1. Cell to cell communication in the nervous system
The synapse
Electrical synapse
Chemical synapse
Role of calcium
“neurocrines”
Receptors
Post-synaptic responses
Terminating synaptic neurotransmission

2. The synapse
Presynaptic cell
Synaptic cleft
Postsynaptic cell

3. Electrical synapse Rapid Few cns neurons, glia Cardiac muscle
Smooth muscle

4. Chemical synapse
Releases neurotransmitter
Synaptic vesicles
Docking

5. The effect of calcium on
synaptic neurotransmission
Action potential
Voltage gated Ca++ channel
Synaptic vesicle docking
Neurotransmitter exocytosis
Ligand/receptor binding on postsynaptic cell.

6. Substances released by neurons
paracrines
Neurotransmitters (act at synapse) and neuromodulators (act away from synapse)
Neurohormones released into blood
Autocrines, same signaling molecules act on the cell that releases them

7. Examples of neurotransmitters
Acetylcholine- neuromuscular jn and CNS
Amino acids – glycine, glutamate, GABA
amino acid derived amines – epinephrine, norepinephrine, dopamine, serotonin
Peptides – substance P, endorphins
Purines - ATP
Gases – nitric oxide

8. Multiple neurotransmitter receptors
Ionotropic – ligand gated channels
Metabotropic – ligands activate 2nd messengers and/or G proteins that gate the channel

9. Ionotropic
receptor
Metabotropic
receptor

10. Multiple neurotransmitter receptors: subtypes
Cholinergic – nicotonic (neuromuscular jn), ligand gated
Muscarinic, 5 subtypes, G protein and 2nd messenger linked

11. Adrenergic receptors Adrenergic – alpha and beta
Linked to G proteins and 2nd messengers
Alpha and beta are linked to different G proteins and different 2nd messengers

12. Glutaminergic receptors
Important in the CNS
Named for agonists
AMPA receptors – ligand gated
NMDA receptors – bind ligand (glutamate) but channel opens during depolarization

13. Glutamate Receptors
NMDA receptor
AMPA receptor

14. Duration of post-synaptic response
Fast synaptic potential, usually from ionotropic receptors.
A channel is opened
Synaptic potential can be depolarizing or hyperpolarizing
Slow synaptic potential
G proteins and 2nd messengers
Slower and lasts longer

15. Neurotransmitter activity is quickly terminated
Acetylcholine is broken down by acetylcholinesterase

16. Neurotransmitter activity is terminated
Norepinephrine is actively transported back to the pre-synaptic axon
CNS neurotransmitters (amines, peptides, amino acids) move into circulation or transported to pre-synaptic terminal.

17. Nervous system Termination of neurotransmitter activity
Integration of Neural Information Transfer
Read ahead for chapter 10: Sensory systems:
general properties (pgs )
Chemoreception (pgs 295 – 298)
The eye and vision (pgs 309 – 319)

18. Neurotransmitter activity is quickly terminated
Acetylcholine is broken down by acetylcholinesterase

19. Neurotransmitter activity is terminated
Norepinephrine is actively transported back to the pre-synaptic axon
CNS neurotransmitters (amines, peptides, amino acids) move into circulation or transported to pre-synaptic terminal.

21. The relationships between many neurons
Integration
Information flows in the nervous system

24. What happens when there are many synaptic inputs ocurring?

25. Excitatory post-synaptic potential
Synaptic junction
Binding of neurotransmitter leads to depolarization of the post-synaptic cell
EPSP, excitatory post synaptic potential

26. Post-synaptic inhibition
At a synaptic junction
The binding of the neurotransmitter causes hyperpolarization
IPSP – inhibitory post synaptic potential

27. Post-synaptic inhibition
-At a synaptic junction
- The binding of the neurotransmitter causes hyperpolarization
- IPSP – inhibitory post synaptic potential

28. Three synaptic junctions, each release an excitatory neurotransmitter
spatial summation

29. Three synaptic junctions, 2 are stimulatory, 1 is inhibitory.
spatial summation

30. Stimuli are very far apart in time. Stimuli don’t occur often.

31. Temporal Summation Subthreshold stimuli arrive
At the trigger zone within a
Short period of time.

32. Synaptic Modulation at the axon terminal