10. Physiology of nerve cells, synaptic transmission in the central nervous system Flashcards
What does nervous system include?
- Neurons
- Neuroglial cells
- Blood vessels, connective tissue
What is neuron?
Function unit of the nervous system
What is neural circuits?
Interconnected neurons
4 types of neuroglial cells in CNS?
- Astrocytes
- Oligodendrocytes
- Microglia
- Ependymal cells
2 types of neuroglial cells in PNS
- Schwann cells
- Satellite cells
What are primary function of neurons?
- Transmission of information
- Processing of information
In the form of special electrical signals
Describe input and output of neural information
Identify 4 basic regions of neuron
Identify parts of neuron
Function of cell body
- Metabolic control center
- Manufacturing and recycling plant (nucleus, ER, Golgi - protein synthesis)
4 characteristics of action potential
- Graded
- Localized
- Spreads with decrement
- Low amplitude
Function of dendrites
Receive incoming signals from other neurons
Function of axon
transmits outgoing signals to axon terminals
Function of axon terminals
Form synapses, where outgoing signals pass to (the dendrite of) another neuron
3 examples of electrotonic potentials of neurons
- Receptor potential (generator potential)
- Excitatory postsynaptic potential (EPSP)
- Inhibitory postsynaptic potential (IPSP) (graded, localized, spreads with decrement, low aplitude)
4 characteristics of action potential
- All-or-none
- Regenerating
- Spreads without decrement
- High amplitude
(a spreading wave of voltage-gated Na+ channel activation)
Example of receptor potential
Pseudounipolar sensory neuron
What type of receptor is receptor potential?
Mechanoreceptor
What type of receptor is receptor potential?
Mechanoreceptor
How does receptor potential work?
- Mechanosensitive cation channel: closed
- Mechanical stimulus
Sensory receptor: generation of action potential
-> How does it happen?
Electrotonic depolarization
-> spreads with decrement
-> Voltage-gated Na+ channels open (TTX-sensitive, lidocaine)
What are the 3 channels participating in generation of action potential in neuron?
- Mechanosensitive Na+
- Voltage-gated Na+
- Voltage-gated K+
Sensory receptor: generation of action potential
-> Identify
Subthreshold mechanical stimulus
Sensory receptor: generation of action potential
-> Identify
Suprathreshold stimulus
Maintained receptor potential induces repititive AP firing
-> What will happen at this time?
Stimulus to sensory receptor
Maintained receptor potential induces repititive AP firing
-> What will happen at this time?
Suprathreshold receptor potential (electrotonic depolarization) is present
Maintained receptor potential induces repititive AP firing
-> What will happen at this time?
- Repolarization below threshold
- Voltage-gated channels return to the closed state (from the inactivated state)
- Voltage-gated K+ channels close
Maintained receptor potential induces repititive AP firing
-> What will happen at this time?
Resting state
Maintained receptor potential induces repititive AP firing
-> What will happen at this time?
- Voltage-gated K+ channels open
- Voltage-gated Na+ channels inactivate
What does the amplitude of receptor potentiall determine?
Action potential frequency
The amplitude of receptor potential determine AP
-> What does the pink part mean?
Suprathreshold, small stimulus
The amplitude of receptor potential determine AP
-> What does the pink part mean?
Strong stimulus
How is AP frequency affected by the strength of stimulus
The stronger the stimulus
-> The higher the amplitude of receptor potential
-> The higher the AP frequency
What are the 2 main classes of synapses?
Electrical and chemical synapses
What are the mechanisms of eletrical and chemical synapses?
E: Electric conduction
C: Chemical neurotransmitter
What are the directions of transmission?
- Bidirectional
- Unidirectional (from pre- to postsynaptic cell)
Do electrical and chemical synapses have delay?
E: No
C: 1 - 5 msec