lecture 7 Flashcards
excitatory post synaptic potential (EPSP)
brief depolarization of a neuron from stimulation
- more likely to produce AP
- influx of Na
inhibitory postsynaptic potential (IPSP)
brief hyperpolarization of neuron membrane from stimulation
- less likely to produce AP
- influx of Cl or efflux of K
how do neurons integrate information
temporal and spatial summation
- if summed inputs exceed threshold it will produce an AP
spatial summation
if a few Na go in far apart nothing happens but if many go in together there will be a larger impact
temporal summation
if 2 Na go in at seperate times they are pumped out but if they all go in at the same time it will have a larger influence
axon hillock
junction of cell body and axon
- EPSPs and IPSPs are integrated
- not where AP starts
initial segement
where AP are initiated
- has many voltage gated ion channels
how is an AP triggered
summed potentials on dendritic tree and cell body hit threshold at the initial segment
- potentials closer to axon hillock have stronger influence
why cant a neuron initiate an AP at its dendrites
because cell body membranes dont have voltage-gated channels
back propagation
reverse movement of an AP from axon to dendritic field
- signals dendritic field that neuron fired an AP (may signal to change properties)
how do sensory stimuli produce APs
varied receptors (all containing ion channels to produce nerve impulses) transudce sensory stimulus into NS activity
hair cells
hair displacement opens stretch sensitive channels that allow ions to flux and depolarize
how do nerve impulses produce movement
spinal motor neurons send nerve impulses to synapse on muscle cells through end plates
- Ach is released here
ACH in movement
attaches to ligand gated channels, allowing them to open and flux Na and K across membrane to depolarize to threshold
muscles generate AP and contract
- very large channels allow Na and K at the same time
myasthenia gravis
disorder where body produces antibodies to attack Ach receptors at neuromuscular junctions- end plates
- produces motor weaknesses
