Flashcards in 2 - Neuroanatomy and Neurophysiology at the Cellular Level: The Foundation of Function Deck (45):
What is the Neuron Doctrine?
Neurons are the basic signaling unit of the nervous system.
What is the Principle of Dynamic Polarization?
Signals flow in a predictable and consistent direction.
What is the Principle of Connectional Specificity?
no direct cytoplasmic connectivity between neurons and the connections formed between neurons are specific (not random).
A generalized neuron has what 4 areas?
1. Receptive Area
2. Integrative Area
3. Conductive Area
4. Output Area
What is the purpose and structures of the receptive area of a neuron?
(for localized input); dendrites and cell body
What is the purpose and structures of the integrative area of a neuron?
(for triggering a response); axon hillock
What is the purpose and structures of the conductive area of a neuron?
(carrying a signal); axon
What is the purpose and structures of the output area of a neuron?
(secretory); axon terminals
What are the ways in which neurons can be classified? (3)
2. Number of Processes
3. Direction they Project
What are the structures and their function of a central nervous system neuron? (5)
1. Dendrite (receptive area)
2. Soma (also a receptive area)
3. Axon hillock, initial segment (integrative area)
4. Axon (conductive area)
4. Terminals (synapse; secretory area)
What two methods of connectivity can a neuron have?
Convergent or Divergent
Afferent can be synonymous with ___ in the PNS while Efferent can be synonymous with ____.
Afferent can be synonymous with Sensory in the PNS while Efferent can be synonymous with motor.
What are the three types of Glial Cells?
What is the purpose of the Glial Cell Astrocytes?
can be supportive cells as well as reparative cells
What is the purpose of the Glial Cell Oligodendrocyes?
mechanism of mylenation (Schwann cells are the myelinating cell of the peripheral nervous system)
What is the purpose of the Glial Cell Microglia?
macrophage of the CNS
What provide mylenation in the PNS and CNS?
PNS : Schwann Cells
CNS : Oligodendrocyes
What are the connective tissue coverings of a neuron? (4)
Mesoneurium; Endo-, Peri, and Epineurium
What are the 4 types of synapses we are redponsible for?
What is a channel of a neuron?
structures that selectively allow the flux of ions into or out of the neuron
What are the two categories of channels?
Gated ion channels
What is the function of a Non-gated channel?
allow for diffusion of small ions
On each Gated ion channel, each receptor is ___
sensory modality specific
What are the two main types of Gated ion channels?
What are the the two types of ligand gated ion channels?
Define Metabotropic Channels
Metabotropic receptors activate a G-protein that in turn activates a secondary messenger, that in turn will activate something else.
(Metabotropic receptors do not have channels and may or may not result in the opening of ion channels somewhere else on the membrane.)
Define Ionotropic Channels
Ionotropic receptors change shape when they are bound by a ligand. This change in shape creates a channel that allows ions to flow through.
Define Voltage channels
Respond to changes in potential
Define Ligand channels
respond to binding to receptor
Describe Local Potentials - Electronic Potential
The change in membrane polarity is graded and decays away from the site of initiation (synapse in the CNS, receptor in the PNS)
What are the two types of Synaptic potentials?
Excitatory Post Synaptic Potentials (EPSP)
Inhibitory Postsynaptic Potentials (IPSP)
In an Excitatory Post Synaptic Potentials (EPSP), electrical activity or membrane polarity becomes ____ with respect to the resting membrane potential
In an Excitatory Post Synaptic Potentials (EPSP), electrical activity or membrane polarity becomes MORE POSITIVE with respect to the resting membrane potential
In an Inhibitory Postsynaptic Potentials (IPSP), electrical activity or membrane polarity becomes ____ with respect to the resting membrane potential
In an Inhibitory Postsynaptic Potentials (IPSP), electrical activity or membrane polarity becomes MORE NEGATIVE with respect to the resting membrane potential
What is an Action Potential?
change in membrane potential along the axon of a neuron
What does an action potential requires the presence of?
voltage gated channels (only located on the axon of a neuron)
What is the All or None Response in terms of an Action potential?
There is no decay in the amplitude or speed of an action potential once it has been generated.
What is the ultimate end of an action potential?
to generate the release of neuroactive substance at its terminal end.
In a normal functioning system, how does an action potential travel?
it is unidirectional, traveling from the axon hillock to all of the axon terminals of each neuron.
Transmitter release is always a response to ___
an action potential
The amount of transmitter released depends on the ___
frequency of action potentials traveling down the axon. (this can be modified at the terminal end, but not along the axon)
Define Habituation and give an example.
decrement of behavioral response during repetitive application of an innocuous or benign stimulus.
Ex. a person learns to ignore the ticking of a mechanical clock.
How is habituation distinguished from simple fatigue?
responsiveness can be rapidly restores (i.e. dishabituated) by the presentation of a strong or novel stimulus.
Define Sensitization and give an example.
strengthening of a response after an intense or noxious stimulus.
Ex. unexpected explosion or firecracker can make a person "jumpy" and after this intense stimulus any small noise can elicit a heightened response.
*General arousal mechanisms are stimulated.
What is Long-Term Potentiation?
LTP is a sustained increase in synaptic strength elicited by brief, high frequency stimulation of excitatory afferents (hippocampus)