Exam 1 Flashcards
What is most directly responsible for the falling (repolarizing) phase of the AP?
There permeability of K+ increases greatly while that to Na+ decreases
What would occur if the concentration of ATP were depleted in a typical nerve cell?
Resting membrane potential would become less negative
Acetylcholine is the main neurotransmitter released by:
Preganglionic sympathetic neurons and motor neurons
An action potential in a neuronal membrane differs from a graded potential in that:
an action potential is propagated without decrement whereas a graded potential decrements with distance
A threshold stimulus applied to a excitable membrane is one that is just sufficient to
Trigger an action potential
A presynaptic synapse:
is any synapse between an axon terminal and another axon’s terminal that can be either excitatory or inhibitory
What is true about the initial segment of an axon
Its threshold potential is more negative than that of the cell body and dendrites
What is the major inhibitory neurotransmitters in the CNS
Gamma-aminobutyric acid
Alzheimer’s disease is thought to involve primarily
Loss of cholinergic neurons
T or F? The absolute refractory period of an excitable membrane roughly corresponds to the period when sodium channels are opening and inactivated
True
The diffusion potential due to the concentration gradient for Na+ across a nerve cell membrane
favor its movement into the cell at the resting membrane potential
Ependymal Cells
CNS
Producing CSF
Microglia
CNS
Remove debris
Oligodendrocytes
CNS
Myelinate CNS axons
Astrocytes
CNS
Maintain BBB
Schwann cells
PNS
Surrond axons in PNS;
Myelinate
Satellite Cells
Surrond neuron cell bodies in ganglia
Absolute refractory period
No stimulus of any strength can produce action potential due to inactivation of Na+ channels
Relative Refractory Period
Strong stimulus can produce another action potential but with a smaller amplitude
Depolarizing
becomes more positive
Repolarizing
becomes more negative (back to resting potential)
Hyperpolarizing
Refractory period where no new AP can be generated
EPSP
Transient postsynaptic membrane depolarization by presynaptic release of neurotransmitter
*ACh and glutamate-gated channels
IPSP
Transient hyper polarization of postsynaptic membrane potential caused by presynaptic release of neurotransmitter
*glycine and GABA-gated channels
Olfactory pathways
Nose directly to the cortex
Equilibrium Pathways
project to the cerebellum with a branch to the cortex via the thalamus
All other pathways
pass through the thalamus before they project to their relevant cortical area
Isometric
Constant Muscle Length
Isotonic
Constant tension after transitional period
