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Nervous System
Nervous System Neuron and Neuroglia
66
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12th Grade
12/09/2012

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Term
Nerves
Definition
Bundles of Axons and their sheaths which extend from the Central Nervous System
Term
Ganglia
Definition
Collections of neuron cell bodies which are outside the Central Nervous System
Term
Central Nervous System
Definition
Brain, Spinal Cord
Term
Peripheral Nervous System
Definition
Nerves and Ganglia
Term
Two kinds of nerves
Definition
Spinal: Nerves which originate from spinal cord
Cranial: Nerves which originate from brain
Term
PNS two divisions
Definition
Afferent/motor: neurons which transmit action potentials from the sensory organs (eyes, ears, skin) to the CNS
Efferent/sensory: Neurons which transmit action potentials from the CNS to the effector organs (muscles and glands)
Term
Efferent two divisions
Definition
Somatic: The system that transmits action potentials from the CNS to the skeletal muscles/voluntary
Autonomic: System that transmits action potentials from the CNS to the smooth muscles, cardiac muscles, and glands/involuntary.
Term
Divisions of ANS
Definition
Sympathetic: Preps body for physical activity
Parasympathetic: regulates resting and nutrition related functions like digestion, defection, and urination
Term
2 kinds of cells which make up the nervous system
Definition
Neurons
Neuroglia
Term
Three basic units of a neuron
Definition
Cell body/Soma: houses nucleus, mitochondria, golgi (secrete neurotransmitters)
Axons: sends action potentials away from the cell body. AP begins on the axon hillock.
Dendrites:short, bring messages in to the cell body, signals travel down dendrites towards the cell body.
Term
# pairs of Cranial
Definition
12
Term
# pairs of spinal nerves
Definition
31
Term
Axons are wrapped in ______
Definition
Myelin Sheath: fatty wrapping that speeds transmission of action potential down the axon. Produced by neuroglia.
Term
If neuron is in the PNS, it is called a ______ ______
Definition
Schwann Cell
Term
If a neuron is in the CNS, it is called a ________________
Definition
Oligodenrocyte
Term
Gaps in myelin sheath is called ______________
Definition
nodes of Ranvier
Term
Axons can split into
Definition
collateral axons
Term
collateral axons can branch into
Definition
presynaptic terminals/terminal boutons
Term
Mature neurons can/cannot undergo mitosis
Definition
cannot
Term
_______ ____________ transmit from the sensory organs to the ________ ________ _________ which sends signals through the _______ __________ to the effector organs.
Definition
Afferent neurons
Central nervous system
Efferent neurons
Term
Structural classification of neurons
Definition
Unipolar: one process, cell body hangs off, pseudo dendrite carries signal toward cell body, usually afferent
Bipolar: Two processes, one axon and a single dendrite into many branches, specialized afferent neurons
Multipolar: several dendrites and one axon, motor or association neurons
Term
spinal nerves are afferent/efferent?
Definition
Both!
Term
Association neurons:
Definition
a neuron that conducts action potentials from one neuron to another within the CNS
Term
Neuroglia
Definition
Glue, many more than neurons, cause brain tumor
Term
Five types of neuroglia
Definition
Oligodenrocyte: binds together and insulates CNS neurons
Schwann: Insulates PSN
Microglia: Specialized phagocytic cells
Astrocytes: Form the blood-brain barrier
Ependymal cells: Ciliated move cerebrospinal fluid, non-ciliated secrete cerebrospinal fluid
Term
Excitability
Definition
The ability to create an action potential in response to a stimulus
Term
2 types of excitable cells
Definition
1 muscle
2 neuron
Term
Neurons are/are not excitable cells
Definition
are
Term
Nueroglia are/are not excitable cells
Definition
are not
Term
Action potentials are electral signals caused by _____ and their interactions with other ________.
Definition
ions, ions
Term
The action potential is a disturbance of the __________.
Definition
membrane
Term
Potential difference
Definition
A measure of the charge difference across the cell membrane
Term
Resting potential
Definition
The difference in charge between the outside surface and inside surface of the cell. It is there when the axon is not carrying any signal and we remember that during the resting potential the inside of the neuron is negative.
Term
An action potential at rest is ________zed.
Definition
polarized
Term
a membrane is polarized because there are _________ trapped inside the cell, and they bear a _________ charge.
Definition
proteins, negative
Term
2 kinds of positive ions
Definition
sodium (Na+) and potassium (K+)
Term
Na+ are transported...
Definition
out of the cell through the membrane in active transportbecause there are more Na+ ions outside than inside
Term
K+ are transported...
Definition
into the cell by active trasnport because there are more K+ ions inside the axon than the outside.
Term
2 ion system =
Definition
Sodium-potassium exchange pump
Term
The sodium ion exchange takes _____ Na+ ions for every ______ K+ ions it takes in. Thus it is more ______ outside than inside. K+ ions tend to ________ while Na+ ions cannot ____ _____.
Definition
3, 2, positive, diffuse out, leak, diffuse out
Term
Depolarization
Definition
Sodium gates open, soidum ions rush into the cell according to diffusion. PD: 30 mV
Term
Polarization
Definition
positive charge outside and negative inside and thus the charges are separate
Term
Repolarization
Definition
Sodium gates close and potassium gates open, potassium rushes out of cell according to diffusion. PD: a bit below -85 mV
Term
4 steps
Definition
1 Resting Potential
2. Depolarization
3. Repolarization
D. Resting Potential Re-Established
Term
Resting Potential (description)
Definition
Sodium and potassium gates are closed while sodium ions are concentrated outside the cell and potassium ions are concentrated inside the cell. PD: -85 mV
Term
Resting Potential Re-Established
Definition
Sodium and potassium gates are closed. Sodium-potassium exchange pump brings the system back to its original state. PD: -85 mV.
Term
If a stimulus is strong enough to trigger the action potential...
Definition
it is called a threshold stimulus
Term
If a stimulus does not reach the threshold...
Definition
it is called a subthreshold stimulus
Term
Local potential
Definition
small change in the potential difference which just dies out because the stimulus was subthreshold
Term
Absolute refractory period
Definition
a time when no matter how strong a stimulus is, no action potential can occur.
Term
Relative refractory period
Definition
Neuron is not really ready to create an action potential, but if stimulus is strong enough, it will occur.
Term
Two ways an action potential can be conducted down an axon
Definition
unmyelinated axon and myelinated
Term
Unmyelinated axon
Definition
two schwann cells encompassing several axons
Term
Myelinated axon
Definition
two Schwann cells encompassing one axon
Term
in unmylenated axon, action potential must travel the _____ ______
Definition
entire axon
Term
continuous conduction
Definition
unmyelinated axon
Term
Saltatory conduction
Definition
myelinated axon
Term
sharp pain =
dull pain
Definition
myelinated
unmyelinated
Term
Presynaptic neuron
Definition
carries signals to the synapse wehre the neuron can connect with another cell.
Term
Post-synaptic neuron
Definition
signal jumps the synapse to the post-synaptic neuron. (axon releases neurotransmitters which travel across the synapse to start an action potential on the membrane of the next cell)
Term
Sinal goes from
Definition
the axon hillock to the synapse
Term
In neuromuscular junction with skeletal muscle, action potential is sent _________
Definition
to the muscle membrane so that the muscle will ctonract
Term
In a neuron-to-neuron synapse, the flow of information is
Definition
regulated from one neuron to the next.
Term
Inhibitory synapses
Definition
synapses that stop all or some information from passing thru, Most are inhibitory
Term
Excitatory chemical synapse
Definition
uses a neurotransmitter to carry the signal across the synaptic cleft.
Term
Events of excitatory chemical response
Definition
action potential causes calcium channels to open once it reaches the presynaptic terminal. Once action potential is inside the cell, the calcium acts as a signal which affects the synaptic vesicles that hold neurotransmitters to release and then travel to the synaptic cleft which travels to a receptor. If it binds to a receptor it opens sodium channels which allow Na+ ions to enter the postsynaptic neuron which depolarizes the postsynaptic neuron.
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