neurotransmitters Flashcards
describe organisaiton of nervous system
CNS = brain and spinal cord
PNS = entire network of nerves outside it
PNS -> somatic and autonomic
Somatic has sensory and motor division
roles of sensory and motor divisions of the somatic ns
sensory: sends info from receptors to CNS
motor: sends info from CNS to effectors
describe neuron structure
- Dendrites
- Soma (and nucleus)
- Axon – myelin sheath (neural transmission rate/prevents interference), Schwann cells (produce myelin) and nodes of Ranvier
- Axon terminals
3 types of neurons?
sensory, motor, inter
what is resting potential?
: charge difference (between inside and outside of neuron) of an unstimulated neuron.
how is resting potential maintained?
by Na+/K+ pumps; for 1 ATP, 3 Na+ go out and 2 K+ come in - net negative charge inside neuron (ie. polarised)`
what happens when nt’s bind to receptors
if this stimulation reach neuron’s threshold, Na+ channels open and allow them to come in (causing net positive charge inside the neuron ie. depolarisation). Then K+ channels will open, and they’ll leave the cell
This moves down the axon, forming an action potential: moving region of depolarisation. It’s electricallll
CHECK
structure of synapse?
• Contains axon terminals of presynaptic neuron, synaptic gap and dendrites of postsynaptic neuron.
what makes the synaptic vesicles exocytosise?
• When the action potential reaches the axon terminal, Ca2+ channels in pm will open, Ca2+ ions will enter the cell, enabling secretory vesicles to undergo exocytosis and release neurotransmitters.
what happens after exocytosis of neurotransmitters
they diffuse across the synaptic cleft, bind to receptors on surface of postsynaptic neuron, potentially stimulating it and forming new action potential
what happens to unused nt’s
• Enzymes on postsynaptic neuron digest the neurotransmitters, or they undergo reuptake in presynaptic neuron.
define: nt
• Substances secreted by presynaptic neuron’s axon terminals, diffuse across the synaptic cleft and bind to receptors on the dendrites of the postsynaptic neuron
nt’s can be
excitatory ir inhibitory
what do excitatory and inhibitory even mean
makes postsynaptic neuron more/less likely to be stimulated
the strength at which nt’s stimulate postsynatpic neurons
can vary
