synapses Flashcards
what happens at a synapse
- AP depolarises terminal
- Ca2+ chan open
- influx of Ca2+
- vesicles fuse w PSM
- NT released by exocytosis
- NT diffuses across SC
- binds to receptor
- post synaptic response
what do electrical, mechanical or chemical stimuli do to transmembrane ion distribution
changes it
local response
- non propagated
- at dendrites and cell body
propagated disturbance
- AP
- all or nothing
- strength does not diminish
what NT is used in EPSPs
ACh
how many molecules of ACh bind at NMJ
2
NT for IPSPS
GABA, Cl- enters which makes cell more -ve. local hyperpolarisation inside
spatial summation
2 EPSPs on adjacent membranes
temporal summation
2 EPSPS close in time
what are classed as aminoacid NTs
Glycine and GABA
what are classed as classical NTs
ACh and NA
what are classed as peptide NTs
TRH and Substance P
what makes ACh
acetyl CoA and Choline
2 types of excitable cells
muscle and nerve
excitable cells
transmit electrochemical signals along their membranes by moving charged ions across the cell membrane
levels of ions in cells
Na+ 15mM
K+ 150mM
Cl- 9mM
protein 150 mM
levels of ions outside cells
Na+ 150 mM
K+ 5.5 mM
Cl- 125 mM
protein 5mM
where does an AP start
axon hillock
what is orthodromic conduction
AP travelling in one direction
what is the charge like inside the axon
transiently positive
