NERVE PHYSIO - Local Current Flow Flashcards
Local current flow is the..
Net movt of positive charge
Wave of depolarization across the membrane
Local current flow
Each action potential triggers a new one at the adjacent area of the membrane by
Local current flow
Flow of positive charges
Active area or active point
No stimulus applied
Inactive point
Current of positive charge moves from INACTIVE point to ACTIVE point
Extracellular fluid
EIA
Current of positive charge will move from
ACTIVATED -> INACTIVE POINT
Intracellular
IAI
Characteristic of nerve impulse
Self propagating
Decrement less
Bidirectional
Velocity of the impulse
Always have to reach its final destination
Self propagating
Magnitude of a potential will not change as it moves across the membrane
Decrement less
Velocity of impulse will vary depending on the
Diameter of the fiber
Whether the nerve fiber is myelinated or unmyelinated
Difference of active area or inactive area
Active point is the Flow of positive charges
while inactive point, there is no stimulus applied.
Ecf vs icf
Ecf- current of + charge moves from inactive to active
Icf-current of + charge moves from active to inactive
Characteristics of nerve impulse
Self propagating Decrementless Bidirectional Velocity of impulse All or none principle Exhibits refractory period
What is self propagating?
Always have to reach its final destination
Decrementless?
Magnitude of a potential will not change as it moves across the membrane
Why is conduction in myelinated fiber faster than unmyelinated?
In myelin sheath, there is an uninsulated area which is the node of ranvier. It causes saltatory conduction wc is jumping from one node of ranvier to another
What is an impulse
It is an electric current aka action potential
Diff types of nerve fibers
A fiber
B fiber
C fiber
A fiber
Large myelinated
Conduct impulse at greatest speed
B fiber
Smaller myelinated
Slower conduction
C fiber
Smallest unmyelinated
Slowest conduction
What is multiple sclerosis
It is a degenerative disease in wc there is an impaired nerve fiber
What is all or none principle
Response of a single nerve fiber is always maximized for the existing conditions at that time
It will either respond or not respond at all
There is accurate transmission of impulse
What is refractory period?
Aka as rest period
Nerve is unexcitable between the time of depolarization and upper 1/3 of repolarization
2 types of refractory period
Absolute ref period
Relative ref period
Absolute refractory?
After a nerve has conducted an impulse, cannot immediately conduct a 2nd impulse at the 2nd time.
Relative refractory?
2nd stronger stimulus given, reaction will occur
What is a synapse?
A site of interaction between 2 neurons or between a neuron and effector cells
Effector cells?
Muscle cells or glands
2 types of synapse
Chemical synapse
Electrical synapse
What kind of synapse is nmj
Chemical synapse
Electrical synapse is between
Neuron to neuron
Chemical synapse is between
Muscle to nerve
No anatomical continuity
Presynaptic neuron
Moves the impulse toward the synapse
Postsynaptic neuron
Moves the impulse away from the synapse
Contain transmitter sybs that either excites or inhibits postsynap neuron
Transmitter vesicles
Provide atp
Mitochondria
Small swelling on an axon branch lying very close to the dendrite of another neuron
Axon bulb
Expanded tip of axon facing sarcolemma
Contain alot of mito and neurotransmitters
Synaptic knob
Cell membrane of muscle tissue
Sarcolemma
Space in bet
Synaptic cleft
Enzyme win synaptic cleft that breaks down acetylcholine into cholic acid and acetyl
Acetylcholinesterase
Impulse transmission across the synapse
Synthesis and storage of ach
Release of transmitter substance via exocytosis
Binding of tranmitter with a receptor forming transmitter receptor complex
End plate potential causing action potential
Dissipation of the transmitter substance
Characteristics of impulse conduction across the synapse
Operates in one direction only
Conduction is slow
Synapse is vulnerable to drug or toxin
Susceptible to fatigue
