Lec 2 Nervous System Flashcards
Myelin is produced by what?
- Oligodendrocyte glia in CNS
- Schwann cells in PNS
What role does micro glia play?
- structural support for neurons
- cleans up debris from damaged cells
What is the neuronal membrane?
Bilipid layer containing ion channels
What is the resting membrane potential?
-70mV. Voltage at which the neuron is resting
What does “Neurons are exitable” mean?
State at which a neuron can not depolarize
What is the neuronal membrane more permeable to?
K+ potassium ions because it contributes to the resting membrane potential
What is meant by Electrical gradient?
A force that pushes ions to an area with the opposite charge.
What is electrochemical equilibrium?
Balance between chemical and electrical driving forces: resting membrane potential
Concentration gradient?
Uneven distribution of ions in a cell membrane
What is decremental conduction/ electrotonic conduction?
Passive current conduction, a small electrical current create by ESPS conducted through cytoplasm of dendrites, soma and axon
What is the Hodgkin-Huxley cycle?
When AP threshold is met, Na+ flows in, depolarises cell, open voltage gated Na+ channels, more Na+
What is EPSP?
Excitatory Post-Synaptic Potential
What is the necessary excitation threshold needed for an AP?
-55mV
What causes Ca+ channels to open?
Depolarization of the axon terminal (AP)
What happens at a synapse?
Calcium influx, vesicles bind to axon terminal button, release NT, binds to PSC, (reuptake, diffusion or enzymatic breakdown)
What is exocytosis?
Release of the NT full vesicles into the synaptic cleft
Describe a presynaptic neuron?
Releases NT into synaptic cleft to trigger either EPSP or IPSP
Describe a postsynaptic neuron?
Recieves NT from presynaptic neuron
What is a voltage gated ion channel?
Channel that requires depolarization of the cell to open
What is saltatory conduction?
The mode of conduction in myelinated neurons. AP’s are generated only down the nodes of Ranvier.
