Physiology 2.3 Flashcards
What is a Purkinje cell?
- class of neurons in cerebellum
- inhibitory projection neuron
- soma with dendritic tree and axons reaching out to cerebellum
- inferior olive fibers and parallel fibers all providing information to the cerebellum/Purkinje cell
- learning coordinated motor skills
What is presynaptic inhibition?
- inhibition of a stimulatory neuron before it synapse by:
- inhibiting Ca2+ entry and blocking downstream processes
- preventing neurotransmitter release
- therefore preventing the neuron generating and EPSP post-synaptically.
What are axosomatic synapes?
-synapse between axon of one neuron and soma of a second neuron
What are axodendritic synapses?
-synapse between the axon of one neuron and the dendrites of another
What is the glutamate synapse?
- main excitatory NT in CNS
- 4 subtypes (3 ionotropic, 1 metabotropic)
- use glia cells for uptake
How is the synapse modified by hypocalcemia?
- inhibits phosphorylation of membrane proteins
- long term depression of synapse
How is the synapse modified by hypercalcemia?
- promotes phosphorylation of membrane proteins
- long term potentiation of synapse
- *Ca2+ blocks voltage-gated Na+ channel
How is the synapse modified by hyperkalemia?
-membrane depolarization
How is the synapse modified by hypokalemia?
-membrane hyperpolarization
How is the synapse modified by hypoxia?
- membrane depolarization
- Na+/K+ pump is turned off without O2
- Na+ stays in cell and draws water in
What is a serotonin receptor?
- direct cation-gated channel [ionotropic]
- GPCR coupled effects on K+ channel [metabotropic]
What is the length constant?
- indicates decay over distance
- determines membrane resistance and internal (longitudinal) resistance
What is the time constant?
- indicates decay over time (rise over time)
- determines membrane resistance and membrane capacitance
What is capacitance?
- amount of charge required to create a given voltage difference
- “measure of separating charge to create a voltage difference”
How is capacitance related to Multiple Sclerosis/
- demyelination
- increases membrane capacitance
- decreases membrane resistance
