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BIO 210 A&P I Chapter 10
Nervous tissue
49
Anatomy
Undergraduate 1
02/21/2011

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Term
Functions of Nervous tissues
Definition
-Sensory input
Term
Central Nervous system
Definition
is composed of the brain and the spinal cord
Term
Peripheral nervous system (PNS)
Definition
Is composed of all other nervous tissue outside the CNS and includes sensory receptors and nerves
Term
Sensory receptors
Definition
Ending of nerve cells or separate, specialized cells that detect temperature, pain, touch, pressure and other stimuli.
Term
Nerves
Definition
bundle of axons and their sheaths
Term
Functional divisions of the nervous system
Definition
Afferent division
Term
Charasteristics of the afferent division
Definition
is the sensory division, transmitts action potential to the CNS from sensory receptors
Term
Efferent division
Definition
is the motor division, transmitts action potential away from the CNS to effector organs
Term
Division of the efferent division
Definition
Somatic Nervous system and automatic nervous system
Term
Somatic nervous system
Definition
transmitts action potential from the CNS skeletal muscle under voluntary control
Term
Sympathetic nervous system
Definition
Active during physical activity, responsible for the "fight or flight" response.
Term
Autonomic nervous system
Definition
Transmits action potentials from the CNS to cardiac muscles, smooth muscles and glands. function under involuntary control it is further divided into the sympathetic, parasympathetic and entric nervous systems
Term
Parasympathetic nervous system
Definition
Regulates resting functions such as digeting food or emptying urinary bladder. " rest & digest"
Term
Enteric Nervous system
Definition
Located in the digestive tract and it controls the digestive tract independently from the CNS
Term
Depolarization
Definition
A decrease in membrane potential
Term
Hyperpolarization
Definition
An increase in membrane potential
Term
what are two methods of propagation?
Definition
-Continuous propagation: Unmyelinated axons
Term
Steps in continuous propagation
Definition
-Affects one segment at the time
Term
Charactristics of Saltatory propagation
Definition
-Acion potential along myelinated axon
Term
factors that affect speed of propagation
Definition
-Ion movement is related to cytoplasm concentration
Term
Characteristics of type A fibers
Definition
-Myelinated
Term
Characteristics of Type B fibers
Definition
-Myelinated
Term
Characteristics of Type C fibers
Definition
-Unmyelinated
Term
Synaptic activity
Definition
Action potentials that are transmitted from presynaptic neuron to postsynaptic cells across a synapse
Term
Electrical synapses
Definition
-Are locke together at  gap junctions
Term
Chemical Synapses
Definition
-Are found in most synapses between neurons and all synapses between neurons and other cells
Term
Exciatory neurotransmitter
Definition
Causes depolarization of postsynaptic membranes, promote action potential
Term
Inhibitory Neurotransmitter
Definition
Causes hyperpolarization of postsynaptic membranes, supress action potentials
Term
Neuromodulators
Definition
Substances released from neurons that can presynaptycally or post synaptically influece the likelyhood that an action potential will be produced in the postsynaptic cell.
Term
Inhibition
Definition
A neuron that recieves many IPSPs is inhibited from producing an action potential because the stimulation needed to reach the threshold is incressed
Term
Summation
Definition
To triger an action potential one EPSP is not enough, EPSP and IPSP combine through sumation
Term
Temporal summation
Definition
Multiple times, rapid repeated stimuli at one synapse
Term
Spatial Summation
Definition
Multiple locations, many stimuli arrive at multiple synapses
Term
Axoaxonic Synapses
Definition
Synapses between the axaons of two neurons
Term
Convergent Pathways
Definition
Many neurons converge and synapse with a smaller number of neurons. Allows for diffrent parts of the nevous system to activate or inhibit the activity of neurons
Term
Divergent pathways
Definition
A smaler ammount of presynaptic neurons synapse with a larger number of postsynaptic neurons. Allows for one part of the nervous system to affect more than one other part of the nervous system
Term
Osclliating Circuits
Definition
Have neurons arranged in a circular fashion, simililar to the possitive feedback mechanisim
Term
Initial stimulus threshold of an Action Potential
Definition
A graded depolarization of the axn hillock large enough (10-15mV) to change the resting potential.
Term
Depolarization phase of an action Potential
Definition
Activation phase of voltage-gated Na+ channels. Rapid Depolarization, Na+ ions rush into cytoplasm, inner membrane changes from negative to possitive.
Term
Repolarization phase of an action potential
Definition
Inactivation of Na+ channels, activation of K+ channels. happens at +30Mv. Inactivation gate closes, Voltage gated K+ channels opens, Repolarization begins.
Term
After potential of action potentials
Definition
K+ channels begin to close when membrane reaches normal resting potential (-70mV). After the K+ channels finish closing, membrane is Hyperpolarized to -90mV, then transmember potential retuns to resting level, action potential is over
Term
The refractory period
Definition
Last from the begining of the action potential to the return to the resting state during which a membrane will not respond normally to any additioanal stimuli
Term
Absolute Refractory period
Definition
Sodium channels are open or innactive, no action potential is possible
Term
Realtive Refractory Period
Definition
Membrane potential is almost normal, a very large stimulus can generate an action potential
Term
Subthreshold stimulus
Definition
Produces a graded potential not strong enough to reach the treshold, no action potential is produced
Term
Maximal Stimulus
Definition
Just strong enough to produce the maximum frequency of action potentials
Term
Threshold stimulus
Definition
produces a graded poteintial just strong enough to reach threshold and cause an action potential
Term
Submaximal stimulus
Definition
All stimulus between the threshold and the maximal stimulus straength. action potential frequency increasses in proporation to the strenght of the stimulus
Term
Supramaxiamal Stimulus
Definition
any stimulus stronger than the maximal stimulus, cannot produce a faster action potential frequency beacuse max frequncy has already been met.
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