Human Physiology Final Flashcards - Nervous System

Front 1

3 Functions of Nervous System

Back 1

Sensory, Integrative, Motor

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Neuroglia

Back 2

Specialized tissue cells that support neurons, attach neurons to blood vessels, produce myelin sheath and carry out phagocytosis

Front 3

Schwann cells

Back 3

aka Neurolemmocytes, they myelinated axons in the PNS

Front 4

Neuron

Back 4

aka nerve cells, they consist of a cell body (soma), many dendrites, and usually a single axon

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Dendrites

Back 5

Conduct impulses from receptors/other neurons to soma

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Axon

Back 6

Conducts nerve impulses from the neuron to dendrites or soma of another neuron or to an effector organ (muscle/gland)

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Tracts

Back 7

Process of neurons arranged into bundles in the CNS

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Nerve

Back 8

Process of neurons arranged into bundles in the PNS

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Ganglia

Back 9

Cluster of nerve cell bodies in the PNS

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Nucleus

Back 10

Cluster of nerve cell bodies and dendrites in the CNS

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Axonal transport

Back 11

Natural mechanism of intracellular transport in neurons to reach the outer parts of the nervous system.

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White matter

Back 12

Aggregations of myelinated processes

Front 13

Gray Matter

Back 13

Contains nerve cell bodies, dendrites, and axon terminals or bundles of unmyelinated axons/neuroglia

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4 Types of Gated Channels

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Voltage, Chemically (ligand), Mechanically, Light

Front 15

Resting membrane potential

Back 15

Membrane of a nonconducting neuron is positive outside and negative inside owing to the distribution of different ions across the membrane, and the relative permeabilities of the membrane toward those ions (3 Na+ out, 2 K+ in) *** -70mV

*RMP closest to equilibrium potential of K+ (ion w/ greatest permeability)

Front 16

2 Dominant anions trapped within cells

Back 16

Organic phosphates, amino acids in proteins

Front 17

Refractory period

Back 17

Another stimulus cannot be generated at all (absolute refractory) or can be triggered only by a supra threshold stimulus (relative refractory)

Mechanism: local anesthetics prevent opening of voltage-gated Na+ channels so nerve impulses can't pass obstructed region

Front 18

Nerve impulse

Back 18

Traveling action potential

Front 19

Saltatory conduction

Back 19

A nerve impulse conduction where the impulse jumps from neurofibril node to node

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All-or-none principle

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If a stimulus is strong enough to generate an action potential, the impulse travels at a constant & max strength for the existing conditions (a stronger stimulus will not cause a larger impulse)

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Factors of Propagation Speed

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Diameter of fibers, Myelinated fibers, Temperature of nerve fibers

-Larger diameters conduct faster impulses
-Myelinated fibers conduct faster impulses
-Warm nerve fibers conduct faster impulses

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Synapse

Back 22

Functional junction between one neuron and another, or an effector like a muscle or gland

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Electrical synapse

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Where ionic current spreads directly from one cell to another through gap junctions, they synchronize the activity of a group of neurons or muscle fibers

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Chemical synapse

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A one-way information transfer from a presynaptic neuron to a postsynaptic cell

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Excitatory Neurotransmitters

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They depolarize the postsynaptic neuron's membrane closer to threshold (excitatory postsynaptic potential EPSP)

ex. Acetylcholine (ACh), Glutamate, Aspartate

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Inhibitory neurotransmitters

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They hyper polarize the membrane of the postsynaptic neuron (inhibitory postsynaptic potential IPSP)

ex. Gamma Aminobutyric acid (GABA), Glycine

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Excitatory & Inhibitory Neurotransmitters

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Catecholamines (Epi, Norepi, Dopamine)

Front 28

Spacial Summation

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Allow for the integration of incoming signals on the postsynaptic cell; 2 presynaptic neurons on 1 postsynaptic neuron

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Temporal Summation

Back 29

Allows for the integration of incoming signals on the postsynaptic cell; 1 presynaptic neuron on 1 postsynaptic neuron

Front 30

Removal of Neurotransmitters from Synaptic Cleft

Back 30

Diffusion, Enzymatic degradation, & Uptake into cells

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Differences between Action Potentials & Postsynaptic potentials

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1. Nature of signal
2. Propagation distance
3. Signal strength
4. Signal amplitude
5. Refractory periods

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Resting Period

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-70 mV Membrane potential
K+ channel closed
Na+ channel activation gate closed

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Depolarizing State

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K+ channel closed
Na+ channel opens, influx of Na+
-70 mV --> +30mV

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Repolarizing State

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Na+ inactivation gate closed
K+ gate opens, influx of K+
Na+ inactivation gate closes
Na+ activation gate closes

Front 35

Suprathreshold stimulus

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A stimulus strong enough to depolarize the membrane above threshold level