PSY 511.001 Spr 2026
“Shape of a typical action potential. The membrane potential remains near a baseline level until at some point in time, it abruptly spikes upward and then rapidly falls. Approximate plot of a typical action potential shows its various phases as the action potential passes a point on a cell membrane. The membrane potential starts out at approximately −70 mV at time zero. A stimulus is applied at time = 1 ms, which raises the membrane potential above −55 mV (the threshold potential). After the stimulus is applied, the membrane potential rapidly rises to a peak potential of +40 mV at time = 2 ms. Just as quickly, the potential then drops and overshoots to −90 mV at time = 3 ms, and finally the resting potential of −70 mV is reestablished at time = 5 ms. By Original by en:User:Chris 73, updated by en:User:Diberri, converted to SVG by tiZom - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=2241513”
“Approximate plot of a typical action potential shows its various phases as the action potential passes a point on a cell membrane. The membrane potential starts out at approximately −70 mV at time zero. A stimulus is applied at time = 1 ms, which raises the membrane potential above −55 mV (the threshold potential). After the stimulus is applied, the membrane potential rapidly rises to a peak potential of +40 mV at time = 2 ms. Just as quickly, the potential then drops and overshoots to −90 mV at time = 3 ms, and finally the resting potential of −70 mV is reestablished at time = 5 ms. By Original by en:User:Chris 73, updated by en:User:Diberri, converted to SVG by tiZom - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=2241513”
Rising phase
Falling phase
Approaching V_K.
Membrane not very permeable.
Can’t be opened for a period of time.
“As an action potential (nerve impulse) travels down an axon, there is a change in electric polarity across the membrane of the axon. In response to a signal from another neuron, sodium- (Na+) and potassium- (K+)–gated ion channels open and close as the membrane reaches its threshold potential. Na+ channels open at the beginning of the action potential, and Na+ moves into the axon, causing depolarization. Repolarization occurs when K+ channels open and K+ moves out of the axon, creating a change in electric polarity between the outside of the cell and the inside. The impulse travels down the axon in one direction only, to the axon terminal where it signals other neurons. By Laurentaylorj - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=26311114”
“Synaptical transmission (chemical). A: Neuron (Presynaptic) B: Neuron (Postsynaptic) Mitochondria Synaptic vesicle full of neurotransmitter Autoreceptor Synaptic cleft Neurotransmitter receptor Calcium Channel Fused vesicle releasing neurotransmitter Neurotransmitter re-uptake pump. By vectorization: Mouagip (talk)Synapse_diag1.png: Drawn by fr:Utilisateur:DakeCorrections of original PNG by en:User:NretsThis W3C-unspecified vector image was created with Adobe Illustrator. - Synapse_diag1.png, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=11438067”
“Synaptical transmission (chemical). A: Neuron (Presynaptic) B: Neuron (Postsynaptic) Mitochondria Synaptic vesicle full of neurotransmitter Autoreceptor Synaptic cleft Neurotransmitter receptor Calcium Channel Fused vesicle releasing neurotransmitter Neurotransmitter re-uptake pump. By vectorization: Mouagip (talk)Synapse_diag1.png: Drawn by fr:Utilisateur:DakeCorrections of original PNG by en:User:NretsThis W3C-unspecified vector image was created with Adobe Illustrator. - Synapse_diag1.png, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=11438067”
“Ion-channel-linked receptor Ions Ligand (such as acetylcholine) When ligands bind to the receptor, the ion channel portion of the receptor opens, allowing ions to pass across the cell membrane. By Isaac Webb - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=32932033.”
Guanine nucleotide-binding proteins
“Cartoon depicting the heterotrimeric G-protein activation/deactivation cycle in the context of GPCR signaling. By Repapetilto - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=10714351”
“The summation of these three EPSPs generates an action potential. By Laurentaylorj - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=26311114”
“Graph displaying an EPSP, an IPSP, and the summation of an EPSP and an IPSP. When the two are summed together the potential is still below the action potential threshold. By Gth768r, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=22926898.”
“Figure 8.3. Types of chemical synapses by location. A) Axodendritic synapses contact the dendrites of the postsynaptic neuron. B) Axosomatic synapses contact the cell body. C) Axoaxonic synapses contact the axon. The synaptic contact sites are highlighted in green. ‘Chemical Synapse Types’ by Casey L. Henley (CC-BY-NC-SA). View detailed alternative text.”
