Neuro L.1 Main Concepts Flashcards
What do oligodendrocytes do?
Form myelin sheath in CNS
What do Schwann cells do?
Form myelin sheath in PNS
What is the resting membrane potential?
-70 mV
What happens during depolarization?
Na channels open: 55 mV → 30 mV
What is the absolute refractory period?
Completely unresponsive to stimuli because Na channels are not reset
Where does depolarization occur?
At nodes of Ranvier: unmyelinated regions with high density of voltage gated channels
What happens during repolarization?
Na channels close, K channels open: 30 mV → -70 mV
What is hyperpolarization?
K channels remain open: -70 mV → -90 mV
What is the relative refractory period?
May respond to larger stimuli since most Na channels are reset
What does the Na/K pump do?
2 K in, 3 Na out
What is the permeability of the cell membrane?
Cell membrane is more permeable to K
What is the charge of intracellular fluid?
Intracellular fluid is more negative
What is the charge of extracellular fluid?
Extracellular fluid is more positive
What is spatial summation?
Multiple EPSPs/IPSPs arrive from multiple presynaptic neurons - impulses added together
What is temporal summation?
Receive repeated EPSPs/IPSPs from one presynaptic neuron - rapid fire from 1 neuron
What is saltatory conduction?
AP leaps from node to node along myelinated axon → quick propagation
What is continuous conduction?
AP propagates along unmyelinated axon → slower
