (NT), Extreme Longevity, Amitotic, High Metabolic Rate
Define neuron, describe its important structural components, and relate each to a functional role.
Perikaryon/Soma - body, the center of biosynthesis
Differentiate between a nerve and a tract, and between a nucleus and a ganglion
Tract- CNS, collection of axons
Nerves - PNS, collection of axons
Nuclei - CNS collection of nerve bodies
Ganglia - PNS collections of nerve bodies
Explain the importance of the myelin sheath and describe how it is formed in the central and peripheral nervous systems.
Myelin Sheath -whitish fatty segmented covering that protecs insulates and increases velocity of axons. Made of oliogodendric cells in the CNS and schwann cells in the PNS
Classify neurons structurally and functionally.
Multipolar - 3 or more processes, brain & spinal cord
Bipolar - signal axon and single dendrite, retina, inner ear and olfactory
Unipolar - Pseudounipolar, extends from cell body associated with receptors at the distal end of PNS
Apply the concepts of voltage, current and resistance with neuron structure and function.
Voltage - difference in electrical charge between two points called potential difference.
Current - Flow of electrical charge or movement of charged particles from point to point.
Resistance - can be altered by opening and closing ion channels, also diameter and insulation.
Distinguish between a pump and a channel, and ID the pumps and channels located along the entire neuron plasma membrane.
Pump - moves substances against the concentration gradient, Active transport. Na+/K+ pumps and Ca++ pumps
Channel - Moves substances with the concentration gradient. Passive transport.
Leaky Channels - Na+ and K+. Always open [found mainly on the soma and dendrites]
Ligand-gated channels - channels that open when bound to a particular NT. K+ and Cl- channels [found in the receptive region]
Voltage gated channels - channels that open in response to change in membrane potential. Voltage gated Na+ are unique, double gated (Resting, Activation and Inactivation stages) [found mostly on initial segement/axon hillock, conductive segment/axon (Na+/K+) and Transmissive segement(Ca++)]
Mechanically gated - receptor is physically deformed to open. Found in response to light/pressure. (found when rubbing your eyes)
define resting membrane potential, state its typical value for neurons and describe its electrochemical basis (i.e. Describe how it is established and maintained in neurons)
RMP - Degree of the difference of eletrical charge between points. Typical value for neuron is -70mV
RMP Established via - permeability to ions. Mainly Na+ and K+ leaky channels and maintained by the Na+/K+Pumps. -- K+: most important factor, if ONLY K+ leaky channels RMP= -90mV. -- Na+: movement of sodium changes RMP to -70mV. moves into the cell due to chemical and electrical gradient. -- Negatively charged proteins (A-): adds to the electrical gradient.
Maintaining RMP - Na+/K+Pumps: help maintain 3 Na+out, 2 K+ in. [2/3 total energy expenditure of the Neuron]
Compare and contrast graded potentials and action potentials.
Topic: Graded | Action
Location: Dendrites/soma | Hillock/axon
Distance: Short | Long
Amplitude: Various/graded | Always the same
Potential: Decays | No Decay
Stimulus: Chemical (NT) | Voltage (Depolarization)
Summation: Temporal/Spatial | No (all or none)
Voltage change: +/- | +>-
Degree of change: Small | Large
Duration: ~1 ms | many ms
Explain how action potentials are generated and propagated along neurons.
Compare and contrast saltatory and continuous conduction
Saltatory - to leap, High conduction velocity, found in myelinated axons
Continuous - Conduct impulses relatively slowly, Unmyelinated
Define synapse. Distinguish between electrical and chemical synapses by structure and by the way they transmit information.
Functional junction that mediates information transfer between neurons or between neurons and effector cells.
Electrical Synapse - Neurons that are electrically coupled via protein channels (gap junctions) and allow for the direct transfer of ions. Only in brains, eyes, and cardiac.
Chemical Synapses - Specialized for release and reception of chemical neurotransmitters. Make up the bulk of synapses.
Explain how neurotransmitters are removed from the synaptic cleft.
Degradation - removed via Enzymes
Reuptake - taken up by astrocytes or presynaptic cell
Diffusion - When it diffuses away from the synaptic cleft
Define absolute and relative refractory periods.
Absolute Refractory Period - Incapable of generating another action potential
Relative Refractory Period - Requires greater than normal amount of stimulation to generate another action potential
Define postsynaptic potential and compare and contrast excitatory and inhibitory postsynaptic potentials.
Postsynaptic Potential - Neurotransmitters that mediate graded potential on the postsynaptic cell
EPSP - Excitatory Postsynaptic Potential, Excitatory neurotransmitter opens Na+ channels and depolarizes the membrane
IPSP - Inhibitory Postsynaptic Potential, Inhibitory neurotransmitters opens either K+ or Cl- channels and hyperpolarizes the membrane
Describe how synaptic events are integrated and modified.
Integration - summation, Temporal & Spatial
Synaptic potentiation - when presynaptic cell is stimulated repeatedly/continously, enhancing the release of the neurotransmitter (like working out a muscle)
Presynaptic inhibition - when another neuron inhibit the release of excitatory NT from presynaptic cell
Neuromodulation - when a neurotransmitter acts via slow changes in target cell metabolism, or when chemicals other than NTs modify neuronal activity. EX: NO & adenosine
Describe several classes of neurotransmitters and give examples of each.
Describe common patterns of neuronal organization and processing.
Distinguish between serial and parallel processing.