Terms in this set (19)
List the basic functions of the nervous system
1) Sensory Input (Afferent) <<< Stimuli
2) Integration (CNS - Brain and Spinal Cord)
3) Motor (Efferent) <<< Muscles, Organs, ETC
Explain the structural and function divisions of nervous system
CNS (Brain and Spinal Cord)
PNS (Nerves from brain and spinal cord)
-------> Motor (Efferent)
-------->Somatic (SNS) Voluntary
-------->Autonomic (ANS) Involuntray
List the types of Neuroglia and cite their functions
1) Astrocytes (CNS) - Regulate chemical environment around neurons and exchange between capillaries. Helps for blood-brain barrier
2) Microglia (CNS) - Glial cells that monitor health and perform immune defense functions and engulf debris from dead or dying neurons
3) Ependymal Cells (CNS) - Line the central cavities of the brain and spinal cord and help in production and circulation of cerebrospinal fluid
4) Oligodendrocytes (CNS) - Wrap around neuron fibers forming myelin sheaths
5) Satellite Cells (PNS) - Surround neuron bodies within ganglia. Protects and regulates nutrient and waste exchange for cell bodies in ganglia
6) Schwann Cells (PNS) - Surround nerve fibers forming myelin sheath
Descrive the 6 distinguishing features common to all neurons
2) Conductivity (Conduct impulses)
3) Secretion (Secretes neurotransmitters)
4) Extreme longevity
5) Amiotic (Doesn't undergo mitosis)
6) High metabolic rate (Lots of glucose and oxygen)
Define Neuron, describe it's important structural components and relate each to a functional role
Neuron: Specialized cells that conduct messages in the form of electrical impulses throughout the body
> Dendrites: Treelike extensions from the beginning of a neuron that receive information from other neurons and transmit electrical stimulation to the Soma (Cell body)
> Soma (Cell Body): Where signals from dendrites are joined and passed on. Maintain the cell and keep neuron functional
> Axon Hillock: Located at the end of the Soma and controls the firing of the neuron. If total strength of signal exceeds threshold, an action potential will occur.
> Axon: Elongated fiber that extends from cell body to terminal endings and transmit neural signals. Some have fatty substance called myelin which acts as an insulator and makes it faster.
>Axon Terminal: Located at the end of the neuron and are responsible for sending a signal to other neurons and it contains a synapse. Neurotransmitters are used to carry the signal across the synapse to other neurons.
Differentiate between nerve and tract, and between nucleus and a ganglion
Collections of axons
> Tract is in the CNS
> Nerve is in the PNS
Collection of Nerve cell bodies
> Nuclei is in the CNS
> Ganglia is in the PNS
Explain the importance of the myelin sheath and describe how it is formed in the central and peripheral nervous systems.
Myelin is an insulating covering around some axons (repeating concentric layers of plasma membrane from oligodendrocytes (CNS) and Schwann cells (PNS)
Classify neurons structurally and functionally.
> Multipolar neurons have three or more processes (brain & spinal cord)
> Bipolar neurons have a single axon and dendrite (retina, inner ear, olfactory)
> Unipolar (also called pseudounipolar) neurons have a single process extending from the cell body that is associated with receptors at the distal end (sensory in
> PNS; the axon and dendrites of these types of neurons fuse into one long process)
> Sensory, or afferent, neurons conduct impulses toward the CNS from receptors.
> Motor, or efferent, neurons conduct impulses from the CNS to effectors.
> Interneurons, or association neurons, conduct impulses between sensory and
Apply the concepts of voltage, current and resistance with neuron structure and function.
> Voltage is a measure of the amount of difference in electrical charge between two points, called the potential difference
>The flow of electrical charge or movement of charged particles from point to point is called current, and is dependent on voltage and resistance
Distinguish between a pump and a channel, and identify the pumps and channels located along the entire neuron plasma membrane
> Pumps: move substances up (against) a concentration gradient, a process that requires energy; the plasma membrane of neurons contains both sodium-potassium (Na+/K+) pumps and calcium (Ca2+) pumps.
> Channels: move substances down (with) a concentration gradient
a) Leak (passive channels): always open (like 7-11 stores); Na+ & K+ channels
b) Chemically-gated (ligand-gated) channels open when the appropriate chemical binds, such as a neurotransmitter, neuromodulator, or other signal molecules; K+ & Cl- channels
c) Voltage-gated channels open in response to a change in membrane potential.
* Most gated channels have one gate that is in either one of two states: closed or open. Voltage-gated sodium channels are unique in that they have two gates (an activation gate and an inactivation gate) and
exhibit three states:
* Resting state: inactivation gate open, activation gate closed
* Activation state: both gates open
* Inactivation state: activation gate open, the inactivation gate is temporarily closed
d. Mechanically gated channels open when a membrane receptor is physically
deformed; found in sensory neurons and response to things like light or pressure
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
>Located in dendrites and cell bodies
>Short distance traveled
>Various amplitude and decays with distance
>Chemical stimulus (neurotransmitter)
>Located in axon hillock and axon
>Long distance traveled
>Always the same amplitude and no decay
>Stimulus is voltage (depolarization)
Explain how action potentials are generated and propagated along neurons
a. Generation of an action potential involves a transient increase in Na+ permeability, followed by restoration of Na+ impermeability, and then a short-lived increase in K+ permeability.
b. Propagation, or transmission, of an action potential occurs as the local currents of an area undergoing depolarization cause depolarization of the forward adjacent area.
Compare and contrast saltatory and continuous conduction
Unmyelinated axons conduct impulses relatively slowly (continuous conduction), while myelinated axons have a high conduction velocity (saltatory conduction).
Define synapse. Distinguish between electrical and chemical synapses by structure and by the way they transmit information
A synapse is a functional junction that mediates information transfer between neurons or between a neuron and an effector cell such as a muscle cell or secretory cell
a. Electrical synapses have neurons that are electrically coupled via protein channels (gap junctions) and allow direct exchange of ions from cell to cell; found within limited regions of the brain and in the eyes; cardiac cells are also connected by electrical synapses
b. Chemical synapses are specialized for release and reception of chemical neurotransmitters; most synapses within the nervous system are chemical
Explain how neurotransmitters are removed from the synaptic cleft
degradation by enzymes from the postsynaptic cell or within the synaptic cleft; reuptake by astrocytes or the presynaptic cell; or diffusion away from the synapse.
Define absolute and relative refractory periods
Absolute: Britney Spears
Relative: Other one
Define postsynaptic potential and compare and contrast excitatory and inhibitory postsynaptic potentials
Postsynaptic Potential: initiating a graded potential in the postsynaptic neuron
> Excitatory postsynaptic potential (EPSPs): excitatory neurotransmitter opens Na+ channels and depolarizes the membrane
> Inhibitory postsynaptic potential (IPSPs): inhibitory neurotransmitter opens either K+ channels or Cl- channels and hyperpolarizes the membrane
Describe how synaptic events are integrated and modified