Write Below are a list of descriptions that apply to either

Write: Below are a list of descriptions that apply to either post synaptic potentials (PSPs), action potentials (APs, both, or neither. Important terms that you should be able to define are bolded. To answer the question online, copy the list of descriptions into the text box, identify PSP AP Both Neither, and then defend your response. In your defense, describe what the bolded terms mean, in your own words. For example: These involve ion channels -both. To change the membrane potential, channels have to open to increase membrane permeability to small charged atom (like Na+, K+, or Cl-). Descriptions: These are graded These are self-propagating These are unidirectional These do not involve K These are in response to ligand gated ion channels

Solution

Answer:

Descriptions

a) These are graded :

Post synaptic potentials are graded potential ( the difference in electric potential between the interior and the exterior of a biological cell.) of the postsynaptic terminal of a chemical synapse and their function is to initiate or inhibit action potentials.

b) These are self-propagating:

Upto some point action potentials are self-propagating. The action potential is generated due to membrane potential reaching threshold due to a graded potential. Threshold is a membrane potential at which the membrane in the trigger region reaches approximately -55mV, a depolarization of about 15 mV. At this point action potentials become self propagating. This means that one action potential automatically triggers the neghboring membrane areas into producing an action potential. Thus once threshold is reached action potentials always propagate down the axon to the synaptic or secretory regions of the axon.

c) These are unidirectional:

Unlike graded potentials, the propagation of actional potential is unidirectional, travels down the axon. Because the absolute refractory period prevents the initiation of an action potential (AP) in a region of membrane that has just produced an AP. In myelinated axons, APs appear to \"jump\" from node to node, in a process called SALTATORY CONDUCTION, because no depolarization occurs between the nodes.

d) These do not involve K:

Both the action potential and post synaptic potentials involve K⁺ ion.

e) These are in response to ligand gated ion channel :

PSPs are in response to both ligand gated and voltage gated ion channels whereas APs are in response to voltage gated ion channel.